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Green tea and skin benefits
Abstract
Most people accept that green tea is well-known as a medicinal plant. It is alwayssuggested for daily health promotion. Moreover, its extracts have been widely used astopical applications for wound-healing, anti-aging, and disease treatments. Catechins arethe prominent compounds in green tea extract and are promising ingredients indermatological products. They are highly reactive with other compounds, such as reactiveoxygen species and biologic macromolecules to scavenge free radicals or initiatebiological effects. Although green tea presents an excellent result in in vitrostudies withpromising activity to benefit human health, the result of in vivo studies has not been fullysatisfied. A few clinical studies reported that green tea extract significantly improved skinelasticity and increased the dermis's thickness; thus, providing skin wrinkle relief. Theskin inflammation induced by UV radiation was decreased substantially when pretreatingthe skin with green tea extract. Many researchers have attempted to explain thecause of skin improvement by several mechanisms. However, the complete picture hasnot been established. On the other hand, some studies revealed that topical formulation ofgreen tea extract could not improve skin nourishing, and skin moisture tended to decreasewhen applying green tea products for a long time. The discrepancy of the in vivo studyresults is due to the limitation of catechins' properties. Instability, less skin permeation,and cutaneous metabolism play a crucial role in the effectiveness of green tea application.Although green tea's benefits for the skin seem unsatisfied in real life, a recent studyrevealed that the appropriate preparation of green tea formulation and deliverytechnology can diminish catechin limitations.
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The major unexplained phenomenon in fibrotic conditions is an increase in replicating fibroblasts. In this report we present evidence that oxygen free radicals can both stimulate and inhibit proliferation of cultured human fibroblasts, and that fibroblasts themselves release superoxide (O2.-) free radicals. Fibroblasts released O2.- in concentrations which stimulated proliferation, a finding confirmed by a dose-dependent inhibition of proliferation by free radical scavengers. Oxygen free radicals released by a host of agents may thus provide a very fast, specific and sensitive trigger for fibroblast proliferation. Prolonged stimulation may result in fibrosis, and agents which inhibit free radical release may have a role in the prevention of fibrosis.
In an industrial context of producing catechin-enriched fractions by electromigration, a new technology demonstrated to be effective for concentration of the two main catechins (EGC and EGCG) of green tea, the recovery yield from tea leaves during brewing would be the most important parameter of the whole process rentability. However, the majority of the kinetic studies were carried-out on black tea, a fermented tea. Consequently, the objective of this study was to investigate the effects of temperature (50, 60, 70, 80 and 90 °C) and brewing duration (0, 5, 10, 20, 40 and 80 min) on the catechin solubilization from green tea, a non-fermented tea. The use of mathematical models revealed that there was a variable interdependence between the brewing duration and the brewing temperature on catechin and caffeine concentrations. It was possible to divide catechins in two groups, the time dependent compounds (EGC and EC) and the time/temperature dependent compounds (C, EGCG, GCG and ECG). Furthermore, the 3D models calculated to represent the evolution of the catechins and caffeine concentrations allowed to determine the best combination of time and temperature for their extraction: 50 °C during 20–40 min for time-dependent compounds, 90 °C during 80 min for the time/temperature-dependent compounds, and 70–80 °C during 20–40 min for caffeine. Furthermore, this research pointed out a very simple two-step procedure to fractionate the EGC and EGCG by modifying brewing temperature and time parameters.
Tea and herbal infusions have been studied for their polyphenolic content, antioxidantactivity and phenolicprofile. The total phenolics recovered by ethyl acetate from the water extract, were determined by the Folin–Ciocalteu procedure and ranged from 88.1 ± 0.42 (Greek mountain tea) to 1216 ± 32.0 mg (Chinese green tea) GAE (Gallic acid equivalents)/cup. The antioxidantactivity was evaluated by two methods, DPPH and chemiluminescence assays, using Trolox and quercetin as standards. The EC50 of herbal extracts ranged from 0.151 ± 0.002 mg extract/mg DPPH (0.38 quercetin equivalents and 0.57 Trolox equivalents), for Chinese green tea, to 0.77 ± 0.012 mg extract/mg DPPH (0.08 quercetin equivalents and 0.13 Trolox equivalents), for Greek mountain tea. Chemiluminescence assay results showed that the IC50 ranged from 0.17 ± 3.4 × 10−3 μg extract/ml of the final solution in the measuring cell (1.89 quercetin and 5.89 Trolox equivalents) for Chinese green tea, to 1.10 ± 1.86 × 10−2 g extract/ml of the final solution in the measuring cell (0.29 quercetin and 0.90 Trolox equivalents) for Greek mountain tea. The phenolicprofile in the herbal infusions was investigated by LC-DAD-MS in the positive electrospray ionization (ESI+) mode. About 60 different flavonoids, phenolic acids and their derivatives have been identified.
Synopsis
Many effective methods such as spray drying, coacervation, ionic gelation, solvent evaporation and sieving have been suggested for entrapping bioactive compounds into micro‐ or nanoparticles. However, those methods still have some limitations owing to high temperature requirement, difficulty in particle harvesting or low entrapment for uncharged molecules. In this study, a novel chitosan microparticle preparation method was developed using water‐in‐silicone emulsion technique with green tea extract as a model active compound. Chitosan microparticles of diameter <5 μm were obtained from 2% chitosan solution with tripolyphosphate (TPP) solution as the hardening agent. The size and properties of the particles appeared to depend on several parameters such as TPP, emulsifier concentrations and pH. High concentration of emulsifier led to low encapsulation and particle aggregation. Entrapment efficiency of chitosan microparticles was improved with lower pH of the tripolyphosphate solution [59.94 ± 3.97 of epigallocatechin gallate (EGCG)] while slowing release of catechins. Epigallocatechin and epicatechin were released almost completely within 2 h under acidic condition whereas EGCG and epicatechin gallate were slowly released. In neutral condition, release of catechins depended on their molecular stabilities. The stabilities of catechins loaded in chitosan microparticles were varied under various temperatures. The degradation of tea catechins increased with temperature. However, the degradation of tea catechins loaded in chitosan microparticles was less than that of free catechins. Thus, the new technique for preparing chitosan microparticles containing heat‐sensitive water soluble green tea extract was successfully developed. The technique is suitable for micro‐encapsulation of hydrophilic compounds into chitosan microparticles with the ease of harvesting technique.
The objective of this Phase I/II study was to assess the potential for green tea to be used as a colorectal cancer chemopreventive agent. This study measured the dose-related biological effects of administration of a single dose of green tea on the rectal mucosa of normal volunteers. Volunteers were admitted to the Robert Wood Johnson Medical School Clinical Research Center for 24 h. Baseline blood and rectal biopsy samples were obtained before the volunteers drank 0.6, 1.2, or 1.8 g of green tea solids dissolved in warm water. Blood samples were taken 2, 4, 8, and 24 h after the tea administration. Rectal biopsies were obtained at 4, 8, and 24 h. Prostaglandin E2 (PGE2) levels were analyzed by ELISA. Tea polyphenol levels in the blood, urine, and rectal tissue were measured by high-performance liquid chromatography using a Coulochem electrode array detection system. Statistical comparisons were made using ANOVA. Decreased levels of PGE2 in rectal mucosa were observed at 4 and 8 h after consumption of green tea. There was no correlation between inhibition of PGE2 and tissue or plasma levels of tea polyphenols. Ten of 14 subjects demonstrated a response to green tea, as evidenced by at least a 50% inhibition of PGE2 levels at 4 h. We conclude that green tea constituents have biological activity in inhibiting PGE2 synthesis. Given the 71% "response rate," we believe these data support the study of green tea as a colorectal chemopreventive agent in more long-term Phase II trials.
A peroxidase-based bioelectrochemical sensor of hydrogen peroxide (H(2)O(2)) and a Clark-type oxygen electrode were applied to continuous monitoring and kinetic analysis of the autoxidation of catechins. Four major catechins in green tea, (-)-epicatechin, (-)-epicatechin gallate, (-)-epigallocatechin, and (-)-epigallocatechin gallate, were used as model compounds. It was found that dioxygen (O(2)) is quantitatively reduced to H(2)O(2). The initial rate of autoxidation is suppressed by superoxide dismutase and H(+), but is independent of buffer capacity. Based on these results, a mechanism of autoxidation is proposed; the initial step is the one-electron oxidation of the B ring of catechins by O(2) to generate a superoxide anion (O(2)(*-)) and a semiquinone radical, as supported in part by electron spin resonance measurements. O(2)(*-) works as a stronger one-electron oxidant than O(2) against catechins and is reduced to H(2)O(2). The semiquinone radical is more susceptible to oxidation with O(2) than fully reduced catechins. The autoxidation rate increases with pH. This behavior can be interpreted in terms of the increase in the stability of O(2)(*-) and the semiquinone radical with increasing pH, rather than the acid dissociation of phenolic groups. Cupric ion enhances autoxidation; most probably it functions as a catalyst of the initial oxidation step of catechins. The product cuprous ion can trigger a Fenton reaction to generate hydroxyl radical. On the other hand, borate ion suppresses autoxidation drastically, due to the strong complex formation with catechins. The biological significance of autoxidation and its effectors are also discussed.
Tea polyphenols, including (+)-catechin, (-)-epicatechin, and (-)-epigallocatechin-3-gallate (EGCG), have been shown to possess potent antioxidant and anticancer activities. The aim of this study was to evaluate the possibility of using liposomes for the local delivery, including skin and tumor deposition, of these polyphenols. Liposomes containing egg phosphatidylcholine, cholesterol, or anionic species were prepared by a solvent evaporation method and then were subjected to a probe sonicator. The size, zeta potential and entrapment efficiency of these liposomal formulations were determined to provide correlations with results from a subsequent in vivo study. The release rate study showed that inclusion of an anionic species, such as deoxycholic acid (DA) or dicetyl phosphate (DP), increased the permeability of the lipid bilayers, leading to the rapid release of these formulations. No significant increase in skin deposition of catechins was observed after topical application of liposomes. On the other hand, a greater amount of catechins were delivered into the solid tumor by liposomes than by the aqueous solution. The drug release rate and vesicle size of liposomes may influence drug deposition in tumor tissues. The isomers, (+)-catechin and (-)-epicatechin, showed different physicochemical properties in liposomes and for local deposition in the skin and tumor. Finally, the presence of gallic acid ester in the structure of EGCG significantly increased the tissue uptake of catechins.
Plant extracts have been widely used as topical applications for wound-healing, anti-aging, and disease treatments. Examples of these include ginkgo biloba, echinacea, ginseng, grape seed, green tea, lemon, lavender, rosemary, thuja, sarsaparilla, soy, prickly pear, sagebrush, jojoba, aloe vera, allantoin, feverwort, bloodroot, apache plume, and papaya. These plants share a common character: they all produce flavonoid compounds with phenolic structures. These phytochemicals are highly reactive with other compounds, such as reactive oxygen species and biologic macromolecules, to neutralize free radicals or initiate biological effects. A short list of phenolic phytochemicals with promising properties to benefit human health includes a group of polyphenol compounds, called catechins, found in green tea. This article summarizes the findings of studies using green tea polyphenols as chemopreventive, natural healing, and anti-aging agents for human skin, and discusses possible mechanisms of action.
Collagen: Structure and Mechanics provides a cohesive introduction to collagen-rich tissues, such as tendon, bone, cornea or arterials walls. Written in a clear and didactic manner, this volume reviews current knowledge on hierarchical structure, mechanical properties, deformation and strengthening mechanisms, and discusses many applications in biomaterials and tissue engineering. Researchers in the fields of materials, (bio-)engineering, physics, chemistry and biology will gain an understanding of the structure and mechanical behavior of type I collagen and collagen-based tissues in vertebrates, across all length scales from the molecular (nano) to the organ (macro) level. Collagen: Structure and Mechanics is a reference for new researchers entering this area and can serve also as a basis for lecturing in the interdisciplinary field of biological materials science. © 2008 Springer Science+Business Media, LLC. All rights reserved.
In human beings, it is known that there is a correlation between the occurrence of acne and the ability to suppress sebum. Sebosuppression may be related to the inhibition of sebocyte proliferation, differentiation, and lipogenesis in sebaceous glands. To investigate the skin sebosuppressive activity of green tea extract, the in vivo effects of its flavonoid compounds on the androgen-dependent stimulation of pigmented macules in hamsters and performed in vitro experiments with human primary sebocytes were examined. Our results imply a dual activity of skin sebosuppression by green tea flavonoids; some catechins including epigallocatechin-3-gallate (EGCG) and gallocatechin-3-gallate (GCG) may reduce the differentiation of sebocytes by inhibiting PPAR-γ1 mRNA expression, whereas some flavonol glycosides including kaempferol may inhibit lipogenesis in sebaceous glands by decreasing levels of the mature form of sterol-sensitive response elements binding protein-1c (SREBP-1c). Therefore, green tea is a potentially effective material for use in the development of health foods or cosmetics for skin sebosuppression.
Four catechins, (–)-epicatechin (EC), (–)-epigallocatechin (EG), (–)-epicatechin gal late (ECg) and (–)-epigallocatechin gallate (EGg), extracted from tea were investigated with respect to the formation of radicals and chemiluminescence during autoxidation. An alkaline solution (0.05 n NaOH) of these catechins indicated ESR absorption accompanying a browning reaction. The spectra of EG and EGg showed a double triplet at the early stage of autoxidation, but the intensity of each decreased rapidly and the shape of the spectra changed with time, suggesting that most of the radicals disappeared and some changed into others. The spectrum of ECg showed a triplet of relatively strong intensity but decreasing slowly. EC exhibited a very weak spectrum due to EG and EGg being present as impurities. From these results, it was concluded that radicals were easily formed on the aromatic ring to which three hydroxyl groups are attached. The chemiluminescence of EG and EGg was strong and decreased rapidly, but was weak with ECg and negligible with EC. The structures of the radicals are proposed, and the relationship between the radicals and the chemiluminescence is discussed.
Up to 1/100 individuals over the age of 45 years suffers from a wound that is difficult to heal. The need for effective treatment to reduce the associated morbidity and costs is therefore paramount. To develop and target such therapies appropriately, an understanding of the pathophysiology of the wound healing process in both normal and chronic non-healing wounds is necessary. This contribution provides an overview of the basic biology of normal wound healing. By applying this knowledge in clinical and laboratory practice, it is hoped that therapeutic interventions in this field will become more successful.
The beneficial effects of green and black tea are generally attributed to the antioxidant activity of their phenolic compounds. Tea is commonly used with milk or lemon. Milk proteins might complex with tea polyphenols and reduce their antioxidant activity. Lemon contains vitamin C (ascorbic acid) which has antioxidative properties and can positively influence the antioxidant potential of tea.The present study aimed to compare, in vitro, the antioxidant activities of different commercially available types of tea, prepared by commonly used domestic methods and to evaluate the possible effects of different doses (5–40 mg/100 ml) of vitamin C (ascorbic acid) on the total antioxidant capacity (TAC) of tea. The antioxidant activity of tea extracts was determined by the photometric method, according to Rice-Evans and Miller [Methods Enzymol. 234 (1994) 279], measuring the formation of the radical cation ABTS. The values of antioxidant activity of teas prepared in the same way as when consumed were in similar ranges, from 13.3 to 21.6 mmol TE (TE = Trolox equivalents) in green tea and 10.4–17.6 mmol TE in black tea. The experiment in which ascorbic acid was added to teas showed that TAC in black tea extracts increased in a linear manner between 5 and 20 mg ascorbic acid/100 ml tea solution (r=0.984; p
Green tea catechins (GTC) and theaflavins (TF) possess a variety of biological activities. The present study focused on stability of GTC and TF in various solutions and drinks. It was observed that both GTC and TF were vulnerable to degradation caused by elevation of temperature and pH of incubation media. In general, GTC was more stable than TF. When boiled in water, four GTCs showed similar rates of degradation, but in sodium phosphate buffer (pH7.4) at room temperature, four GTCs demonstrated varying stability, with epigallocatechin gallate (EGCG) and epigallocatechin (EGC) being completely degraded in 6 h of incubation, while epicatechin (EC) and epicatechin gallate (ECG) were only degraded by less than 35%. Four TFs also demonstrated varying stability, with theaflavin-3,3′-digallate (TF3) and theaflavin-3′-gallate- B (TF2B) in general being more stable than theaflavin-1 (TF1) and theaflavin-3-gallate-A (TF2A) in either boiling water or alkaline sodium phosphate buffer. When incubated in various solutions and soft drinks, both GTC and TF had poor long-term stability and decayed by at least 50% during the first month of storage at room temperature.
Green tea catechins (GTCs), which include (−)-epicatechin (EC), (−)-epicatechin gallate (ECG), (−)-epigallocatechin (EGC) and (−)-epigallocatechin gallate (EGCG), possess a variety of biological activities. We have previously studied the effect of dietary GTCs as a mixture on membrane oxidation of red blood cells and found that GTCs were partially absorbed and detected in the blood of rats given an oral ingestion of 100 mg of GTCs. To explain the partial absorption of GTCs and their varying free-radical scavenging capacity at different pH, the present paper was to study further the pH stability of these GTC isomers because there is a sharp increase in pH from the acidic stomach to the slightly alkaline intestine. Longjing GTCs as a mixture in alkaline solutions (pH > 8) were extremely unstable and degraded almost completely in a few minutes, whereas in acidic solutions (pH < 4) they were very stable. For the pH between 4 and 8, the stability of GTCs was pH-dependent, i.e., the lower the pH, the greater the stability. Four epicatechin isomers examined demonstrated varying stability in alkaline solutions with EGCG and EGC being equally instable, and EC and ECG being relatively stable. The present results suggest that part of the mechanism by which GTCs were partially absorbed may be attributed to instability of EGCG and EGC in the intestine where the pH is neutral or alkaline. Keywords: Epicatechin; epicatechin gallate; epigallocatechin gallate; epigallocatechin; longjing tea
The effect of different extraction set-ups that influence the extraction efficiency of catechins and caffeine from green tea leaves (variety Fanning Belas, China) were studied using different aqueous and pure solvents (acetone, ethanol, methanol, acetonitrile, water), different temperatures (60, 80, 95 and 100 °C) and times (5–240 min). Raw extracts were analysed for contents of major catechins (EC, EGC, ECG, EGCG), caffeine, proanthocyanidins and flavonols (myricetin, caempherol, quercetin). Starting material was found to contain 191 g major catechins/kg material, 36 g caffeine/kg material and 5.2 g flavonols/kg material on a dry mass basis. The content of major catechins in green tea extracts varied from approximately 280–580 g/kg dry extract, with extraction efficiencies of major catechins varying from 61% to almost 100%. Content of caffeine in extract was in the range of 75 g/kg, where its extraction efficiency varied from 62% to 76%. Average extraction yield was 30% with exceptions when using pure acetone and acetonitrile, where extraction yield was about 3%. Contents of flavonols and proanthocyanidins were in the ranges 6–20 and 12–19 g/kg, respectively. Different extraction procedures with water were also investigated and optimal conditions determined: maximum achieved extraction efficiency of catechins with water was obtained at 80 °C after 20 min (97%) and at 95 °C after 10 min of extraction (90%). Degradation of catechins was observed at higher extraction temperatures and with prolonged extraction times. Using a lower ratio of solvent to material, extraction efficiencies were increased by applying a multi-step extraction procedure. Optimal extraction procedure was then performed using decaffeinated green tea leaves, which were obtained by high-pressure extraction with CO2, when 98% of caffeine was selectively isolated without significant impact on valuable catechins.
Gallic acid and catechin derivatives were oxidized in alkaline solution (pH 10.0–13.0) with K3[Fe(CN)6] under anaerobic conditions, and electron spin resonance (ESR) spectra of the radicals produced were measured. Gallic acid, epicatechin gallate, gallocatechin gallate, epigallocatechin, and epigallocatechin gallate showed hyperfine structures. Gallic acid was found to be oxidatively C—O coupled in alkaline solution (pH 10.5–12.0). It was found that an unpaired electron delocalized over gallocatechin gallate and epigallocatechin molecules, but was localized on the galloyl group and the A-ring of epicatechin gallate and epigallocatechin gallate. The galloyl group of gallo-catechin gallate was readily alkali-hydrolyzed but those of epicatechin gallate and epigallocatechin gallate were resistant to alkaline hydrolysis.
A simple, rapid and reproducible method is presented for the analysis of green-tea extracts in different cosmetic formulations
and in in-vitro skin extracts. Cosmetically active principal components were used for determination of complex assembled green-tea
extracts. The catechins selected were catechin, epicatechin, epigallocatechin, epigallocatechin gallate, and epicatechin gallate,
because of their efficacy and their concentrations in green-tea extracts. The determination was performed by high-performance
liquid chromatography (HPLC), on a reversed-phase (RP) column, coupled to a single-quadrupole mass spectrometer (MS) via an
electrospray ionization (ESI) interface. Detection was performed in the negative selected-ion-monitoring (SIM) mode. A detection
limit between 5 and 15 ng g−1 was achieved in methanol-water-ascorbic acid extracts from different emulsions. A routine analytical procedure could be established
with good quantitative reliability. During validation, the repeatabilities (relative standard deviation) for catechin standard
solutions were found to be 1.1–2.7% (within one day) and 2.2–4.3% (day-to-day). Recoveries from spiked placebos were 98–105%.
The method was successfully used to determine the storage stability of green-tea extract in cosmetic formulations and the
in-vitro penetration of green-tea extract into the skin.
The relative effectiveness of oxidizing (.OH, H2O2), ambivalent (O2−) and reducing free radicals (e− and CO2−) in causing damage to membranes and membrane-bound glyceraldehyde-3-phosphate dehydrogenase of resealed erythrocyte ghosts has been determined. The rates of damage to membranebound glyceraldehyde-3-phosphate dehydrogenase (R(enz)) were measured and the rates of damage to membranes (R(mb)) were assessed by measuring changes in permeability of the resealed ghosts to the relatively low molecular weight substrates of glyceraldehyde-3-phosphate dehydrogenase. Each radical was selectively isolated from the mixture produced during gamma-irradiation, using appropriate mixtures of scavengers such as catalase, superoxide dismutase and formate. .OH, O2− and H2 O2 were approximately equally effective in inactivating membrane-bound glyceraldehyde-3-phosphate dehydrogenase, while e− and CO2− were the least effective. R(enz) values of O2− and H2O2 were 10-times and of .OH 15-times that of e−. R(mb) values were quite similar for e− and H2O2 (about twice that of O2−), while that of .OH was 3-times that of O2−. Hence, with respect to R(mb): , and with respect to R(enz): . The difference between the effectiveness of the most damaging and the least damaging free radicals was more than 10-fold greater in damage to the enzyme than to the membranes. Comparison between H2O2 added as a chemical reagent and H2O2 formed by irradiation showed that membranes and membrane-bound glyceraldehyde-3-phosphate dehydrogenase were relatively inert to reagent H2O2 but markedly susceptible to the latter.
Encapsulation of olive leaf extract (OLE) in chitosan micropsheres was carried out by a spray-drying process. The interaction of polyphenolic compounds (PPCs) present in OLE within the polysaccharide matrix was studied using various physico-chemical techniques. Both the placebo and the OLE loaded microspheres were characterised by optical and scanning electron microscopy, particle size distribution analysis, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The particles obtained after spray-drying were found to be spherical and had uniform particle size distribution patterns. FTIR and DSC indicate that there are interactions of polyphenolic compounds in OLE with the chitosan matrix. Further studies on encapsulation of OLE and its activity were analysed after the total hydrolysis of OLE loaded chitosan microspheres. The released polyphenolic compounds in OLE were estimated to confirm the activity of OLE loaded into the microspheres. The loading percent of polyphenolic compounds through encapsulation of OLE achieved was 27%.
The three main categories of tea: green, black and oolong, result from different processing procedures. In recent years tea has attracted more and more attention because of reported health benefits, in particularly as an antioxidant, but also as an anticarcinogenic and antiarteriosclerotic agent. It is generally believed that flavonoids are mainly responsible for these actions. Tea is now consumed throughout the world not just as a popular beverage, but, because its extracts have been prepared in a variety of physical forms, for example, strong infusions, soft extracts and powders, it is now widely available in a range of food, beverage, and toiletry and cosmetic products.
Catechins are major antioxidants in green tea (Camellia sinensis or Camellia assamica), but because they do not permeate the skin well, the application of green tea in cosmetic products has so far been limited. This study aims to evaluate the cutaneous absorption of catechins from an extract of green tea and from a green tea extractloaded chitosan microparticle. The catechin skin metabolism was also examined. The results suggest that chitosan microparticles significantly improve the ability of catechins to permeate skin. The cutaneous metabolism of the catechins significantly affected their permeation profiles. Epicatechin (EC) and epigallocatechin (EGC) penetrated the skin more than epigallocatechin gallate (EGCG) and epicatechin gallate (ECG). The galloyl groups in EGCG and ECG were enzymatically hydrolysed to EGC and EC, respectively. Dehydroxylation of catechins was also observed. Chitosan microparticles effectively prevented enzymatic changes of the catechins; therefore, chitosan microparticles are here found to be the promising carriers for enhancing the skin permeation.
Skin-wound healing is an orchestrated biological phenomena consisting of three sequential phases, inflammation, proliferation, and maturation. Many biological substances are involved in the process of wound repair, and this short and simplified overview of wound healing can be adopted to determine wound vitality or wound age in forensic medicine. With the development of genetically engineered animals, essential molecules for skin-wound healing have been identified. Especially, cytokines, and growth factors are useful candidates and markers for the determination of wound vitality or age. Moreover, bone marrow-derived progenitor cells would give significant information to wound age determination. In this review article, some interesting observations are presented, possibly contributing to the future practice of forensic pathologists.
Synopsis
Herbal anti‐wrinkle cosmetics were formulated from ginkgo ( Ginkgo biloba ), a mixture of tea and rooibos ( Camellia sinensis and Aspalathus linearis ) and soybean ( Glycine soja ). These extracts were incorporated into the preliminary developed stable gel base with good preference. The gingko formulation was found to be more stable than the formula containing a mixture of tea and rooibos and the soybean formula. Clinical efficacies of the ginkgo formula and the formula containing a mixture of tea and rooibos were compared following 28 days of application. The ginkgo preparation increased skin moisturization (27.88%) and smoothness (4.32%) and reduced roughness (0.4%) and wrinkles (4.63%), whereas the formula containing tea and rooibos showed the best efficacy on wrinkle reduction (9.9%). In comparison to the tea and rooibos formula, gingko significantly improved skin moisturization ( P = 0.05).
Green tea (Camellia sinensis) and Ginkgo biloba extracts in cosmetic formulations have been suggested to protect the skin against UV-induced damage and skin ageing. Thus, it is very important to assess the human skin penetration of their major flavonoids to verify if they penetrate and remain in the skin to exert their proposed effects. The aim of this study was to evaluate the human skin penetration of epigallocatechin-3-gallate (EGCG) and quercetin from green tea and G. biloba extracts vehiculated in cosmetic formulations. This study was conducted with fresh dermatomed human Caucasian skin from abdominal surgery mounted on static Franz diffusion cells. Skin samples were mounted between two diffusion half-cells and 10 mg/cm(2) of formulations supplemented with 6% of green tea or G. biloba extract were applied on the skin surface. The receptor fluid was removed after 6 and 24 h and analyzed by high-performance liquid chromatography for the quantification of the flavonoids. The stratum corneum was removed by tape stripping and immersed in methanol and the epidermis was mechanically separated from the dermis and triturated in methanol to extract EGCG and quercetin. The results showed that the flavonoids under study penetrated into the skin, without reaching the receptor fluid. The majority of EGCG was quantified in the stratum corneum (0.87 microg/cm(2)), which was statistically higher than the EGCG concentrations found in viable epidermis (0.54 microg/cm(2)) and in the dermis (0.38 microg/cm(2)). The majority of quercetin was quantified in the viable epidermis (0.23 microg/cm(2)), which was statistically higher than the EGCG concentration found in the stratum corneum layer (0.17 microg/cm(2)). Finally, it can be concluded that EGCG and quercetin from green tea and G. biloba extracts vehiculated in cosmetic formulations presented good skin penetration and retention, which can favor their skin effects.
A wide variety of normal and malignant cell types generate and release superoxide or hydrogen peroxide in vitro either in response to specific cytokine/growth factor stimulus or constitutively in the case of tumour cells. These species at submicromolar levels appear to act as novel intra and intercellular "messengers" capable of promoting growth responses in culture. The mechanisms may involve direct interaction with specific receptors or oxidation of growth signal transduction molecules such as protein kinases, protein phosphatases, transcription factors, or transcription factor inhibitors. It is also possible that hydrogen peroxide may modulate the redox state and activity of these important signal transduction proteins indirectly through changes in cellular levels of GSH and GSSG. Critical balances appear to exist in relation to cell proliferation on one hand and lipid peroxidation and cell death on the other. Progression to a more prooxidant state whilst initially leading to enhanced proliferative responses results subsequently in increased cell death.
There is increasing interest in the biological effects of tea- and wine-derived polyphenols and many studies in vitro and in vivo are demonstrating their antioxidant properties. Tea is a major source of dietary polyphenols and an even richer source of the flavanols, the catechins and catechin/gallate esters. Although there are limited studies on the bioavailability of the polyphenols, the absorption of flavanols in humans has been shown. The studies described in this chapter discuss the relative antioxidant potentials of the polyphenolic flavonoids in vitro against radicals generated in the aqueous phase in comparison with their relative effectiveness as antioxidants against propagating lipid peroxyl radicals, and how their activity influences that of alpha-tocopherol in low-density lipoproteins exposed to oxidative stress.
1. In physiological situations the proliferation of epidermal cells (keratinocytes) in the skin is a tightly controlled process. 2. However, in many common skin diseases, such as in psoriasis, the control mechanisms go awry resulting in pathological epidermal hyperplasia (thickening). 3. In those situations the keratinocytes enter the alternative pathway of proliferation characterized by excessive growth rate, aberrant responses to growth factors, faulty differentiation, and increased migratory capacity. 4. The participation of different growth factors in enhancing or inhibiting keratinocyte growth, both in physiological and pathological conditions, has been reviewed. 5. The regulatory processes governing epidermal growth have relevance for the understanding of the mechanism of action of the drugs used in the treatment of skin diseases associated with epidermal hyperplasia.
(-)-Epigallocatechin gallate (EGCG), the main physiologically active polyphenol of green tea, is associated with antitumor and antimutagenic activities. The goal of this study was to determine the stability and pharmacokinetic parameters of pure EGCG administered topically to human and mouse skin.
EGCG was investigated by measuring drug levels of a 10% ointment formulation stored under different conditions over a period of 6 months. To determine pharmacokinetic parameters of EGCG following topical application. EGCG was applied as 10% EGCG in hydrophilic ointment USP to full-thickness mouse or human skin in vitro. The transdermal and intradermal. Penetration of EGCG was measured by reverse phase HPLC assays at different time-points.
The stability of EGCG in hydrophilic ointment USP was dependent on time, temperature and the degree of oxidation. For example, 10% EGCG was lost after 2 days at 37 degrees C, but the same formulation supplemented with 0.1% butylated hydroxytoluene (BHT) had significantly longer stability with > or =90% EGCG remaining after 130 days at 37 degrees C. Topical application of EGCG in hydrophilic ointment USP to human or mouse skin resulted in substantial intradermal uptake of up to 1-20% of the applied dose. However, transdermal penetration was observed only in mouse skin.
The present study showed that topical application of EGCG in hydrophilic ointment USP achieved high concentrations in skin but negligible systemic availability. The drug was susceptible to oxidation, but if supplemented with BHT, the hydrophilic ointment formulation could potentially be used in clinical trials of skin cancer prevention.
Interaction of tea catechins with lipid bilayers was investigated with liposome systems, which enabled us to separate liposomes from the external medium by centrifugation. We found that epicatechin gallate had the highest affinity for lipid bilayers, followed by epigallocatechin gallate, epicatechin, and epigallocatechin. Epicatechin gallate and epigallocatechin gallate in the surface of lipid bilayer perturbed the membrane structure.
Studies during the past few years have indicated an inhibitory effect of green tea or tea polyphenols on tumorigenesis in animal and even in human. The purpose of this study was to observe the possible effects of tea polyphenols on skin cell growth and on apoptosis in rat primary cultured keratinocytes and fibroblasts. The release of a cell plasma enzyme (LDH), lipid peroxidation products (MDA production), and GSH-Px (glutathione peroxidase) into the medium in cultured cells was determined after treatment with tea polyphenols in a primary culture of skin cells. The percentage of cells in each cell cycle phase and in apoptosis were assayed by flow cytometry (FCM). Tea polyphenols may have a beneficial effect on skin cells at concentrations from 0.05% to 0.1%, showing a dose-dependent decrease in LDH, MDA (malondialdehyde) production, and a significant dose-dependent increase in GSH-Px and cell number. These effects were more obvious after exposure for 24 h than after 12 h. The results indicate that tea polyphenols may stabilize and protect the cell membrane against the release of cell plasma enzyme LDH, and its anti-peroxidation effect is also important for cell growth. FCM analysis revealed that treatment with 0.01% to 0.1% tea polyphenols decreased the percentage of cells in the G1/G0 (quiescent) phase from 81.32% to 74.38%, and increased the percentage of cells in S and G2/M phase from 9.87% to 15.26%, and from 6.51% to 10.36%, respectively. Tea polyphenols also increased the value of PI (proliferation index) from 18.17 to 25.62. At the same time it decreased the percentage of apoptosis from 27.10% to 17.97%, which indicates that green tea stimulates cell growth and inhibits the occurrence of apoptosis. Our results indicate that tea polyphenols are effective anti-oxidants and also inhibit apoptosis, which may improve the proliferative capacity of primary skin cells in vitro.
Magnesium deficiency is known to produce myocardial fibrosis in different animal models, but the underlying mechanisms are unclear. However, circulating levels of pro-oxidant and mitogenic factors are reported to be elevated in a rodent model of acute magnesium deficiency, suggesting a role for humoral factors in the pathogenesis of the cardiovascular lesions. Probing the mechanism of cardiac fibrogenesis in magnesium deficiency, the present study furnished evidence that serum from magnesium-deficient rats has a more marked effect than serum from magnesium-sufficient rats on mitogenesis, net collagen production, and superoxide generation in cardiac fibroblasts from young adult rats. The enhanced mitogenic response was abolished by superoxide dismutase and N-acetyl cysteine, showing that it is mediated by superoxide anion. Further, a modest inhibitory effect of the neurokinin-1 receptor antagonist, spantide, suggested that factors acting via neurokinin-1 receptors may partly modulate cardiac fibroblast function in magnesium deficiency. The findings are consistent with the postulation that serum factors may activate cardiac fibroblasts via a superoxide-mediated mechanism and contribute to the fibrogenic response in the heart in magnesium deficiency.
Epigallocatechin gallate (EGCG) is a potent polyphenolic antioxidant extracted from green tea. Due to its antimutagenic and antitumor activities, it is a promising candidate for use in topical formulations for skin cancer prevention. The overall goal of this study was therefore to determine the influence of several factors on the stability of EGCG in solution to obtain information that would facilitate the subsequent development of topical formulations. Our first objective was to determine the influence of pH, temperature, and ionic strength on the aqueous stability of EGCG. A second objective was to determine the stability of EGCG in various solvents in the presence and absence of different antioxidants. A simple and rapid stability indicating high-performance liquid chromatography assay for EGCG was developed. Stability studies were performed in 0.05 M aqueous buffers at pH 3, 5, 7, and 9 at 4, 25, and 50 degrees C. The effect of ionic strength on EGCG stability was evaluated in 0.05 M acetate buffer, pH 5, adjusted to the desired ionic strength with sodium chloride. An accelerated stability study of EGCG was performed at 50 degrees C in the organic solvents glycerin and Transcutol P in the presence of antioxidants. The degradation of EGCG increased rapidly as temperature and solution pH were increased. Ionic strength increases also caused an accelerated degradation. The solution stability of EGCG was prolonged in glycerin and Transcutol P compared with an aqueous environment. The addition of 0.1% concentrations of several antioxidants in combination with 0.025% EDTA caused variable effects on EGCG stability. Butylated hydroxytoluene in glycerin produced the greatest stability improvement for EGCG. The t(90) (time for 10% degradation to occur) was 76.1 days at 50 degrees C. It can be concluded that glycerin-based vehicles are suitable for stabilizing EGCG.
The purpose of this study was the development and evaluation of an anhydrous glycerin-based Carbopol gel in order to study the stability of the oxygen/water-sensitive agent epigallocatechin gallate (EGCG).
Various Carbopol polymers were investigated rheologically at concentrations of 0.25-1% using a Brookfield viscometer in order to evaluate their ability to form anhydrous glycerin-based formulations. The addition of Transcutol P was evaluated in order to create a gel that can be utilized for the incorporation of more lipophilic compounds. The suitability of standard neutralizers and their useful concentrations were determined to develop guidelines for formulation optimization. An accelerated stability study was performed at 50 degrees C to evaluate the degradation of EGCG in an anhydrous glycerin gel.
It was found that Carbopol 974 is the most efficient thickener for anhydrous glycerin formulations. In contrast to aqueous gels, anhydrous gels are formed without the addition of neutralizers. The rank-order viscosity of the nonneutralized gels studied was 974 > 971 > 981 > Pemulen TR-2 approximately 980. The addition of neutralizers resulted in a further increase in gel viscosity, with a maximum being reached at a concentration of approximately 0.5% w/w. The incorporation of Transcutol P resulted in a concentration-dependent loss of gel viscosity. The stability data showed that no degradation of EGCG had occurred.
It was shown that anhydrous glycerin-based Carbopol gels can be prepared without the need for neutralization. Such vehicles are promising for the incorporation of oxygen/water-sensitive drugs.
Consumption of green tea has been associated with prevention of cancer development, metastasis, and angiogenesis. Given the crucial role of the matrix metallo-proteinase-2 (MMP-2) on the degradation of the extracellular matrix instrumental to invasion, we examined the effect of the main flavanol present, (-)epigallocatechin-3-gallate (EGCG), on membrane-type 1 MMP (MT1-MMP), the receptor/activator of MMP-2. In-solution fluorimetric assay with activated MT1-MMP and gelatin-zymography with MT1-MMP catalytic domain alone and pro-MMP-2 activation by the same domain revealed dose-dependent inhibition of MT1-MMP at EGCG concentrations slightly lower than that reported to inhibit MMP-2 and MMP-9. Cytofluorimetry and immunolocalization revealed that EGCG does not impair MT1-MMP/TIMP-2/MMP-2 presence on the cell membrane. In the membrane extract of HT-1080 human fibrosarcoma cells, 10 micro M EGCG caused a strong increase in MT1-MMP level and accumulation of pro-MMP-2 while leaving activated MMP-2 unchanged. EGCG thus exerts inhibition of MT1-MMP, which restrains activation of MMP-2; this may confer the antiangiogenic and antimetastatic activity associated with green tea.
In skin and hair research drug targeting to the hair follicle is of great interest. Therefore the influence of permeant lipophilicity and vehicle composition on local accumulation has been examined using confocal laser scanning microscopy (CLSM). Formulations saturated with either Oregon Green 488, Bodipy FL C(5) or Bodipy 564/570 C(5) were prepared. The dyes were applied in citric acid buffer, 8% (w/v) surfactants in citric acid buffer or 8% (w/v) surfactants/20% (w/v) propylene glycol in citric acid buffer. Flow-through diffusion experiments were performed with fresh human scalp skin, after which the skin was imaged using CLSM. Diffusion studies showed for Oregon Green 488 (low lipophilicity) a higher flux when applied in citric acid buffer compared to surfactants. In contrast the fluxes of the more lipophilic dyes (Bodipy FL C(5) and Bodipy 564/570 C(5)) are highest when applied in surfactants/propylene glycol. CLSM studies revealed that follicular accumulation increased with (i) a lipophilic dye and (ii) application of lipophilic dyes in surfactants-propylene glycol. Therefore we conclude that targeting to the hair follicle can be increased by the use of lipophilic drugs in combination with surfactant solutions and propylene glycol.
Levels of essential elements with antioxidant activity, as well as catechins, gallic acid, and caffeine levels, in a total of 45 samples of different teas commercialized in Spain have been evaluated. Chromium, manganese, selenium, and zinc were determined in the samples mineralized with HNO(3) and V(2)O(5), using ETAAS as the analytical technique. The reliability of the procedure was checked by analysis of a certified reference material. Large variations in the trace element composition of teas were observed. The levels ranged from 50.6 to 371.4 ng/g for Cr, from 76.1 to 987.6 microg/g for Mn, from 48.5 to 114.6 ng/g for Se, and from 56.3 to 78.6 ng/g for Zn. The four major catechins [(-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epicatechin (EC)], gallic acid (GA), and caffeine were simultaneously determined by a simple and fast HPLC method using a photodiode array detector. In all analyzed samples, EGCG ranged from 1.4 to 103.5 mg/g, EGC from 3.9 to 45.3 mg/g, ECG from 0.2 to 45.6 mg/g, and EC ranged from 0.6 to 21.2 mg/g. These results indicated that green tea has a higher content of catechins than both oolong and fermented teas (red and black teas); the fermentation process during tea manufacturing reduces the levels of catechins significantly. Gallic acid content ranged from 0.039 to 6.7 mg/g; the fermentation process also elevated remarkably gallic acid levels in black teas (mean level of 3.9 +/- 1.5 mg/g). The amount of caffeine in the analyzed samples ranged from 7.5 to 86.6 mg/g, and the lower values were detected in green and oolong teas. This study will be useful for the appraisal of trace elements and antioxidant components in various teas, and it will also be of interest for people who like drinking this beverage.
Dermal substitution and wound healing are areas of medicine in which there have been many recent advances, but neither the commercially available products nor the products currently described in experimental studies are able to fully substitute for natural living skin. There is an overall consensus that to heal wounds, the substitution of connective tissue matrix, the main component of each wound, is necessary. Both artificial and natural polymers have been used to reconstitute dermis. Nowadays, collagen has been discovered again. Collagen is a natural substrate for cellular attachment, growth and differentiation, and promotes cellular proliferation and differentiation. Once dermis reconstruction is done, the covering of the wound surface with both in vitro expanded epidermis and autologous split-skin transplants is significantly easier and has an improved chance of success. Nowadays, many commercial and experimental products have been introduced to improve cutaneous wound healing. This review discusses some of both acellular and cell-containing products used in the treatment of skin wounds.
This study outlines a simple 'Profilometric' method for measuring the size and function of the wrinkles. Wrinkle size was measured in relaxed conditions and the representative parameters were considered to be the mean 'Wrinkle Depth', the mean 'Wrinkle Area', the mean 'Wrinkle Volume', and the mean 'Wrinkle Tissue Reservoir Volume' (WTRV). These parameters were measured in the wrinkle profiles under relaxed conditions. The mean 'Wrinkle to Wrinkle Distance', which measures the distance between two adjacent wrinkles, is an accurate indicator of the muscle relaxation level during replication. This parameter, identified as the 'Muscle Relaxation Level Marker', and its reduction are related to increased muscle tone or contraction and vice versa. The mean Wrinkle to Wrinkle Distance is very important in experiments where the effectiveness of an anti-wrinkle preparation is tested. Thus, the correlative wrinkles' replicas, taken during follow up in different periods, are only those that show the same mean Wrinkle to Wrinkle Distance. The wrinkles' functions were revealed by studying the morphological changes of the wrinkles and their behavior during relaxed conditions, under slight increase of muscle tone and under maximum wrinkling. Facial wrinkles are not a single groove, but comprise an anatomical and functional unit (the 'Wrinkle Unit') along with the surrounding skin. This Wrinkle Unit participates in the functions of a central neuro-muscular system of the face responsible for protection, expression, and communication. Thus, the Wrinkle Unit, the superficial musculoaponeurotic system (superficial fascia of the face), the underlying muscles controlled by the CNS and Psyche, are considered to be a 'Functional Psycho-Neuro-Muscular System of the Face for Protection, Expression and Communication'. The three major functions of this system exerted in the central part of the face and around the eyes are: (1) to open and close the orifices (eyes, nose, and mouth), contributing to their functions; (2) to protect the eyes from sun, foreign bodies, etc.; (3) to contribute to facial expression, reflecting emotions (real, pretended, or theatrical) during social communication. These functions are exercised immediately and easily, without any opposition ('Wrinkling Ability') because of the presence of the Wrinkle Unit that gives (a) the site of refolding (the wrinkle is a waiting fold, ready to respond quickly at any moment for any skin mobility need) and (b) the appropriate skin tissue for extension or compression (this reservoir of tissue is measured by the parameter of WTRV). The Wrinkling Ability of a skin area is linked to the wrinkle's functions and can be measured by the parameter of 'Skin Tissue Volume Compressed around the Wrinkle' in mm(3) per 30 mm wrinkle during maximum wrinkling. The presence of wrinkles is a sign that the skin's 'Recovery Ability' has declined progressively with age. The skin's Recovery Ability is linked to undesirable cosmetic effects of ageing and wrinkling. This new Profilometric method can be applied in studies where the effectiveness of anti-wrinkle preparations or the cosmetic results of surgery modalities are tested, as well as in studies focused on the functional physiology of the Wrinkle Unit.
The transfollicular administration of pharmacologically active molecules is of current therapeutic interest, mainly with regard to delivery to specific sites of the hair follicle (HF) and the reduction of hepatic metabolism and systemic toxicity. HF are privileged pathways for specific molecules depending on formulations, which enter faster into these shunts than through the stratum corneum. The aim was to optimize the delivery of fluorescent microspheres into the HF, thereby, developing a standardized protocol for follicular targeting with microspheres. The number of HF showing penetration, as well as the depth of penetration, was determined. Freshly excised skin samples with terminal HF were divided into groups, with or without prior treatment with cyanoacrylate skin surface stripping-technique (CSSS). Thereafter microspheres at a size of 0.75-6.0 microm were applied according to the developed standardized protocol. Skin biopsies were obtained, shock-frozen, and sectioned in 5 microm slices. We demonstrated a selective penetration route of the microspheres into the HF. Optimal microsphere size proved to be approximately 1.5 microm, with a 55% rate of all HF, and with a maximum penetration depth of >2300 microm. Without previous CSSS treatment of the skin, the transfollicular microsphere penetration was below 27% with a maximum penetration depth of 1000 microm. Thus, the basis for follicular targeting of essential structures containing stem cells for keratinocytes, melanocytes, and mast cells has been laid.
The aim of this study was to investigate the feasibility of the transdermal delivery of catechins and caffeine from green tea extract. Drug-in-adhesive patches containing 1.35, 1.03, 0.68, and 0.32 mg cm(-2) green tea extract were formulated and the dissolution of (-)-epigallocatechin gallate (EGCg), (-)-epigallocatechin (EGC) and (-)-epicatechin (EC) from these was determined. Transdermal delivery was determined across full thickness pig ear skin from saturated solutions of green tea extract in pH 5.5 citrate-phosphate buffer, polyethylene glycol 400 and a 50:50 mixture of the citrate phosphate buffer and polyethylene glycol in addition to patches containing 1.35 mg cm(-2) green tea extract. Dissolution experiments indicated first order release which was dose dependent in respect of the loading level, although the amounts permeated were not always proportional to the amounts in the formulation. The highest percentage permeation of EGCg was found to be from the patch formulation. EGCg, EGC and EC were all successfully delivered transdermally from saturated solutions and adhesive patches containing green tea extract in this study. There was some evidence for the dermal metabolism of EGCg, but after 24 h 0.1% permeated from the patches containing 1.35 mg cm(-2) green tea extract. This was equivalent to the percentage absorbed after intragastric administration of green tea extract in rats. In addition, the concentration of EGCg in the Franz cell receptor chamber after 24 h permeation from the 0.9 cm diameter patch containing 1.35 mg cm(-2) was within the range of Cmax plasma levels achieved after oral dosing of 2.2-4.2 gm(-2) green tea extract. Caffeine was also delivered at concentrations above those previously reported.
The most abundant green tea polyphenol, epigallocatechin-3-gallate (EGCG), was found to induce differential effects between tumor cells and normal cells. Nevertheless, how normal epithelial cells respond to the polyphenol at concentrations for which tumor cells undergo apoptosis is undefined. The current study tested exponentially growing and aged primary human epidermal keratinocytes in response to EGCG or a mixture of the four major green tea polyphenols. EGCG elicited cell differentiation with associated induction of p57/KIP2 within 24 h in growing keratinocytes, measured by the expression of keratin 1, filaggrin, and transglutaminase activity. Aged keratinocytes, which exhibited low basal cellular activities after culturing in growth medium for up to 25 days, renewed DNA synthesis and activated succinate dehydrogenase up to 37-fold upon exposure to either EGCG or the polyphenols. These results suggest that tea polyphenols may be used for treatment of wounds or certain skin conditions characterized by altered cellular activities or metabolism.
Green tea extracts have gained popularity as ingredients in topical skin care preparations to treat aging skin. Green tea polyphenolic compounds have significant antioxidant and anti-inflammatory activities, and studies suggest that these extracts help mediate ultraviolet radiation damage.
To evaluate the effects of a combination regimen of topical and oral green tea supplementation on the clinical and histologic characteristics of photoaging.
Forty women with moderate photoaging were randomized to either a combination regimen of 10% green tea cream and 300 mg twice-daily green tea oral supplementation or a placebo regimen for 8 weeks.
No significant differences in clinical grading were found between the green tea-treated and placebo groups, other than higher subjective scores of irritation in the green tea-treated group. Histologic grading of skin biopsies did show significant improvement in the elastic tissue content of treated specimens (p<.05).
Participants treated with a combination regimen of topical and oral green tea showed histologic improvement in elastic tissue content. Green tea polyphenols have been postulated to protect human skin from the cutaneous signs of photoaging, but clinically significant changes could not be detected. Longer supplementation may be required for clinically observable improvements.