stilbenes and acteoside

Anti-inflammatory and skin tumour preventing effects of resveratrol have been extensively studied pre-clinically and resveratrol has been proposed for clinical investigations. To provide a basis or/and limitations for topical administration to human skin, molecular mechanisms underlying resveratrol effects towards normal human epidermal keratinocytes (NHEK) were evaluated. NHEK were challenged by either resveratrol alone or by its combination with TNFalpha or TGFalpha, and time-dependent molecular events were monitored. Interleukin 8 (IL-8) expression and its mRNA stability, ERK1/2, p65/RelA, and EGFR phosphorylation were determined. Intracellular distribution of EGFR/P-EGFR was measured in the membrane, cytoplasmic, and nuclear fractions. Specific DNA binding activity of NFκB (p65/RelA) and AP-1(c-Fos), NHEK proliferation, and molecular markers of apoptosis/cell cycle were detected. Resveratrol induced delayed, long-lasting and steadily growing IL-8 gene and protein over-expression as well as enhanced EGFR phosphorylation, both abrogated by the EGFR kinase inhibitor PD168393. However, resveratrol did not act as a phosphatase inhibitor. ERK phosphorylation was transiently inhibited at early time-points and activated at 6-24 h. Accordingly, c-Fos-specific DNA binding was increased by resveratrol. Cellular distribution of EGFR/P-EGFR was shifted to membrane and nucleus while cytosolic levels were reduced concomitant with enhanced degradation. Notwithstanding high nuclear levels of EGFR/P-EGFR, spontaneous and TGFalpha-triggered cell proliferation was strongly suppressed by resveratrol mainly through cell cycle arrest.. Resveratrol synergized with TNFα in the induction of delayed, long-lasting IL-8 expression through sustained EGFR-ERK axis activation. The time course indicates that resveratrol metabolites could be implicated. Topical administration of Resv to psoriatic patients over-expressing TNFα, IL-8 and EGFR-ERK in the skin should be cautiously considered. Since high nuclear levels of EGFR correspond to increased risk of tumorigenesis, chronic resveratrol application to the skin may be potentially dangerous. Wound healing acceleration by resveratrol could not be envisaged due to its anti-proliferative effects towards normal keratinocytes.

Topics: Administration, Cutaneous; Blotting, Western; Cell Cycle; Cell Membrane; Cell Nucleus; Cell Proliferation; Cytoplasm; DNA Primers; Enzyme-Linked Immunosorbent Assay; ErbB Receptors; Gene Expression Regulation; Glucosides; Humans; Interleukin-8; Keratinocytes; Phenols; Phosphorylation; Real-Time Polymerase Chain Reaction; Resveratrol; Reverse Transcriptase Polymerase Chain Reaction; Stilbenes; Time Factors

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

Topics: Anti-Inflammatory Agents; Cells, Cultured; Glucosides; Humans; Keratinocytes; Nitric Oxide; Peroxides; Peroxynitrous Acid; Phenols; Quercetin; Resveratrol; Stilbenes; Ultraviolet Rays

Excessive exposure to solar UVA and UVB radiation is widely considered to cause skin cancers such as squamous cell carcinoma and basalioma. Direct UVB damage to skin cell DNA as well as UV-induced chronic skin inflammation, accelerated keratinocyte proliferation, inhibited apoptosis, and immunosuppression seem to underlie the UV-induced carcinogenesis. Also, UVB induces cytochrome P450 subfamilies (CYP1A1 and CYP1B1) involved in metabolic activation of organic pro-carcinogens and their conversion to ultimate carcinogens. Here, the effects of several glycosylated and non-glycosylated plant polyphenols (verbascoside, resveratrol, polydatin, rutin, and quercetin) on the inflammatory, apoptotic, metabolic, and proliferative responses of cultured human epidermal keratinocytes (HEK) to non-cytotoxic doses of solar-simulated UVA+UVB and chemical mediators of UV signalling in HEK, 6-formylindolo[3,2-b]carbazole and squalene isolated from photo-oxidized skin surface lipids (SSL), were evaluated. We showed that the stilbenes and quercetin being exposed to UV were photo-destroyed within a short period of time, while verbascoside and rutin were photo-stable. When SSL were exposed to UV, the stilbenes and quercetin remarkably accelerated photo-oxidation of alpha-tocopherol, squalene, and cholesterol fractions, whilst verbascoside protected them. Verbascoside invariably inhibited molecular pathways in HEK leading to inflammatory cytokine expression (NFkappaB and EGFR/ERK phosphorylation), and cell proliferation (EGFR nuclear translocation), and displayed a stimulus-specific effect on the metabolic axis aryl hydrocarbon receptor (AhR)-CYP1A1/CYP1B1. By contrast, the stilbenes inhibited UV-connected inflammatory cytokines excluding IL-8, but they prevalently stimulated NFkappaB, EGFR nuclear translocation and the AhR-CYP pathway. We conclude that, among the PPs investigated, verbascoside does interfere with multiple UV-sensitive signalling in HEK in a way that it could have a major impact on skin cancer chemoprevention.

Topics: Aryl Hydrocarbon Hydroxylases; Carbazoles; Cell Proliferation; Cell Survival; Cells, Cultured; Chemoprevention; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP1B1; Cytokines; Glucosides; Humans; Keratinocytes; Oxidation-Reduction; Phenols; Polyphenols; Skin Neoplasms; Squalene; Stilbenes; Ultraviolet Rays

We investigated the in vitro effects of acteoside on the proliferation, cell cycle regulation and differentiation of HL-60 human promyelocytic leukemia cells. Acteoside inhibited the proliferation of HL-60 cells in a concentration- and time-dependent manner with an IC50, approximately 30 microM. DNA flow cytometric analysis indicated that acteoside blocked cell cycle progression at the G1 phase in HL-60 human promyelocytic leukemia cells. Among the G1 phase cell cycle-related proteins, the levels of cyclin-dependent protein kinase (CDK)2, CDK6, cyclin D1, cyclin D2, cyclin D3 and cyclin E were reduced by acteoside, whereas the steady-state level of CDK4 was unaffected. The protein and mRNA levels of CDK inhibitors (cyclin-dependent kinase inhibitors), such as p21(CIP1/WAF1) and p27(KIP1), were gradually increased after acteoside treatment in a time-dependent manner. In addition, acteoside markedly enhanced the binding of p21(CIP1/WAF1) and p27(KIP1) to CDK4 and CDK6, resulting in the reduction of CDK2, CDK4 and CDK6 activities. Moreover, the hypophosphorylated form of retinoblastoma increased, leading to the enhanced binding of protein retinoblastoma (pRb) and E2F1. Our results further suggest that acteoside is a potent inducer of differentiation of HL-60 cells based on biochemical activities and the expression level of CD14 cell surface antigen. In conclusion, the onset of acteoside-induced G1 arrest of HL-60 cells prior to the differentiation appears to be tightly linked to up-regulation of the p21(CIP1/WAF1) and p27(KIP1) levels and decreases in the CDK2, CDK4 and CDK6 activities. These findings, for the first time, reveal the mechanism underlying the anti-proliferative effect of acteoside on human promyelocytic HL-60 cells.

Topics: Antineoplastic Agents, Phytogenic; Cell Cycle; Cell Differentiation; Cell Division; Epidermal Growth Factor; G1 Phase; Glucosides; HL-60 Cells; Humans; Muscle Cells; Phenols; Resting Phase, Cell Cycle; Resveratrol; Stilbenes; Tetradecanoylphorbol Acetate

Two new phenylpropanoid glycosides, caerulescenoside ( 1), and 3'-methyl crenatoside ( 2), as well as five known phenylpropanoid glycosides [acteoside ( 3), isoacteoside ( 4), campneoside II ( 5), crenatoside ( 6), and desrhamnosyl acteoside ( 7)] were isolated from the whole plant of Orobanche caerulescens. The antioxidative effects of compounds 1 - 7 on human low-density lipoprotein were evaluated. All these compounds suppress concentration-dependently conjugated diene formation with IC (50) values of 1.25 +/- 0.06, 2.97 +/- 0.31, 0.31 +/- 0.01, 1.01 +/- 0.05, 1.15 +/- 0.04, 1.69 +/- 0.15, and 0.64 +/- 0.03 microM, respectively. Comparison of their antioxidative activities with that of resveratrol (IC (50) : 6.75 +/- 1.05 microM), a natural phenolic antioxidant isolated from grape, demonstrated that the prolonged effect on lag-time and the damping effect on oxidative rate by compounds 1 - 7 were all more potent.

Topics: Adult; Antioxidants; Cholesterol, LDL; Glucosides; Glycosides; Humans; Inhibitory Concentration 50; Lipid Peroxidation; Male; Orobanche; Phenols; Phytotherapy; Plant Components, Aerial; Plant Extracts; Resveratrol; Stilbenes