ABSTRACT
A series of diarylpropane compounds was isolated by screening a plant extract library for inhibitors of mushroom tyrosinase. The most potent compound, 1-(2,4-dihydroxyphenyl)-3-(2,4-dimethoxy-3-methylphenyl)propane (UP302: CAS# 869743-37-3), was found in the medicinal plant Dianella ensifolia. Synthetic and plant-derived versions of UP302 inhibited mushroom tyrosinase with similar potencies. UP302 inhibited mushroom tyrosinase with K(i)=0.3 microM, in a competitive and reversible fashion. UP302 was 22 times more potent than Kojic acid in inhibiting murine tyrosinase, with IC(50) values of 12 and 273 microM respectively. Experiments on mouse melanoma cells B16-F1 and on human primary melanocytes demonstrated that UP302 inhibits melanin formation with IC(50) values of 15 and 8 microM respectively. Long-term treatment of cultured melanocytes with up to 62 microM of UP302 revealed no detectable cytotoxicity. In a reconstructed skin model (MelanoDerm) topical application of 0.1% UP302 resulted in significant skin lightening and decrease of melanin production without effects on cell viability, melanocyte morphology or overall tissue histology. In conclusion, UP302 is a novel tyrosinase inhibitor that suppresses melanin production in both cultured melanocytes and reconstructed skin with high potency and without adverse side effects.
Subject(s)
Dermatologic Agents/chemical synthesis , Dermatologic Agents/pharmacology , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Monophenol Monooxygenase/antagonists & inhibitors , Phenols/chemical synthesis , Phenols/pharmacology , Pigmentation Disorders/drug therapy , Propane/analogs & derivatives , Agaricales/enzymology , Animals , Antioxidants/chemistry , Antioxidants/pharmacology , Cell Line , Kinetics , Liliaceae/chemistry , Melanins/biosynthesis , Melanocytes/drug effects , Melanocytes/enzymology , Melanocytes/metabolism , Melanoma, Experimental/drug therapy , Melanoma, Experimental/pathology , Mice , Monophenol Monooxygenase/metabolism , Pigmentation Disorders/pathology , Propane/chemical synthesis , Propane/pharmacology , Pyrones/chemistry , Pyrones/pharmacologyABSTRACT
A reversed-phase HPLC method for the quantification of aloesin, aloeresin a and anthraquinone (as barbaloin) in Aloe ferox Miller and aloe-related products has been developed and validated. The method utilized a C18 column with a water-methanol gradient and UV detection at 297 nm. The method validation included linearity, accuracy, precision, limit of detection, limit of quantitation, specificity and standard solution stability. The method showed good linearity (r > 0.99 for all components) and recovery (>85% for all components). The detection and quantitation limits for barbaloin were determined to be 0.02 and 0.1 ppm at signal-to-noise ratios of approximately 3:1 and 10:1, respectively.
