tyrosinase inhibitory activity within hexane extract of ten screened plants from kurdistan province of iran

objective: tyrosinase as the key enzyme in melanin biosynthesis, involves in determining the color of mammalian skin and hair. a variety of dermatological disorders, come up from an unnecessary level of epidermal pigmentation. plants are low-cost and rich sources of active compounds.  methods: more than seventy native plants collected from the central region of kurdistan province collected. inhibitory effect of hexane extracts from aerial parts of them was tested on tyrosinase activity. all extracts were screened for their tyrosinase inhibitory activity at 1, 0.1, 0.01, 0.001 µg/ml concentrations. assay method was based on microplate spectrophotometric study of absorption in 492 nm, arbutin and kojic acid were used as positive controls. results: among the evaluated hexane extracts, only 10 cases showed more than 50% tyrosinase inhibitory activities, including gundelia tourneforti l., astragalus vegetus bunge, vicia hyrcanica fisch. & c.a. mey, campanula involucrate auch.ex dc, isatis cappadocica desv, sanguisorba minor scop., eremostachys laevigata bunge, ballota nigra l., aristolochia bottae  jaub.&spach, astragalus caryolobus bge, and among them  gundelia tournefortii  l. l., showed considerable inhibition with ic50 of 0.173 µg/ml. these results suggest that the most effective plant extracts, especially that of gundelia tourneforti  l. be worthy of further investigation.