Skin photoprotection by natural polyphenols: anti-inflammatory, antioxidant and DNA repair mechanisms

Sargassum fulvellum Protects HaCaT Cells and BALB/c Mice from UVB-Induced Proinflammatory Responses

Ultraviolet (UV) radiation has been reported to induce cutaneous inflammation such as erythema and edema via induction of proinflammatory enzymes and mediators. Sargassum fulvellum is a brown alga of Sargassaceae family which has been demonstrated to exhibit antipyretic, analgesic, antiedema, antioxidant, antitumor, fibrinolytic, and hepatoprotective activities. The purpose of this study is to investigate anti-inflammatory effects of ethylacetate fraction of ethanol extract of Sargassum fulvellum (SFE-EtOAc) in HaCaT keratinocytes and BALB/c mice. In HaCaT cells, SFE-EtOAc effectively inhibited UVB-induced cytotoxicity (60 mJ/cm²) and the expression of proinflammatory proteins such as cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and inducible nitric oxide synthase (iNOS). Furthermore, SFE-EtOAc significantly reduced UVB-induced production of proinflammatory mediators including prostaglandin E₂ (PGE₂) and nitric oxide (NO). In BALB/c mice, topical application of SFE-EtOAc prior to UVB irradiation (200 mJ/cm²) effectively suppressed the UVB-induced protein expression of COX-2, iNOS, and TNF-α and subsequently attenuated generation of PGE₂ and NO as well. In another experiment, SFE-EtOAc pretreatment suppressed UVB-induced reactive oxygen species production and exhibited an antioxidant potential by upregulation of antioxidant enzymes such as catalase and Cu/Zn-superoxide dismutase in HaCaT cells. These results suggest that SFE-EtOAc could be an effective anti-inflammatory agent protecting against UVB irradiation-induced skin damages.

Nanodesign of olein vesicles for the topical delivery of the antioxidant resveratrol

OBJECTIVES

The ex-vivo percutaneous absorption of the natural antioxidant resveratrol in liposomes and niosomes was investigated. The influence of vesicle composition on their physicochemical properties and stability was evaluated. Liposomes containing resveratrol were formulated using soy phosphatidylcholine (Phospholipon90G). Innovative niosomes were formulated using mono- or diglycerides: glycerol monooleate (Peceol) and polyglyceryl-3 dioleate (Plurol OleiqueCC), respectively, two suitable skin-compatible oleins used in pharmaceutical formulations as penetration enhancers.

METHODS

Small, negatively charged vesicles with a mean size of approximately 200 nm were prepared. The accelerated stability of vesicles was evaluated using Turbiscan Lab Expert, and the bilayer deformability was also assessed. Ex-vivo transdermal experiments were carried out in Franz diffusion cells, on newborn pig skin, to study the influence of the different vesicle formulations on resveratrol skin delivery.

KEY FINDINGS

Results indicated a high cutaneous accumulation and a low transdermal delivery of resveratrol, especially when Peceol niosomes were used.

CONCLUSIONS

Overall, niosomes formulated with Plurol oleique or Peceol showed a better behaviour than liposomes in the cutaneous delivery of resveratrol.

The use of antioxidants in radiotherapy-induced skin toxicity

Radiation-induced skin damage is one of the most common complications of radiotherapy. In order to combat these side effects, patients often turn to alternative therapies, which often include antioxidants. Antioxidants such as those in the polyphenol chemical class, xanthine derivatives, tocepherol, sucralfate, and ascorbate have been studied for their use in either preventing or treating radiotherapy-induced skin damage. Apart from their known role as free radical scavengers, some of these antioxidants appear to alter cytokine release affecting cutaneous and systemic changes. We review the role of antioxidants in treating and preventing radiation-induced skin damage as well as the possible complications of using such therapy.

Effects of pre- and post-treatment with plant polyphenols on human keratinocyte responses to solar UV

BACKGROUND

The understanding of the anti-inflammatory mechanisms of action of plant polyphenols (PPs) and clarification of the relationship between their anti-inflammatory and antioxidant properties may result in a new therapeutic approach to skin cancers.

OBJECTIVE

To elucidate the underlying mechanism, we analyzed the ability of PPs to attenuate inflammatory, metabolic and oxidative cellular responses to UV irradiation.

METHODS

Normal human epidermal keratinocytes (NHEK) were exposed to physiologically relevant dose of solar-simulated UV irradiation. Effects of pre- and post-treatment with PPs on the overproduction of peroxides and inflammatory mediators (mRNA and protein) were analyzed using real-time RT-PCR, enzyme-linked immunosorbent and fluorometric techniques.

RESULTS

Differences between the effectiveness of pre- and post-treatment with polyphenols was found. In particular, PPs post-treatment, but not pretreatment, completely abolished overexpression of Cyp1a1 and Cyp1b1 genes and elevation of intracellular peroxides in NHEK irradiated by UV. Post-treatment with PPs also more efficiently than pretreatment prevented UV-induced overexpression of IL-1 beta, IL-6 and COX2 mRNAs.

CONCLUSION

Our data strongly suggest that PPs predominantly affect delayed molecular and cellular events initiated in NHEK by solar UV rather than primary photochemical reactions. PPs may be important component in cosmetic formulations for post-sun skin care.

Conditioned serum-free medium from umbilical cord mesenchymal stem cells has anti-photoaging properties

Chronic exposure to solar radiation is the primary cause of photoaging and benign and malignant skin tumors. A conditioned serum-free medium (SFM) was prepared from umbilical cord mesenchymal stem cells (UC-MSCs) and its anti-photoaging effect, following chronic UV irradiation in vitro and in vivo, was evaluated. UC-MSC SFM had a stimulatory effect on human dermal fibroblast proliferation and reduced UVA-induced cell death. In addition, UC-MSC SFM blocked UVA inhibition of superoxide dismutase activity. Topical application of UC-MSC SFM to mouse skin prior to UV irradiation blocked the inhibition of superoxide dismutase and glutathione peroxidase activities, and prevented the upregulation of malonaldehyde. UC-MSC SFM thus protects against photoaging induced by UVA and UVB radiation and is a promising candidate for skin anti-photoaging treatments.

Targeting the redox balance in inflammatory skin conditions

Reactive oxygen species (ROS) can be both beneficial and deleterious. Under normal physiological conditions, ROS production is tightly regulated, and ROS participate in both pathogen defense and cellular signaling. However, insufficient ROS detoxification or ROS overproduction generates oxidative stress, resulting in cellular damage. Oxidative stress has been linked to various inflammatory diseases. Inflammation is an essential response in the protection against injurious insults and thus important at the onset of wound healing. However, hampered resolution of inflammation can result in a chronic, exaggerated response with additional tissue damage. In the pathogenesis of several inflammatory skin conditions, e.g., sunburn and psoriasis, inflammatory-mediated tissue damage is central. The prolonged release of excess ROS in the skin can aggravate inflammatory injury and promote chronic inflammation. The cellular redox balance is therefore tightly regulated by several (enzymatic) antioxidants and pro-oxidants; however, in case of chronic inflammation, the antioxidant system may be depleted, and prolonged oxidative stress occurs. Due to the central role of ROS in inflammatory pathologies, restoring the redox balance forms an innovative therapeutic target in the development of new strategies for treating inflammatory skin conditions. Nevertheless, the clinical use of antioxidant-related therapies is still in its infancy.

Riboflavin-photosensitized oxidation is enhanced by conjugation in unsaturated lipids

Methyl esters of polyunsaturated fatty acids were found to quench triplet-excited riboflavin ((3)Rib) in efficient bimolecular reactions with rate constants, as determined by laser flash photolysis, linearly depending upon the number of bis-allylic methylene (from 1 to 5). Deactivation of (3)Rib is predicted by combining the experimental second-order rate constants k2 determined for acetonitrile/water (8:2, v/v) at 25 °C with density functional theory (DFT) calculations of bond dissociation energy to have an upper limiting value of 1.22 × 10(7) L mol(-1) s(-1) for hydrogen abstraction from bis-allylic methylene groups in unsaturated lipid by (3)Rib. Still, ergosterol was found to deactivate (3)Rib with k2 = 6.2 × 10(8) L mol(-1) s(-1), which is more efficient than cholesterol, with 6.9 × 10(7) L mol(-1) s(-1). Likewise conjugated (9E,11E) methyl linoleate (CLA) reacts with 3.3 × 10(7) L mol(-1) s(-1), 30 times more efficient than previously found for methyl α-linolenate. Conjugation as in CLA and ergosterol is concluded to enhance (3)Rib deactivation, and dietary plant sterols and CLA may accordingly be important macronutrients for eye and skin health, protecting against light exposure through efficient deactivation of (3)Rib.

Dietary plant phenolic improves survival of bacterial infection in Manduca sexta caterpillars

Plant phenolics are generally thought to play significant roles in plant defense against herbivores and pathogens. Many plant taxa, including Solanaceae, are rich in phenolic compounds and some insect herbivores have been shown to acquire phenolics from their hosts to use them as protection against their natural enemies. Here we demonstrate that larvae of an insect specialist on Solanaceae, the tobacco hornworm, Manduca sexta L. (Lepidoptera: Sphingidae), acquire the plant phenolic chlorogenic acid (CA), and other caffeic acid derivatives as they feed on one of their hosts, Nicotiana attenuata L. (Solanaceae), and on artificial diet supplemented with CA. We test the hypothesis that larvae fed on CA-supplemented diet would have better resistance against bacterial infection than larvae fed on a standard CA-free diet by injecting bacteria into the hemocoel of fourth instars. Larvae fed CA-supplemented diet show significantly higher survival of infection with Enterococcus faecalis (Andrewes & Horder) Schleifer & Kilpper-Bälz, but not of infection with the more virulent Pseudomonas aeruginosa (Schroeter) Migula. Larvae fed on CA-supplemented diet possess a constitutively higher number of circulating hemocytes than larvae fed on the standard diet, but we found no other evidence of increased immune system activity, nor were larvae fed on CA-supplemented diet better able to suppress bacterial proliferation early in the infection. Thus, our data suggest an additional defensive function of CA to the direct toxic inhibition of pathogen proliferation in the gut.

Photoprotective and antioxidant effects of Rhubarb: inhibitory action on tyrosinase and tyrosine kinase activities and TNF-α, IL-1α and α-MSH production in human melanocytes

BACKGROUND

Exposure to ultraviolet (UV) radiation causes various forms of acute and chronic skin damage, including immunosuppression, inflammation, premature aging and photodamage. Furthermore, it induces the generation of reactive oxygen species, produces proinflammatory cytokines and melanocyte-stimulating hormone (MSH) and increases tyrosinase activity. The aim of this study was to evaluate the potential photoprotective effects of Rheum rhaponticum L. rhizome extract on human UV-stimulated melanocytes.

METHODS

The effects of Rheum rhaponticum rhizome extract on tyrosine kinase activity, and on interleukin-1α (IL-1α), tumour necrosis factor α (TNF-α), and α-MSH production in human epidermal melanocytes were evaluated under UV-stimulated and non-stimulated conditions. Antioxidant activity was evaluated by lipid peroxidation and 1,1-dyphenyl-2-picryl-hydrazyl (DPPH) assays, while anti-tyrosinase activity was evaluated by the mushroom tyrosinase method.

RESULTS

Rheum rhaponticum L. rhizome extract showed in vitro antioxidant properties against lipid peroxidation, free radical scavenging and anti-tyrosinase activities, and inhibited the production of IL-1α, TNF-α, α-MSH, and tyrosine kinase activity in melanocytes subjected to UV radiation.

CONCLUSIONS

These results support the inclusion of Rheum rhaponticum L. rhizome extract into cosmetic, sunscreen and skin care products for the prevention or reduction of photodamage.

Empetrum nigrum var. japonicum Extract Suppresses Ultraviolet B-Induced Cell Damage via Absorption of Radiation and Inhibition of Oxidative Stress

This study focused on the protective actions of Empetrum nigrum against ultraviolet B (UVB) radiation in human HaCaT keratinocytes. An ethyl acetate extract of E. nigrum (ENE) increased cell viability decreased by exposure to UVB rays. ENE also absorbed UVB radiation and scavenged UVB-induced intracellular reactive oxygen species (ROS) in HaCaT keratinocytes. In addition, ENE shielded HaCaT keratinocytes from damage to cellular components (e.g., peroxidation of lipids, modification of proteins, and breakage of DNA strands) following UVB irradiation. Furthermore, ENE protected against UVB-induced apoptotic cell death, as determined by a reduction in the numbers of apoptotic bodies and sub-G1 hypodiploid cells, as well as by the recovery of mitochondrial membrane potential. The results of the current study therefore suggest that ENE safeguards human keratinocytes against UVB-induced cellular damage via the absorption of UVB ray and scavenging of UVB-generated ROS.

Photo-damage protective effect of two facial products, containing a unique complex of Dead Sea minerals and Himalayan actives

BACKGROUND

Skin appearance is badly affected when exposed to solar UV rays, which encourage physiological and structural cutaneous alterations that eventually lead to skin photo-damage.

AIMS

To test the capability of two facial preparations, extreme day cream (EXD) and extreme night treatment (EXN), containing a unique complex of Dead Sea water and three Himalayan extracts, to antagonize biological effects induced by photo-damage.

METHODS

Pieces of organ cultures of human skin were used as a model to assess the biological effects of UVB irradiation and the protective effect of topical application of two Extreme preparations. Skin pieces were analyzed for mitochondrial activity by MTT assay, for apoptosis by caspase 3 assay, and for cytokine secretion by solid phase ELISA. Human subjects were tested to evaluate the effect of Extreme preparations on skin wrinkle depth using PRIMOS and skin hydration by a corneometer.

RESULTS

UVB irradiation induced cell apoptosis in the epidermis of skin organ cultures and increased their pro-inflammatory cytokine, tumor necrosis α (TNFα) secretion. Topical applications of both preparations significantly attenuated all these effects. Furthermore, in human subjects, a reduction in wrinkle depth and an elevation in the intense skin moisture were observed.

CONCLUSIONS

The observations clearly show that EXD and EXN preparations have protective anti-apoptotic and anti-inflammatory properties that can attenuate biological effects of skin photo-damage. Topical application of the preparations improves skin appearance by reducing its wrinkles depth and increasing its moisturizing impact.

Evaluation of the effect of hydroxypropyl-β-cyclodextrin on topical administration of milk thistle extract

Two water in oil emulsions composed by eudermic ingredients as glycerin, cocoa butter, almond oil and a variety of lipids, were enriched respectively with milk thistle dry extract (MT) or with a binary complex composed by MT and hydroxypropyl-β-cyclodextrin (HP) (1:4 w/w) correspondent to 1% (w/w) in sylimarine in order to obtain two different emulsions designed for the skin delivery and determine influence of hydroxypropyl-β-cyclodextrin on the extract delivery and permeation. Uv-vis spectrophotometric analyses demonstrated that phytocomplex formation influences the finding of MT after the complexation process and the in vitro antioxidant activity. Further in vitro and ex vivo experiments demonstrated that the penetration capability of MT from formulations is strictly influenced by the phytocomplex able to control MT permeation; moreover phytocomplex increases flavonoids stability during the in vitro tests. Additionally, in vivo studies showed that the penetration into the stratum corneum of the active ingredients is effectively achieved by the phytocomplex formation, in fact about 80% of MT is absorbed by the skin along 1h despite the 30% of MT not complexed absorbed during the same period.

Oral green tea catechin metabolites are incorporated into human skin and protect against UV radiation-induced cutaneous inflammation in association with reduced production of pro-inflammatory eicosanoid 12-hydroxyeicosatetraenoic acid

Green tea catechins (GTC) reduce UV radiation (UVR)-induced inflammation in experimental models, but human studies are scarce and their cutaneous bioavailability and mechanism of photoprotection are unknown. We aimed to examine oral GTC cutaneous uptake, ability to protect human skin against erythema induced by a UVR dose range and impact on potent cyclo-oxygenase- and lipoxygenase-produced mediators of UVR inflammation, PGE2 and 12-hydroxyeicosatetraenoic acid (12-HETE), respectively. In an open oral intervention study, sixteen healthy human subjects (phototype I/II) were given low-dose GTC (540 mg) with vitamin C (50 mg) daily for 12 weeks. Pre- and post-supplementation, the buttock skin was exposed to UVR and the resultant erythema quantified. Skin blister fluid and biopsies were taken from the unexposed and the UVR-exposed skin 24 h after a pro-inflammatory UVR challenge (three minimal erythema doses). Urine, skin tissue and fluid were analysed for catechin content and skin fluid for PGE2 and 12-HETE by liquid chromatography coupled to tandem MS. A total of fourteen completing subjects were supplement compliant (twelve female, median 42·5 years, range 29–59 years). Benzoic acid levels were increased in skin fluid post-supplementation (P= 0·03), and methylated gallic acid and several intact catechins and hydroxyphenyl-valerolactones were detected in the skin tissue and fluid. AUC analysis for UVR erythema revealed reduced response post-GTC (P= 0·037). Pre-supplementation, PGE2 and 12-HETE were UVR induced (P= 0·003, 0·0001). After GTC, UVR-induced 12-HETE reduced from mean 64 (sd 42) to 41 (sd 32) pg/μl (P= 0·01), while PGE2 was unaltered. Thus, GTC intake results in the incorporation of catechin metabolites into human skin associated with abrogated UVR-induced 12-HETE; this may contribute to protection against sunburn inflammation and potentially longer-term UVR-mediated damage.

Molecular mechanisms of garlic-derived allyl sulfides in the inhibition of skin cancer progression

Skin cancer is a serious concern whose incidence is increasing at an alarming rate. Allyl sulfides—i.e., sulfur metabolites in garlic oil—have been demonstrated to have anticancer activity against several cancer types, although the mechanisms underlying these effects remain enigmatic. Our previous study showed that diallyl trisulfide (DATS) is more potent than mono- and disulfides against skin cancer. DATS inhibits cell growth of human melanoma A375 cells and basal cell carcinoma (BCC) cells by increasing the levels of intracellular reactive oxygen species (ROS) and DNA damage and by inducing G2/M arrest, endoplasmic reticulum (ER) stress, and mitochondria-mediated apoptosis, including the caspase-dependent and -independent pathways. This short review focuses on the molecular mechanisms of garlic-derived allyl sulfides on skin cancer prevention.

Histamine: an undercover agent in multiple rare diseases?

Histamine is a biogenic amine performing pleiotropic effects in humans, involving tasks within the immune and neuroendocrine systems, neurotransmission, gastric secretion, cell life and death, and development. It is the product of the histidine decarboxylase activity, and its effects are mainly mediated through four different G-protein coupled receptors. Thus, histamine-related effects are the results of highly interconnected and tissue-specific signalling networks. Consequently, alterations in histamine-related factors could be an important part in the cause of multiple rare/orphan diseases. Bearing this hypothesis in mind, more than 25 rare diseases related to histamine physiopathology have been identified using a computationally assisted text mining approach. These newly integrated data will provide insight to elucidate the molecular causes of these rare diseases. The data can also help in devising new intervention strategies for personalized medicine for multiple rare diseases.

Comparative evaluation of different co-antioxidants on the photochemical- and functional-stability of epigallocatechin-3-gallate in topical creams exposed to simulated sunlight

The catechin (−)-epigallocatechin-3-gallate (EGCG) exhibits high antioxidant activity and it has been reported to provide protection of the skin against damage induced by solar UV radiation. However, EGCG is highly unstable under sunlight. The present study aimed to compare the effectiveness of the co-antioxidant agents vitamin E, butylated hydroxytoluene, vitamin C and α-lipoic acid for their potential to protect the catechin from photochemical degradation. Model creams (oil-in-water emulsions) containing EGCG (1%, w/w) alone or combined with equimolar concentrations of co-antioxidant were exposed to a solar simulator at an irradiance corresponding to natural sunlight. Photodegradation was evaluated by HPLC-UV and HPLC-ESI-MS/MS. Addition of the co-antioxidants vitamin C and α-lipoic acid to the formulation significantly reduced the light-induced decomposition of EGCG from 76.9 ± 4.6% to 20.4 ± 2.7% and 12.6 ± 1.6%, respectively. Conversely, butylated hydroxytoluene had no effect (EGCG loss, 78.1 ± 4.6%) and vitamin E enhanced the EGCG photolysis to 84.5 ± 3.4%. The functional stability of the catechin in the creams exposed to the solar simulator was also evaluated by measuring the in vitro antioxidant activity. Following irradiation, the reduction of the EGCG formulation antioxidant power was lower (21.8%) than the extent of degradation (76.9%), suggesting the formation of photoproducts with antioxidant properties. The influence of the examined co-antioxidants on the functional stability of the catechin under simulated sunlight paralleled that measured for the EGCG photodecomposition, α-lipoic acid exerting the greatest stabilising effect (antioxidant activity decrease, 1.4%). These results demonstrated that α-lipoic acid is an effective co-antioxidant agent for the stabilization of EGCG in dermatological products for skin photoprotection.

Eicosanoids in skin inflammation

Eicosanoids play an integral part in homeostatic mechanisms related to skin health and structural integrity. They also mediate inflammatory events developed in response to environmental factors, such as exposure to ultraviolet radiation, and inflammatory and allergic disorders, including psoriasis and atopic dermatitis. This review article discusses biochemical aspects related to cutaneous eicosanoid metabolism, the contribution of these potent autacoids to skin inflammation and related conditions, and considers the importance of nutritional supplementation with bioactives such as omega-3 and omega-6 polyunsaturated fatty acids and plant-derived antioxidants as means of addressing skin health issues.

Soy isoflavones (daidzein & genistein) inhibit 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cutaneous inflammation via modulation of COX-2 and NF-κB in Swiss albino mice

It is well established that aberrant production of inflammatory mediators has been associated with most the toxic manifestations and the genesis of different chronic diseases including cancer. The basic aim of the present study is to investigate the effects of soy isoflavones (SIF) on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cutaneous inflammatory responses and to explore the underlying molecular mechanisms. We have studied the protective effects of SIF against TPA induced oxidative stress, pro-inflammatory cytokines level, activation of NF-κB, expression of COX-2 and ki-67 in mouse skin. Animals were divided into five groups I-V (n=6). Groups II, III and IV received topical application of TPA at the dose of 10 nmol/0.2 ml of acetone/animal/day, for 2 days. Animals of the groups III and IV were pre-treated with SIF 1.0 μg (D1) and 2.0 μg (D2) topically 30 min prior to each TPA administration, while groups I and V were given acetone (0.2 ml) and SIF (D2), respectively. We have found that SIF pretreatment significantly inhibited TPA induced oxidative stress, proinflammatory cytokines production and activation of NF-κB. SIF also inhibited the expression of COX-2 and ki-67. Histological findings further supported the protective effects of SIF against TPA-induced cutaneous damage. Thus, our results suggest that inhibitory effect of SIF on TPA-induced cutaneous inflammation includes inhibition of proinflammatory cytokines, attenuation of oxidative stress, activation of NF-κB and expression of COX-2.

Plants vs. cancer: a review on natural phytochemicals in preventing and treating cancers and their druggability

Cancer remains to be one of the leading causes of death in the United States and around the world. The advent of modern drug-targeted therapies has undeniably improved cancer patients' cares. However, advanced metastasized cancer remains untreatable. Hence, continued searching for a safer and more effective chemoprevention and treatment is clearly needed for the improvement of the efficiency and to lower the treatment cost for cancer care. Cancer chemoprevention with natural phytochemical compounds is an emerging strategy to prevent, impede, delay, or cure cancer. This review summarizes the latest research in cancer chemoprevention and treatment using the bioactive components from natural plants. Relevant molecular mechanisms involved in the pharmacological effects of these phytochemicals are discussed. Pharmaceutical developmental challenges and opportunities in bringing the phytochemicals into the market are also explored. The authors wish to expand this research area not only for their scientific soundness, but also for their potential druggability.

Epigallocatechin-3-gallate up-regulates tumor suppressor gene expression via a reactive oxygen species-dependent down-regulation of UHRF1

Ubiquitin-like containing PHD and Ring finger 1 (UHRF1) contributes to silencing of tumor suppressor genes by recruiting DNA methyltransferase 1 (DNMT1) to their hemi-methylated promoters. Conversely, demethylation of these promoters has been ascribed to the natural anti-cancer drug, epigallocatechin-3-gallate (EGCG). The aim of the present study was to investigate whether the UHRF1/DNMT1 pair is an important target of EGCG action. Here, we show that EGCG down-regulates UHRF1 and DNMT1 expression in Jurkat cells, with subsequent up-regulation of p73 and p16(INK4A) genes. The down-regulation of UHRF1 is dependent upon the generation of reactive oxygen species by EGCG. Up-regulation of p16(INK4A) is strongly correlated with decreased promoter binding by UHRF1. UHRF1 over-expression counteracted EGCG-induced G1-arrested cells, apoptosis, and up-regulation of p16(INK4A) and p73. Mutants of the Set and Ring Associated (SRA) domain of UHRF1 were unable to down-regulate p16(INK4A) and p73, either in the presence or absence of EGCG. Our results show that down-regulation of UHRF1 is upstream to many cellular events, including G1 cell arrest, up-regulation of tumor suppressor genes and apoptosis.

Oxidative stress and skin cancer: an overview

Skin is the largest body organ that serves as an important environmental interface providing a protective envelope that is crucial for homeostasis. On the other hand, it is a major target for toxic insult by a broad spectrum of physical and chemical agents that are capable of altering its structure and function. There are a large number of dietary contaminants and drugs can manifest their toxicity in skin. These environmental toxicants or their metabolites are inherent oxidants and/or directly or indirectly drive the production of a variety of reactive oxidants also known as reactive oxygen species. These are short-lived entities that are continuously generated at low levels during the course of normal aerobic metabolism. These are believed to activate proliferative and cell survival signaling that can alter apoptotic pathways that may be involved in the pathogenesis of a number of skin disorders. The skin possesses an array of antioxidant defense mechanisms that interact with toxicants to obviate their deleterious effect. The "antioxidant power" of a food is an expression of its capability both to defend the human organism from the action of the free radicals and to prevent degenerative disorders. Plants like olive trees have their own built-in protection against the oxidative damage of the sun, and these built-in protectors function as cell protectors in our own body. Although many antioxidants have shown substantive efficacy in cell culture systems and in animal models of oxidant injury, unequivocal confirmation of their beneficial effects in human populations has proven elusive.

Novel, biocatalytically produced hydroxytyrosol dimer protects against ultraviolet-induced cell death in human immortalized keratinocytes

Compounds derived from botanicals, such as olive trees, have been shown to possess various qualities that make them function as ideal antioxidants and, in doing so, protect them against the damaging effect of ultraviolet (UV)-derived oxidative stress. The aim of this study was to biocatalytically synthesize a dimeric product (compound II) from a known botanical, 3-hydroxytyrosol, and test it for its antioxidant ability using a human immortalized keratinocyte cell line (HaCaT). 2,2-Diphenyl-picryhydrazyl (DPPH) antioxidant assays showed 33 and 86.7% radical scavenging activity for 3-hydroxytyrosol and its dimer, respectively. The ferric-reducing antioxidant power (FRAP) assay corroborated this by showing a 3-fold higher antioxidant activity for the dimer than 3-hydroxytyrosol. Western blot analyses, showing cells exposed to 500 μM of the dimeric product when ultraviolet A (UVA)-irradiated, increased the anti-apoptotic protein Bcl-2 expression by 16% and reduced the pro-apoptotic protein Bax by 87.5%. Collectively, the data show that the dimeric product of 3-hydroxytyrosol is a more effective antioxidant and could be considered for use in skin-care products, health, and nutraceuticals.

Updated knowledge about polyphenols: functions, bioavailability, metabolism, and health

Polyphenols are important constituents of food products of plant origin. Fruits, vegetables, and beverages are the main sources of phenolic compounds in the human diet. These compounds are directly related to sensory characteristics of foods such as flavor, astringency and color. Polyphenols are extensively metabolized both in tissues and by the colonic microbiota. Normally, the circulating polyphenols are glucuronidated and/or sulphated and no free aglycones are found in plasma. The presence of phenolic compounds in the diet is beneficial to health due to their antioxidant, anti-inflammatory, and vasodilating properties. The health effects of polyphenols depend on the amount consumed and their bioavailability. Moreover, polyphenols are able to kill or inhibit the growth of microorganisms such as bacteria, fungi, or protozoans. Some dietary polyphenols may have significant effects on the colonic flora providing a type of prebiotic effect. The anti-nutrient properties of polyphenols are also discussed in this paper. The antioxidant, anti-inflammatory, vasodilating, and prebiotic properties of polyphenols make them potential functional foods.

Oxidative DNA adducts detected in vitro from redox activity of cigarette smoke constituents

Cigarette smoke contains a variety of carcinogens, cocarcinogens, mutagens, and tumor promoters. In addition to polycyclic aromatic carcinogens and tobacco-specific nitrosamines, cigarette smoke also contains an abundance of catechols, aldehydes, and other constituents, which are DNA damaging directly or indirectly; therefore, they can also contribute to cigarette smoke-mediated carcinogenicity. In this study, we investigated the potential of cigarette smoke constituents to induce oxidative damage to DNA through their capacity to redox cycle. When DNA (300 μg/mL) was incubated with cigarette smoke condensate (0.2 mg of tobacco particulate matter/mL) and CuCl(2) as a catalyst (50-100 μM), a variety of oxidative DNA adducts were detected by (32)P-postlabeling/TLC. Of the total adduct burden (2114 ± 419 adducts/10(6) nucleotides), over 40% of all adducts were attributed to the benchmark oxidative DNA lesion, 8-oxodeoxyguanosine (8-oxodG). Adducts were formed dose dependently. Essentially, similar adduct profiles were obtained when cigarette smoke condensate was substituted with ortho- and para-dihydroxybenzenes. Vehicle treatment with Cu(2+) or CSC alone did not induce any significant amount of oxidative DNA damage. Furthermore, coincubation of cigarette smoke condensate and ortho-dihydroxybenzene with DNA resulted in a higher amount of oxidative DNA adducts than obtained with the individual entity, suggesting that adducts presumably originated from catechols or catechol-like compounds in cigarette smoke condensate. Adducts resulting from both cigarette smoke condensate and pure dihydroxybenzenes were chromatographically identical to adducts formed by reaction of DNA with H(2)O(2), which is known to produce 8-oxodG, and many other oxidative DNA adducts. When the cigarette smoke condensate-DNA reaction was performed in the presence of ellagic acid, a known antioxidant, the adduct formation was inhibited dose dependently, further suggesting that adducts originated from oxidative pathway. Our data thus provide evidence of the capacity of catechols or catechol-like constituents in cigarette smoke to produce oxidative DNA damage, which may contribute to the tumor-promoting activity of cigarette smoke.

Saponins from Tribulus terrestris L. protect human keratinocytes from UVB-induced damage

Chronic exposure to solar UVB radiation damages skin, increasing the risk to develop cancer. Hence the identification of compounds with a photoprotective efficacy is essential. This study examined the role of saponins derived from Tribulus terrestris L. (TT) on the modulation of apoptosis in normal human keratinocytes (NHEK) exposed to physiological doses of UVB and to evaluate their antitumoral properties. In NHEK, TT saponins attenuate UVB-induced programmed cell death through inhibition of intrinsic apoptotic pathway. In squamous cell carcinomas (SCC) TT saponins do not make the malignant keratinocytes more resistant to UVB and determine an enhanced apoptotic response. The photoprotective effect of TT saponins is tightly correlated to the enhancement of NER genes expression and the block of UVB-mediated NF-κB activation. Collectively, our study shows experimental evidence that TT has a preventive efficacy against UVB-induced carcinogenesis and the molecular knowledge on the mechanisms through which TT saponins regulate cell death suggests great potential for TT to be developed into a new medicine for cancer patients.

Effect of Seasonality on Chemical Composition and Antibacterial and Anticandida Activities of Argentine Propolis. Design of a Topical Formulation

The effect of seasonality on Argentine propolis collected during one year on its phenolic and flavonoid content and on the growth of Gram-positive and Gram-negative antibiotic resistant bacteria and Candida species was evaluated. Extracts of propolis samples collected in the summer and spring showed higher phenolic and flavonoid contents than the samples collected in other seasons (5.86 to 6.06 mg GAE/mL and 3.77 to 4.23 mg QE/mL, respectively). The propolis collected in summer and autumn showed higher antibacterial activity (30 μg/mL) than the other samples (MIC values between 30 and 120 μg/mL). No antibacterial activity was detected against Gram-negative bacteria. Also, these extracts were able to inhibit the development of five Candida species, with MFC values of 15-120 μg/mL. Pharmaceutical formulations containing the more active propolis extract were prepared. The hydrogel of acrylic acid polymer containing summer propolis extract as an antimicrobial agent showed microbiological, physical and functional stability during storage for 180 days. The pharmaceutical preparation, as well as the propolis extracts, was active against Candida sp. and antibiotic-multi-resistant Gram-positive bacteria. These results reveal that propolis samples collected by scraping in four seasons, especially in summer in Calingasta, San Juan, Argentina, can be used to obtain tinctures and hydrogels with antibacterial and antimycotic potential for topical use.

Vascular effects of phytoestrogens and alternative menopausal hormone therapy in cardiovascular disease

Phytoestrogens are estrogenic compounds of plant origin classified into different groups including isoflavones, lignans, coumestans and stilbenes. Isoflavones such as genistein and daidzein are the most studied and most potent phytoestrogens, and are found mainly in soy based foods. The effects of phytoestrogens are partly mediated via estrogen receptors (ERs): ERα, ERβ and possibly GPER. The interaction of phytoestrogens with ERs is thought to induce both genomic and non-genomic effects in many tissues including the vasculature. Some phytoestrogens such as genistein have additional non-ER-mediated effects involving signaling pathways such as tyrosine kinase. Experimental studies have shown beneficial effects of phytoestrogens on endothelial cells, vascular smooth muscle, and extracellular matrix. Phytoestrogens may also affect other pathophysiologic vascular processes such as lipid profile, angiogenesis, inflammation, tissue damage by reactive oxygen species, and these effects could delay the progression of atherosclerosis. As recent clinical trials showed no vascular benefits or even increased risk of cardiovascular disease (CVD) and CV events with conventional menopausal hormone therapy (MHT), phytoestrogens are being considered as alternatives to pharmacologic MHT. Epidemiological studies in the Far East population suggest that dietary intake of phytoestrogens may contribute to the decreased incidence of postmenopausal CVD and thromboembolic events. Also, the WHO-CARDIAC study supported that consumption of high soybean diet is associated with lower mortalities from coronary artery disease. However, as with estrogen, there has been some discrepancy between the experimental studies demonstrating the vascular benefits of phytoestrogens and the data from clinical trials. This is likely because the phytoestrogens clinical trials have been limited in many aspects including the number of participants enrolled, the clinical end points investigated, and the lack of long-term follow-up. Further investigation of the cellular mechanisms underlying the vascular effects of phytoestrogens and careful evaluation of the epidemiological evidence and clinical trials of their potential vascular benefits would put forward the use of phytoestrogens as an alternative MHT for the relief of menopausal symptoms and amelioration of postmenopausal CVD.

The dual action of epigallocatechin gallate (EGCG), the main constituent of green tea, against the deleterious effects of visible light and singlet oxygen-generating conditions as seen in yeast cells

Green tea extracts (GTEs) as well as their main component, the polyphenol epigallocatechin gallate (EGCG), are known for their versatile antioxidant, antimicrobial, antitumoral or anti-inflammatory effects. In spite of the huge beneficial action, there is increasing evidence that under certain conditions green tea and its components can be detrimental to living organisms. Using Saccharomyces cerevisiae strains with various defects in the response to oxidative stress, we found that GTEs or EGCG act in synergy with visible light, exhibiting either deleterious or protective effects depending on the solvent employed. Similar synergistic effects could be observed under singlet oxygen-generating conditions, such as light exposure in the presence of photosensitizers or UV-A irradiation, therefore solvent variance may represent a powerful tool to modulate the preparation of green tea extracts, depending on the intended target.

Differential effects of Oroxylum indicum bark extracts: antioxidant, antimicrobial, cytotoxic and apoptotic study

Stem bark of Oroxylum indicum (L) (SBOI) is used by ethnic communities of North East India as health tonic and in treating diseases of humans and animals. The objective of this research was to carry out a detailed investigation including total phenolic and flavonoid content, antioxidant, antimicrobial, cytotoxic and apoptotic activities of different solvent extracts of SBOI and to establish correlation between some parameters. Among petroleum ether (PE), dichloromethane and methanol (MeOH) extract of SBOI, MeOH extract contained the highest amount of total phenolic (320.7 ± 34.6 mg Gallic acid equivalent/g extract) and flavonoid (346.6 ± 15.2 mg Quercetin equivalent/g extract) content. In vitro antioxidant activity (IC(50) 22.7 μg/ml) was highest in MeOH extract (p > 0.05) and also a significant inverse correlation was observed between phenolic (r = 0.886)/flavonoid (r = 0.764) content and corresponding DPPH IC(50). Only MeOH extract inhibited both bacteria and fungi. Although, individual extract showed cytotoxicity on HeLa cells with characteristic features of apoptosis, PE extract caused maximum cytotoxicity (IC(50) of 112.3 μg/ml, p < 0.05) and apoptotic activity (33.2 % sub-G0/G1 population) on HeLa cells. But, there was a significant non-inverse correlation of the MTT IC(50) with total phenolic (r = 0.812, p < 0.05)/flavonoid (r = 0.998, p < 0.05) content in the three solvent extracts. TLC analysis showed three unique compounds in PE extract which may have a role in apoptosis mediated cytotoxicity. These results called for futher chemical characterisation of MeOH and PE extract of SBOI for specific bioactivity.

Taxifolin suppresses UV-induced skin carcinogenesis by targeting EGFR and PI3K

Skin cancer is one of the most commonly diagnosed cancers in the United States. Taxifolin reportedly exerts multiple biologic effects, but the molecular mechanisms and direct target(s) of taxifolin in skin cancer chemoprevention are still unknown. In silico computer screening and kinase profiling results suggest that the EGF receptor (EGFR), phosphoinositide 3-kinase (PI3K), and Src are potential targets for taxifolin. Pull-down assay results showed that EGFR, PI3K, and Src directly interacted with taxifolin in vitro, whereas taxifolin bound to EGFR and PI3K, but not to Src in cells. ATP competition and in vitro kinase assay data revealed that taxifolin interacted with EGFR and PI3K at the ATP-binding pocket and inhibited their kinase activities. Western blot analysis showed that taxifolin suppressed UVB-induced phosphorylation of EGFR and Akt, and subsequently suppressed their signaling pathways in JB6 P+ mouse skin epidermal cells. Expression levels and promoter activity of COX-2 and prostaglandin E(2) (PGE(2)) generation induced by UVB were also attenuated by taxifolin. The effect of taxifolin on UVB-induced signaling pathways and PGE(2) generation was reduced in EGFR knockout murine embryonic fibroblasts (MEF) compared with EGFR wild-type MEFs. Taxifolin also inhibited EGF-induced cell transformation. Importantly, topical treatment of taxifolin to the dorsal skin significantly suppressed tumor incidence, volume, and multiplicity in a solar UV (SUV)-induced skin carcinogenesis mouse model. Further analysis showed that the taxifolin-treated group had a substantial reduction in SUV-induced phosphorylation of EGFR and Akt in mouse skin. These results suggest that taxifolin exerts chemopreventive activity against UV-induced skin carcinogenesis by targeting EGFR and PI3K.

Dual drug-loaded nanoparticles on self-integrated scaffold for controlled delivery

Antioxidant (quercetin) and hypoglycemic (voglibose) drug-loaded poly-D,L-lactideco-glycolide nanoparticles were successfully synthesized using the solvent evaporation method. The dual drug-loaded nanoparticles were incorporated into a scaffold film using a solvent casting method, creating a controlled transdermal drug-delivery system. Key features of the film formulation were achieved utilizing several ratios of excipients, including polyvinyl alcohol, polyethylene glycol, hyaluronic acid, xylitol, and alginate. The scaffold film showed superior encapsulation capability and swelling properties, with various potential applications, eg, the treatment of diabetes-associated complications. Structural and light scattering characterization confirmed a spherical shape and a mean particle size distribution of 41.3 nm for nanoparticles in the scaffold film. Spectroscopy revealed a stable polymer structure before and after encapsulation. The thermoresponsive swelling properties of the film were evaluated according to temperature and pH. Scaffold films incorporating dual drug-loaded nanoparticles showed remarkably high thermoresponsivity, cell compatibility, and ex vivo drug-release behavior. In addition, the hybrid film formulation showed enhanced cell adhesion and proliferation. These dual drug-loaded nanoparticles incorporated into a scaffold film may be promising for development into a transdermal drug-delivery system.

Food-related compounds that modulate expression of inducible nitric oxide synthase may act as its inhibitors

Natural compounds commonly found in foods may contribute to protect cells against the deleterious effects of inflammation. These anti-inflammatory properties have been linked to the modulation of transcription factors that control expression of inflammation-related genes, including the inducible nitric oxide synthase (iNOS), rather than a direct inhibitory action on these proteins. In this study, forty two natural dietary compounds, known for their ability to exert an inhibitory effect on the expression of iNOS, have been studied in silico as docking ligands on two available 3D structures for this protein (PDB ID: 3E7G and PDB ID: 1NSI). Natural compounds such as silibinin and cyanidin-3-rutinoside and other flavonoids showed the highest theoretical affinities for iNOS. Docking affinity values calculated for several known iNOS inhibitors significatively correlated with their reported half maximal inhibitory concentrations (R = 0.842, P < 0.0001), suggesting the computational reliability of the predictions made by our docking simulations. Moreover, docking affinity values for potent iNOS inhibitors are of similar magnitude to those obtained for some studied natural products. Results presented here indicate that, in addition to gene expression modulation of proteins involved in inflammation, some chemicals present in food may be acting by direct binding and possible inhibiting actions on iNOS.

WITHDRAWN: Epigallocatechin-3-gallate up-regulates tumor suppressor gene expression via a reactive oxygen species-dependent down-regulation of UHRF1

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Discovering the link between nutrition and skin aging

Skin has been reported to reflect the general inner-health status and aging. Nutrition and its reflection on skin has always been an interesting topic for scientists and physicians throughout the centuries worldwide. Vitamins, carotenoids, tocopherols, flavonoids and a variety of plant extracts have been reported to possess potent anti-oxidant properties and have been widely used in the skin care industry either as topically applied agents or oral supplements in an attempt to prolong youthful skin appearance. This review will provide an overview of the current literature "linking" nutrition with skin aging.

Protective mechanisms of green tea polyphenols in skin

Skin is frequently exposed to a variety of environmental, chemical, and genotoxic agents that contribute to disease and carcinogenesis. Ultraviolet light (UVR) is the main external stress that leads to immunosuppresion, oxidative stress, premature aging, and tumor formation. Scientists and health professionals emphasize the importance of prevention strategies to circumvent such unfavorable outcomes. Plant polyphenols are a promising approach to disease prevention and treatment. Green tea is an abundant source of plant polyphenols that exhibit significant antioxidant, chemopreventive, and immunomodulatory effects in protecting the skin.