Article

Inactivation of Airborne Influenza Virus by Tea Tree and Eucalyptus Oils

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Abstract

Our previous studies demonstrated that precoating of filter fibres with biologically active tea tree oil (TTO) enhances physical collection efficiency of conventional HVAC filters and provides cost effective and rapid inactivation of captured bacterial and fungal particles on the filter surface. The main aim of this study was to investigate the antiviral activity of two natural disinfectants, i.e. TTO and eucalyptus oil (EUO) against the influenza virus captured onto the filter surface. It was found that both tested oils possess strong antiviral properties when used as fibre coating materials, capable of inactivating captured microorganisms within 5–10 minutes of contact on the fibre surface. The antiviral activity of TTO was also successfully challenged in aerosol form by mixing viable airborne viral particles with oil droplets in the rotational aerosol chamber. The results look very promising for further development of virus inactivating procedures and technologies for air quality applications.

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... Filters were tested with a starch concentration of only up to 4 %, due to higher concentrations resulting in the filters becoming too fragile to adequately perform. Finally, tea tree and eucalyptus oils have also been applied as coatings and used as natural disinfectants (Pyankov et al., 2012). The oils were used to coat different filters and challenged against a strain of the influenza virus, where both oils were shown to inactivate the filtered virus within 5-10 min. ...
... The natural disinfectants, dialdehyde starch, tea tree oil, and eucalyptus oils are available to purchase and are safe for use. However, their inactivation and filtration rates are not competitive compared to other sources of inactivation in this section (Woo et al., 2012;Pyankov et al., 2012). ...
... Filter Coatings (Joe et al., 2014;Park and Hwang, 2014;Heo et al., 2020;Pazokifard et al., 2012;Woo et al., 2012;Pyankov et al., 2012;Chen and Liang, 2020;Ziental et al., 2020;Monge et al., 2010;Skyspring, 2021;Sigma-Aldrich, 2021) • Relatively easy to incorporate coated filters into an existing HVAC system. • The nanoparticle field is currently growing and will continue to expand in applications and available technology. ...
Article
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COVID-19 forced the human population to rethink its way of living. The threat posed by the potential spread of the virus via an airborne transmission mode through ventilation systems in buildings and enclosed spaces has been recognized as a major concern. To mitigate this threat, researchers have explored different technologies and methods that can remove or decrease the concentration of the virus in ventilation systems and enclosed spaces. Although many technologies and methods have already been researched, some are currently available on the market, but their effectiveness and safety concerns have not been fully investigated. To acquire a broader view and collective perspective of the current research and development status, this paper discusses a comprehensive review of various workable technologies and methods to combat airborne viruses, e.g., COVID-19, in ventilation systems and enclosed spaces. These technologies and methods include an increase in ventilation, high-efficiency air filtration, ionization of the air, environmental condition control, ultraviolet germicidal irradiation, non-thermal plasma and reactive oxygen species, filter coatings, chemical disinfectants, and heat inactivation. Research gaps have been identified and discussed, and recommendations for applying such technologies and methods have also been provided in this article.
... Interestingly, citric acid based buffer solution containing nasal sprays were quoted to reduce the titer of an influenza A Sydney/5/97 (H3N2) influenza strain by up to 3 logs after 1 minute contact time [32,33]. Similarly, some oils, such as tea tree oil or oil of thyme are associated with good anti-viral properties [34]. For any use on masks and on surfaces that are easily touched, it is of course important to use disinfectants that are low in toxicity and are ideally found in existing daily use items. ...
... Ionic species and substances with strong hydrogen bonding are expected to disrupt the viral packaging layer or 'docking' surfaces described as trimeric spike glycoproteins [48]. From an alternative point of view, tea tree oil for example has also been reported as having good antiviral properties when applied on surfaces [34], or citric acid which has strong ionic features in the low pH range that is regarded as anti-viral [10]. Our intent here is not to specify the exact anti-viral properties and individual pro/cons of specific disinfectants, but rather to show how such active compounds could be easily applied in an improvised manner and whether they can remain on surfaces as very thin layers. ...
... The residue of a commercial disinfectant cleaner product (Pine-Sol, mostly surfactant in water) easily remained on the crystal surface for 24 h at both temperatures (Fig. 11). In contrast, despite its attractive smell and anti-viral properties [34], tea tree oil dissolved in the alcohol/water mix quickly disappeared within 1 h at 25°C (Fig. 12). Tea tree oil might be helpful for short-term disinfection, but clearly will not remain sufficiently on surfaces. ...
Article
The current COVID-19 pandemic has resulted in globally constrained supplies for face masks and personal protective equipment (PPE). Production capacity is limited in many countries and the future course of the pandemic will likely continue with shortages for high quality masks and PPE in the foreseeable future. Hence, expectations are that mask reuse, extended wear and similar approaches will enhance the availability of personal protective measures. Repeated thermal disinfection could be an important option and likely easier implemented in some situations, at least on the small scale, than UV illumination, irradiation or hydrogen peroxide vapor exposure. An overview on thermal responses and ongoing filtration performance of multiple face mask types is provided. Most masks have adequate material properties to survive a few cycles (i.e. 30 min disinfection steps) of thermal exposure in the 75 °C regime. Some are more easily affected, as seen by the fusing of plastic liner or warping, given that preferred conditioning temperatures are near the softening point for some of the plastics and fibers used in these masks. Hence adequate temperature control is equally important. As guidance, disinfectants sprayed via dilute solutions maintain a surface presence over extended time at 25 and 37 °C. Some spray-on alcohol-based solutions containing disinfectants were gently applied to the top surface of masks. Neither moderate thermal aging (less than 24 h at 80 and 95 °C) nor gentle application of surface disinfectant sprays resulted in measurable loss of mask filter performance. Subject to bio-medical concurrence (additional checks for virus kill efficiency) and the use of low risk non-toxic disinfectants, such strategies, either individually or combined, by offering additional anti-viral properties or short term refreshing, may complement reuse options of professional masks or the now ubiquitous custom-made face masks with their often unknown filtration effectiveness.
... Aromaterapi dengan tea tree oil dan eucalyptus oil dipercaya dapat mengurangi keluhan batuk pilek. tea tree (Melaleuca alternifolia Cheel) merupakan tanaman asli Australia, mirip dengan pohon teh (Camalia spp) yang digunakan sebagai antiseptik terhadap bakteri, jamur dan virus, obat-obatan dan kosmetika, dikenal sebagai tea tree oil karena diekstrak dari daunnya [8]. ...
... Menurut penelitian Oleg V. Pyankov (2012) mengatakan bahwa tea tree dapat digunakan sebagai antiseptik terhadap bakteri, jamur dan virus, obat-obatan dan kosmetika. Hasil penelitian mengatakan bahwa Tea Tree Oil memiliki aksi anti virus yang kuat untuk membunuh virus di Udara, aktivitas antivirus dari Tea Tree Oil efektif terhadap virus influenza dalam bentuk aerosol dengan pelaksanaan selama 15 menit pada debit 4 L / menit [8]. Hasil penelitian Icca Narayani Pramudaningsih (2019) mengatakan bahwa reponden yang menggunakan Eucalyptus oil sesak nafasnya berkurang hal ini dikarenakan minyak Eucalyptus mengandung senyawa kimia 1,8-sineol yang memiliki aktifitas antiseptik dan ekspektoran yang digunakan pada pelega hidung dan tenggorokan sehingga dapat mengurangi sesak nafas pada penderita asma. ...
... Hal ini sejalan penelitian Oleg V. Pyankov (2012) mengatakan bahwa tea tree dapat digunakan sebagai antiseptik terhadap bakteri, jamur dan virus, obat-obatan dan kosmetika. Hasil penelitian mengatakan bahwa Tea Tree Oil memiliki aksi antivirus yang kuat untuk membunuh virus diudara, aktivitas antivirus dari Tea Tree Oil efektif terhadap virus influenza dalam bentuk aerosol dengan pelaksanaan selama 15 menit pada debit 4 L / menit [8]. ...
Article
Common cold is a mild viral infection of the upper respiratory tract, nose, and throat. Common cold suffered by each toddler in Indonesia is predicted to occur three to six times a year, which means that a toddler may experience three to six times of coughs and colds every year. Common cold is also a symptom of Covid-19 whose early treatments used symptomatic and non-pharmacological therapy including tea tree oil and eucalyptus oil aromatherapy. Related to this, this paper reveals the effectiveness of tea tree oil and eucalyptus oil aromatherapy for the healing period of 1 to 2-year-old toddlers in T W Independent Midwifery Practice (IMP). This paper employs quasy experiment design with non-equivalent control group model. Sample includes 14 toddlers with the age of 1 to 2-year-old. Seven of them were given tea tree oil, while the rest were given eucalyptus oil aromatherapy with accidental sampling technique. Aromatherapy was given once a day for seven days. Findings showed that the healing period of the control and intervention group was four to five days and according to the Mann Whitney trial, p-value of 0,530 (0,05) was obtained. In conclusion, there is no difference between the healing period of common cold using tea tree oil and eucalyptus oil aromatherapy for 1 to 2-year-old toddlers in T W Independent Midwifery Practice (IMP). Tea tree oil and eucalyptus oil aromatherapy can be used to accelerate the healing period of common cold suffered by toddlers.
... Phytochemicals, on the contrary, are an attractive source of environmental friendly, relatively inexpensive and available disinfectants [4]. Among them, various essential oils (EOs) from plants have been screened to assess their antimicrobial, antifungal, and antiviral activities [6]. Essential oils are complex mixtures of volatile compounds, such as monoterpenes, sesquiterpenes and phenylpropenes [7,8], which have been investigated for a wide range of properties [9][10][11]. ...
... Cont. The components are reported according to their elution order on apolar column; 2 Linear Retention Indices measured on apolar column; 3 Linear Retention indices from the literature;4 Percentage mean values of C. bergamia vapor phase components;5 Percentage mean values of I. verum vapor phase components;6 Percentage mean values of M. alternifolia vapor phase components;7 Percentage mean values of E. globulus vapor phase components; -Not detected; tr: traces (mean value <0.1%). ...
Article
Influenza viruses are transmitted from human to human via airborne droplets and can be transferred through contaminated environmental surfaces. Some works have demonstrated the efficacy of essential oils (EOs) as antimicrobial and antiviral agents, but most of them examined the liquid phases, which are generally toxic for oral applications. In our study, we describe the antiviral activity of Citrus bergamia, Melaleuca alternifolia, Illicium verum and Eucalyptus globulus vapor EOs against influenza virus type A. In the vapor phase, C. bergamia and M. alternifolia strongly reduced viral cytopathic effect without exerting any cytotoxicity. The E. globulus vapor EO reduced viral infection by 78% with no cytotoxicity, while I. verum was not effective. Furthermore, we characterized the EOs and their vapor phase by the head-space gas chromatography–mass spectrometry technique, observing that the major component found in each liquid EO is the same one of the corresponding vapor phases, with the exception of M. alternifolia. To deepen the mechanism of action, the morphological integrity of virus particles was checked by negative staining transmission electron microscopy, showing that they interfere with the lipid bilayer of the viral envelope, leading to the decomposition of membranes. We speculated that the most abundant components of the vapor EOs might directly interfere with influenza virus envelope structures or mask viral structures important for early steps of viral infection.
... A study shows that a layer of sulphated polysaccharides on sanitary items destroys SARS-COV-2 on the surface [43]. Apart from algal derived compounds, tea tree oil and eucalyptus oils with biologically active compounds has natural virucidal properties which can be possibly used to coat surfaces for gaining antiviral properties [44].These essential oils showed significant antiviral action against wide-rangingorganisms such as bacterial, fungal, and virus-related species, and mainly were found to be active in inactivation of airborne influenza virus as soon as it was applied on the mesh surfaces as the pre-coating of the mesh fibers [44]. Recently, a study showed that by modifying cyclodextrins, a naturally occurring glucose derivatives from starch rich natural sources, non-toxic antiviral materials can be developed which have a competence to destroy viruses on coming in contact with the materials [45]. ...
... A study shows that a layer of sulphated polysaccharides on sanitary items destroys SARS-COV-2 on the surface [43]. Apart from algal derived compounds, tea tree oil and eucalyptus oils with biologically active compounds has natural virucidal properties which can be possibly used to coat surfaces for gaining antiviral properties [44].These essential oils showed significant antiviral action against wide-rangingorganisms such as bacterial, fungal, and virus-related species, and mainly were found to be active in inactivation of airborne influenza virus as soon as it was applied on the mesh surfaces as the pre-coating of the mesh fibers [44]. Recently, a study showed that by modifying cyclodextrins, a naturally occurring glucose derivatives from starch rich natural sources, non-toxic antiviral materials can be developed which have a competence to destroy viruses on coming in contact with the materials [45]. ...
Article
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Abstract- The review is aimed at understanding the immune dysregulation by the novel virus, COVID-19. The review also highlighted the significant findings that have been published in the previous studies through secondary research about the mechanism of immune dysregulation, transmission, and progression of the virus across the globe. Adults above the age of 60 year with co-morbidities such as cardiac and renal dysfunction, hypertension, and diabetes are predisposed to a greater risk of COVID-19 infection. The virus impairs the physiological, psychological, and metabolic functioning of the patient. The paper gained an insight into the need for immunization priority for the Indian population and recommendations for effective policy making in vaccine development and distribution. Keywords: Covid-19, transmission, immune response, Covid-19 vaccine, immunization, immune dysregulation, Covid-19 India Graphical Abstract:
... In an effort to identify efficient antimicrobial materials, many researchers have investigated natural products for potential use in air filters and have demonstrated that some natural products suppress the growth and reproduction of, or are lethal to, microorganisms (Kuroyanagi et al. 1999;Donaldson et al. 2005;Pibiri et al. 2006). Natural antimicrobial products such as Melaleuca alternifolia (tea tree oil) and Eucalyptus oil can be used as a coating for filters to inactivate fungal spores, bacteria, and influenza viruses (Pyankov et al. 2008;Huang et al. 2010;Pyankov et al. 2012). Lee et al. (2013) used Mukdenia rossil (olive) Koidz to create an antimicrobial air filter . ...
Article
Bioaerosols, such as bacterial and fungal cells and their spores, are components of indoor airborne particulate matter and have been associated with human health problems as well as various environmental issues. Natural antimicrobial products have been used in air filters for bioaerosol control. However, natural products may lose some function due to their sensitivity to environmental factors such as temperature and humidity. In this study, we investigated the effects of temperature on antimicrobial fiber filters coated with nanoparticles of a natural product, namely, Sophora flavescens extract. Inactivation efficiency decreased with increasing temperature and treatment time. A quantitative chemical analysis of the filters revealed that the quantities of antimicrobial compounds decreased noticeably, with a consequent decrease in antimicrobial activity. In addition, the S. flavescens nanoparticles on the filter fiber surface melted gradually as treatment time increased at temperatures >100°C. This change in nanoparticle morphology in turn affected the pressure and filtration efficiency of filters, both of which decreased with increasing temperature and treatment time. These results could provide a scientific basis for the improvement of indoor air-quality control using antimicrobial air filters coated with S. flavescens nanoparticles.Copyright 2014 American Association for Aerosol Research
... Grinshpun et al. [39] investigated inactivation of aerosolized bacteriophage MS2 in a continuous air flow chamber with axial heating for periods of 0.1-1 s. Pyankov et al. [40] used sprayed tea tree and eucalyptus oils for inactivating influenza virus A stain NWS/G70C (H11N9). However, to our knowledge, no research on the inactivation of airborne viruses by Ag nanoparticles has been released to the public. ...
... Currently grate progress has been made in the biological activity of essential oils of eucalyptus family. These studies well supported the application of some of essential oils of eucalyptuses for antibacterial [1][2][3] , antifungal 4-12 , antioxidant 13,14 , cytotoxic 15 and medical treatment [16][17][18][19][20][21] . Ishikawa and coworkers 22 demonstrated that the Eucalyptus extract promotes decreased ceramide (CER) synthesis in cultured keratinocytes and accelerates the recovery of hydration in a barrier-disrupted model of human skin. ...
Article
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This study was designed to examine the chemical composition of essential oils of three Eucalyptus spices (E. spathulata, E. microtheca, and E. torquata) and in vitro antifungal activities of the essential oils of five Eucalyptus spices (E. largiflorens, E. oleosa, E. spathulata, E. microtheca, and E. torquata). The chemical composition of the hydrodistilled essential oils of leaves of these three spices were analyzed by GC-MS and GC-FID. The predominant and common components in the all oils were α-pinene (2.3 - 14.5 %), 1,8- cineole (6.6 - 69.6 %), terpinen-4-ol (0.8 - 9.6 %), α-terpineol (1.1 - 4.3 %), aromadenderene (0.3 - 10.5 %) and viridiflorol (0.0 - 5.7 %). The antifungal activities of essential oils have been investigated by minimum inhibitory concentration (MIC) and disc diffusion methods against A. flavus, A. parasiticus, A. niger, P. chryzogenum and P. citrinum. A high antifungal activity was found in the leaf oil of E. largiflorens. The relationship between the some major constituents and the antifungal activity was also discussed. We concluded that the terpinen-4-ol may be considered as correspond antifungal constituent.
... Recently, extracts of natural products with antimicrobial activity have been considered as novel, efficient, and cost-effective materials for the development of antimicrobial filter media (Dixon, 2001). Plant extracts, such as Melaleuca alternifolia (tea tree), Eucalyptus, and Sophora flavescens, in particular, can be used as a coating for filters to inactivate fungal spores, bacteria, and influenza viruses (Huang et al., 2010;Hwang et al., 2015aHwang et al., , 2015bPyankov et al., 2008;Pyankov et al., 2012). The treatment of filter surfaces with nanosized particles of a natural product is an effective method for enhancing their antimicrobial activity, because the nanosized natural products provide the maximum possible specific surface area to contact surrounding agents. ...
Article
In this study, we demonstrated an antimicrobial nanoparticle-coated electrostatic (ES) air filter. Antimicrobial natural-product Sophora flavescens nanoparticles were produced using an aerosol process, and were continuously deposited onto the surface of air filter media. For the electrostatic activation of the filter medium, a corona discharge electrification system was used before and after antimicrobial treatment of the filter. In the antimicrobial treatment process, the deposition efficiency of S. flavescens nanoparticles on the ES filter was ~12% higher than that on the pristine (Non-ES) filter. In the evaluation of filtration performance using test particles (a nanosized KCl aerosol and submicron-sized Staphylococcus epidermidis bioaerosol), the ES filter showed better filtration efficiency than the Non-ES filter. However, antimicrobial treatment with S. flavescens nanoparticles affected the filtration efficiency of the filter differently depending on the size of the test particles. While the filtration efficiency of the KCl nanoparticles was reduced on the ES filter after the antimicrobial treatment, the filtration efficiency was improved after the recharging process. In summary, we prepared an antimicrobial ES air filter with >99% antimicrobial activity, ~92.5% filtration efficiency (for a 300-nm KCl aerosol), and a ~0.8mmAq pressure drop (at 13cm/s). This study provides valuable information for the development of a hybrid air purification system that can serve various functions and be used in an indoor environment. Copyright © 2015 Elsevier B.V. All rights reserved.
... Recently, technologies including electrostatic precipitator (ESP), mechanical heating system, and antimicrobial agent (such as tea tree, eucalyptus oil, and carbon nanotube (CNT))-coated air filter have been tested for controlling and inactivating airborne virus particles [11][12][13][14]. In our previous study, aerosolized bacteriophage MS2 virus was inactivated with synthesized SiO 2 -Ag nanoparticles, which were 400 nm silica particles decorated with 30 nm silver nanoparticles [15]. ...
... Studies have also shown the virucidal effects of natural compounds such as essential oils (eg, eucalyptus oil, tea tree oil). 47,48 These studies demonstrated the complete loss of viability of influenza virus, and nonenveloped phage M13, when exposed to aerosolized oils for >30 seconds; however, concentrations were harmful. Other materials, such as eugenol, a natural oil, and several commercially available air sanitizers were tested against aerosolized viruses (phage surrogates) and shown to have an efficacy that varied with RH and the phage type (ie, enveloped or nonenveloped, RNA or DNA) (Caroline Duchaine, 2016). ...
Article
Transmission of bacterial, fungal, and viral pathogens is of primary importance in public and occupational health and infection control. Although several standardized protocols have been proposed to target microbes on fomites through surface decontamination, use of microbicidal agents, and cleaning processes, only limited guidance is available on microbial decontamination of indoor air to reduce the risk of pathogen transmission between individuals. This article reviews the salient aspects of airborne transmission of infectious agents, exposure assessment, in vitro assessment of microbicidal agents, and processes for air decontamination for infection prevention and control. Laboratory-scale testing (eg, rotating chambers, wind tunnels) and promising field-scale methodologies to decontaminate indoor air are also presented. The potential of bacteriophages as potential surrogates for the study of airborne human pathogenic viruses is also discussed.
... Airborne particles also include various bacteria, viruses, fungi, spores, pollen and allergens, [126] some of which could do harm to human health. [18] To inhibit pathogen transmission and epidemic disease outbreak, many efforts have been devoted to the preparation of antibacterial membranes by exploiting additives, which are mainly divided into two types, i.e., inorganics such as Ag, [127] Cu, [128] CNTs, [129] and TiO 2 , [130] and some natural plants extracts (e.g., Melaleuca alternifolia extracts, [131] Sophora flavescens extracts, [71] eucalyptus extracts, [132] and green soy protein [133] ). Selvam et al. [86] performed a study on antibacterial filters by incorporating diverse weight percentages of Ag nanoparticles in electrospun PAN fibers, where the PAN solvent (dimethylformamide), also serves as a reducing agent for Ag nanoparticle formation. ...
Article
In modern society, traffic and transportation and the manufacturing industry and construction industries continuously release large amounts of dust and particles into the atmosphere, which can cause heavy air pollution, leading to health hazards. The haze disaster, a serious problem in developing countries such as China and India, has become one of the main issues of global environmental pollution in recent decades. Many air filtration technologies have been developed. Air filtration using electrospun fibers that intercept fine particles/volatile organic gases/bacterium is a relatively new, but highly promising, technique. Due to their interconnected nanoscale pore structures, highly specific surface areas, fine diameters, and porous structure as well as their ability to incorporate active chemistry on a nanoscale surface, electrospun fibers are becoming a promising versatile platform for air filtration. In this review, following a short introduction concerning the need for air filtration and filtration theory and mechanism, electrospun nanofibers membranes for air filtration have been highlighted, including the preparation (electrospinning process) and the parameters relevant to filtration efficacy. Additionally, various types (function) of the electrospun air filtration membranes have been classified in detail. Furthermore, their potential in the filtration of fine particles and chemical pollutants has been discussed. Finally, the challenges of their practical application and the future prospects have been summarized. Given that some advanced electrospun air filtration nanofibrous membranes exist for treating different contaminants from various types of polluted atmosphere, it is believed that they should make a significant contribution in protection against air pollution. (Figure presented.).
... The introduction of the vapor of essential oil blend (EOB) to the pulverization chamber at 0.5, 1.0 and 1.5 min, before the end of the air suspension time of 1.5 min, resulted in gradual increase in reduction of the frequency of H9N2 positive embyonated eggs equivalent to 22.3%, 27.0% and 42.5%, respectively (Table 3). This is in agreement with previous reports documenting the relationship in increments of contact time to the increase in effectiveness of aerosolized sanitizers against the target virus [48]. The obtained relationship in this study between the contact time and the decrease in recovery of the virus from transport medium is indicative of the effectiveness of the EOB against suspended H9N2 in the air. ...
Article
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The aim of this research is to standardize the conditions of a constructed impinger, enabling to evaluate quantitatively the anti-aerosolized H9N2 avian influenza virus (AIV) activity by vapors of a chemically-characterized essential oil blend. The standardization resulted in 100% recovery of the aerosolized H9N2 virus when the impinger’s conditions were set at aerosolized viral particles count of 1.2 × 106/c.c. of Tryptose Phosphate Broth, temperature of 35°C, average micelle diameter of 44.3 μm, negative pressure of 6 mbar, air-suspension time of H9N2 virus of 1.5 min, collection chamber and its transport medium volumes of 250 cc and 25 cc, respectively. The adoption of the above standardized conditions, with an inclusion of vaporized essential oil (EO) at 1.0 × 10-4 μl EO/μl volume of the pulverization chamber, and contact times of 0.5-1.5 min with the H9N2 virus, resulted in 84.6% reduction in viral titer at 1.5 min contact time, compared to the control virus, deprived from contact with vaporized EO (P<0.05). This new finding will help in future investigations related to application of safe essential oils in reduction of air-suspended influenza virus in closed systems harboring domestic animals and human populations.
... Likewise, tea tree oil (Melaleuca alternifolia) has been widely investigated for its acknowledged antimicrobial, anti-inflammatory and antiseptic properties (Bakkali et al., 2008).- (Sailer et al., 1998) Usachev et al. (2013) reported a strong antiviral efficiency of the vapors of tea tree and eucalyptus oils against two different viruses, highlighting the use of essential oils as natural disinfectants for the further development of air treatment technologies and indoor air quality improvement (Pyankov et al., 2012). Tea tree oil is also commonly incorporated into household products, but to our knowledge, no scientific data have shown that this oil has air sanitation properties related to the improvement of indoor air quality from a chemical point of view. ...
Article
Essential-oils have attracted increasing interest due to their performance as inhibitors of the metabolic functions of microorganisms. They are widely promoted as easy-to-use compounds to improve indoor air quality and are associated with purifying actions. This study aims to assess the emissions of molecules contained in essential-oils in confined environments by employing different diffusion mechanisms under realistic conditions. Terpenes and carbonyl compounds are the typical identified and quantified compounds emitted from the tea tree essential-oil. Contrasted concentration levels and kinetic parameters are evidenced depending on the mechanism of diffusion, and the concentration levels can exceed the recommended critical exposure level by one order of magnitude. Additionally, the relative contributions of individual terpenes in the gas phase vary throughout the diffusion process for all the investigated diffusers. To assess the duration of the impact of essential-oil diffusion on indoor air quality, the mass emission rates of individual terpenes are estimated. This study shows that, depending on the diffusion mechanism, the impact of essential-oil diffusion in confined environments varies from 5 h to 60 days. The proposed experimental approach and the results provided offer the first insights into the definition of risk scenarios and human exposure to essential-oils in indoor environments.
... Tea tree oils and eucalyptus capturing at the fiber coating substances are able to inactivating influenza virus [19]. Chinese mahogany , Chinese language liquorices , crimson spider lily , the rhizome of Scythian lamb , and its extract or compound, have suggested antiSARS-CoV-1 action in Vero cells with the SARS-CoV-1 infection model [20], [21].Although a few natural merchandises as baicalein and becalein had been traditional Chinese language remedy formula composed of an aggregate of 13 herbs [22]. ...
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ABSTRACT Coronaviruses are a broad family of viruses which might also source of infection in animals or human beings. In human beings, many coronaviruses are recognized to influence breathing infections ranging from the not unusual bloodless to greater severe diseases together with the Middle East respiratory Syndrome (MERS) and severe Acute breathing Syndrome (SARS). The maximum recently found coronavirus causes coronavirus disorder COVID-19. The disease spreads in general from individual to person via small droplets from the nose or mouth, which are expelled when someone with COVID-19 coughs, sneezes, or speaks. As healthcare researchers around the globe compete with finding an effective remedy and cure for COVID-19, Health officials in China have begun encouraging an opportunity type of traditional medication to help people that get coronavirus. Herbal medicinal drug had continually played a vital role in the primary healthcare in growing countries. This is in most cases due to the overall belief that herbal remedies are with none facet effects except being cheap and domestically available. Based on the world health organization (WHO), the usage of natural remedies or the duration of the world exceeds that of the conventional medications by two to a few times .In this takes a look at we are focused on an herbal treatments which can be beneficial to managing signs of Covid19.
... 117 There have been many studies on incorporating different biocidal additives into the fibers of filter media, such as silver, 118-120 copper oxide, 121 N-halamines, 122,123 quaternary ammonium salts, 124 and herbal extracts. [125][126][127] However, most studies only investigated the antibacterial properties, and limited studies 121,126 evaluated the effectiveness of the additives in deactivating pathogenic viruses. For example, Borkow et al. 121 demonstrated that impregnation of CuO nanoparticles endowed masks with antiviral properties against the human influenza A virus (H1N1) and the avian influenza virus (H9N2) ( Figure 8A). ...
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Air-filtering masks, also known as respirators, protect wearers from inhaling fine particulate matter (PM2.5) in polluted air, as well as airborne pathogens during a pandemic, such as the ongoing COVID-19 pandemic. Fibrous medium, used as the filtration layer, is the most essential component of an air-filtering mask. This article presents an overview of the development of fibrous media for air filtration. We first synthesize the literature on several key factors that affect the filtration performance of fibrous media. We then concentrate on two major techniques for fabricating fibrous media, namely, meltblown and electrospinning. In addition, we underscore the importance of electret filters by reviewing various methods for imparting electrostatic charge on fibrous media. Finally, this article concludes with a perspective on the emerging research opportunities amid the COVID-19 crisis. Considering that air pollution will continue to be a major health concern in newly industrialized countries and the ongoing COVID-19 pandemic may create lasting cultural shifts around the world to increase mask usages, the pursuit of more efficient and cost-effective masks will be a cornerstone to maintaining public health. This review provides a comprehensive picture of the historic development of air-filtering masks, identifies remaining knowledge gaps, and envisions emerging research opportunities amid the pressing challenges of air pollution and COVID-19.
... Tea tree oils and eucalyptus capturing at the fiber coating substances are able to inactivating influenza virus [19]. Chinese mahogany , Chinese language liquorices , crimson spider lily , the rhizome of Scythian lamb , and its extract or compound, have suggested antiSARS-CoV-1 action in Vero cells with the SARS-CoV-1 infection model [20], [21].Although a few natural merchandises as baicalein and becalein had been traditional Chinese language remedy formula composed of an aggregate of 13 herbs [22]. ...
Article
Full-text available
Coronaviruses are a broad family of viruses which might also source of infection in animals or human beings. In human beings, many coronaviruses are recognized to influence breathing infections ranging from the not unusual bloodless to greater severe diseases together with the Middle East respiratory Syndrome (MERS) and severe Acute breathing Syndrome (SARS). The maximum recently found coronavirus causes coronavirus disorder COVID-19. The disease spreads in general from individual to person via small droplets from the nose or mouth, which are expelled when someone with COVID-19 coughs, sneezes, or speaks. As healthcare researchers around the globe compete with finding an effective remedy and cure for COVID-19, Health officials in China have begun encouraging an opportunity type of traditional medication to help people that get coronavirus. Herbal medicinal drug had continually played a vital role in the primary healthcare in growing countries. This is in most cases due to the overall belief that herbal remedies are with none facet effects except being cheap and domestically available. Based on the world health organization (WHO), the usage of natural remedies or the duration of the world exceeds that of the conventional medications by two to a few times .In this takes a look at we are focused on an herbal treatments which can be beneficial to managing signs of Covid19.
... The compound citronellol was major component (59.31%) present in C. citrodora. Eucalyptol along with other compounds like alpha-terpinene, gamma-terpinene, alpha-pinene, p-cymene, terpinen-4-ol, alpha-terpineol, thymol, citral obtained from essential oils have shown good potential against (HSV-1) herpes simplex virus type 1 in vitro research, but among all the compounds ␣-pinene and ␣-terpineol were slightly superior in their anti-viral activity [29]. ...
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Background The current health concern to the entire world is the chronic respiratory disease caused by coronavirus 2 (COVID-19). A specific treatment or proper therapy is still lacking, and the investigations from across the world for proper drug/vaccine development towards disease control are in progress. The Coronavirus replication takes place by the conversion of the polypeptide into functional protein and this occurs due to the key enzyme Main protease (Mpro). Therefore, identification of natural and effective Mpro inhibitors could be a safe and promising approach for COVID-19 control. Methods The present in silico study evaluates the effect of bioactive compounds found in Eucalyptus and Corymbia species essential oil on Mpro by docking. Molecular docking of the major seven compounds of essential oil (citronellol, alpha-terpineol, eucalyptol, d-limonene, 3-carene, o-cymene, and alpha-pinene) with Mpro was studied by AutoDock 4.2, and the properties were analysed by PreADMET and Biovia Discovery Studio visualizer. Results The calculated parameters such as binding energy, hydrophobic interactions, and hydrogen bond interactions of 6LU7 (Mpro) with Eucalyptus and Corymbia volatile secondary metabolites represented its scope as an effective therapy option against covid-19. Among the docked compounds, eucalyptol shows the least binding energy without toxicity. Conclusions The outcome of this study reported that the essential oil of Eucalyptus and Corymbia species, mainly eucalyptol can be utilized as a potential inhibitor against COVID-19 and also it can be used in its treatment. Hence, further analysis was required to explore its potential application in medicine.
... [20], therefore the ability of substances to prevent subsequent growth of the virus from aerosols might be important to reduce the spread of this disease. A previous study has demonstrated that aerosolized tea tree oil (from Melaleuca sp.) or eucalyptus oil can inactivate aerosolized influenza virus in a concentration and time dependent manner, with viral titres being uncountable within 30 min of exposure [27,42]. An aerosol of an essential oil blend of tea tree (Melaleuca sp.), eucalyptus and lemon myrtle in the ratio 4.5:4.5:1 ...
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Transmission of pathogens present in the indoor air can occur through aerosols. This study evaluated the efficacy of an evaporated mix of essential oils to reduce the numbers of cultura-ble aerosolized coronavirus, bacterium and fungus. The essential oil-containing gel was allowed to vaporize inside a glass chamber for 10 or 20 min. Aerosols of a surrogate of SARS-CoV-2, murine hepatitis coronavirus MHV-1, Escherichia coli or Aspergillus flavus spores were produced using a collision nebuliser and passed through the essential oil vapours, then collected on a six-stage Andersen sampler. The six-stages of the impact sampler capture aerosols in sizes ranging from 7 to 0.65 µm. The number of culturable microbes present in the aerosols collected in the different stages were enumerated and compared to the number of culturable microbes in control microbial aerosols that were not exposed to the evaporated essential oils. After 10 and 20 min evaporation, the essential oils reduced the numbers of culturable aerosolized coronavirus by 48% (log10 reduction = 0.3; p = 0.002 vs. control) and 53% (log10 reduction = 0.3; p = 0.001 vs. control), respectively. The essential oils va-porised for 10 min, reduced the number of viable E. coli by 51% (log10 reduction = 0.3; p = 0.032 vs. control). The Aspergillus flavus spores were mostly observed in the larger aerosols (7.00 µm to 2.10 µm) and the essential oils vaporised for 10 min reduced the number of viable spores by 72% (log10 reduction = 0.6; p = 0.008 vs. control). The vapours produced by a gel containing naturally occurring essential oils were able to significantly reduce the viable numbers of aerosolized coronavirus, bacteria and fungal spores. The antimicrobial gel containing the essential oils may be able to reduce aerosol transmission of microbes when used in domestic and workplace settings.
... For example, Pyankov's group demonstrated that tea tree and eucalyptus oil coatings exhibited good antiviral activity against the influenza virus. 10 However, integrating and applying these oils as effective coatings are somewhat challenging. Another proposed strategy is to incorporate metal nanomaterials such as copper, silver, and zinc, which act as antiviral agents. ...
... Various studies propose that secondary metabolites, like sesquiterpenes, interact with viral particles present or released before they make contact with a cell again (34). ...
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The treatments being investigated for the pandemic associated with a severe acute respiratory syndrome caused by the new coronavirus (SARS-CoV2) aim to inhibit viral replication or inhibit enzymatic elastase in the lung, responsible for the SARS-CoV cell entry mechanism and the pathogenesis of severe pneumonia caused by infection. There is also a need to improve alveolar surfactant capacity and inhibition of the exacerbated inflammatory response. Current knowledge allows us to infer that Citrus essential oils could be considered an individual or a complementary highly valuable alternative for the viral infection caused by SARS-CoV due to its antiviral activity, particularly against coronavirus, anti-elastase, anti-inflammatory, antibacterial and antibiofilm properties. Furthermore, its proven capacity of biosurfactants, antioxidants, and pain inhibitors would help to treat acute respiratory syndrome. This review aims to encourage the development of more detailed studies on Citrus essential oils as a new multi-objective strategy to treat SARS-CoV2 infection. Abbreviations: SARS-CoV: Severe Acute Respiratory Syndrome Coronavirus; GRAS: Generally Recognized as Safe; TRP: Transient Receptor Proteins; HeLa-CEACAM1a: HeLa-epithelial carcinoembryonic antigen-related cell adhesion molecule 1a; HSV: Herpes Simplex Virus; FDA: Food and Drug Administration; ANMAT: National Administration of Medicines, Food and Medical Technology, Argentina; AFSSAPS: Agence Française de Sécurité Sanitaire des Produits de Santé, France; ACE2:Angiotensin-converting enzyme-2
... 7. Essential oils. The use of essential oils from natural products used in aerosol form, such as eucalyptus oil, has been shown to have a viricidal effect [35,36]. ...
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Based on a rigorous updated review of the characteristics of the spread of COVID 19, we present for its disclosure our method of personal prevention of viral infection. This method was already exposed in a previous publication in Revista Boliviana de Química (June 2020) by the first author of this review and is based on the triple alliance abbreviated as 3XAL, or nasal, oral and manual hygiene in contrast to the only manual hygiene proclaimed by the health authorities of Bolivia and worlwide. Apart from 3XAL, the sustained use of the galenic preparation (Vicks-VapoRub® or Mentholatum®, or Mentisan®) based on natural products, essential oils in the prevention of viral development in the respiratory system is equally important and impressive. This topical ointment not only has a broad spectrum of antiviral, antibacterial and anti-inflammatory activity, but it has also shown to have specific activity against COVID 19 coronavirus for two of its four active ingredients, which makes it an effective anti-COVID 19. This publication concludes with the use the essential oil of Eucalyptus globulus (the most widespread species of this genus in the world) and other plant species, which contains eucalyptol as a major antiviral principle, in its use as a disinfectant of closed spaces and without ventilation, in a home or work context.
... 1,8-cineole is well known for its mucolytic and spasmolytic action on the respiratory tract with proven clinical efficacy. The drug has also shown therapeutic benefits in inflammatory airway diseases in reducing excessive immune reactions in various preclinical investigations.[3][4][5][6][7][8] Therefore, Soledum ® Capsules Forte 200 mg may be a good potential drug candidate against COVID-19 with a higher incidence of bilateral pneumonia and pleural effusion. ...
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Soledum Capsules Forte 200 mg is a recipe-free drug in Germany due to its negligible side effects. It is a strong helper against the agonizing symptoms of bronchitis, common colds, and respiratory tract influenza. The gastric-resistant capsules have pure 1,8-cineole as their active ingredient. 1,8-cineole is well known for its mucolytic and spasmolytic action on the respiratory tract with proven clinical efficacy. The drug has also shown therapeutic benefits in inflammatory airway diseases in reducing excessive immune reactions in various preclinical investigations. Therefore, Soledum ® Capsules Forte 200 mg may be a good potential drug candidate against COVID-19 with a higher incidence of bilateral pneumonia and pleural effusion.
... 7. Aceites esenciales. Está demostrado el uso de aceites esenciales de productos naturales utilizado en forma de aerosol como el aceite de eucalipto que ha demostrado tener un efecto virucida [35,36] 8. Otros. Descarga de plasma, fotocatálisis, filtración y tratamiento químico, filtros in situ con ozono, descarga eléctrica o fibras de carbón activado. ...
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Basados en una rigurosa revisión bibliográfica actualizada sobre las características de la propagación de COVID 19, presentamos para su divulgación nuestro método empírico de prevención de la infección viral. Este método fue anteriormente expuesto en una publicación previa en Revista Boliviana de Química (junio de 2020) por el autor corresponsal del presente artículo, y está basado en la triple alianza abreviada como 3XAL, o higiene nasal, bucal y manual en contraste con la sola higiene manual proclamada por las autoridades sanitarias de Bolivia y del mundo. Aparte de la 3XAL, es crucialmente importante e impactante el uso sostenido de la preparación galénica en base a productos naturales, aceites esenciales, de nombre comercial MENTISAN® en la prevención del desarrollo viral en el sistema respiratorio. Esta pomada de uso tópico no solo presenta un amplio espectro de actividad antiviral, antibacteriano y antiinflamatorio, sino que ha demostrado para dos de sus cuatro principios activos tener actividad específica contra coronavirus COVID 19, lo que lo convierte en un eficaz antiviral para prevención y terapia contra COVID 19. La presente publicación concluye con el uso del alcanfor, aceite esencial de Eucaliptus globulus (la especie de este género más difundida en el mundo) y otras especies vegetales, que contiene como principio antiviral mayoritario al eucaliptol, en su uso como desinfectante de espacios cerrados y sin ventilación, en un contexto hogareño o laboral.
... Several EOs, such as those from cinnamon bark, lemongrass and thyme, have been shown to be the most effective in this field. Antimicrobial and antiseptic properties and antiviral activity have been studied in eucalyptus oils and tea tree oil (Melaleuca alternifolia) [42][43][44], and their use as disinfectants for indoor air quality after adequate development of air technologies has been suggested [45,46]. ...
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The chemical composition of essential oils (EOs) from dried and fresh flowers of Lavandula angustifolia L. (lavender), named LA 2019 and LA 2020, respectively, grown in central Italy was analyzed and compared by GC and GC-MS. For both samples, 61 compounds were identified, corresponding to 97.9% and 98.1% of the total essential oils. Explorative data analysis, performed to compare the statistical composition of the samples, resulted in a high level of global similarity (around 93%). The compositions of both samples were characterized by 10 major compounds, with a predominance of Linalool (35.3–36.0%), Borneol (15.6–19.4%) and 1,8-Cineole (11.0–9.0%). The in vitro antibacterial activity assay by disk diffusion tests against Bacillus subtilis PY79 and Escherichia coli DH5α showed inhibition of growth in both indicator strains. In addition, plate counts revealed a bactericidal effect on E. coli, which was particularly noticeable when using oil from the fresh lavender flowers at the highest concentrations. An in vitro antifungal assay showed that the EOs inhibited the growth of Sclerotium rolfsii, a phytopathogenic fungus that causes post-harvest diseases in many fruits and vegetables. The antioxidant activity was also assessed using the ABTS free radical scavenging assay, which showed a different antioxidant activity in both EOs. In addition, the potential application of EOs as a green method to control biodeterioration phenomena on an artistic wood painting (XIX century) was evaluated.
... In particular, Cinnamon bark, Lemongrass and Thyme oils are evidenced as the most effective for this purpose (Inouye et al., 2001). Some authors have also revealed a strong antimicrobial efficiency of Tea tree and Eucalyptus EOs vapors highlighting the use of EOs as natural disinfectants for the further development of air treatment technologies and indoor air quality improvement (Sailer et al., 1998;Pyankov et al., 2012;Usachev et al., 2013). ...
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Bioaerosols play an important role in Cultural Heritage (CH) spaces air quality and biodeterioration risk and there is a growing interest to reduce them in actual conservation strategies. Essential oils (EOs) have been well-known in several fields for their antimicrobial properties and they have found use in a number of applications. In this work Melaleuca alternifolia (Tea tree) and Thymus vulgaris (Thyme) EOs are cold diffused in unventilated lab spaces for reducing air bacterial and fungi contamination. Moreover, Tea tree EO was also tested in an unventilated real CH space. The effectiveness of EOs in reducing air bacterial and fungi contamination in unventilated indoor spaces during 24 h was evaluated. Air quality was also analyzed by means of temperature, humidity and particulate matter variation. EOs’ diffusion system CH artworks risks was studied by means of thermography, diffusion range and EOs compounds deposition on the artistic materials by GC–MS. Tea tree EOs vaporization showed the best results with 77,3% and 95,0% fungi and bacteria air contamination reduction, with no thermohydrometric alteration and absence of EOs components deposition on the artistic vault.
... Several studies have reported the anti-IFV capacity of Eucalyptus essential oil [22,34,50,51]. For example, Usachev et al. [40] investigated the antiviral activity of E. polybractea against influenza A virus (NWS/G70C/H11N9) in air. ...
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Given the limited therapeutic management of infectious diseases caused by viruses, such as influenza and SARS-CoV-2, the medicinal use of essential oils obtained from Eucalyptus trees has emerged as an antiviral alternative, either as a complement to the treatment of symptoms caused by infection or to exert effects on possible pharmacological targets of viruses. This review gathers and discusses the main findings on the emerging role and effectiveness of Eucalyptus essential oil as an antiviral agent. Studies have shown that Eucalyptus essential oil and its major monoterpenes have enormous potential for preventing and treating infectious diseases caused by viruses. The main molecular mechanisms involved in the antiviral activity are direct inactivation, that is, by the direct binding of monoterpenes with free viruses, particularly with viral proteins involved in the entry and penetration of the host cell, thus avoiding viral infection. Furthermore, this review addresses the coadministration of essential oil and available vaccines to increase protection against different viruses, in addition to the use of essential oil as a complementary treatment of symptoms caused by viruses, where Eucalyptus essential oil exerts anti-inflammatory, mucolytic, and spasmolytic effects in the attenuation of inflammatory responses caused by viruses, in particular respiratory diseases.
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1,8-cineole is a licensed medicinal product formulated in gastric resistant capsules (200 mg/capsule) in Germany due to its negligible side effects. It is a strong helper against the agonizing symptoms of bronchitis, common colds, and respiratory tract influenza. Additionally, 1,8-cineole is well known for its mucolytic and spasmolytic action on the respiratory tract with proven clinical efficacy. The medicine has also shown therapeutic benefits in inflammatory airway diseases in reducing excessive immune reactions in various preclinical investigations. Therefore, 1,8-cineole can be a good medical candidate against COVID-19 variant omicron, which triggers milder illness with symptoms such as cough, fever, and fatigue in the majority of those it infects. The medicine can keep the airways of patients suffering from respiratory diseases free for breathing. 1,8-cineole can help the patients wining enough time to build antibodies against COVID-19 variant omicron through their immune systems.
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Thesis
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Essential oils and isolated essential oil compounds are known to exert various pharmacological effects, such as antibacterial, antifungal, antiviral, anti-inflammatory, anti-immunomodulatory, antioxidant, and wound healing effects. Based on selected articles, this review deals with the potential antiviral and virucidal activities of essential oils and essential oil compounds together with their mechanism of action as well as in silico studies involving viral and host cell-specific target molecules that are indispensable for virus cell adsorption, penetration, and replication. The reported in vitro and in vivo studies highlight the baseline data about the latest findings of essential oils and essential oil compounds antiviral and virucidal effects on enveloped and non-enveloped viruses, taking into account available biochemical and molecular biological tests. The results of many in vitro studies revealed that several essential oils and essential oil compounds from different medicinal and aromatic plants are potent antiviral and virucidal agents that inhibit viral progeny by blocking different steps of the viral infection/replication cycle of DNA and RNA viruses in various host cell lines. Studies in mice infected with viruses causing respiratory diseases showed that different essential oils and essential oil compounds were able to prolong the life of infected animals, reduce virus titers in brain and lung tissues, and significantly inhibit the synthesis of proinflammatory cytokines and chemokines. In addition, some in vitro studies on hydrophilic nano-delivery systems encapsulating essential oils/essential oil compounds exhibited a promising way to improve the chemical stability and enhance the water solubility, bioavailabilty, and antiviral efficacy of essential oils and essential oil compounds.
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Rapid and precise bioaerosol detection in different environments has become an important research and technological issue over last decades. Previously, we employed a real-time PCR protocol in conjunction with personal bioaerosol sampler for rapid detection of airborne viruses. The approach has been proved to be specific and sensitive. However, a period of time required for entire procedure was in manner of hours. Some new developments are required to decrease the detection time down to real-time protocols. Presently, a surface plasmon resonance (SPR)–based immunosensor that coupled with a specific antigen–antibody reaction could offer sensitive, specific, rapid and label-free detection. This study describes the possibility of combining the personal sampler with SPR technology for qualitative and extremely rapid detection of airborne micro-organisms. Common viral surrogate MS2 bacteriophage, frequently used in bioaerosol studies, was employed as a model organism. The results of the sensor functionalizing procedure with monoclonal anti-MS2 antibody and optimization of the chip performance are presented. The SPR-based detection of the airborne virus was found to be very fast; the viral presence was detected in less than 2 min, and the entire procedure (sampling and analysis) was undertaken in 6 min, which could be considered as real-time detection for this type of measurements. The combination of SPR with the personal sampler targeted towards bioaerosol detection was proven to be feasible. The SPR sensor was found to be highly stable and suitable for multiple utilizations without significant decrease in response. The suggested approach opens new possibilities for the development of portable and rapid (almost real time) bioaerosol monitors. This technology is the first in the world real-time bioaerosol monitor. This outcome would be of strong interest to individuals representing public health, biosecurity, defence forces, environmental sciences and many others.
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While various sampling methods exist for collecting and enumerating airborne bacteria and fungi, no credible methodology has yet been developed for airborne viruses. A new sampling method for monitoring the personal exposure to bioaerosol particles has recently been developed and evaluated with bacteria and fungi. In this method, bacterial/fungal aerosol is aspirated and transported through a porous medium, which is submerged into a liquid layer. As the air is split into numerous bubbles, the particles are scavenged by these bubbles and effectively removed. The current feasibility study was initiated to evaluate the efficiency of the new personal sampler prototype (“bubbler”) with airborne viable viruses. Two common viral strains, Influenza (stress-sensitive) and Vaccinia (robust), were aerosolized in the test chamber and collected by two identical “bubblers” that operated simultaneously for a duration of upto 5 min. A virus maintenance liquid, proven to be the optimum collecting environment for the test organisms, was used as a collection fluid. After sampling, the collecting fluid was analyzed and the viral recovery rate was determined. The overall recovery (affected not only by the sampling but also by the aerosolization and the aerosol transport) was 20% for Influenza virus and 89% for Vaccinia virus. The new sampling method was found feasible for the collection and enumeration of robust airborne viruses.
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Aims: To investigate the effectiveness of infrared (IR) radiation heating in disinfecting air filters loaded with bioaerosols. Methods and Results: An irradiation device was constructed considering the unique characteristics of IR and the physical dimensions and radiative properties of air filters. Filters loaded with test bioaerosols were irradiated with the device and flash heated to an ultra-high temperature (UHT). A maximum of 3·77-, 4·38- and 5·32-log inactivation of B. subtilis spores, E. coli, and MS2 virus respectively was achieved within 5 s of irradiation. Inactivation efficiency could be increased by using a higher IR power. Microscopic analysis showed no visible damage from the heat treatment that would affect filtration efficiency. Conclusions: Because the disinfection was a dry heat process, a temperature greater than 200°C was found necessary to successfully inactivate the test micro-organisms. The results demonstrate that IR is able to quickly disinfect filters given sufficient incident power. Compared to existing filter disinfection technologies, it offers a faster and more effective solution. Significance and Impact of the Study: It has been shown that IR heating is a feasible option for filter disinfection; possibly reducing fomite transmission of collected micro-organisms and preventing bioaerosol reaerosolization.
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Alternative methods for controlling bacterial endospore contamination are desired in a range of industries and applications. Attention has recently turned to natural products, such as essential oils, which have sporicidal activity. In this study, a selection of essential oils was investigated to identify those with activity against Bacillus subtilis spores. Spores were exposed to thirteen essential oils, and surviving spores were enumerated. Cardamom, tea tree, and juniper leaf oils were the most effective, reducing the number of viable spores by 3 logs at concentrations above 1%. Sporicidal activity was enhanced at high temperatures (60 degrees C) or longer exposure times (up to one week). Gas chromatography-mass spectrometry analysis identified the components of the active essential oils. However, none of the major oil components exhibited equivalent activity to the whole oils. The fact that oil components, either alone or in combination, did not show the same level of sporicidal activity as the complete oils suggested that minor components may be involved, or that these act synergistically with major components. Scanning electron microscopy was used to examine spores after exposure to essential oils and suggested that leakage of spore contents was the likely mode of sporicidal action. Our data have shown that essential oils exert sporicidal activity and may be useful in applications where bacterial spore reduction is desired.
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A new personal sampler had been previously developed and verified for monitoring of viable airborne viruses. The aims of this project were to investigate a possibility of the utilization of the polymerase chain reaction (PCR) method to speed up the time consuming analytical procedures and to evaluate a lower detection limit of the combined (sampler-PCR) device. Tenfold serial dilutions of the initial suspension of the Vaccinia virus were aerosolized in the chamber and airborne viruses were monitored by two simultaneously operating samplers. The results of monitoring were successfully obtained by a standard plaque assay (live microbes) and by the PCR method (total DNA). The corresponding calculations to identify the minimal detectable concentration in the ambient air were then performed. It was found that the minimal detectable concentration of airborne viruses in the ambient air depends on the sampling time. As demonstrated, such concentration should be at least 125×103 PFU m−3 for a sampling time of as short as 1 min. The detectable concentration decreases with the increase of the sampling time and reaches 25×103 and 10×103 PFU m−3 for 5 and 12.5 min of sampling respectively. Yes Yes
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Tea tree oil has recently emerged as an effective topical antimicrobial agent active against a wide range of organisms. Tea tree oil may have a clinical application in both the hospital and community, especially for clearance of methicillin-resistant Staphylococcus aureus (MRSA) carriage or as a hand disinfectant to prevent cross-infection with Gram-positive and Gramnegative epidemic organisms. Our study, based on the time-kill approach, determined the kill rate of tea tree oil against several multidrug-resistant organisms, including MRSA, glycopeptide-resistant enterococci, aminoglycoside-resistant klebsiellae, Pseudomonas aeruginosa and Stenotrophomonas maltophilia, and also against sensitive microorganisms. The study was performed with two chemically different tea tree oils. One was a standard oil and the other was Clone 88 extracted from a specially bred tree, which has been selected and bred for increased activity and decreased skin irritation. Our results confirm that the cloned oil had increased antimicrobial activity when compared with the standard oil. Most results indicated that the susceptibility pattern and Gram reaction of the organism did not influence the kill rate. A rapid killing time (less than 60 min) was achieved with both tea tree oils with most isolates, but MRSA was killed more slowly than other organisms.
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The effect of tea tree oil (TTO) on the formation of germ tubes by Candida albicans was examined. Two isolates were tested for germ tube formation (GTF) in the presence of TTO concentrations (% v/v) ranging from 0.25% (1/2 minimum inhibitory concentration [MIC]) to 0.004% (1/128 MIC). GTF at 4 h in the presence of 0.004 and 0.008% (both isolates) and 0.016% (one isolate) TTO did not differ significantly (P > 0.05) from controls. At all other concentrations at 4 h, GTF differed significantly from controls (P < 0.01). A further eight isolates were tested for GTF in the presence of 0.031% TTO, and at 4h the mean GTF for all 10 isolates ranged 10.0-68.5%. Two isolates were examined for their ability to form germ tubes after 1 h of pre-exposure to several concentrations of TTO, prior to induction of germ tubes in horse serum. Cells pre-exposed to 0.125 and 0.25% TTO formed significantly fewer germ tubes than control cells at 1 h (P < 0.05), but only those cells pre-exposed to 0.25% differed significantly from control cells at later time points (P < 0.01). GTF by C. albicans is affected by the presence of, or pre-exposure to, sub-inhibitory concentrations of TTO. This may have therapeutic implications.
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FULL TEXT available free from http://cmr.asm.org/content/19/1/50.full.pdf+html?sid=eccd451a-5b42-44f2-b9cc-fe6223ee045a 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.
Article
Resent respiratory infection outbreak events, including Avian and Swine Influenza and SARS virus spread in various countries ignited a strong interest towards investigations in the area of airborne virus behavior in the ambient air. One of the most important parameters, related to airborne disease transmission is survival of disease causing microorganisms in the ambient air environment. This project investigates survival of airborne influenza virus of different sub-types at common room conditions where risk of disease due to microbial transmission could be particularly high, especially at poorly ventilated environments, where viral concentration in the air reaches significant magnitudes. The results obtained for H1N1 and H5N1 strains show close trend with regards to inactivation in the ambient air; rapid inactivation of approximately 60% of microorganisms over the first 30 min with following inactivation at much slower rate over the remaining 60 min of experiment. A different picture was observed for the H3N2 strain, which demonstrated much higher robustness compared to other subtypes; even after 90 min, around 50% of viral particles were still alive. The results of this research could be directly utilized in health and epidemiological studies, modeling of HVAC systems, microbiological studies and many others. (c) 2012 Elsevier Ltd. All rights reserved.
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The yields of essential oils obtained from dried leaves of Eucalyptus citriodora and E. camaldulensis ranged according to the location between 2.3% and 5.9% for E. citriodora and between 0.6% and 1.4% for E. camaldulensis. Twenty-eight components were identified by GC/MS. In E. citriodora and E. camaldulensis, 90% of the isolated oils were obtained after one hour distillation and they contained maximal amounts of citronellal (75%) for E. citriodora oil and 1,8-cineole (47–71%) for E. camaldulensis oil. At longer isolation times further quantities of oils collected became negligible and the proportions of the main constituents fell significantly. The chemical composition of the oils of E. citriodora and E. camaldulensis obtained from plants located in the economically most relevant areas of Benin depended on location and harvesting time. The effects of these two parameters are different for the two oils. An oil of E. citriodora rich in citronellal (>75%) could be obtained throughout the year with a yield of 5% at Calavi, while even at the best time (June to August) the yield of oil was only 2.5% at Kétou. For E. camaldulensis, the best yield was approximatively 1.3% at Calavi (February-March) and Kétou (April-May). The Sémé-Ekpé location afforded an oil with a high level of 1,8-cineole (70%) with highest yield in February-March. The Calavi location was exploitable only during that period.
Article
Volatile constituents of essential oils of eight different clones propagated from the Australian tea tree (Melaleuca alternifolia) were analyzed by gas chromatography and gas chromatography/mass spectrometry. The oils isolated by a simultaneous purging and solvent extraction method (SPE) contained high levels of monoterpenes, including α-thujene, sabinene, α-terpinene, γ-terpinene, 1,8-cineole, terpinolene, and limonene. The volatile composition of oils prepared by a simultaneous steam distillation and solvent extraction method (SDE) varied significantly among different clones. Six oils contained 1,8-cineole as the major constituent, whereas two oils had terpinen-4-ol as the major component of the SDE samples. More compounds were found in SDE samples than in SPE samples. A principal component analysis on volatile compositions of eight oils conducted by computer indicated that sabinene and α-thujene in SPE samples and terpinen-4-ol and α-terpinene in SDE samples are highly correlated with each other.
Article
An elevated risk associated with exposure to bioaerosols calls for the development and implementation of new, efficient and cost effective methods of airborne biological particle control. While filtration remains the most efficient method of removal of airborne particles, some issues related to possible re-entrainment of captured particles from the rear face of the filter back into the air carrier have to be addressed. Obviously, viable biological particles blown off from the filter surface could still cause substantial damage to human and animal health and contaminate the ambient air environment. A new technology utilizing coating of filter fibres by biologically active tea tree oil (TTO) is considered in this paper. It was found that precoating of filter fibres with TTO and following usage of such filters for bioaerosol control could provide significant benefits in terms of rapidly inactivating captured microorganisms and, minimizing the number of live/viable particles possibly blown off from the filter by the air. Three bacterial strains with a range of biological stress sensitivity were used in this research. It was found that 99% of stress sensitive Eschericliia coli and Pseudomons fluorescens are inactivated on the surface of the TTO coated filter within 8 and 2 min of exposure, respectively. A robust strain of Bacillus subtilis demonstrated inactivation in the order of one logarithm per 30 min of process operation. These results look very promising for the implementation of this new technology for the control of air quality in domestic and industrial applications. Yes Yes
Article
Liquid aerosols produced in many manufacturing and refining processes need to be filtered from the exhaust streams. Where wettable fibers are used in the filters, the aerosol liquid collects on the fibers. Observation shows that thin films develop on the fibers, and the liquid drains down the fibers under the action of gravity. A model is developed for the flow of liquid in these films, and careful experimentation confirms the nature and importance of the flow pattern. The resultant overall efficiencies of the filter are also calculated from a theoretical analysis and compared with the results of experimentation using counting techniques. The theoretical and experimental results agree excellently for the range of aerosol sizes that are detectable by laser diffraction and cascade impactor techniques.
Article
Aims: The aim of this study was to analyse the antimycotic properties of Melaleuca alternifolia essential oil (tea tree oil, TTO) and its principal components and to compare them with the activity of 5-fluorocytosine and amphotericin B. Methods and Results: The screening for the antimycotic activity was performed by serial twofold dilutions in Roswell Park Memorial Institute medium with the inclusion of Tween-80 (0·5%). TTO and terpinen-4-olo were the most active compounds. Conclusions: The majority of the organisms were sensitive to the essential oil, with TTO and terpinen-4-olo being the most active oils showing antifungal activity at minimum inhibitory concentration values lower than other drugs. Significance and Impact of the study: This study provides a sample large enough to determine the antifungal properties of TTO and terpinen-4-olo and suggests further studies for a possible therapeutic use.
Article
In our previous work it has been shown that perfectly spherical polystyrene latex (PSL) particles have higher filtration efficiency compared to cubic magnesium oxide (MgO) particles of the same electrical mobility as PSL particles. This disparity was ascribed to the different nature of motion of the spherical and cubic particles along the fibre surface, following the initial collision. After touching the fibre surface and before coming to rest, the spherical particles could either slide or roll compared to the cubic ones, which could slide or tumble. During tumbling, the area of contact between the particle and the fibre changes significantly, thus affecting the bounce probability, whilst for the spheres, the area of contact remains the same for any point of particle trajectory. In this project, the polypropylene filter was coated with a thin layer of mineral oil that was used to absorb the energy and, respectively, to minimize particle motion along the fibre after collision. The filtration efficiency of spherical PSL, and cubic MgO particles was measured in the size range of 50–300 nm, for filtration velocity of 10 and 20 cm/s. It was found that, regardless of shape, both particle types have very similar filtration efficiency. The theoretical predictions are in good agreement with our experimental results. Therefore, the conclusion can be drawn that the oil coating minimizes the amount of particle motion along the fibre after initial collision, making results for all particle shapes similar.
Article
A silver ion doped TiO2 based photocatalyst, with improved destruction of airborne microbes, has been developed. The performance of the silver ion doped photocatalyst is demonstrated using a catalyst coated filter in a recirculating air experimental facility. Bacillus cereus, Staphylococcus aureus, Escherichia coli, Aspergillus niger, and MS2 Bacteriophage have been used as indexes to demonstrate the high disinfection efficiency of the enhanced photocatalysis process. The microbial destruction performance of the enhanced photocatalyst is found to be an order of magnitude higher than that of a conventional TiO2 photocatalyst. The process of enhanced photocatalysis can thus be used effectively against high concentrations of airborne microorganisms, making it an attractive option as a defense against bio-terrorism.
Article
Microbial aerosols could cause various human and animal health problems and their control is becoming a significant scientific and technological topic for consideration. Filtration is considered to be one of the main processes of the removal of biological aerosols from the air carrier minimizing bioaerosol concentration in industrial and domestic dwellings. However, with regards to biologically active particles, their removal from the air carrier does not solely solve the problem of microbial contamination of the ambient air. Considering that in some situations bioaerosol particles collected on the filter could re-enter the air carrier, some disinfection is required to ensure that no biologically active particles could possibly be removed from the filter surface and reach human occupied areas. This article describes the results of laboratory investigations involving Melaleuca alternifolia (tea tree oil) as disinfecting media for inactivation of common environmental fungal spores on the filter surface. It was found that 50% and 40% of Aspergillus niger and Rhizopus stolonifer spores, respectively, were inactivated over a period of 60 minutes. A single factor ANOVA test confirmed that the reported rates of inactivation were statistically significant (> 95%). For Rhizopus statistically significant inactivation by 31% was also observed after 30 minutes with no inactivation occurring over shorter time periods. No statistically significant inactivation occurred for Aspergillus niger for any time shorter than 60 min. Yes Yes
Article
Our previous study demonstrated that Melaleuca alternifolia (tea tree) oil (TTO) had an interesting antiviral activity against Influenza A in MDCK cells. In fact, when we tested TTO and some of its components, we found that TTO had an inhibitory effect on influenza virus replication at doses below the cytotoxic dose; terpinen-4-ol, terpinolene, and alfa-terpineol were the main active components. The aim of this study was to investigate the mechanism of action of TTO and its active components against Influenza A/PR/8 virus subtype H1N1 in MDCK cells. None of the test compounds showed virucidal activity nor any protective action for the MDCK cells. Thus, the effect of TTO and its active components on different steps of the replicative cycle of influenza virus was studied by adding the test compounds at various times after infection. These experiments revealed that viral replication was significantly inhibited if TTO was added within 2h of infection, indicating an interference with an early step of the viral replicative cycle of influenza virus. The influence of the compound on the virus adsorption step, studied by the infective center assay, indicated that TTO did not interfere with cellular attachment of the virus. TTO did not inhibit influenza virus neuraminidase activity, as shown by the experiment measuring the amount of 4-methylumbelliferone, cleaved by the influenza virus neuraminidase from the fluorogenic substrate 2'-O-(4-methylumbelliferyl)-N-acetylneuraminic acid. The effect of TTO on acidification of cellular lysosomes was studied by vital staining with acridine orange using bafilomycin A1 as positive control. The treatment of cells with 0.01% (v/v) of TTO at 37°C for 4h before staining inhibited the acridine orange accumulation in acid cytoplasmic vesicles, indicating that TTO could inhibit viral uncoating by an interference with acidification of intralysosomal compartment.
Article
The abundant use of anti-infective agents resulted in the emergence of drug-resistant bacteria, fungi and viruses. To overcome the increasing resistance of pathogenic microbes, a variety of medicinal plants have been screened worldwide for their antimicrobial properties. The aim is to find new effective antimicrobial agents with novel modes of actions. Essential oils derived from aromatic medicinal plants have been reported to exhibit exceptional good antimicrobial effects against bacteria, yeasts, filamentous fungi and viruses. The progress of this expanding scientific field will be documented by the most important results published in the last decade.
Article
Neuraminidase genes from A/tern/Australia/G70C/75 (H11N9) and A/whale/Maine/1/84 (H13N9) influenza viruses have been sequenced. Seventy-two nucleotide changes were found, 17 of which result in changes in the amino acid sequence of the neuraminidase; 3 in the stalk region and 14 in the heads. To our surprise, all of the sequence changes in the head region are located on the base of the neuraminidase tetramer, resulting in conservation of antigenic sites on top of the neuraminidase which vary extensively in human influenza virus neuraminidase. Whale N9 neuraminidase, like tern N9 neuraminidase, possesses high levels of hemagglutinating activity but, unlike the tern neuraminidase, failed to form large well-ordered crystals. However, when the neuraminidase was complexed with Fab fragments of monoclonal antibodies, which were made against the tern N9 neuraminidase, large crystals of the complexes were obtained which diffract X-rays to beyond 3 A.
Article
The antiviral effect of Australian tea tree oil (TTO) and eucalyptus oil (EUO) against herpes simplex virus was examined. Cytotoxicity of TTO and EUO was evaluated in a standard neutral red dye uptake assay. Toxicity of TTO and EUO was moderate for RC-37 cells and approached 50% (TC50) at concentrations of 0.006% and 0.03%, respectively. Antiviral activity of TTO and EUO against herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) was tested in vitro on RC-37 cells using a plaque reduction assay. The 50% inhibitory concentration (IC50) of TTO for herpes simplex virus plaque formation was 0.0009% and 0.0008% and the IC50 of EUO was determined at 0.009% and 0.008% for HSV-1 and HSV-2, respectively. Australian tea tree oil exhibited high levels of virucidal activity against HSV-1 and HSV-2 in viral suspension tests. At noncytotoxic concentrations of TTO plaque formation was reduced by 98.2% and 93.0% for HSV-1 and HSV-2, respectively. Noncytotoxic concentrations of EUO reduced virus titers by 57.9% for HSV-1 and 75.4% for HSV-2. Virus titers were reduced significantly with TTO, whereas EUO exhibited distinct but less antiviral activity. In order to determine the mode of antiviral action of both essential oils, either cells were pretreated before viral infection or viruses were incubated with TTO or EUO before infection, during adsorption or after penetration into the host cells. Plaque formation was clearly reduced, when herpes simplex virus was pretreated with the essential oils prior to adsorption. These results indicate that TTO and EUO affect the virus before or during adsorption, but not after penetration into the host cell. Thus TTO and EUO are capable to exert a direct antiviral effect on HSV. Although the active antiherpes components of Australian tea tree and eucalyptus oil are not yet known, their possible application as antiviral agents in recurrent herpes infection is promising.
Article
The aim of this study was to analyse the antimycotic properties of Melaleuca alternifolia essential oil (tea tree oil, TTO) and its principal components and to compare them with the activity of 5-fluorocytosine and amphotericin B. The screening for the antimycotic activity was performed by serial twofold dilutions in Roswell Park Memorial Institute medium with the inclusion of Tween-80 (0.5%). TTO and terpinen-4-olo were the most active compounds. The majority of the organisms were sensitive to the essential oil, with TTO and terpinen-4-olo being the most active oils showing antifungal activity at minimum inhibitory concentration values lower than other drugs. This study provides a sample large enough to determine the antifungal properties of TTO and terpinen-4-olo and suggests further studies for a possible therapeutic use.
Article
The efficiency and pressure drop of filters made from polyolefin fibers carrying electrical charges were compared with efficiency and pressure drop for filters made from uncharged glass fibers to determine if the efficiency of the charged filters changed with use. Thirty glass fiber filters and 30 polyolefin fiber filters were placed in different, but nearly identical, air-handling units that supplied outside air to a large building. Using two kinds of real-time aerosol counting and sizing instruments, the efficiency of both sets of filters was measured repeatedly for more than 19 weeks while the air-handling units operated almost continuously. Pressure drop was recorded by the ventilation system's computer control. Measurements showed that the efficiency of the glass fiber filters remained almost constant with time. However, the charged polyolefin fiber filters exhibited large efficiency reductions with time before the efficiency began to increase again toward the end of the test. For particles 0.6 microm in diameter, the efficiency of the polyolefin fiber filters declined from 85% to 45% after 11 weeks before recovering to 65% at the end of the test. The pressure drops of the glass fiber filters increased by about 0.40 in. H2O, whereas the pressure drop of the polyolefin fiber filters increased by only 0.28 in. H2O. The results indicate that dust loading reduces the effectiveness of electrical charges on filter fibers.
Article
To date, of the Australian essential oils, only tea tree (Melaleuca alternifolia) and Eucalyptus spp. have undergone extensive investigation. In this study a range of Australian essential oils, including those from Anethole anisata, Callistris glaucophyllia, Melaleuca spp. and Thyptomine calycina, were assayed for in vitro antibacterial activity. M. alternifolia was also included for comparison purposes. Activity was determined using standard disc diffusion assays with each oil assayed at 100%, 10% and 1% against five bacteria (Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Pseudomonas aeruginosa and Alcaligenes faecalis) and the yeast, Candida albicans. All bacteria, with the exception of Ps. aeruginosa, were susceptible to one or more of the essential oils at 100%, with only Eremophilia mitchelli inhibiting the growth of any bacteria at 1% (inhibition of Sal. typhimurium). Where multiple samples of a single oil variety were tested variability in activity profiles were noted. This suggests that different methods of preparation of essential oils, together with variability in plant chemical profiles has an impact on whether or not the essential oil is of use as an antimicrobial agent. These results show that essential oils from Australian plants may be valuable antimicrobial agents for use alone or incorporated into cosmetics, cleaning agents and pharmaceutical products.
Article
The antibacterial activity of Eucalyptus globulus leaf extract was determined for 56 isolates of Staphylococcus aureus, 25 isolates of Streptococcus pyogenes, 12 isolates of Streptococcus pneumoniae and seven isolates of Haemophilus influenzae obtained from 200 clinical specimens of patients with respiratory tract disorders. MIC50s for these species were 64, 32, 16 and 16 mg/L, respectively; MIC90s were 128, 64, 32 and 32 mg/L, respectively; and MBCs were 512, 128, 64 and 64 mg/L, respectively. These results suggest that further studies to clarify the possible therapeutic role of E. globulus leaf extract in the treatment of respiratory tract infection are warranted.
Article
An indoor air purification technique, which combines unipolar ion emission and photocatalytic oxidation (promoted by a specially designed RCI cell), was investigated in two test chambers, 2.75 m3 and 24.3 m3, using nonbiological and biological challenge aerosols. The reduction in particle concentration was measured size selectively in real-time, and the Air Cleaning Factor and the Clean Air Delivery Rate (CADR) were determined. While testing with virions and bacteria, bioaerosol samples were collected and analyzed, and the microorganism survival rate was determined as a function of exposure time. We observed that the aerosol concentration decreased approximately 10 to approximately 100 times more rapidly when the purifier operated as compared to the natural decay. The data suggest that the tested portable unit operating in approximately 25 m3 non-ventilated room is capable to provide CADR-values more than twice as great than the conventional closed-loop HVAC system with a rating 8 filter. The particle removal occurred due to unipolar ion emission, while the inactivation of viable airborne microorganisms was associated with photocatalytic oxidation. Approximately 90% of initially viable MS2 viruses were inactivated resulting from 10 to 60 min exposure to the photocatalytic oxidation. Approximately 75% of viable B. subtilis spores were inactivated in 10 min, and about 90% or greater after 30 min. The biological and chemical mechanisms that led to the inactivation of stress-resistant airborne viruses and bacterial spores were reviewed.
Article
The activity of Eucalyptus globulus essential oil was determined for 120 isolates of Streptococcus pyogenes, 20 isolates of S. pneumoniae, 40 isolates of S. agalactiae, 20 isolates of Staphylococcus aureus, 40 isolates of Haemophilus influenzae, 30 isolates of H. parainfluenzae, 10 isolates of Klebsiella pneumoniae, 10 isolates of Stenotrophomonas maltophilia and two viruses, a strain of adenovirus and a strain of mumps virus, all obtained from clinical specimens of patients with respiratory tract infections. The cytotoxicity was evaluated on VERO cells by the MTT test. The antibacterial activity was evaluated by the Kirby Bauer paper method, minimum inhibitory concentration, and minimum bactericidal concentration. H. influenzae, parainfluenzae, and S. maltophilia were the most susceptible, followed by S. pneumoniae. The antiviral activity, assessed by means of virus yield experiments titered by the end-point dilution method for adenovirus, and by plaque reduction assay for mumps virus, disclosed only a mild activity on mumps virus.
Article
Abstract Abstract Continuous emission of unipolar ions has been shown to improve the performance of respirators and stationary filters challenged with non-biological particles. In this study, we investigated the ion-induced enhancement effect while challenging a low-efficiency heating, ventilation and air-conditioning (HVAC) filter with viable bacterial cells, bacterial and fungal spores, and viruses. The aerosol concentration was measured in real time. Samples were also collected with a bioaerosol sampler for viable microbial analysis. The removal efficiency of the filter was determined, respectively, with and without an ion emitter. The ionization was found to significantly enhance the filter efficiency in removing viable biological particles from the airflow. For example, when challenged with viable bacteria, the filter efficiency increased as much as four- to fivefold. For viable fungal spores, the ion-induced enhancement improved the efficiency by a factor of ∼2. When testing with virus-carrying liquid droplets, the original removal efficiency provided by the filter was rather low: 9.09 ± 4.84%. While the ion emission increased collection about fourfold, the efficiency did not reach 75–100% observed with bacteria and fungi. These findings, together with our previously published results for non-biological particles, demonstrate the feasibility of a new approach for reducing aerosol particles in HVAC systems used for indoor air quality control.