title: UV irradiation affects melanocyte stimulatory activity and protein binding of piperine.
abstract: Piperine, the major alkaloid of black pepper (Piper nigrum L.; Piperaceae), stimulates melanocyte proliferation and dendrite formation in vitro. This property renders it a potential treatment for the skin depigmentation disorder vitiligo. However, piperine does not stimulate melanin synthesis in vitro, and treatments based on this compound may therefore be more effective with concomitant exposure of the skin to ultraviolet (UV) radiation or sunlight. The present study investigated the effect of UVA and simulated solar radiation (SSR) on the chemical stability of piperine, its melanocyte stimulatory effects and its ability to bind protein and DNA. Chromatographic and spectroscopic analysis confirmed the anticipated photoisomerization of irradiated piperine and showed the absence of any hydrolysis to piperinic acid. Isomerization resulted in the loss of ability to stimulate proliferation of a mouse melanocyte cell line, and to bind to human serum albumin. There was no evidence of DNA binding by piperine either before or after irradiation, showing the absence of photoadduct formation by either piperine or its geometric isomers. This is unlike the situation with psoralens, which form DNA adducts when administered with UVA in treating skin diseases. The present study suggests that exposure to bright sunlight should be avoided both during active application of piperine to the skin and in the storage of piperine products. If UVA radiation is used with piperine in the treatment of vitiligo, application of the compound and irradiation should be staggered to minimize photoisomerization. This approach is shown to effectively induce pigmentation in a sparsely pigmented mouse strain.
authors: Department of Pharmacy, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NN, UK. soumyana@ohsu.edu
authors: Amala
authors: A
authors: Soumyanath
authors: Radhakrishnan
authors: R
authors: Venkatasamy
authors: Meghna
authors: M
authors: Joshi
authors: Laura
authors: L
authors: Faas
authors: Bimpe
authors: B
authors: Adejuyigbe
authors: Alex F
authors: AF
authors: Drake
authors: Robert C
authors: RC
authors: Hider
authors: Antony R
authors: AR
authors: Young
mesh_terms: D000470:Alkaloids / Q000737:chemistry / Q000494:pharmacology* / Q000528:radiation effects*; D000818:Animals; D052117:Benzodioxoles / Q000737:chemistry / Q000494:pharmacology* / Q000528:radiation effects*; D002455:Cell Division / Q000528:radiation effects; D002460:Cell Line; D065607:Cytochrome P-450 Enzyme Inhibitors; D006801:Humans; D008544:Melanocytes / Q000502:physiology* / Q000528:radiation effects*; D051379:Mice; D008958:Models, Molecular; D029222:Piper nigrum; D010880:Piperidines / Q000737:chemistry / Q000494:pharmacology* / Q000528:radiation effects*; D053284:Polyunsaturated Alkamides / Q000737:chemistry / Q000494:pharmacology* / Q000528:radiation effects*; D011485:Protein Binding; D012709:Serum Albumin / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013472:Sunlight; D014466:Ultraviolet Rays
chemical_list: D000470:Alkaloids; D052117:Benzodioxoles; D065607:Cytochrome P-450 Enzyme Inhibitors; D010880:Piperidines; D053284:Polyunsaturated Alkamides; D012709:Serum Albumin; C008922:piperine