Polyphenolic Antioxidant (-)-Epigallocatechin-3-Gallate from Green Tea Reduces UVB-lnduced Inflammatory Responses and Infiltration of Leukocytes in Human Skin

An extensive review on phenolic compounds and their potential estrogenic properties on skin physiology

Polyphenolic compounds constitute a diverse group of natural components commonly occurring in various plant species, known for their potential to exert both beneficial and detrimental effects. Additionally, these polyphenols have also been implicated as endocrine-disrupting (ED) chemicals, raising concerns about their widespread use in the cosmetics industry. In this comprehensive review, we focus on the body of literature pertaining to the estrogenic properties of ED chemicals, with a particular emphasis on the interaction of isoflavones with estrogen receptors. Within this review, we aim to elucidate the multifaceted roles and effects of polyphenols on the skin, exploring their potential benefits as well as their capacity to act as ED agents. By delving into this intricate subject matter, we intend to provoke thoughtful consideration, effectively opening a Pandora's box of questions for the reader to ponder. Ultimately, we invite the reader to contemplate whether polyphenols should be regarded as friends or foes in the realm of skincare and endocrine disruption.

Assessment of a Formulation Containing a Castanea sativa Shells Extract on Skin Face Parameters: In Vivo Evaluation

In the last years, the demand for new eco-friendly ingredients has increased on the cosmetic market. Consumers are more aware of sustainable principles and, simultaneously, more conscious regarding the skin aging process. Chestnut (Castanea sativa) shells are a food by-product produced in high quantities in Europe. This waste has been described as a rich source of phenolic compounds with skin biological effects, such as antioxidant, antiradical, and anti-inflammatory activities. Despite the huge number of assays reporting the richness of chestnut shell extracts in bioactive compounds as well as the development of cosmetic formulations containing these extracts, no in vivo assays have assessed their clinical efficacy in human volunteers. The aim of this study was to evaluate the effect on skin face parameters of a formulation containing a chestnut shell extract in human volunteers (n = 22) who applied the product twice per day, for 56 days. For that, biophysical techniques, including Corneometer®, Cutometer®, and PrimosPremium, were employed, allowing the quantification of skin hydration and firmness, as well as of wrinkles’ depth and volume and wrinkles’ skin roughness. The results demonstrated that the formulation led to a slight decrease in roughness and wrinkles’ depth, although no significant differences with respect to a placebo were observed. In addition, a clear improvement of skin hydration was achieved (t0 = 54.00 Arbitrary Units (A.U.) and t56 = 58.62 A.U.). In contrast to the placebo, the active formulation increased skin firmness up to 31.76% in 50.00% of the volunteers, but without significant differences with respect to the placebo, probably due to the short period of treatment. A long-term use of the product is recommended to possibly observe significant differences in all parameters.

Effects of Collagen-Tripeptide and Galacto-oligosaccharide Mixture on Skin Photoaging Inhibition in UVB-exposed Hairless Mice

Collagen-tripeptide (CTP) and galacto-oligosaccharide (GOS), which improve collagen homeostasis and barrier function in the skin, are widely used in the food industry to improve wrinkle-related parameters and skin health. In this study, the photoprotective effect of CTP/GOS mixtures (3:1, 1:1, and 1:3) in ultraviolet (UV) B-irradiated hairless mice was examined. Skin parameter analysis, histological approaches, molecular biology techniques and HPLC analysis were applied to investigate the photoaging protective effect, signaling pathways and changes in the microbiota. Oral administration of CTP/GOS mixtures ameliorated photoaged physical parameters and serum levels of pro-inflammatory cytokines compared to UV-irradiated control group. Administration of the 1:3 mixture showed significant changes in the extracellular matrix-related gene expression compared to other mixture groups. The cecal short-chain fatty acid (SCFA) content showed a significant increase in the CTP/GOS mixed group with a higher GOS content than the control group. In the 16S rRNA-based analysis of cecal microbiota, the relative abundance ratio of the Akkermansia genus belonging to the Verrucomicrobia phylum was higher in CTP and GOS mixture-administered groups than in the UV-irradiated control group. Taken together, CTP/GOS mixtures showed a synergistic effect on photoprotective activity through changes in the gene expression, cytokine levels and intestinal microbiota composition.

Ultraviolet radiation‐induced degradation of dermal extracellular matrix and protection by green tea catechins: a randomised controlled trial

Background

Aim

Methods

Results

Conclusions

Effect of green tea extract loaded chitosan microparticles on facial skin: A split-face, double-blind, randomized placebo-controlled study

INTRODUCTION

The bioactivities of green tea extract were indicated to promote skin health in vitro. Few clinical studies reported on skin nourishment of topical applying green tea extract due to the limited skin absorption.

METHODS

This current study evaluated the clinical effectiveness and safety of green tea extract encapsulated chitosan microparticles (GTP) in emulsion base on a split-face, double-blind, randomized placebo-controlled study. Twenty-nine female volunteers were recruited into the study. They were randomly assigned to apply GTP and placebo creams on each half face for 8 weeks. The facial skin properties on both sides were monitored and evaluated every 2 weeks.

RESULTS

The results revealed that skin elasticity (R2) of half face treated with GTP cream (0.748 ± 0.05) was superior to another that received placebo cream (0.722 ± 0.05) at 4th week. In addition, melanin index implying skin dullness of the half face that received GTP cream significantly improved within the 6th week after application (placebo =295.60 ± 58.81, GTP =282.70 ± 59.62). Most importantly, the photographs clearly indicated that the decreasing in facial wrinkles of volunteers applied with GTP cream was more than those applying placebo cream. Signs of skin irritation were not evident in both treatment and placebo cream groups.

CONCLUSION

Based on study outcomes, the green tea extract encapsulated chitosan microparticles appear to be the promising active candidate for promoting skin elasticity and improving skin dullness and wrinkles.

Plant-Derived Compounds as Promising Therapeutics for Vitiligo

Vitiligo is the most common depigmenting disorder characterized by white patches in the skin. The pathogenetic origin of vitiligo revolves around autoimmune destruction of melanocytes in which, for instance, oxidative stress is responsible for melanocyte molecular, organelle dysfunction and melanocyte specific antigen exposure as well as melanocyte cell death and thus serves as an important contributor for vitiligo progression. In recent years, natural products have shown a wide range of pharmacological bioactivities against many skin diseases, and this review focuses on the effects and mechanisms of natural compounds against vitiligo models. It is showed that some natural compounds such as flavonoids, phenols, glycosides and coumarins have a protective role in melanocytes and thereby arrest the depigmentation, and, additionally, Nrf2/HO-1, MAPK, JAK/STAT, cAMP/PKA, and Wnt/β-catenin signaling pathways were reported to be implicated in these protective effects. This review discusses the great potential of plant derived natural products as anti-vitiligo agents, as well as the future directions to explore.

Therapeutic effects of green tea on endometriosis

Endometriosis is a chronic disorder characterized by the presence of endometrial glands and stroma outside the uterine cavity. It affects 8%-10% of women in their reproductive years, and represents a major clinical problem with deleterious social, sexual and reproductive consequences. Current treatment options include pain relief, hormonal intervention and surgical removal. However, these treatments are deemed unsatisfactory owing to varying success, significant side effects and high recurrence rates. Green tea and its major bioactive component, (-)-epigallocatechin gallate (EGCG), possess diverse biological properties, particularly anti-angiogenic, anti-proliferation, anti-metastasis, and apoptosis induction. In recent years, preclinical studies have proposed the use of green tea to inhibit the growth of endometriosis. Herein, the aim of this review is to summarize the potential therapeutic effects of green tea on molecular and cellular mechanism through inflammation, oxidative stress, invasion and adhesion, apoptosis and angiogenesis in endometriosis.

Mitigating Visible Light and Long Wavelength UVA1-induced Effects with Topical Antioxidants

The role of topical antioxidants (AOs) on visible light plus ultraviolet A1 (VL+UVA1)-induced skin changes were evaluated. Twenty subjects with skin phototypes (SPTs) I-VI had placebo and concentrations of an AO blend applied to their back (AO 0.5%, 1.0% and 2.0%). Treated and control sites were irradiated with VL+UVA1. Colorimetric and diffuse reflectance spectroscopy (DRS) assessments were performed immediately, 24 h and 7 days after irradiation. Subjects with SPT I-III had erythema that faded within 24 h, while SPT IV-VI had persistent pigmentation. SPT I-III demonstrated significantly less erythema at the 2% AO site while SPT IV-VI demonstrated significantly less immediate pigmentation at 2% AO site and less pigmentation (approaching significance, P = 0.07) on day 7 compared with control. Immunohistochemistry from biopsies of 2% AO and placebo at 24 h did not demonstrate a significant change in COX-2 or MART-1 for any SPT. There was a decrease in cyclin D1 for SPT IV-VI which was approaching significance (P = 0.06) but not for SPT I-III. The results indicate that topical AO inhibits erythema in SPT I-III and reduces pigmentation in SPT IV-VI caused by VL+UVA1. AO may help prevent worsening of pigmentary disorders and should be incorporated into photoprotection.

Exploring the Molecular Pathways Behind the Effects of Nutrients and Dietary Polyphenols on Gut Microbiota and Intestinal Permeability: A Perspective on the Potential of Metabolomics and Future Clinical Applications

The gut microbiota is involved in the regulation of the intestinal permeability (IP), whose disruption is a frequent condition in older people and is associated with the development of several diseases. The diet can affect the gut microbiota and IP, although the molecular mechanisms involved are unclear. Metabolomics is one of the suitable approaches to study the effects of diet on gut microbiota and IP, although, up to now, the research has focused only on a few dietary components. The aim here was to review the most recent literature concerning the application of metabolomics to the study of the diet-induced alterations of gut microbiota and the effects on IP, with a particular focus on the molecular pathways involved. An additional aim was to give a perspective on the future research involving dietary polyphenols, because despite their potential use in the management of increased IP, few studies have been reported to date.

Areca nut procyanidins prevent ultraviolet light B-induced photoaging via suppression of cyclooxygenase-2 and matrix metalloproteinases in mouse skin

Chronic exposure to solar ultraviolet (UV) light induces photoaging in human skin. Our previous results have shown that areca nut procyanidins (ANPs) have antioxidant capacity and possess potential anti-inflammatory effects. Here, we aimed to investigate the effect of ANPs on UVB-induced photoaging. In the present study, dorsal skin of CD-1 mice was exposed to UVB at a minimal erythema dose (130 mJ/cm²) throughout a 3-week period. The effects of ANPs and epigallocatechin-3-gallate (EGCG), a polyphenolic constituent of green tea, on UVB-induced photoaging were compared. The results show that oral administration of ANP prevented UVB-induced photoaging, indicated by epidermal thickness and collagen disorientation, and inhibited UVB-induced expression of cyclooxygenase-2 and matrix metalloproteinases (MMPs), such as MMP-2, MMP-9, and TIMP1. The protective potential of ANP on UVB-induced photodamage was comparable to that of EGCG. These data suggest that ANP could be useful as a dietary supplement to attenuate solar UVB-induced premature skin aging.

Agro-Industrial By-Products and Their Bioactive Compounds—An Ally against Oxidative Stress and Skin Aging

The increased consumer awareness towards hazards related with sun exposure has given a boost in the cosmetics industry and particularly the sun care market. Human skin is continually being threatened by the UV irradiation present in sunlight and acute UV exposure leads to skin photoaging. Cosmetic and/or dermatological applications include several bioactive compounds that contribute to the regulation of epidermal homeostasis by providing protection against solar radiation and improving the antioxidant activity of epidermis. Plant extracts are sources of active ingredients with intense therapeutic properties, and the topical application or oral intake of these compounds could ameliorate skin condition. Nowadays, there is a growing demand for the application of the bioactive agents contained in agro-industrial byproducts in sun care products, since many of them have shown promising properties as skin photoprotectants. However, well-conducted clinical studies are required to prove their safety and efficacy before they could be regularly used. Environmentally friendly extraction and sustainable techniques are therefore under examination for recovering such compounds from agro-industrial byproducts and converting them into innovative high-value natural ingredients used in cosmetic formulations.

Antinociceptive Effect of Hydroalcoholic Extract of Iranian Green tea in the Formalin Test in Rats

BACKGROUND

Tea (Camellia sinensis) has been utilised, since time immemorial, as a beverage possessing encouraging health benefits. Little scientific evidence exists in literature on the effect of this plant on pain.

OBJECTIVES

To investigate the antinociceptive activity of Iranian green tea extract.

MATERIALS AND METHODS

The hydroalcoholic extract was administered to male Wistar rats. Formalin paw test was used to evaluate the antinociceptive activity. Plant extract (25, 50, 100 and 200 mg/kg, i.p.) (n = 6 for each group) or vehicle (n = 6) was administered 30 min before the subplantar formalin injection.

RESULTS

The extract caused a significant dose-related (50, 100, 200 mg /kg, i.p.) inhibition of the first phase and onset of chronic phase (200 mg /kg, i.p.) of formalin induced nociception. The results showed that the pre-treatment of rats with naloxone (1 mg/kg, i.p.) significantly (P < 0.001) reversed antinociception by Green tea extract (GTE) (200 mg/kg, i.p.) in the inflammatory phase and had no effect on phase 1.

CONCLUSIONS

These results indicate that GTE produces dose-related antinociception in chemical pain model and one of its possible mechanisms involves opioid pathways.

Oligonol inhibits UVB-induced COX-2 expression in HR-1 hairless mouse skin--AP-1 and C/EBP as potential upstream targets

Oxidative stress and inflammatory tissue damage are two major events frequently implicated in carcinogenesis. Numerous polyphenolic compounds derived from plants possess antioxidant and anti-inflammatory activities and are hence effective in preventing cancer. Oligonol is a polyphenol formulation enriched with catechin-type oligomers. As an initial approach to assess the chemopreventive potential of oligonol, we have determined its effects on inflammatory as well as oxidative damage in mouse skin irradiated with UVB. Topical application of oligonol onto the dorsal skin of male HR-1 hairless mice 30 min prior to UVB exposure diminished epidermal hyperplasia and formation of 4-hydroxynonenal, a biochemical hallmark of lipid peroxidation. Topical application of oligonol also significantly inhibited UVB-induced cyclooxygenase (COX-2) expression in mouse skin. Oligonol diminished the DNA binding of activator protein-1 (AP-1) and CCAAT/enhancer binding protein (C/EBP), and the expression of C/EBPdelta in mouse skin exposed to UVB. Our study also revealed that oligonol attenuated UVB-induced catalytic activity as well as expression of p38 mitogen-activated protein (MAP) kinase. Moreover, UVB-induced phosphorylation of another upstream kinase Akt was attenuated by oligonol. Taken together, oligonol showed antioxidative and anti-inflammatory effects in UVB-irradiated mouse skin by inhibiting COX-2 expression via blockade of the activation of AP-1 and C/EBP, and upstream kinases including p38 MAP kinase and Akt.

Dual mechanisms of green tea extract (EGCG)-induced cell survival in human epidermal keratinocytes

Beneficial effects attributed to green tea, such as its anticancer and antioxidant properties, may be mediated by (-)-epigallocatechin-3-gallate (EGCG). In this study, the effects of EGCG on cell proliferation and UV-induced apoptosis were investigated in normal epidermal keratinocytes. When topically applied to aged human skin, EGCG stimulated the proliferation of epidermal keratinocytes, which increased the epidermal thickness. In addition, this topical application also inhibited the UV-induced apoptosis of epidermal keratinocytes. EGCG was found to increase the phosphorylation of Bad protein at the Ser112 and Ser136. Moreover, EGCG-induced Erk phosphorylation was found to be critical for the phosphorylation of Ser112 in Bad protein, and the EGCG-induced activation of the Akt pathway was found to be involved in the phosphorylation of Ser136. Furthermore, EGCG increased Bcl-2 expression but decreased Bax expression, causing an increase in the Bcl-2-to-Bax ratio. In addition, we demonstrate the differential growth inhibitory effects of EGCG on cancer cells. In conclusion, this study demonstrates that EGCG promotes keratinocyte survival and inhibits the UV-induced apoptosis via two mechanisms: by phosphorylating Ser112 and Ser136 of Bad protein through Erk and Akt pathways, respectively, and by increasing the Bcl-2-to-Bax ratio. Moreover, these two proposed mechanisms of EGCG-induced cell proliferation may differ kinetically to promote keratinocyte survival.

Neuroprotection and neurorescue against Abeta toxicity and PKC-dependent release of nonamyloidogenic soluble precursor protein by green tea polyphenol (-)-epigallocatechin-3-gallate

Green tea extract and its main polyphenol constituent (-)-epigallocatechin-3-gallate (EGCG) possess potent neuroprotective activity in cell culture and mice model of Parkinson's disease. The central hypothesis guiding this study is that EGCG may play an important role in amyloid precursor protein (APP) secretion and protection against toxicity induced by beta-amyloid (Abeta). The present study shows that EGCG enhances (approximately 6-fold) the release of the non-amyloidogenic soluble form of the amyloid precursor protein (sAPPalpha) into the conditioned media of human SH-SY5Y neuroblastoma and rat pheochromocytoma PC12 cells. sAPPalpha release was blocked by the hydroxamic acid-based metalloprotease inhibitor Ro31-9790, which indicated mediation via alpha-secretase activity. Inhibition of protein kinase C (PKC) with the inhibitor GF109203X, or by down-regulation of PKC, blocked the EGCG-induced sAPPalpha secretion, suggesting the involvement of PKC. Indeed, EGCG induced the phosphorylation of PKC, thus identifying a novel PKC-dependent mechanism of EGCG action by activation of the non-amyloidogenic pathway. EGCG is not only able to protect, but it can rescue PC12 cells against the beta-amyloid (Abeta) toxicity in a dose-dependent manner. In addition, administration of EGCG (2 mg/kg) to mice for 7 or 14 days significantly decreased membrane-bound holoprotein APP levels, with a concomitant increase in sAPPalpha levels in the hippocampus. Consistently, EGCG markedly increased PKCalpha and PKC in the membrane and the cytosolic fractions of mice hippocampus. Thus, EGCG has protective effects against Abeta-induced neurotoxicity and regulates secretory processing of non-amyloidogenic APP via PKC pathway.