title: 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.
abstract: 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.
authors: Laboratory of Phytomedicines, Department of Pharmacology, Institute of Biosciences, Universidade Estadual Paulista (UNESP), Botucatu, São Paulo CEP 18618-970, Brazil.
authors: Jéssica P S
authors: JP
authors: Silveira
authors: Leonardo N
authors: LN
authors: Seito
authors: Samara
authors: S
authors: Eberlin
authors: Gustavo C
authors: GC
authors: Dieamant
authors: Cecília
authors: C
authors: Nogueira
authors: Maria C V
authors: MC
authors: Pereda
authors: Luiz C
authors: LC
authors: Di Stasi
mesh_terms: D000975:Antioxidants / Q000494:pharmacology* / Q000627:therapeutic use; D001713:Biphenyl Compounds / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis*; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D053582:Interleukin-1alpha / Q000096:biosynthesis; D015227:Lipid Peroxidation / Q000187:drug effects; D008544:Melanocytes / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors*; D008517:Phytotherapy; D010851:Picrates / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D012250:Rheum; D027343:Rhizome; D012867:Skin / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D012871:Skin Diseases / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D014466:Ultraviolet Rays; D000521:alpha-MSH / Q000096:biosynthesis*
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D016207:Cytokines; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D018836:Inflammation Mediators; D053582:Interleukin-1alpha; D010851:Picrates; D010936:Plant Extracts; D014409:Tumor Necrosis Factor-alpha; D000521:alpha-MSH; C004931:1,1-diphenyl-2-picrylhydrazyl; D014442:Monophenol Monooxygenase; D011505:Protein-Tyrosine Kinases