Alexander KM Leung - Screening of Chinese Herbal Medicines for Antityrosinase Activity in A Cell Free System and B16 Cells

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  Publication Details (including relevant citation   information):

  Journal   of Ethnopharmacology, Vol.   129(3), 387-390 (2010)


  Aim of the study

  Tyrosinase inhibitors are becoming increasingly important in   controlling skin hyperpigmentation. We aimed to screen 50   extracts from traditional Chinese medicines (TCM) for tyrosinase   activity-inhibiting agents.

  Materials and methods

  The 50 herbal extracts were prepared from 32 herbs and 18 TCM   formulas, which are used as folk skin whiteners in China and have   not been investigated for their skin-whitening mechanisms. Each   herb and formula was extracted with 30% ethanol and water,   respectively, and followed by column chromatography for isolating   bioactive substances such as saponins, flavonoids and alkaloids   for the antityrosinase activity study. Every extract was tested   using the cell free mushroom tyrosinase inhibitory assay at 2   mg/ml for the single herb extracts and 1 mg/ml for formula   extracts. Extracts showing greater than 50% inhibition against   mushroom tyrosinase activity were further examined by cellular   tyrosinase assay in mouse B16 cells. The cytotoxicity in B16   cells was measured by methyl thiazolyl tetrazolium bromide (MTT)   assay.


  In the cell-free assay, 10 out of the 50 extracts demonstrated   more than 50% inhibition against mushroom tyrosinase activity.   These 10 extracts were further assessed by cellular tyrosinase   assay, and 6 showed > 50% inhibition with IC50  values <1 mg/ml. The 6 extracts are from 3 herbs namely   Ampelopsis japonica, Lindera aggregata, and   Polygonatum odoratum, and 3 formulas namely   Qian-wang-hong-bai-san, Qiong-yu-gao, and San-bai-tang. As   compared with vitamin C, these 6 extracts showed similar or   greater ratio of cell growth IC50 to cellular   tyrosinase IC50. As compared with arbutin, extract   from Ampelopsis japonica, Lindera aggregata,   Qian-wang-hong-bai-san, or San-bai-tang had a similar, although   extract from Polygonatum odoratum or Qiong-yu-gao had a   greater, IC50 value against murine tyrosinase   activity.


  From the screening assays we identified three Chinese medicinal   herbs and three TCM formulas that have appreciable antityrosinase   activity. Further studies are warranted to develop them as   skin-whitening agents with convenient dosage forms or to identify   active constituents from the extracts as useful leads for the   development of skin whiteners.

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