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چکیده
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Introduction: Tyrosinase is a multicopper monooxygenase enzyme with wide distribution. It is responsible for pigmentation of skin, eyes and hair. The enzyme is involved in the undesired browning of bruised or cut fruits and vegetables. In insects, Tyrosinase is one of the key enzymes in the molting process. Investigating for inhibitors of this enzyme may lead to the development of novel skin whitening agents, anti -browning substances or insect control compounds. Materials and Methods: In searching for effective tyrosinase inhibitors from natural products, seventy native and naturalized plants collected from the central region of Kurdistan province. Inhibitory effect of methanol extracts from aerial parts of them was tested on tyrosinase activity. All extracts were screened for their tyrosinase inhibitory activity at 400, 100, 25, 6.2 µg/ml final concentrations in reaction mixture. Assay method was based on Microplate spectrophotometric study of absorption in 492 nm and arbutin was used as positive control. Results: From the methanol extracts evaluated, only 9 plant extracts showed more than 60% Tyrosinase inhibitory activities, including Bongardia chrysogonum (L.) Spach, Podophylaceae, Heptaptera anatolica (Boiss.) Tutin, Apiaceae, Hyoscyamus kurdicus Bornm, Solanaceaes, Hypericum scabrum, Marrubium cuneatum, Nonea hypoleia, Salvia suffruticosa, Scrophularia pruinosa Boiss, Scrophulariaceae and Verbascum phoenicum L, Scrophulariaceae, (400 µg/ml) and two plant extracts including Asperugo procumbens L, Boraginaceae and Astragalus siliquosus Boiss.subsp.siliquosus, Papilionaceae (25µg/ml). Saliva suffruticosa showed a considerable inhibition value, 92.62 (400 µg/ml) and according to kinetic analysis its inhibition type is noncompetitive. Conclusion: These results suggest that the most effective plant extracts, especially that of Saliva suffruticosa deserve further investigation with the aim of obtaining new Tyrosinase inhibitors with a broad range of applications for
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