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Topically applied Melaleuca alternifolia (tea tree) oil causes direct anti-cancer cytotoxicity in subcutaneous tumour bearing mice
Abstract
Melaleuca alternifolia (tea tree) oil (TTO) applied topically in a dilute (10%) dimethyl sulphoxide (DMSO) formulation exerts a rapid anti-cancer effect after a short treatment protocol. Tumour clearance is associated with skin irritation mediated by neutrophils which quickly and completely resolves upon treatment cessation.
To examine the mechanism of action underlying the anti-cancer activity of TTO.
Immune cell changes in subcutaneous tumour bearing mice in response to topically applied TTO treatments were assessed by flow cytometry and immunohistochemistry. Direct cytotoxicity of TTO on tumour cells in vivo was assessed by transmission electron microscopy.
Neutrophils accumulate in the skin following topical 10% TTO/DMSO treatment but are not required for tumour clearance as neutrophil depletion did not abrogate the anti-cancer effect. Topically applied 10% TTO/DMSO, but not neat TTO, induces an accumulation and activation of dendritic cells and an accumulation of T cells. Although topical application of 10% TTO/DMSO appears to activate an immune response, anti-tumour efficacy is mediated by a direct effect on tumour cells in vivo. The direct cytotoxicity of TTO in vivo appears to be associated with TTO penetration.
Future studies should focus on enhancing the direct cytotoxicity of TTO by increasing penetration through skin to achieve a higher in situ terpene concentration. This coupled with boosting a more specific anti-tumour immune response will likely result in long term clearance of tumours.
... [26] Hence, it confirms that TTO might obtain its effect by inhibiting rapidly dividing cells more readily than slower growing non-cancerous cells. [27] It is also noted that drug-sensitive and drug-resistant melanoma cells were mainly interfered with the migration and invasion processes by TTO and its major component, terpinen-4-ol. [8] Other studies which investigated the efficacy of topical TTO on aggressive, subcutaneous, and chemoresistant tumors in fully immune-competent mice. ...
... [8] Other studies which investigated the efficacy of topical TTO on aggressive, subcutaneous, and chemoresistant tumors in fully immune-competent mice. [3,27] The other studies have shown that topical treatment with 10% TTO, which was given once a day for 4 consecutive days, induced a significant, regression of established subcutaneous AE17 tumors and slowed the growth of B16-F10 tumors. A penetration enhancer DMSO was necessary to induce the antitumor effect; no effects were evident when using TTO or solvents other than DMSO (i.e., isopropanol or acetone). ...
... [3] The transmission electron microscopy analysis of AE17 tumor sections from mice treated topically with TTO revealed that following in vivo TTO treatment, tumor cells undergo primary necrosis as originally suggested in vitro studies. [9,27] Conclusion AS far as potential anticancer activity of essential oils is concerned, still there is no much information available. Hence, lot of research needs to be progressed in this regard. ...
... Previous study showed that tea tree oil (TTO) from M. alternifolia reduces melanoma cell viability by triggering apoptosis 11 . Ireland et al.,(2012) showed that topically applied 10% M. alternifolia oil in DMSO decrease cell viability in subcutaneous tumor-bearing mice 12 . ...
... Recent studies have explored the potential anticancer effects of M. alternifolia essential oil. Topically applied, it demonstrates direct cytotoxicity against subcutaneous tumors in mice, suggesting its potential as a topical anticancer treatment 12 . ...
Origanum compactum, Melaleuca alternifolia, and Cinnamomum camphora essential oils are recognized for their therapeutic potential, including their selective cytotoxicity against cancer cell lines. Our research focused on examining the cytotoxic effects of these essential oils on three human carcinoma cell lines: lung carcinoma (H460), cervical adenocarcinoma (HeLa), and colorectal carcinoma (HCT116). The MTT-based cell viability assay was used to assess the cytotoxicity of essential oils. The results demonstrated that all three essential oils exhibited dose-dependent cytotoxic potential, with varying levels of growth inhibition across the cell lines. Notably, the highest sensitivity was observed in H460 cells, and the lowest sensitivity was found in HCT116 cells. Origanum compactum demonstrated the strongest cytotoxicity across all cell lines (GI50 73 - 154 nL/mL), making it the most promising candidate for further investigation, particularly for lung and cervical cancer treatment.
... It has also been incorporated into many topical formulations to treat cutaneous infections, speed wound healing, and as an ingredient in skin products [1][2][3][4][5][6][7][8]. In vivo and in vitro studies report antiproliferative effects in tumors and skin disorders [9][10][11][12][13][14][15][16][17], but the molecular mechanisms underlying this effect remain to be fully elucidated. In 2004, we found that TTO and its main active component terpinen-4-ol were able to impair the growth of human melanoma M14 WT cells. ...
... Actin, microtubule, and vimentin cytoskeletons are retained key players that underpin cancer cellular processes such as cancer cell migration, cell adhesion structures, and metastasis formation [22]. In vivo and in vitro studies report antiproliferative effects of TTO in tumors and skin disorders [9][10][11][12][13][14][15][16][17], but the molecular mechanisms underlying this effect remain to be fully elucidated. The effect of TTO and its main active component terpinen-4-ol on the cytoskeletal apparatus has been poorly explored until now. ...
Tea tree oil is an essential oil distilled from the leaves of Melaleuca alternifolia, a plant native to Australia. It has been used in traditional medicine for its antiseptic and anti-inflammatory properties to treat various skin conditions and infections. It has also been incorporated into many topical formulations to treat cutaneous infections and speed wound healing. In vivo and in vitro studies report antiproliferative effects in skin disorders but the molecular mechanisms underlying this effect remain to be still elucidated. In this study MTT assay, scanning electron microscopy-field emission gun, flow cytometry, cell cycle assays, and laser scanning confocal microscopy were utilized to investigate a novel mechanism underlying the antiproliferative effects of tea tree oil and terpinen-4-ol on transformed skin (melanoma) M14 cells. The analysis of the actin cytoskeleton by laser scanning confocal microscopy evidenced a clear action of both essential oil and its main active component on F-actin, which interfered with bundling of actin microfilaments in stress fibers. As for the microtubular network, both tea tree oil and terpinen-4-ol induced a disorganization of the perinuclear cage with the rupture and collapse of microtubules. Finally, they noticeably changed the intermediate filaments architecture by inducing the formation of large vimentin cables. Results obtained in the present study point to the cytoskeleton as a further target of tea tree oil and terpinen-4-ol and could account for the inhibition of proliferation and invasion of skin transformed M14 cells. In our experimental conditions, vimentin intermediate filaments appear to be the cytoskeletal element more affected by the treatments. Moreover, the role of cross-linker proteins in the mechanism of action of tea tree oil has been discussed.
... Two recent studies investigated the efficacy of topical TTO on aggressive, subcutaneous, chemoresistant tumors in fully immune-competent mice [42,43]. The studies showed that topical treatment with 10% TTO, given once a day for 4 consecutive days, induced a significant, though temporary, regression of established subcutaneous AE17 tumors and slowed the growth of B16-F10 tumors. ...
... A follow-up study investigated the mechanism of action underlying the antitumor activity of topical TTO reporting that topically applied 10% TTO induced a direct cytotoxicity on subcutaneous AE17 tumor cells, which was associated with nontumor specific activation of local immune response (i.e., neutrophils, dendritic, and T cells) [43]. In particular transmission electron microscopy analysis of AE17 tumor sections from mice treated topically with TTO revealed loss of cellular organization with increased intercellular spaces and accumulation of cell debris, nuclear shrinkage, chromatin condensation, mitochondria swelling and loss of cristae and membranes, significant alteration of endoplasmic reticulum, and less defined cellular membranes. ...
Essential oils are complex mixtures of several components endowed with a wide range of biological activities, including antiseptic, anti-inflammatory, spasmolytic, sedative, analgesic, and anesthetic properties. A growing body of scientific reports has recently focused on the potential of essential oils as anticancer treatment in the attempt to overcome the development of multidrug resistance and important side effects associated with the antitumor drugs currently used. In this review we discuss the literature on the effects of essential oils in in vitro and in vivo models of cancer, focusing on the studies performed with the whole phytocomplex rather than single constituents.
... Subsequently, an in vivo study investigated the effect of topically applied TTO on the incidence of skin cancer in similar cell lines. Topically applied TTO was observed to directly exert anti-cancer cytotoxicity in subcutaneous tumor bearing mice (Ireland et al., 2012). ...
Over the past few decades, complementary and alternative treatments have become increasingly popular worldwide. The purported therapeutic characteristics of natural products have come under increased scrutiny both in vitro and in vivo as part of efforts to legitimize their usage. One such product is tea tree oil (TTO), a volatile essential oil primarily obtained from the native Australian plant, Melaleuca alternifolia, which has diverse traditional and industrial applications such as topical preparations for the treatment of skin infections. Its anti-inflammatory-linked immunomodulatory actions have also been reported. This systematic review focuses on the anti-inflammatory effects of TTO and its main components that have shown strong immunomodulatory potential. An extensive literature search was performed electronically for data curation on worldwide accepted scientific databases, such as Web of Science, Google Scholar, PubMed, ScienceDirect, Scopus, and esteemed publishers such as Elsevier, Springer, Frontiers, and Taylor & Francis. Considering that the majority of pharmacological studies were conducted on crude oils only, the extracted data were critically analyzed to gain further insight into the prospects of TTO being used as a neuroprotective agent by drug formulation or dietary supplement. In addition, the active constituents contributing to the activity of TTO have not been well justified, and the core mechanisms need to be unveiled especially for anti-inflammatory and immunomodulatory effects leading to neuroprotection. Therefore, this review attempts to correlate the anti-inflammatory and immunomodulatory activity of TTO with its neuroprotective mechanisms.
... Local administration of Gr -1 mAb, a reduction in neutrophil concentration together with skin irritation was observed; however, cytotoxicity degree of the medication did not diminish. High specificity in mode of action can be another breakpoint of novel cancer therapy methods (Ireland et al., 2012). Unsatisfied amount of the oil (3-5%) was combined with prolonged therapy interval to compensate the shortage of the agent. ...
Melaleuca alternifolia (Maiden & Betche) Cheel oil (Tea Tree Oil, TTO) is an essential oil appropriate for medicinal and cosmetic usage. Tea tree oil is composed of complex formulation with more than 100 components; however, the most pharmaceutically active one is terpinen-4-ol. TTO can be implemented for decolonization of multi-resistant Staphylococcus aureus, anti-tumor therapy and antifungal activity based on different doses and exposure-duration proportionate with the targeted species. Antioxidant activity is related to α-terpinene, α-terpinolene and γ-terpinene. Hypersensitivity may occur as mild dermatitis or being aggravated to hepatitis and central nervous system reactions due to chronic or acute poisoning. Acne treatment prognosis shows significant improvement after TTO application proceeding by Propionibacterium acnes colony destruction. Plus, TTO usage psoriasis is also possible. Further investigations have premised TTO’s insecticidal effects performed by anticholinesterase activity. Destructive ability of the oil on Pityrosporum ovale is also indisputable and including TTO as the active ingredient has been highly beneficial for curing scalp dandruff. Expeditious antiviral activity is also considered as the promising characteristic suggested for this oil. Still, little information is available about feasibility of in vivo utilization.
... Aromatic essential oils are oils that can be applied especially on the skin by massage. In an in vivo study, topically applied TTO essential oil has also been reported to have antitumoral properties (3,19). The other essential oil obtained from Canarium luzonicum is a valuable oil that can be used for human health with its ingredients (20). ...
... In this manuscript, we report properties of pluronics P123/F127 micellar systems and the influences of water structure making salt NaCl and phytochemicals like tea tree essential oil (TTO) and curcumin on them. Both TTO and curcumin are known to exhibit antimicrobial, wound healing and anti-cancer properties [47][48][49][50][51][52][53][54][55][56][57][58][59]. As observed by us recently, TTO induce spherical-to-worm like micelles-to-vesicular structural transitions in aqueous P123 solutions, and the dynamics of these transitions remain slow at the room temperature [45]. ...
Pluronics P123 and F127 mixed micellar system has been studied extensively for drug delivery applications because of its non-toxic nature, good solubilization capacity of lipophilic substances and its effectiveness against multi drug resistance (MDR) cancer cells. The constituent pluronics of this system have large difference in their hydrophilic lipophilic balance (HLB) and consequently are strikingly different in their self-assembly characteristics. In this work, we show how the properties of this system compare vis-à-vis the aqueous systems of its constituent pluronics and how pluronics P123 and F127 behave as drug delivery agents in antimicrobial and wound healing applications. DLS, SANS, ITC and rheological studies show that aggregation characteristics in the mixed micellar system is dictated by P123 up to its mole fraction of as low as 0.30. Thus, like pure aqueous P123 solutions, the mixed micellar systems exhibit spherical-to-worm like micelles-to-vesicular structural transitions in the presence of additives like NaCl and tea tree essential oil (TTO), and the dynamics of such structural transitions remains slow at the room temperature. TTO is chosen as additive as it exhibits anticancer, antimicrobial and wound healing properties and like water structure making salt NaCl, it brings about micellar structural changes in aqueous surfactant systems by increasing the hydrophobicity of the surfactant aggregates. ITC and phytochemical solubilization studies suggest that the mixed micellar system does not exhibit synergism in aggregation and lipophile solubilization characteristics. Our antimicrobial and wound healing studies quite interestingly reveal that hydrophobic pluronic P123 remains more effective than F127 as carrier for antimicrobial agent, whereas pluronic F127 based liquid crystalline hydrogel stands superior as topical drug delivery matrix than its P123 counterpart because of its better wound healing abilities. The observed results give insight into the structural and therapeutic properties of P123/F127 system, which were not understood hitherto.
... TTO is a natural essential oil which is composed of several organic substances such as terpene hydrocarbons, terpene alcohols, and terpene phenols. ere are several reports regarding antimicrobial and anticancer properties of TTO [170,171]. However, like other EOs, the application of TTO remains limited due to its chemical instability in exposure to air and high temperatures [172]. ...
The growth of global food demand combined with the increased appeal to access different foods from every corner of the globe is forcing the food industry to look for alternative technologies to increase the shelf life. Essential oils (EOs) as naturally occurring functional ingredients have shown great prospects in active food packaging. EOs can inhibit the growth of superficial food pathogens, modify nutritious values without affecting the sensory qualities of food, and prolong the shelf life when used in food packaging as an active ingredient. Since 2016, various reports have demonstrated that combinations of electrospun fibers and encapsulated EOs could offer promising results when used as food packaging. Such electrospun platforms have encapsulated either pure EOs or their complexation with other antibacterial agents to prolong the shelf life of food products through sustained release of active ingredients. This paper presents a comprehensive review of the essential oil-loaded electrospun fibers that have been applied as active food packaging material.
... Consequently it can be hypothesized that such natural products can represent additional determinants of the observed biological activity featuring essential oils. For example TTO has been recently shown to efficiently have an in vivo topic anti-cancer effect in subcutaneous tumours [30]. This effect could be partly explained by the presence of 7-isopentenyloxycoumarin 1, boropinic acid 4, and 4 -geranyloxyferulic acid 5, all able to act as powerful anti-cancer agent on several cancer cell lines both in vitro and in vivo [23]. ...
An efficient analytical strategy based on different extraction methods of biologically active naturally occurring oxyprenylated umbelliferone and ferulic acid derivatives 7-isopentenyloxycoumarin, auraptene, umbelliprenin, boropinic acid, and 4'-geranyloxyferulic acid and quantification by UHPLC with spectrophotometric (UV/Vis) detection from Tea tree oil is reported. Absorption of the pure oil on Al2O3(Brockmann activity II) prior washing the resulting solid with MeOH and treatment of this latter with CH2Cl2resulted the best extraction methodology in terms of yields of oxyprenylated secondary metabolites. Among the five O-prenylphenylpropanoids herein under investigation auraptene and umbelliprenin were never detected while 4'-geranyloxyferulic acid was the most abundant compound resulting from all the three extraction methods employed. The UHPLC analytical methodology set up in the present study resulted to be an effective and versatile technique for the simultaneous characterization and quantification of prenyloxyphenylpropanoids in Tea tree oil and applicable to other complex matrices from the plant kingdom.
... Aqueous solutions of this Pluronic exhibit time dependent sphere-to-rod micellar growth below their cloud points because of slow dynamics of micellar restructuring processes in them [4,29,30]. TTO on the other hand, has been subjected to extensive studies in recent times because of its broad spectrum antimicrobial properties and probable cure for diseases ranging from simple wounds [31][32][33][34][35][36][37][38][39][40][41][42][43][44] to critical ones like cancers [45][46][47][48][49][50][51][52][53][54]. It is sparingly soluble in water, so in the aqueous medium its therapeutic efficacies are studied using nonionic surfactants as dispersing agent [50][51][52][53][54][55][56]. ...
Pluronics are used in industry as solubilizing agents for a variety of lipophilic compounds. The influence of different lipophiles on aggregation characteristics of Pluronics quite expectedly remained a subject of fundamental interest for the last few decades. In this manuscript, we show that solubilization of tea tree essential oil (TTO) brings about spherical-to-worm like micelles-to-vesicular structural transitions in aqueous solutions of Pluronic P123. TTO exhibits broad-spectrum antimicrobial properties and have therapeutic potential for wide range of diseases ranging from common wounds to different forms of cancers. Its solubilization in Pluronic solutions was carried out by subjecting the aqueous TTO-Pluronic systems into heat cycling through their phase separation temperature. We suggest that accelerated dynamics of micellar restructuring process in Pluronic P123 solutions at high temperature is responsible for solubilization of TTO upon heat cycling. Such instances of oil solubilization upon heat treatment and subsequent systematic micellar structural transitions are first of its kind in aqueous systems of nonionic surfactants. TTO solubilized Pluronic solutions exhibit antimicrobial property and cytotoxicity to breast (MCF7) and lung (A549) cancer cells, which suggest that therapeutic activity of TTO is not destroyed upon heating induced micellar solubilization.
... In vitro and in vivo studies, including in humans, have demonstrated anti-inflammatory properties of tea tree oil. A study in mice demonstrated the effectiveness of diluted tea tree oil (10%) against skin tumours (Ireland et al. 2012). ...
This chapter presents clinical evidence, pre-clinical evidence, mechanisms of action, interactions, contraindications, information about adverse effects and dosage of Tea Tree (Oil) (Melaleuca alternifolia). Tea tree oil is used topically as an antiseptic and to aid wound healing, and in products to treat acne, head lice and scabies. It is also used in inhalations to treat respiratory diseases (colds, bronchitis, asthma etc.). There is variability in the chemical profile of tea tree oil and six chemotypes (varieties) of M. alternifolia are recognised, each with a distinct chemical composition. Traditionally, Aboriginal peoples of Australia crushed the leaves to inhale the vapour to treat respiratory infections and used them topically to treat insect bites and skin infections. Today M. alternifolia is commercially cultivated, predominantly in northern New South Wales.
... Results attained in an in vitro model demonstrate, however, that a significantly larger inhibitory effect was noted in cell lines treated with myrrh essential oil as compared to treatment with frankincense and a mixture of both oils [32]. Melaleuca oil, carrot oil, rose hip (Rosa canina L.), colchicum oil, flaxseed oil, and caraway oil are also reported to have benefit [33][34][35][36][37] (level of evidence 5,5,5,5,5,5). ...
Purpose of Review
Non-melanoma skin cancer outnumbers all other cancers combined by three to four-fold while melanoma is the fifth most common cancer overall, and the deadliest form of skin cancer. Despite treatment advancements in the past several decades, incidence continues to rise. Phytochemicals and other naturally occurring substances may provide sustainable chemopreventive solutions. The purpose of this study is to review the key findings from the literature and report on the level of evidence based on study design.
Recent Findings
A comprehensive PubMed search was completed from 1984 to present using keywords “skin cancer chemoprevention” alone and with “phytochemicals,” “alternative,” “essential oils,” and “vitamins.” This search demonstrated that the literature strongly endorses the role of naturally occurring substances in the context of skin cancer chemoprevention, however the literature is predominantly comprised of data based on in vitro and animal based models.
Summary
Prior to acceptance into mainstream practice, high quality prospective studies to evaluate the role of naturally occurring compounds in the context of skin cancer chemoprevention are indicated.
... This species is widely cultivated to use as fragrances, and flavours in the perfume and food industries, as well as in aromatherapy (Ponce, del Valle, & Roura, 2004). Previous studies on M. alternifolia essential oil mainly focused on its antimicrobial and anti-inflammatory effects Ireland et al., 2012;Thomsen, Hammer, Riley, Van Belkum, & Carson, 2013). Few studies have demonstrated that the essential oil of M. alternifolia is biologically active as an antifeedant or for contact against H. armigera. ...
Pesticide resistance has developed as a result of long-term and extensive use of chemical pesticides. Essential oils from aromatic plants may provide a new and safe alternative to conventional insecticides. In this study, the insecticidal activities of the essential oil of Melaleuca alternifolia and their chemical constituents against Helicoverpa armigera Hubner were investigated, and the underlying mechanisms were studied. The essential oil showed distinct antifeedant (AFC50 = 8.93 mg/ml) and good contact (LD50 = 50.28 μg/larva) activities against H. armigera at 24 hr. Ten chemical components were identified using a gas chromatograph/mass spectrometer, and mainly included terpinen-4-ol (40.09%), γ-terpinene (21.85%), α-terpinene (11.34%), α-terpineol (6.91%), α-pinene (5.86%), terpinolene (3.24%) and 1,8-cineole (1.83%). Among them, five components were determined and results showed that these constituents possessed obvious antifeedant activities. The activities of acetylcholinesterase and glutathione S-transferase were notably inhibited by the essential oil, as compared with the control, with strong dose- and time-dependent effects. The results provide a basis for their development and utilization in the control of insects in the future.
... Studies performed in vivo presented that 10%TTO/DMSO caused damage to tumour cells, such as mitochondrial membrane disruption, gross swelling and dissolution of internal structures. These results indicated that the application of diluted tea tree oil might be used for skin cancer therapy [24]. Also, Muto et al. have recommended using oleanolic oil, abundant in terpenes, for skin cancer therapy [25]. ...
... The major compound present in tea tree oil is the oxygenated monoterpenoid terpinen-4-ol, which has been shown to possess antimicrobial properties (Carson and Riley 1995). The oil and constituents contained therein continue to be investigated for various pharmacological properties to this very day (Hart et al. 2000;Greay et al. 2010;Ireland et al. 2012;Lim and Hammer 2015). Essential oils distilled from Australian plant species triggered great interest and laid a foundation for natural product chemistry research and industrial production of such products early on. ...
The importance of plants and other natural reserves as sources for biologically important compounds, particularly for application in food and medicine, is undeniable. Herein we provide a historical context of the major scientific research programs conducted in Australia that have been aimed at discovering novel bioactive natural products from terrestrial plants. Generally speaking, the main approaches used to guide the discovery of novel bioactive compounds from natural resources have included random, ethnobotanical and chemotaxonomic strategies. Previous Australian plant natural product research campaigns appear to have lacked the use of a fourth strategy with equally high potential, namely the ecologically guided approach. In addition, many large studies have sampled plant material predominantly from tropical regions of Australia, even though arid and semi-arid zones make up 70% of mainland Australia. Therefore, plants growing in arid zone environments, which are exposed to different external stressors (e.g. low rainfall, high ultraviolet exposure) compared with tropical flora, remain an untapped reservoir of potentially novel bioactive compounds. Research of Australian arid zone plants that is ecologically guided creates a new opportunity for the discovery of novel bioactive compounds from plants (and potentially other biota) for application in health care, food and agricultural industries.
... In this regard, Tea tree oil (TTO) of Melaleuca alternifolia has been widely used as antimicrobial (Carson et al. 2006;Mikus et al. 2000) and anti-inflammatory phytotherapic coumpound [(reduction of Tumor necrosis factor-α, Interferon-γ, Interleukin-2] (Baldissera et al. 2014) for the presence of terpinen-4-ol and 1.8-cineole (Caldefie-Chezet et al. 2006;Dalwai et al. 2014;de Campos Rasteiro et al. 2014;Furneri et al. 2006;Greay et al. 2010;Hammer 2015;Ireland et al. 2012;Mantil et al. 2015;Nogueira et al. 2014). TTO is also known to exert antioxidant effects on human peripheral blood mononuclear cells by reducing reactive oxigen species production and IL-2 secretion in T lymphocytes, and increasing the secretion of the anti-inflammatory cytokines such as Interleukin-4 and Interleukin-10 (Caldefie-Chezet et al. 2006). ...
The aim of this evaluation study was to assess the possible role of a specific nutraceutical diet in relieving main clinical symptoms of chronic bilateral otitis externa (occlusion of ear canal, erythema, discharge quantity, and odor) in 30 adult dogs. Thirty dogs of different breeds (mean age ± SEM; 6.03 ± 0.15 years and mean weight ± SEM; 32.01 ± 1.17 Kg; 53.3 % males, 46.6 % females) with evident chronic clinical otitis symptoms were equally divided and randomly assigned to receive either the nutraceutical diet (ND group) or a standard diet (SD group) over a period of 90 days. In all cases a topical pharmacological treatment was given. The nutraceutical diet, also endowed with anti-inflammatory and antioxidant activities, significantly decreased the mean score intensity of all symptoms after 90 days of intervention (P < 0.0001) with the exception of Malassezia pachydermatis infection which was only slightly reduced. Our investigation is one of the few evidence-based results where a commercial nutraceutical diet has been proven effective, in combination with drugs, in relieving otitis externa-related symptoms. This study opens new insights into otitis externa clinical management providing evidence of efficacy of a combined therapy with drugs and a specific nutraceutical diet.
... Topical application of narrow-leaved paperbark (M. alternifolia) oil activated immune response and directly exerted inhibitory effect on tumour cells in vivo (Ireland et al., 2012). Thymoquinone, a significant component of black cumin (N. ...
... Furthermore, it has potent activity against many fungi (Hammer et al., 2003(Hammer et al., , 2004, protozoa (Carson et al., 2006;Mikus et al., 2000), and certain viruses, including herpes simplex and influenza viruses (Carson and Riley, 2001;Garozzo et al., 2011). Besides the well-known antimicrobial activities, TTO has been shown to possess a number of other therapeutic properties, including anti-inflammatory (Hart et al., 2000;Koh et al., 2002;Pearce et al., 2005) and anti-tumor properties (Bozzuto et al., 2011), especially in skin cancer (Greay et al., 2010;Ireland et al., 2012). Hydrogels containing TTO were already tested in a burn wound model and suggested to increase the rate of wound healing (Jandera et al., 2000). ...
In this paper we propose an in situ forming ionically cross-linked alginate (Alg) hydrogel delivering a Tea tree oil microemulsion (MeTTO) and potentially useful as an advanced dressing for infected wounds. Alg hydrogels were prepared by a spray-by-spray deposition method with the aim to minimize the discomforts during application. From pseudoternary phase diagrams, it was found that proper combination of TTO, water, polysorbate 80 and ethanol gave stable spherical MeTTO with good antimicrobial activity. On this basis, MeTTO at 20% TTO was selected for further inclusion in an Alg hydrogel prepared by alternating sprays of Alg/MeTTO and calcium chloride solutions. Homogeneous dispersion of MeTTO inside cross-linked Alg was assessed by different macroscopic and microscopic methods demonstrating the superior propensity of MeTTO to be integrated in the water-based hydrogel as compared to TTO. Antimicrobial effect of Alg/MeTTO hydrogels on Escherichia Coli strains was remarkable, highlighting the potential of the system as bioactive wound dressing.
... By day three the mitochondria had burst and the endoplasmic reticulum had dissolved. These results serve as an indication that topical application of tea tree oil could potentially be used in skin cancer therapy [167]. ...
Most anti-cancer drugs are derived from natural resources such as marine, microbial and botanical sources. Cutaneous malignant melanoma is the most aggressive form of skin cancer, with a high mortality rate. Various treatments for malignant melanoma are available, but due to the development of multi-drug resistance, current or emerging chemotherapies have a relatively low success rates. This emphasizes the importance of discovering new compounds that are both safe and effective against melanoma. In vitro testing of melanoma cell lines and murine melanoma models offers the opportunity for identifying mechanisms of action of plant derived compounds and extracts. Common anti-melanoma effects of natural compounds include potentiating apoptosis, inhibiting cell proliferation and inhibiting metastasis. There are different mechanisms and pathways responsible for anti-melanoma actions of medicinal compounds such as promotion of caspase activity, inhibition of angiogenesis and inhibition of the effects of tumor promoting proteins such as PI3-K, Bcl-2, STAT3 and MMPs. This review thus aims at providing an overview of anti-cancer compounds, derived from natural sources, that are currently used in cancer chemotherapies, or that have been reported to show anti-melanoma, or anti-skin cancer activities. Phytochemicals that are discussed in this review include flavonoids, carotenoids, terpenoids, vitamins, sulforaphane, some polyphenols and crude plant extracts.
... Several recent works have presented DMSO as vehicle of different anticancer compounds administered systemically or topically in 1 ~ 10% solution. [68][69][70][71] ...
Background:
Pyrostegia venusta (Ker. Gawl.) Miers (Bignoniacea) is a medicinal plant from the Brazilian Cerrado used to treat leucoderma and common diseases of the respiratory system.
Objective:
To investigate the antitumor activity of P.venusta extracts against melanoma.
Materials and methods:
The cytotoxic activity and tumor induced cell death of heptane extract (HE) from P. venusta flowers was evaluated against murine melanoma B16F10-Nex2 cells in vitro and in a syngeneic model in vivo.
Results:
We found that HE induced apoptosis in melanoma cells by disruption of the mitochondrial membrane potential, induction of reactive oxygen species and late apoptosis evidenced by plasma membrane blebbing, cell shrinkage, chromatin condensation and DNA fragmentation, exposure of phosphatidylserine on the cell surface and activation of caspase-2,-3,-8,-9. HE was also protective against singeneyc subcutaneous melanoma HE compounds were also able to induce cell cycle arrest at G2/M phases on tumor cells. On fractionation of HE in silica gel we isolated a cytotoxic fraction that contained a mixture of saturated hydrocarbons identified by (1)H NMR and GC-MS analyses. Predominant species were octacosane (C28H58-36%) and triacontane (C30H62-13%), which individually showed significant cytotoxic activity against murine melanoma B16F10-Nex2 cells in vitro and a very promising antitumor protection against subcutaneous melanoma in vivo.
Conclusion:
The results suggest that the components of the heptane extract, mainly octasane and triacontane, which showed antitumor properties in experimental melanoma upon regional administration, might also be therapeutic in human cancer, such as in the mostly epidermal and slowly invasive melanomas, such as acral lentiginous melanoma, as an adjuvant treatment to surgical excision.
... Aqueous solutions of this Pluronic exhibit time dependent sphere-to-rod micellar growth below their cloud points because of slow dynamics of micellar restructuring processes in them [4,29,30]. TTO on the other hand, has been subjected to extensive studies in recent times because of its broad spectrum antimicrobial properties and probable cure for diseases ranging from simple wounds [31][32][33][34][35][36][37][38][39][40][41][42][43][44] to critical ones like cancers [45][46][47][48][49][50][51][52][53][54]. It is sparingly soluble in water, so in the aqueous medium its therapeutic efficacies are studied using nonionic surfactants as dispersing agent [50][51][52][53][54][55][56]. ...
Dynamic Stokes' shift and fluorescence anisotropy measurements of coumarin 153 (C153) and coumarin 151 (C151) as fluorescence probes have been carried out to understand the influence of electrolytes (NaCl and LiCl) on the hydration behavior of aqueous (ethylene oxide)100-(propylene oxide)70-(ethylene oxide)100 (EO100-PO70-EO100, F127) block copolymer micelles. A small blue shift in the fluorescence spectra of C153 has been observed in presence of electrolytes due to the dehydration of the oxyethylene chains in the PEO-PPO region, although fluorescence spectra of C151 remain unaltered. The close vicinity of bulk water for C151 probably negates the effect of dehydration in the PEO region. Fluorescence anisotropy measurements indicate a gradual increase in microviscosity with electrolyte concentrations. The partial collapse of copolymer blocks in the presence of electrolytes has been suggested as a reason for the increase in microviscosity along with the strong hydration of ions in the corona region. The interplay between the ion hydration and the mechanically trapped water content, and specific interaction of ions, such as complexation of Li+ ions with the copolymer block, is found to control solvation dynamics in the corona region. In addition to that, it has been established that Na+ ions reside deep into the corona region whereas Li+ ions prefer to reside closer to the surface. Owing to its higher lyotropicity, LiCl influences the corona hydration to a greater extent than NaCl and sets in micelle-micelle interaction above the 2 M LiCl concentration, as reflected in the saturation of solvation time constants. The formation of larger clusters of F127 micelles above 2 M LiCl has been confirmed by dynamic light scattering measurements; however, such cluster formation is not evident with NaCl.
The leaves of tea tree (Melaleuca alternifolia) plant are the major source of tea tree essential oil extracted via steam distillation. The use of this oil is quite common in cosmetic, pharmaceutical, agrofood, and nonfood industries. The use of essential oils has upshot due to increased demand of natural alternatives to chemically synthesized pharmaceutical and cosmetic products. The aromatic oil of tea tree contains more than 100 different phytochemicals majorly the monoterpenes, sesquiterpenes, and their related alcohols. Terpinen-4-ol has been recognized as a major compound responsible for broad antimicrobial and antiinflammatory activities. Apart from its beneficial effects and natural origin, tea tree oil is subjected to safety concerns like allergic reactions upon topical applications and toxic effects when ingested. In this context, this chapter discusses various aspects of tea tree oil including its phytochemistry, extraction methods, applications, and safety concerns.
Essential oils (EO) are aromatic compounds from the plant secondary metabolism. Melaleuca alternifolia EO is well known for its medicinal properties and promising use as an antimicrobial agent. Pythiosis is a difficult-to-treat and emerging disease caused by the oomycete Pythium insidiosum. This study evaluated a nanoemulsion formulation of M. alternifolia (NEMA) in topical and intralesional application to treat experimental pythiosis. Dermal toxicity tests were performed on M. alternifolia EO in Wistar rats. Pythiosis was reproduced in rabbits (n = 9) that were divided into groups: group 1 (control), cutaneous lesions with daily topical application of a non-ionizable gel-based formulation and intralesional application of sterile distilled water every 48 h; group 2 (topical formulation), lesions treated daily with topical application of a non-ionizable gel-based formulation containing 5 mg/ml of NEMA; and group 3 (intralesional formulation), lesions treated with NEMA at 5 mg/ml in aqueous solution applied intralesionally/48 h. The animals were treated for 45 days, and the subcutaneous lesion areas were measured every 5 days. M. alternifolia EO showed no dermal toxicity. The lesion areas treated with intralesional NEMA reduced at the end of treatment, differing from groups 1 and 2 (P < 0.05). In the topically treated group, the lesion areas did not differ from the control group, although the number of hyphae significantly reduced (P < 0.05). Under the experimental conditions of this study, the NEMA formulations presented a favorable safety profile. However, further studies are required to evaluate if this safety applies to higher concentrations of NEMA and to validate its use in clinical pythiosis.
This following chapter represents a brief summary of phytochemicals which presents anticancer properties besides the effects known and for which they have been used since ancient times. Recent studies about phytocompounds have shown that they represent a good alternative to the conventional skin cancer therapy, even metastatic forms, statement sustained through in vitro and in vivo experiments. Modern drug delivery systems, such as liposomes, ethosomes, solid lipid nanoparticles, and nanoemulsions, were developed and tested in order to increase stability and bioavailability of the active compound.KeywordsPhytochemicalsSkin cancerMelanomaDrug delivery systemBioavailability
The antitumor activity of the tea tree oil (TTO) derived product, Melaleuca Alternifolia Concentrate (MAC) was characterized mechanistically at the molecular and cellular level. MAC was analyzed for its anticancer activity against human prostate (LNCaP) and breast (MCF-7) cancer cell lines growing in vitro. MAC (0.02–0.06% v/v) dose-dependently induced the intrinsic (mitochondrial) apoptotic pathway in both the LNCaP and MCF-7 cell lines, involving increased mitochondrial superoxide production, loss of mitochondrial membrane potential (MMP), caspase 3/7 activation, as well as the presence of TUNEL⁺ and cleaved-PARP⁺ cell populations. At concentrations of 0.01–0.04% v/v, MAC caused cell cycle arrest in the G0/1–phase, as well as autophagy. The in vivo anticancer actions of MAC were examined as a treatment in the FVB/N c-Neu murine model for spontaneously arising breast cancers. Intratumoral MAC injections (1–4% v/v) significantly suppressed tumor progression in a dose-dependent manner and was associated with greater levels of tumor infiltrating neutrophils exhibiting anticancer cytotoxic activity. Induction of breast cancer cell death by MAC via the mitochondrial apoptotic pathway was also replicated occurring in tumors treated in vivo. In conclusion, our data highlights the potential for the Melaleuca-derived MAC product inducing anticancer neutrophil influx, supporting its application as a novel therapeutic agent.
An increased interest by consumers toward pharmacologically active plant-derived natural products as alternatives to synthetic drugs has increased the attention of global scientists. Among the various plant-derived natural products, essential oils have gained popularity because of its use in food, cosmetics, and pharmaceutical industries. Constituting an array of many lipophilic and highly volatile components, derived from a wide range of different chemical classes, essential oils are characterized by a wide range of biological activities, such as antiseptic, anti-inflammatory, spasmolytic, sedative, analgesic, and anesthetic. A growing interest has recently focused on the potential of essential oils as an anticancer treatment to overcome the development of multidrug resistance and important side effects associated with the currently used antitumor drugs. The anticancer potential of essential oils has been widely explored till date. A recent Medline survey on PubMed for “essential oil and cancer” retrieves 926 results with a remarkable surge in publications over the last 16 years (688 out of 926 studies), while a search for “essential oil and cytotoxicity” has shown 434 results, of which 392 were published in the last 10 years. These numbers suggested that the studies in this field have been initiated rather lately, even though essential oils have been known since ancient times. The aim of the present chapter is to provide an overview on the scientific reports published for in vivo and in vitro studies in reference to essential oils of a wide variety of plants, viz., Cymbopogon flexuosus, Eucalyptus benthamii, Laurus nobilis, Melissa officinalis, Myristica fragrans, Rosmarinus officinalis, Salvia miltiorrhiza, Satureja thymbra, Thymus broussonetii, etc., or their main constituents. Moreover, the various mechanisms of action of different essential oils and their constituents having anticancer properties are also discussed.
The purpose of this study was to investigate some possible mechanisms underlying the in vitro antitumor activity of tea tree oil (TTO) on human and mouse breast cancer cells (MCF-7 and 4T1, respectively) and its cytotoxicity on fibroblasts (HFF-1) and on peripheral blood mononuclear cells (PBMCs). TTO High-Resolution Gas Chromatography (HRGC) showed seventeen main constituents, such as Terpinen-4-ol, γ-Terpinene, and α-Terpinene. High TTO concentrations (≥ 600 μg/mL) showed a remarkable antitumor activity, decreasing cell viability and cell proliferation of MCF-7 and 4T1 cells. TTO at 300 μg/mL increased the number of MCF-7 cells in the early stages of apoptosis and increased the BAX/BCL-2 genes ratio. TTO, mainly at 300 μg/mL, decreased cell growth and arrested MCF-7 cells in the S phase of the cell cycle. Lower antitumor concentrations (≤300 μg/mL) evaluated in MCF-7 and 4T1 cells were not cytotoxic to PBMCs and HFF-1. Also, TTO (300 μg/mL) was able to induce cell proliferation in fibroblasts after 72 h, indicating non-cytotoxic effect in these cells. TTO exhibited in vitro antitumor effect on MCF-7 and 4T1 cells by decreasing cell viability and modulating apoptotic pathways and cell cycle arrestment of MCF-7 cells. In this sense, our study provides new perspectives on the potential use of TTO for the development of new alternative therapies to treat topically locally advanced breast cancer (LABC).
This work describes the effect of cold nitrogen plasma to enhance the antibacterial activity of poly(ethylene oxide) (PEO) nanofibers containing antibacterial agent. Beta-cyclodextrin (β-CD) and tea tree oil (TTO) were used as a host-guest to form water-soluble inclusion complex. The encapsulation efficiency of TTO in inclusion complex could reach 73.23% at 60 °C. As antibacterial agent, the inclusion complex was encapsulated into PEO matrix by electrospun. After plasma treatment, the release efficiency of antibacterial agent from PEO nanofibers was improved. As a result, the antibacterial activity of PEO nanofibers was enhanced accordingly. The plasma-treated nanofiber membranes achieved the highest antibacterial activity against Escherichia coli O157:H7, which was tested on the beef for 7 days, with inhibition efficiently of 99.99% whether at 4 °C or 12 °C. The plasma-treated PEO nanofiber membranes containing TTO/β-CD inclusion complex (TTO/β-CD-IC) can prolong the shelf-life of beef, suggesting it has potential application in active food packaging.
This work demonstrates the potential of fast multiple heart-cut enantioselective multidimensional gas chromatography (GC-eGC) and enantioselective comprehensive two-dimensional gas chromatography (eGC×GC), to perform the stereoisomeric analysis of three key chiral monoterpenes (limonene, terpinen-4-ol and α-terpineol) present in tea tree oil (TTO). In GC-eGC, separation was conducted using a combination of mid-polar first dimension ((1)D) column and a chiral second dimension ((2)D) column, providing interference-free enantioresolution of the individual antipodes of each optically active component. A combination of (1)D chiral column and (2)D polar columns (ionic liquid and wax phases) were tested for the eGC×GC study. Quantification was proposed based on summation of two major modulated peaks for each antipode, displaying comparable results with those derived from GC-eGC. Fast chiral separations were achieved within 25min for GC-eGC and<20min for eGC×GC, while ensuring adequate interference-free enantiomer separation. The suitability of using these two enantioselective multidimensional approaches for the routine assessment of chiral monoterpenes in TTO was evaluated and discussed. Exact enantiomeric composition of chiral markers for authentic TTOs was proposed by analysing a representative number of pure TTOs sourced directly from plantations of known provenance in Australia. Consistent enantiomeric fractions of 61.6±1.5% (+):38.4±1.5% (-) for limonene, 61.7±1.6% (+):38.3±1.6% (-) for terpinen-4-ol and 79.6±1.4% (+):20.4±1.4% (-) for α-terpineol were obtained for the 57 authentic Australian TTOs. The results were compared (using principle component analysis) with commercial TTOs (declared as derived from Melaleuca alternifolia) obtained from different continents. Assessing these data to determine adulteration, or additives that affect the enantiomeric ratios, in commercially sourced TTOs is discussed. The proposed method offers distinct advantages over eGC, especially in terms of analysis times and selectivity which can serve as a reliable platform for authenticity control of TTO.
Copyright © 2015 Elsevier B.V. All rights reserved.
Many cyclic hydrocarbons, e.g. aromatics, cycloalkanes, and terpenes, are toxic to microorganisms. The primary site of the toxic action is probably the cytoplasmic membrane, but the mechanism of the toxicity is still poorly understood. The effects of cyclic hydrocarbons were studied in liposomes prepared from Escherichia coli phospholipids. The membrane-buffer partition coefficients of the cyclic hydrocarbons revealed that these lipophilic compounds preferentially reside in the membrane. The partition coefficients closely correlated with the partition coefficients of these compounds in a standard octanol-water system. The accumulation of hydro carbon molecules resulted in swelling of the membrane bilayer, as assessed by the release of fluorescence self-quenching of fluorescent fatty acid and phospholipid analogs. Parallel to the expansion of the membrane, an increase in membrane fluidity was observed. These effects on the integrity of the membrane caused an increased passive flux of protons and carboxyfluorescein. In cytochrome c oxidase containing proteoliposomes, both components of the proton motive force, the pH gradient and the electrical potential, were dissipated with increasing concentrations of cyclic hydrocarbons. The dissipating effect was primarily the result of an increased permeability of the membrane for protons (ions). At higher concentrations, cytochrome c oxidase was also inactivated. The effective concentrations of the different cyclic hydrocarbons correlated with their partition coefficients between the membrane and aqueous phase. The impairment of microbial activity by the cyclic hydrocarbons most likely results from hydrophobic interaction with the membrane, which affects the functioning of the membrane and membrane-embedded proteins.
Terpinen-4-ol, a monoterpene component of the essential oils of several aromatic plants, exhibits antitumor effects. In this study, the antitumor effects of terpinen-4-ol and the cellular and molecular mechanisms responsible for it were evaluated and studied, respectively on human nonsmall cell lung cancer (NSCLC) cells. Our results indicated that terpinen-4-ol elicited a dose-dependent cytotoxic effect, as determined by MTT assay. Increased sub-G1 population and annexin-V binding, activation of caspases 9 and 3, cleavage of poly(ADPribose) polymerase (PARP), and a decrease of mitochondrial membrane potential (MMP) indicated involvement of the mitochondrial apoptotic pathway in terpinen-4-ol-treated A549 and CL1-0 cells. Elevation of the Bax/Bcl-2 ratio and a decrease in IAP family proteins XIAP and survivin were also observed following terpinen-4-ol treatment. Notably, terpinen-4-ol was able to increase p53 levels in A549 and CL1-0 cells. Diminution of p53 by RNA interference induced necrosis instead of apoptosis in A549 cells following terpinen-4-ol treatment, indicating that terpinen-4-ol-elicited apoptosis is p53-dependent. Moreover, intratumoral administration of terpinen-4-ol significantly suppressed the growth of s.c. A549 xenografts by inducing apoptosis, as confirmed by TUNEL assay. Collectively, these data provide insight into the molecular mechanisms underlying terpinen-4-ol-induced apoptosis in NSCLC cells, rendering this compound a potential anticancer drug for NSCLC.
The sap from Euphorbia peplus, commonly known as petty spurge in the U.K. or radium weed in Australia, has been used as a traditional treatment for a number of cancers.
To determine the effectiveness of E. peplus sap in a phase I/II clinical study for the topical treatment of basal cell carcinomas (BCC), squamous cell carcinomas (SCC) and intraepidermal carcinomas (IEC).
Thirty-six patients, who had refused, failed or were unsuitable for conventional treatment, were enrolled in a phase I/II clinical study. A total of 48 skin cancer lesions were treated topically with 100-300 μL of E. peplus sap once daily for 3 days.
The complete clinical response rates at 1 month were 82% (n = 28) for BCC, 94% (n = 16) for IEC and 75% (n = 4) for SCC. After a mean follow-up of 15 months these rates were 57%, 75% and 50%, respectively. For superficial lesions < 16 mm, the response rates after follow-up were 100% for IEC (n = 10) and 78% for BCC (n = 9).
The clinical responses for these relatively unfavourable lesions (43% had failed previous treatments, 35% were situated in the head and neck region and 30% were > 2 cm in diameter), are comparable with existing nonsurgical treatments. An active ingredient of E. peplus sap has been identified as ingenol mebutate (PEP005). This clinical study affirms community experience with E. peplus sap, and supports further clinical development of PEP005 for the treatment of BCC, SCC and IEC.
Cytotoxicity of Australian tea tree oil (oil of Melaleuca alternifolia) and its major oxygenated monoterpenes: terpinen-4-ol, 1,8-cineole and a-terpineol were investigated using the MTS [(3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H- tetrazolium)] assay at two exposure times: 4 and 24 h on five different human cell lines. These cell lines included: Hep G2, a heptaocellular carcinomic human cell line; HeLa, an epithelioid carcinomic cell line; MOLT-4, a human lymphoblastic leukaemic T-cell line; K-562, a human chronic myelogenous leukaemia cell line; and CTVR-1, an early B-cell line from the bone marrow cells of a patient with acute myeloid leukaemia. The overall rating for cytotoxicity of tea tree oil and its components was α-terpineol>tea tree oil>terpinen-4-ol> 1,8-cineole and with comparison with the controls used mercuric chloride>tea tree oil>aspirin. Antimicrobial activity (MICs) displayed a similar pattern where α-terpineol>terpinen-4-ol>tea tree oil>1,8-cineole. The IC50 (a concentration that causes a reduction by half of the activity of mitochondrial dehydrogenase) value of tea tree oil ranged from 0.02 g/L for the Hep G2 cell line to 2.8 g/L for the HeLa cell line.
Systemic toxicity coupled with long treatment regimes of approved topical chemotherapeutic agents such as imiquimod and 5-fluorouracil (5-FU) are limiting. There is now more focus on the potential use of topical terpene agents as skin cancer treatments. Here, we show for the first time that topical Melaleuca alternifolia (tea tree) oil (TTO), abundant in terpenes, has in vivo antitumour activity.
Topical TTO formulations applied to immunocompetent tumour-bearing mice were assessed for antitumour efficacy by monitoring tumour growth and by histological analysis following treatment.
Four, daily, topical treatments of 10% TTO/DMSO regressed subcutaneous AE17 mesotheliomas in mice for a period of 10 days and significantly retarded the growth of subcutaneous B16-F10 melanomas. The antitumour effect of topical 10% TTO/DMSO was accompanied by skin irritation similar to other topical chemotherapeutic agents, but unlike other approved topical agents, quickly and completely resolved. Furthermore, we show that topical 10% TTO/DMSO caused an influx of neutrophils and other immune effector cells in the treated area, with no evidence of systemic toxicity.
TTO combined with an effective carrier significantly inhibited the growth of aggressive, subcutaneous, chemo-resistant tumours in immunocompetent mice. Taken together, these findings highlight the potential of topical TTO as an alternative topical antitumour treatment.
In this study we present new data from experiments focused on the antitumor activity of tea tree oil (TTO), an essential oil distilled from Melaleuca alternifolia. TTO proved to be capable of inhibiting the growth of melanoma cells and of overcoming multidrug resistance (MDR), as we reported in our previous study. Moreover, the survival role of the MDR-marker P-glycoprotein appears to be involved in the mechanism of invasion of melanoma cells. The results reported herein indicate that TTO and its main active component, terpinen-4-ol, can also interfere with the migration and invasion processes of drug-sensitive and drug-resistant melanoma cells.
To examine the in vitro anticancer activity of Melaleuca alternifolia (tea tree) oil (TTO), and its major active terpene component, terpinen-4-ol, against two aggressive murine tumour cell lines, AE17 mesothelioma and B16 melanoma.
Effects of TTO and terpinen-4-ol on the cellular viability of two tumour cell lines and fibroblast cells were assessed by MTT assay. Induction of apoptotic and necrotic cell death was visualised by fluorescent microscopy and quantified by flow cytometry. Tumour cell ultrastructural changes were examined by transmission electron microscopy and changes in cell cycle distribution were assessed by flow cytometry, with changes in cellular morphology monitored by video time lapse microscopy.
TTO and terpinen-4-ol significantly inhibited the growth of two murine tumour cell lines in a dose- and time-dependent manner. Interestingly, cytotoxic doses of TTO and terpinen-4-ol were significantly less efficacious against non-tumour fibroblast cells. TTO and terpinen-4-ol induced necrotic cell death coupled with low level apoptotic cell death in both tumour cell lines. This primary necrosis was clarified by video time lapse microscopy and also by transmission electron microscopy which revealed ultrastructural features including cell and organelle swelling following treatment with TTO. In addition, both TTO and terpinen-4-ol induced their inhibitory effect by eliciting G1 cell cycle arrest.
TTO and terpinen-4-ol had significant anti-proliferative activity against two tumour cell lines. Moreover, the identification of primary necrotic cell death and cell cycle arrest of the aggressive tumour cells highlights the potential anticancer activity of TTO and terpinen-4-ol.
Background
Previous studies suggested that essential oils suppressed the adherence response of human neutrophils in vitro and that intraperitoneal application of geranium oil suppressed the neutrophil accumulation into peritoneal cavity in vivo. Usually, essential oils are applied through skin in aromatherapy in inflammatory symptoms. The purpose of this study is to assess the effects of cutaneous application of essential oils on the accumulation of neutrophils in inflammatory sites in skin of mice.
Methods
Inflammation with accumulation of inflammatory cells was induced by injection of curdlan, a (1→3)-β-D-glucan in skin or peritoneal cavity of mice. Essential oils were applied cutaneously to the mice immediately and 3 hr after intradermal injection of curdlan. The skin with inflammatory lesion was cut off 6 hr after injection of curdlan, and the homogenates were used for myeloperoxidase (MPO: a marker enzyme of neutrophil granule) assay.
Results
The MPO activity of the skin lesion induced by curdlan was suppressed dose-dependently by cutaneous application of geranium oil. Other oils such as lavender, eucalyptus and tea tree oils also suppressed the activity, but their activities seemed weaker than geranium. Juniper oil didn't suppress the activity
Conclusion
Cutaneous application of essential oils, especially geranium oil, can suppress the inflammatory symptoms with neutrophil accumulation and edema.
Systemic anticancer chemotherapy is immunosuppressive and mostly induces nonimmunogenic tumor cell death. Here, we show that even in the absence of any adjuvant, tumor cells dying in response to anthracyclins can elicit an effective antitumor immune response that suppresses the growth of inoculated tumors or leads to the regression of established neoplasia. Although both antracyclins and mitomycin C induced apoptosis with caspase activation, only anthracyclin-induced immunogenic cell death was immunogenic. Caspase inhibition by Z-VAD-fmk or transfection with the baculovirus inhibitor p35 did not inhibit doxorubicin (DX)-induced cell death, yet suppressed the immunogenicity of dying tumor cells in several rodent models of neoplasia. Depletion of dendritic cells (DCs) or CD8+T cells abolished the immune response against DX-treated apoptotic tumor cells in vivo. Caspase inhibition suppressed the capacity of DX-killed cells to be phagocytosed by DCs, yet had no effect on their capacity to elicit DC maturation. Freshly excised tumors became immunogenic upon DX treatment in vitro, and intratumoral inoculation of DX could trigger the regression of established tumors in immunocompetent mice. These results delineate a procedure for the generation of cancer vaccines and the stimulation of anti-neoplastic immune responses in vivo.
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Complementary and alternative medicines such as tea tree (melaleuca) oil have become increasingly popular in recent decades. This essential oil has been used for almost 100 years in Australia but is now available worldwide both as neat oil and as an active component in an array of products. The primary uses of tea tree oil have historically capitalized on the antiseptic and anti-inflammatory actions of the oil. This review summarizes recent developments in our understanding of the antimicrobial and anti-inflammatory activities of the oil and its components, as well as clinical efficacy. Specific mechanisms of antimicrobial and anti-inflammatory action are reviewed, and the toxicity of the oil is briefly discussed.
Harnessing neutrophils for the eradication of cancer cells remains an attractive but still controversial notion. In this study, we provide evidence that neutrophils are required to prevent relapse of skin tumors following topical treatment with a new anticancer agent, ingenol-3-angelate (PEP005). Topical PEP005 treatment induces primary necrosis of tumor cells, potently activates protein kinase C, and was associated with an acute T cell-independent inflammatory response characterized by a pronounced neutrophil infiltrate. In Foxn1(nu) mice depleted of neutrophils and in CD18-deficient mice (in which neutrophil extravasation is severely impaired) PEP005 treatment was associated with a >70% increase in tumor relapse rates. NK cell or monocyte/macrophage deficiency had no effect on relapse rates. Both in vitro and in mice, PEP005 induced MIP-2/IL-8, TNF-alpha, and IL-1beta, all mediators of neutrophil recruitment and activation. In vitro, PEP005 activated human endothelial cells resulting in neutrophil adhesion and also induced human neutrophils to generate tumoricidal-reactive oxygen intermediates. Treatment of tumors with PEP005 significantly elevated the level of anticancer Abs, which were able to promote neutrophil-mediated Ab-dependent cellular cytotoxicity (ADCC) in vitro. PEP005 treatment of tumors grown in SCID mice was also associated with >70% increase in tumor relapse rates. Taken together, these data suggest a central role for neutrophil-mediated ADCC in preventing relapse. PEP005-mediated cure of tumors therefore appears to involve initial chemoablation followed by a neutrophil-dependent ADCC-mediated eradication of residual disease, illustrating that neutrophils can be induced to mediate important anticancer activity with specific chemotherapeutic agents.
Dimethyl sulfoxide (DMSO) is a small amphiphilic molecule which is widely employed in cell biology as an effective penetration enhancer, cell fusogen, and cryoprotectant. Despite the vast number of experimental studies, the molecular basis of its action on lipid membranes is still obscure. A recent simulation study employing coarse-grained models has suggested that DMSO induces pores in the membrane (Notman, R.; Noro, M.; O'Malley, B.; Anwar, J. J. Am. Chem. Soc. 2006, 128, 13982-13983). We report here the molecular mechanism for DMSO's interaction with phospholipid membranes ascertained from atomic-scale molecular dynamics simulations. DMSO is observed to exhibit three distinct modes of action, each over a different concentration range. At low concentrations, DMSO induces membrane thinning and increases fluidity of the membrane's hydrophobic core. At higher concentrations, DMSO induces transient water pores into the membrane. At still higher concentrations, individual lipid molecules are desorbed from the membrane followed by disintegration of the bilayer structure. The study provides further evidence that a key aspect of DMSO's mechanism of action is pore formation, which explains the significant enhancement in permeability of membranes to hydrophilic molecules by DMSO as well as DMSO's cryoprotectant activity. The reduction in the rigidity and the general disruption of the membrane induced by DMSO are considered to be prerequisites for membrane fusion processes. The findings also indicate that the choice of DMSO concentration for a given application is critical, as the concentration defines the specific mode of the solvent's action. Knowledge of the distinct modes of action of DMSO and associated concentration dependency should enable optimization of current application protocols on a rational basis and also promote new applications for DMSO.
Therapeutic use of IL-2 can generate antitumor immunity; however, a variety of different mechanisms have been reported. We injected IL-2 intratumorally (i.t.) at different stages of growth, using our unique murine model of mesothelioma (AE17; and AE17 transfected with secretory OVA (AE17-sOVA)), and systematically analyzed real-time events as they occurred in vivo. The majority of mice with small tumors when treatment commenced displayed complete tumor regression, remained tumor free for >2 mo, and survived rechallenge with AE17 tumor cells. However, mice with large tumors at the start of treatment failed to respond. Timing experiments showed that IL-2-mediated responses were dependent upon tumor size, not on the duration of disease. Although i.t. IL-2 did not alter tumor Ag presentation in draining lymph nodes, it did enhance a previously primed, endogenous, tumor-specific in vivo CTL response that coincided with regressing tumors. Both CD4(+) and CD8(+) cells were required for IL-2-mediated tumor eradication, because IL-2 therapy failed in CD4(+)-depleted, CD8(+)-depleted, and both CD4(+)- and CD8(+)-depleted C57BL/6J animals. Tumor-infiltrating CD8(+) T cells, but not CD4(+) T cells, increased in association with a marked reduction in tumor-associated vascularity. Destruction of blood vessels required CD8(+) T cells, because this did not occur in nude mice or in CD8(+)-depleted C57BL/6J mice. These results show that repeated doses of i.t. (but not systemic) IL-2 mediates tumor regression via an enhanced endogenous tumor-specific CTL response concomitant with reduced vasculature, thereby demonstrating a novel mechanism for IL-2 activity.
Microbial transformations of cyclic hydrocarbons have received much attention during the past three decades. Interest in the degradation of environmental pollutants as well as in applications of microorganisms in the catalysis of chemical reactions has stimulated research in this area. The metabolic pathways of various aromatics, cycloalkanes, and terpenes in different microorganisms have been elucidated, and the genetics of several of these routes have been clarified. The toxicity of these compounds to microorganisms is very important in the microbial degradation of hydrocarbons, but not many researchers have studied the mechanism of this toxic action. In this review, we present general ideas derived from the various reports mentioning toxic effects. Most importantly, lipophilic hydrocarbons accumulate in the membrane lipid bilayer, affecting the structural and functional properties of these membranes. As a result of accumulated hydrocarbon molecules, the membrane loses its integrity, and an increase in permeability to protons and ions has been observed in several instances. Consequently, dissipation of the proton motive force and impairment of intracellular pH homeostasis occur. In addition to the effects of lipophilic compounds on the lipid part of the membrane, proteins embedded in the membrane are affected. The effects on the membrane-embedded proteins probably result to a large extent from changes in the lipid environment; however, direct effects of lipophilic compounds on membrane proteins have also been observed. Finally, the effectiveness of changes in membrane lipid composition, modification of outer membrane lipopolysaccharide, altered cell wall constituents, and active excretion systems in reducing the membrane concentrations of lipophilic compounds is discussed. Also, the adaptations (e.g., increase in lipid ordering, change in lipid/protein ratio) that compensate for the changes in membrane structure are treated.
Background
Actinic keratosis lesions occur frequently on sun-exposed skin of Caucasians. They become more prevalent with advancing age and are important in identifying the risk factor of those people possibly predisposed to invasive squamous cell carcinoma. Topical therapies are useful alternatives to cryotherapy for treating diffuse actinic damage and a number of preparations have been developed for treating actinic keratosis.
Objectives
A cumulative meta-analysis was performed to determine the efficacy of imiquimod 5% cream, which presents a new alternative topical therapy for actinic keratosis, and to compare it to 5-fluorouracil for the treatment of actinic keratosis lesions of the face and scalp.
Methods
We searched MEDLINE (1966 to October 2004) for relevant studies evaluating the efficacy of actinic keratosis topical agents imiquimod and 5-fluorouracil (0.5%, 1%, and 5%). Studies included in this meta-analysis required a dosage regimen that was not significantly different from that approved by Health Canada and the U.S. FDA. Studies also required a well-defined treatment duration and followup period, with the primary efficacy variable being the complete (100%) clearance of all actinic keratosis lesions defined as the proportion of patients at followup with no clinically visible lesions in the treatment area. To determine the average efficacy rate for both drugs, the data from each study were combined for that drug.
Results
Ten studies were included in the analysis. The average efficacy rate for each drug (with 95% confidence interval) was 5-fluorouracil, 52 ± 18% ( n = 6 studies, 145 subjects) and imiquimod, 70 ± 12% ( n = 4 studies, 393 subjects).
Conclusions
The results of this meta-analysis show that both imiquimod and 5-fluorouracil are effective methods for the treatment of actinic keratosis and provide a useful alternative to cryotherapy. However, this analysis suggests that imiquimod may have higher efficacy than 5-fluorouracil for actinic keratosis lesions located on the face and scalp and therefore provides another option to dermatologists.
Microbial transformations of cyclic hydrocarbons have received much attention during the past three decades. Interest in the degradation of environmental pollutants as well as in applications of microorganisms in the catalysis of chemical reactions has stimulated research in this area. The metabolic pathways of various aromatics, cycloalkanes, and terpenes in different microorganisms have been elucidated, and the genetics of several of these routes have been clarified. The toxicity of these compounds to microorganisms is very important in the microbial degradation of hydrocarbons, but not many researchers have studied the mechanism of this toxic action. In this review, we present general ideas derived from the various reports mentioning toxic effects. Most importantly, lipophilic hydrocarbons accumulate in the membrane lipid bilayer, affecting the structural and functional properties of these membranes. As a result of accumulated hydrocarbon molecules, the membrane loses its integrity, and an increase in permeability to protons and ions has been observed in several instances. Consequently, dissipation of the proton motive force and impairment of intracellular pH homeostasis occur. In addition to the effects of lipophilic compounds on the lipid part of the membrane, proteins embedded in the membrane are affected. The effects on the membrane-embedded proteins probably result to a large extent from changes in the lipid environment; however, direct effects of lipophilic compounds on membrane proteins have also been observed. Finally, the effectiveness of changes in membrane lipid composition, modification of outer membrane lipopolysaccharide, altered cell wall constituents, and active excretion systems in reducing the membrane concentrations of lipophilic compounds is discussed. Also, the adaptations (e.g., increase in lipid ordering, change in lipid/protein ratio) that compensate for the changes in membrane structure are treated.
Dimethyl sulfoxide (DMSO), an efficient transdermal enhancer, is proposed to alter the skin barrier by, at least partially, disturbing the lipid phase of the stratum corneum (SC). We have investigated, using differential scanning calorimetry and vibrational microspectroscopy, the effect of DMSO on the phase behavior of a lipid mixture formed by N-palmitoyl-d-erythro-sphingosine, deuterated palmitic acid, and cholesterol, mimicking the SC lipid phase. Our results reveal that DMSO favors the disordering of the lipid acyl chains. Moreover, the effect of DMSO is strongly concentration dependent and this dependence is reminiscent of that describing the DMSO transdermal enhancement. DMSO-induced fluidification affects primarily the fatty acid in the mixture. Therefore, it is proposed that the molecular mechanism of the transdermal transport enhancement caused by DMSO is associated with its H-bonding properties; its presence alters the interfacial H-bond network involving the fatty acid molecules and consequently the cohesive lipid packing.
Numerous immunotherapy treatments for cancer are undergoing clinical trials or are already approved for use. One particular area of interest is targeting mechanisms of immune tolerance. Using a murine model of mesothelioma, we investigated the roles of regulatory T-cells, intratumoural transforming growth factor (TGF)-β and the negative regulator molecule cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) in immune tolerance to tumours. It was found that treatments targeting a single negative regulator molecule mechanism were not as effective against tumours as targeting multiple mechanisms simultaneously. Most importantly, it was found that a combined triple treatment of anti-CD25 monoclonal antibody (mAb), anti-CTLA-4 mAb and TGF-β soluble receptor resulted in long-term clearance of tumours and memory against tumour rechallenge. These data suggest that clinical application of immunotherapies against tumours may be improved by simultaneously targeting multiple mechanisms of immune suppression.
The interaction between dimethylsulfoxide (DMSO) and phospholipid monolayers with different polar headgroups was studied using "in situ" Brewster angle microscopy (BAM) coupled to a Langmuir trough. For a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayer, DMSO was shown to significantly impact the structure of the liquid expanded (LE) and gaseous phases. The domains reorganized to much larger domain structures. Domains in the liquid condensed (LC) phase were formed on the DMSO-containing subphase at the mean molecular area where only gaseous and LE phases were previously observed on the pure water subphase. These results clearly demonstrate the condensing and caging effect of DMSO molecules on the DPPC monolayer. Similar effects were found on dipalmitoyl phosphatidyl ethanolamine, glycerol, and serine phospholipids, indicating that the condensing and caging effect is not dependent upon the phospholipid headgroup structure. The DMSO-induced condensing and caging effect is the molecular mechanism that may account for the enhanced permeability of membranes upon exposure to DMSO.
The plant Perilla frutescens is widely employed in Asian medicine. The active components of Perilla include cyclic terpenes, which have a diverse range of antimicrobial, anticancer, sedative, and anti-inflammatory properties, hinting at a membrane-mediated mechanism of action. We have used molecular dynamics (MD) simulations and isothermal titration calorimetry (ITC) to investigate the interaction of four terpenes with model lipid bilayers. The ITC and MD data are mostly in accordance. The terpenes partition into membranes, pack along the lipid tails, and alter bilayer structure and dynamics. Three of the four molecules could cross the bilayer. The carboxylate-group-containing terpene modifies headgroup repulsion and increases the area per lipid by more than 10%, in a manner reminiscent of membrane-thinning peptides and solvents such as DMSO. Our results support the possibility that at least some medicinal properties of volatile Perilla extracts might arise from interactions with the lipid bilayer component of biological membranes.
We have reported previously that a combined intratumoral treatment with anti-CD25mAb/transforming growth factor-β (TGF-β) soluble receptor induced regression of established and subcutaneous AE17 murine mesotheliomas. Here, we have investigated the mechanisms underlying this observation by analyzing the concentrations of interferon-γ (IFN-γ) and TGF-β within tumors at various time points following single regulatory T-cell (T(reg)) depleting anti-CD25mAb, TGF-β soluble receptor, or combined anti-CD25mAb/TGF-β soluble receptor treatment. The combined treatment maintains the intratumoral TGF-β concentration at a significantly lower level than either the untreated controls or the single anti-CD25mAb treatment alone. Also, the lower level of TGF-β correlated with a significantly higher concentration of IFN-γ compared with the single anti-CD25mAb treatment. It was hypothesized that TGF-β was the master regulator of immune suppression in the AE17 model of mesothelioma. However, it was found that although important, this cytokine alone is not responsible for maintaining immune suppression and that multiple mechanisms of suppression exist. Specifically, we have shown that the presence of T(regs) in the tumor draining lymph nodes alters the phenotype of dendritic cells in the same location. These data suggest that because the antitumor immune response is inhibited by multiple mechanisms of suppression, development of immunotherapeutic treatment regimes will be more successful if these mechanisms can be simultaneously inhibited.
To conduct a systematic review to determine clearance rates and adverse effects of topical imiquimod or fluorouracil therapy in the treatment of nonmelanoma skin cancers such as basal (BCC) and squamous cell carcinoma (SCC), and to develop recommendations for the use of topical imiquimod or fluorouracil to treat BCC and SCC.
MEDLINE, CANCERLIT, and Cochrane databases.
Prospective, retrospective, and case studies in English containing a minimum of 4 subjects and a 6-month follow-up or posttreatment histologic evaluation.
We calculated the rate of clearance and adverse effects for BCC subtypes and invasive and in situ SCC treated with topical imiquimod or fluorouracil.
Clearance rates varied by drug regimen, and most of the studies lacked long-term follow-up. Imiquimod use produced the following clearance rates: 43% to 100% for superficial BCC, 42% to 100% for nodular BCC, 56% to 63% for infiltrative BCC, 73% to 88% for SCC in situ, and 71% for invasive SCC. Fluorouracil use produced the following clearance rates: 90% for superficial BCC and 27% to 85% for SCC in situ. Up to 100% and 97% of patients applying imiquimod and fluorouracil, respectively, experienced at least 1 adverse event. Adverse event intensity ranged from mild to severe; erythema, pruritus, and pain were common.
Evidence supports the use of topical imiquimod as monotherapy for superficial BCC and topical fluorouracil as monotherapy for superficial BCC and SCC in situ. Based on the available evidence, the strength of any recommendations for the use of these 2 agents in the primary treatment of these tumors is weak. We recommend that their use be limited to patients with small tumors in low-risk locations who will not or cannot undergo treatment with better-established therapies for which long-term clearance rates have been determined. Long-term clinical follow-up is essential for patients treated with topical imiquimod or fluorouracil. Limitations of therapy include high rates of adverse effects, lower clearance rates than other treatment modalities, dependence on patient adherence to treatment, and higher costs than other therapies.
Imiquimod use in the treatment of basal cell carcinoma (BCC) has proven to be successful in a large percentage of cases, inducing tumor regression; however, the exact cellular mechanism has not been fully clarified.
To measure the morphological changes in the tumor microenvironment and the markers of apoptosis in skin biopsies from patients with BCC before and after imiquimod treatment.
In this open label study, skin biopsies obtained from 11 patients with BCC were evaluated before and after imiquimod treatment for: (i) morphological changes in the tumor microenvironment, with specific emphasis on the immunophenotype of inflammatory cells around the tumor; and (ii) markers of apoptosis, including expression of death receptors.
Imiquimod treatment induced a significant increase in the mononuclear inflammatory response. In the majority of cases, the cellular infiltrate was predominantly composed of CD3(+)/CD4(+) T cells, suggesting that the effector response is mediated by CD3(+)/CD4(+) lymphocytes, with a minor cytotoxic and natural killer (NK) component. An increase in the cytotoxic CD3(+)/CD8(+) T-cell population was also observed. Imiquimod treatment was associated with a marked increased in CD20(+) B cells, and a less pronounced enhancement in cells of monocyte-macrophage origin (CD68(+)) surrounding, or within, the tumor. This finding indicates either that macrophages play a minor role in the imiquimod-induced response, or the recruitment of these cells is related to time and dose. Imiquimod treatment decreased CD1A(+) Langerhans cells in the epidermis and increased the number of CD1A(+) dendritic cells within the tumor aggregates. Imiquimod reduced Bcl-2 expression, but no difference was found in Bax, Fas/FasL, and p53 expression in BCC cells.
Our results support the hypothesis that imiquimod activity in the treatment of BCC is partly a result of a pro-inflammatory action mediated by CD3(+)/CD4(+) lymphoid cells and of a pro-apoptotic activity associated with decreased Bcl-2 expression.
Suppression of an anti-tumor immune response by regulatory T cells (T(regs)) in tumor-bearing hosts is now well established. Previously, we have reported that the intratumoral administration of T(reg)-depleting anti-CD25 monoclonal antibody every 10 days is highly effective at inhibiting the further development of established murine mesotheliomas. Here we investigate the dosage, kinetics, and immunology of this treatment. Further, we show that by precisely timing neutralization of transforming growth factor-β (TGF-β) within treated tumors using a TGF-β-soluble receptor, the efficacy of the treatment can be significantly improved, resulting in tumor regression. We suggest that this combined intratumoral treatment approach can be applied clinically for the treatment of mesothelioma.
Microbial transformations of cyclic hydrocarbons have received much attention during the past three decades. Interest in the degradation of environmental pollutants as well as in applications of microorganisms in the catalysis of chemical reactions has stimulated research in this area. The metabolic pathways of various aromatics, cycloalkanes, and terpenes in different microorganisms have been elucidated, and the genetics of several of these routes have been clarified. The toxicity of these compounds to microorganisms is very important in the microbial degradation of hydrocarbons, but not many researchers have studied the mechanism of this toxic action. In this review, we present general ideas derived from the various reports mentioning toxic effects. Most importantly, lipophilic hydrocarbons accumulate in the membrane lipid bilayer, affecting the structural and functional properties of these membranes. As a result of accumulated hydrocarbon molecules, the membrane loses its integrity, and an increase in permeability to protons and ions has been observed in several instances. Consequently, dissipation of the proton motive force and impairment of intracellular pH homeostasis occur. In addition to the effects of lipophilic compounds on the lipid part of the membrane, proteins embedded in the membrane are affected. The effects on the membrane-embedded proteins probably result to a large extent from changes in the lipid environment; however, direct effects of lipophilic compounds on membrane proteins have also been observed. Finally, the effectiveness of changes in membrane lipid composition, modification of outer membrane lipopolysaccharide, altered cell wall constituents, and active excretion systems in reducing the membrane concentrations of lipophilic compounds is discussed. Also, the adaptations (e.g., increase in lipid ordering, change in lipid/protein ratio) that compensate for the changes in membrane structure are treated.
Many cyclic hydrocarbons, e.g. aromatics, cycloalkanes, and terpenes, are toxic to microorganisms. The primary site of the toxic action is probably the cytoplasmic membrane, but the mechanism of the toxicity is still poorly understood. The effects of cyclic hydrocarbons were studied in liposomes prepared from Escherichia coli phospholipids. The membrane-buffer partition coefficients of the cyclic hydrocarbons revealed that these lipophilic compounds preferentially reside in the membrane. The partition coefficients closely correlated with the partition coefficients of these compounds in a standard octanol-water system. The accumulation of hydrocarbon molecules resulted in swelling of the membrane bilayer, as assessed by the release of fluorescence self-quenching of fluorescent fatty acid and phospholipid analogs. Parallel to the expansion of the membrane, an increase in membrane fluidity was observed. These effects on the integrity of the membrane caused an increased passive flux of protons and carboxyfluorescein. In cytochrome c oxidase containing proteoliposomes, both components of the proton motive force, the pH gradient and the electrical potential, were dissipated with increasing concentrations of cyclic hydrocarbons. The dissipating effect was primarily the result of an increased permeability of the membrane for protons (ions). At higher concentrations, cytochrome c oxidase was also inactivated. The effective concentrations of the different cyclic hydrocarbons correlated with their partition coefficients between the membrane and aqueous phase. The impairment of microbial activity by the cyclic hydrocarbons most likely results from hydrophobic interaction with the membrane, which affects the functioning of the membrane and membrane-embedded proteins.
Defensins, a family of cationic, structurally related, antimicrobial peptides, contribute to host defense by disrupting the cytoplasmic membrane of microbes. Here we show that human neutrophil defensins selectively induce the migration of human CD4+/CD45RA+ naive and CD8+, but not CD4+/CD45RO+ memory, T cells. Moreover, human neutrophil defensins are chemotactic for immature human dendritic cells derived from either CD34+ progenitors or peripheral blood monocytes. Upon maturation induced by treatment with tumor necrosis factor alpha (TNF-alpha), dendritic cells lose their responsiveness to human neutrophil defensins. The chemotactic effect of human neutrophil defensins on both T and dendritic cells is pertussis toxin-sensitive, suggesting that a G(ialpha) protein-coupled receptor is responsible. Human neutrophil defensins are also chemotactic for immature murine dendritic cells. These data suggest that, in addition to their antimicrobial role, human neutrophil defensins also contribute to adaptive immunity by mobilizing T cells and dendritic cells.
Acute inflammatory lung injury is often a delayed complication of critical illness and is associated with increased mortality. High mobility group-1 (HMG-1) protein, in addition to its role as a transcriptional regulatory factor, has recently been identified as a late mediator of endotoxin lethality. In the present studies, HMG-1 given intratracheally produced acute inflammatory injury to the lungs, with neutrophil accumulation, the development of lung edema, and increased pulmonary production of IL-1beta, TNF-alpha, and macrophage-inflammatory protein-2. In endotoxin-induced acute lung inflammation, administration of anti-HMG-1 Abs either before or after endotoxin exposure decreased the migration of neutrophils to the lungs as well as lung edema. These protective effects of anti-HMG-1 were specific, because pulmonary levels of IL-1beta, TNF-alpha, or macrophage-inflammatory protein-2 were not decreased after therapy with anti-HMG-1. Together, these findings indicate that HMG-1 is a distal mediator of acute inflammatory lung injury.
"... It is likely that the leukocyte granulations are in fact secretory products, which the cell dissolves and spreads to the environment as needed", Paul Ehrlich, 1900. Neutrophil granules have long been recognized as mediators of innate host defense. Newly discovered functions for individual granule proteins suggest that granule constituents may also participate in adaptive immune responses. Neutrophil granule-derived cathepsin G, azurocidin/CAP37 and alpha-defensins have been shown to be chemotactic for mononuclear cells and neutrophils. Analysis of the chemotactic activity of alpha-defensins shows that they induce CD45RA+ and CD8 T-lymphocyte cell migration at concentrations 10 to 100-fold below that required for direct bactericidal activity. Additionally, alpha and beta defensins form chemotactic gradients for immature dendritic cells. Recruiting immature dendritic cells to sites of infection is one way for neutrophil granule proteins to initiate adaptive immune responses. Granules found in other leukocytes such as mast cells also contain serine proteases, such as chymase, that are known to chemoattract neutrophils and mononuclear cells. Preliminary evidence suggests that exocytosis of granule-derived products from a variety of leukocytes can mobilize inflammatory cells and immunocytes. Thus, leukocyte granule-derived proteins, more rapidly than chemokines, can mobilize cells that mediate innate host defense and adaptive immunity.
We have investigated the effects of 1,8-cineole [the main component of essential oil prepared from bay-leaves Laurus nobilis L.)] on DNA of human leukemia cell lines, Molt 4B, HL-60 and stomach cancer KATO III cells. Specific induction of apoptosis by 1,8-cineole was observed in human leukemia Molt 4B and HL-60 cells, but not in human stomach cancer KATO III cells. Morphological changes showing apoptotic bodies were observed in the human leukemia HL-60 cells treated with 1,8-cineole. The fragmentations of DNA by cineole to oligonucleosomal-sized fragments that is a characteristic of apoptosis were concentration- and time-dependent in Molt 4B and HL-60 cells, but not in KATO III cells. The present study shows that the suppression growth by 1,8-cineole in the leukemia cell lines results from the induction of apoptosis by this compound.
Standard chemotherapeutic agents used for the treatment of pre-cancerous skin lesions and non-melanoma skin cancers are not completely effective. Several studies have suggested that repeated inflammatory sunburn reactions, which include the induction of cyclooxygenase-2 (COX-2) and the subsequent production of prostaglandins, play a role in skin cancer development. COX-2 inhibition has been demonstrated to be a potent means of preventing skin cancer development in mice; however, COX-2 inhibitors alone are not effective as chemotherapeutic agents. Data in a variety of cancer types suggest greater efficacy in treating tumors with combination chemotherapies. Therefore, we hypothesized that a combination of the chemotherapeutic agent 5-fluorouracil (5-FU) and the COX-2 inhibitor and anti-inflammatory drug celecoxib would act synergistically to regress tumors in a murine model of ultraviolet light B- (UVB-) induced carcinogenesis. We found that topical treatment with 5-FU and celecoxib together was up to 70% more effective in reducing the number of UVB-induced skin tumors than 5-FU treatment alone. Our data suggest that more effective chemotherapy regimens can be developed to treat the millions of pre-cancerous and cancerous skin lesions that arise every year, which could ultimately lead to a significant reduction in costs and cosmetic defects (scarring) associated with surgical interventions.
The search for innovative therapeutic approaches based on the use of new substances is gaining more interest in clinical oncology. In this in vitro study the potential anti-tumoral activity of tea tree oil, distilled from Melaleuca alternifolia, was analyzed against human melanoma M14 WT cells and their drug-resistant counterparts, M14 adriamicin-resistant cells. Both sensitive and resistant cells were grown in the presence of tea tree oil at concentrations ranging from 0.005 to 0.03%. Both the complex oil (tea tree oil) and its main active component terpinen-4-ol were able to induce caspase-dependent apoptosis of melanoma cells and this effect was more evident in the resistant variant cell population. Freeze-fracturing and scanning electron microscopy analyses suggested that the effect of the crude oil and of the terpinen-4-ol was mediated by their interaction with plasma membrane and subsequent reorganization of membrane lipids. In conclusion, tea tree oil and terpinen-4-ol are able to impair the growth of human M14 melanoma cells and appear to be more effective on their resistant variants, which express high levels of P-glycoprotein in the plasma membrane, overcoming resistance to caspase-dependent apoptosis exerted by P-glycoprotein-positive tumor cells.
Topical 5-fluorouracil (5-FU) cream is widely used in the treatment of actinic keratoses (AKs) but the optimum treatment regimen that provides efficacy while minimizing side-effects remains unclear.
A randomized trial to compare the efficacy and side-effects of daily vs. weekly application of 5% 5-FU in the treatment of AKs of the scalp and face.
Twenty patients were recruited and randomized to two groups. Group 1 (13 patients) applied 5% 5-FU twice daily for 3 weeks, group 2 (seven patients) applied 5% 5-FU twice daily for 1 day per week for 12 weeks. Patients were reviewed at weeks 3, 12, 24 and 52. At each review a lesion count and lesion map were completed and patients were asked to score efficacy and inflammation.
At week 0 the median lesion count was the same in both groups, 17.5 lesions. At 12 weeks the median lesion count in group 1 had fallen to 0 where it remained for the duration of follow-up. In group 2 the median lesion count fell to 6 at 12 weeks, 5.5 at 24 weeks and was 3 at 52 weeks. The difference in the lesion count was significant at all time points after week 0: P < 0.05 at weeks 12 and 52, and P < 0.01 at week 24. The mean inflammation score was higher in patients clear of AKs at 12 weeks compared with those who had not cleared, 3.8 compared with 1.9. This difference was statistically significant (P < 0.05) suggesting that inflammation is necessary for efficacy.
We conclude that daily application of 5% 5-FU cream is more effective than weekly application at clearing AKs from the scalp and face. Our results also suggest that inflammation is likely to be required to achieve a therapeutic effect.
The essential oil of Melaleuca alternifolia, also known as tea tree or melaleuca oil, is widely available and has been investigated as an alternative antimicrobial, anti-inflammatory and anti-cancer agent. While these properties are increasingly well characterised, relatively limited data are available on the safety and toxicity of the oil. Anecdotal evidence from almost 80 years of use suggests that the topical use of the oil is relatively safe, and that adverse events are minor, self-limiting and occasional. Published data indicate that TTO is toxic if ingested in higher doses and can also cause skin irritation at higher concentrations. Allergic reactions to TTO occur in predisposed individuals and may be due to the various oxidation products that are formed by exposure of the oil to light and/or air. Adverse reactions may be minimised by avoiding ingestion, applying only diluted oil topically and using oil that has been stored correctly. Data from individual components suggest that TTO has the potential to be developmentally toxic if ingested at higher doses, however, TTO and its components are not genotoxic. The limited ecotoxicity data available indicate that TTO is toxic to some insect species but more studies are required.
Tea tree oil is the essential oil steam-distilled from Melaleuca alternifolia, an Australian native plant. In recent years it has become increasingly popular as an antimicrobial for the treatment of conditions such as tinea pedis and acne.
To investigate the anti-inflammatory properties of tea tree oil on histamine-induced weal and flare.
Twenty-seven volunteers were injected intradermally in each forearm (study and control assigned on an alternating basis) with histamine diphosphate (5 microg in 50 microL). Flare and weal diameters and double skin thickness were measured every 10 min for 1 h to calculate flare area and weal volume. At 20 min, 25 microL of 100% tea tree oil was applied topically to the study forearm of 21 volunteers. For six volunteers, 25 microL paraffin oil was applied instead of tea tree oil.
Application of liquid paraffin had no significant effect on histamine-induced weal and flare. There was also no difference in mean flare area between control arms and those on which tea tree oil was applied. However, mean weal volume significantly decreased after tea tree oil application (10 min after tea tree oil application, P = 0.0004, Mann-Whitney U-test).
This is the first study to show experimentally that tea tree oil can reduce histamine-induced skin inflammation.
Actinic keratosis lesions occur frequently on sun-exposed skin of Caucasians. They become more prevalent with advancing age and are important in identifying the risk factor of those people possibly predisposed to invasive squamous cell carcinoma. Topical therapies are useful alternatives to cryotherapy for treating diffuse actinic damage and a number of preparations have been developed for treating actinic keratosis.
A cumulative meta-analysis was performed to determine the efficacy of imiquimod 5% cream, which presents a new alternative topical therapy for actinic keratosis, and to compare it to 5-fluorouracil for the treatment of actinic keratosis lesions of the face and scalp.
We searched MEDLINE (1966 to October 2004) for relevant studies evaluating the efficacy of actinic keratosis topical agents imiquimod and 5-fluorouracil (0.5%, 1%, and 5%). Studies included in this meta-analysis required a dosage regimen that was not significantly different from that approved by Health Canada and the U.S. FDA. Studies also required a well-defined treatment duration and followup period, with the primary efficacy variable being the complete (100%) clearance of all actinic keratosis lesions defined as the proportion of patients at followup with no clinically visible lesions in the treatment area. To determine the average efficacy rate for both drugs, the data from each study were combined for that drug.
Ten studies were included in the analysis. The average efficacy rate for each drug (with 95% confidence interval) was 5-fluorouracil, 52 +/- 18% (n = 6 studies, 145 subjects) and imiquimod, 70 +/- 12% (n = 4 studies, 393 subjects).
The results of this meta-analysis show that both imiquimod and 5-fluorouracil are effective methods for the treatment of actinic keratosis and provide a useful alternative to cryotherapy. However, this analysis suggests that imiquimod may have higher efficacy than 5-fluorouracil for actinic keratosis lesions located on the face and scalp and therefore provides another option to dermatologists.
We hypothesised that T(reg) cells preferentially expand/infiltrate inside murine mesotheliomas. Immunotherapy based on the manipulation of T(reg) cell populations should therefore be targeted to the tumour site. The AE17 murine mesothelioma model was used for this study. Both intra-tumoural T(reg) cells and those in the periphery of tumour-bearing mice were identified by flow cytometry. The effect on tumour growth of intra-tumoural depletion of T(reg) cells using the PC61 anti-CD25 mAb was then examined. We identified CD4+ T(reg) cells co-expressing both the CD25 cell surface marker and the transcription factor Foxp3 within murine mesotheliomas. These intra-tumoural T(reg) cells increase significantly as a percentage of total CD4+ T cells within the tumour as it grows. We showed that the depletion of intra-tumoural T(reg) cells with anti-CD25 mAb injected directly into the tumours can cause significantly reduced tumour growth. Localised, intra-tumoural depletion of T(reg) cells is a new, clinically relevant treatment option for established tumours.
Tea tree oil (TTO) is the essential oil steam-distilled from Melaleuca alternifolia, a species of northern New South Wales, Australia. It exhibits a broad-spectrum antimicrobial activity and an antifungal activity. Only recently has TTO been shown to inhibit the in vitro growth of multidrug resistant (MDR) human melanoma cells. It has been suggested that the effect of TTO on tumor cells could be mediated by its interaction with the plasma membrane, most likely by inducing a reorganization of lipid architecture. In this paper we report biophysical and structural results obtained using simplified planar model membranes (Langmuir films) mimicking lipid "rafts". We also used flow cytometry analysis (FCA) and freeze-fracturing transmission electron microscopy to investigate the effects of TTO on actual MDR melanoma cell membranes. Thermodynamic (compression isotherms and adsorption kinetics) and structural (Brewster angle microscopy) investigation of the lipid monolayers clearly indicates that TTO interacts preferentially with the less ordered DPPC "sea" and that it does not alter the more ordered lipid "rafts". Structural observations, performed by freeze fracturing, confirm that TTO interacts with the MDR melanoma cell plasma membrane. Moreover, experiments performed by FCA demonstrate that TTO does not interfere with the function of the MDR drug transporter P-gp. We therefore propose that the effect exerted on MDR melanoma cells is mediated by the interaction with the fluid DPPC phase, rather than with the more organized "rafts" and that this interaction preferentially influences the ATP-independent antiapoptotic activity of P-gp likely localized outside "rafts".
Anthracyclin-treated tumor cells are particularly effective in eliciting an anticancer immune response, whereas other DNA-damaging agents such as etoposide and mitomycin C do not induce immunogenic cell death. Here we show that anthracyclins induce the rapid, preapoptotic translocation of calreticulin (CRT) to the cell surface. Blockade or knockdown of CRT suppressed the phagocytosis of anthracyclin-treated tumor cells by dendritic cells and abolished their immunogenicity in mice. The anthracyclin-induced CRT translocation was mimicked by inhibition of the protein phosphatase 1/GADD34 complex. Administration of recombinant CRT or inhibitors of protein phosphatase 1/GADD34 restored the immunogenicity of cell death elicited by etoposide and mitomycin C, and enhanced their antitumor effects in vivo. These data identify CRT as a key feature determining anticancer immune responses and delineate a possible strategy for immunogenic chemotherapy.
For the last four decades, the treatment of cancer has relied on four treatment modalities, namely surgery, radiotherapy, cytotoxic chemotherapy, and hormonotherapy. Most of these therapies are believed to directly attack and eradicate tumor cells. The emerging concept that cancer is not just a disease of a tissue or an organ but also a host disease relies on evidence of tumor-induced immunosuppression and polymorphisms in genes involved in host protection against tumors. This theory is now gaining new impetus, based on our recent data showing that optimal therapeutic effects require the immunoadjuvant effect of tumor cell death induced by cytotoxic anticancer agents. Here, we show that the release of the high mobility group box 1 protein (HMGB1) by dying tumor cells is mandatory to license host dendritic cells (DCs) to process and present tumor antigens. HMGB1 interacts with Toll-like receptor 4 (TLR4) on DCs, which are selectively involved in the cross-priming of anti-tumor T lymphocytes in vivo. A TLR4 polymorphism that affects the binding of HMGB1 to TLR4 predicts early relapse after anthracycline-based chemotherapy in breast cancer patients. This knowledge may be clinically exploited to predict the immunogenicity and hence the efficacy of chemotherapeutic regimens.
Treatment with 5-fluorouracil and celecoxib displays synergistic regression of ultraviolet light B-induced skin tumors
- Breza Ta Wilgus
- Ts Jr
- Kl Tober
- Oberyszyn
Wilgus TA, Breza Jr TS, Tober KL, Oberyszyn TM. Treatment with 5-fluorouracil and celecoxib displays synergistic regression of ultraviolet light B-induced skin tumors. J Invest Dermatol 2004;122:1488–94.
Effect of dimethyl sulfoxide on the phase behavior of model stratum corneum lipid mixtures Intra-tumoural regulatory T cells: a potential new target in cancer immunotherapy
- S Kwak
- M Lafleur
- Dj Needham
- Jx Lee
- Beilharz
Kwak S, Lafleur M. Effect of dimethyl sulfoxide on the phase behavior of model stratum corneum lipid mixtures. Chem Phys Lipids 2009;161:11–21. [35] Needham DJ, Lee JX, Beilharz MW. Intra-tumoural regulatory T cells: a potential new target in cancer immunotherapy. Biochem Biophys Res Commun 2006;343:684–91.
Mechanisms of membrane toxicity of hydrocarbons Cancer Chemother Pharmacol key component of the antitumor inflammation
- J Sikkema
- Ja De
- Poolman
Sikkema J, de Bont JA, Poolman B. Mechanisms of membrane toxicity of hydrocarbons. Microbiol Rev 1995;59:201–22. oil. Cancer Chemother Pharmacol key component of the antitumor inflammation. Brit J Dermatol D.J. Ireland et al. / Journal of Dermatological Science 67 (2012) 120–129 128
The immune system. Second of two parts
- Delves
Topical imiquimod or fluorouracil therapy for basal and squamous cell carcinoma: a systematic review
- Love