title: Modulation of antioxidant defense by Alpinia galanga and Curcuma aromatica extracts correlates with their inhibition of UVA-induced melanogenesis.
abstract: Ultraviolet A (UVA) irradiation is suggested to contribute to melanogenesis through promoting cellular oxidative stress and impairing antioxidant defenses. An overproduction of melanin can be associated with melanoma skin cancer and hyperpigmentation. Therefore, developing effective antimelanogenic agents is of importance. Alpinia galanga (AG) and Curcuma aromatica (CA) are traditional medicinal plants widely used for skin problems. Hence, this study investigated the antimelanogenic effects of AG and CA extracts (3.8-30 microg/ml) by assessing tyrosinase activity, tyrosinase mRNA levels, and melanin content in human melanoma cells (G361) exposed to UVA. The roles in protecting against melanogenesis were examined by evaluating their inhibitory effects on UVA-induced cellular oxidative stress and modulation of antioxidant defenses including antioxidant enzymes, catalase (CAT) and glutathione peroxidase (GPx), and intracellular glutathione (GSH). In addition, possible active compounds accountable for biological activities of the extracts were identified by thin layer chromatography (TLC)-densitometric analysis. Our study demonstrated that UVA (8 J/cm(2)) induced both tyrosinase activity and mRNA levels and UVA (16 J/cm(2))-mediated melanin production were suppressed by the AG or CA extracts at noncytotoxic concentrations. Both extracts were able to protect against UVA-induced cellular oxidant formation and depletion of CAT and GPx activities and GSH content in a dose-dependent manner. Moreover, TLC-densitometric analysis detected the presence of eugenol and curcuminoids in AG and CA, respectively. This is the first report representing promising findings on AG and CA extract-derived antityrosinase properties correlated with their antioxidant potential. Inhibiting cellular oxidative stress and improving antioxidant defenses might be the mechanisms by which the extracts yield the protective effects on UVA-dependent melanogenesis.
authors.affiliation: Department of Pharmacology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand. siuks@mahidol.ac.th
authors.forename: Uraiwan
authors.initials: U
authors.lastname: Panich
authors.forename: Kamolratana
authors.initials: K
authors.lastname: Kongtaphan
authors.forename: Tassanee
authors.initials: T
authors.lastname: Onkoksoong
authors.forename: Kannika
authors.initials: K
authors.lastname: Jaemsak
authors.forename: Rattana
authors.initials: R
authors.lastname: Phadungrakwittaya
authors.forename: Athiwat
authors.initials: A
authors.lastname: Thaworn
authors.forename: Pravit
authors.initials: P
authors.lastname: Akarasereenont
authors.forename: Adisak
authors.initials: A
authors.lastname: Wongkajornsilp
mesh_terms: D032429:Alpinia / Q000737:chemistry*; D002374:Catalase / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D030024:Curcuma / Q000737:chemistry*; D004354:Drug Screening Assays, Antitumor; D005562:Formazans / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008543:Melanins / Q000378:metabolism / Q000528:radiation effects; D008544:Melanocytes / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D008545:Melanoma / Q000188:drug therapy* / Q000378:metabolism / Q000532:radiotherapy; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects* / Q000528:radiation effects; D010936:Plant Extracts / Q000494:pharmacology*; D013778:Tetrazolium Salts / Q000378:metabolism; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D005562:Formazans; D008543:Melanins; D010936:Plant Extracts; D013778:Tetrazolium Salts; C079782:MTT formazan; D007770:L-Lactate Dehydrogenase; D002374:Catalase; D005979:Glutathione Peroxidase; D014442:Monophenol Monooxygenase; D005978:Glutathione