Inhibitory effects of methanol extracts of selected plants on the proliferation of two human melanoma cell lines

Purpose: The aim of the current study was to investigate the in vitro antiproliferative activity of methanolic extracts of six plants regardless of their claimed ethnopharmacological application. Methods: Methanol extracts of different parts of Glycyrrhizaglabra L. (Licorice), Matricaria chamomilla L. (Chamomile), Salvia triloba L. (Sage), Rheum palmatum L. (Rhubarb), Trigonella foenum-graecum L. (Fenugreek) and Sambucusebulus L. (Dwarf Elder) were prepared. The antiproliferative effects of the extracts were tested on two skin cancer melanoma cell lines namely A375.S2 (low tyrosinase expression) and WM 136.1A (high tyrosinase expression) using MTT assay. The IC 50 values for the active extracts were determined against the two melanoma cell lines. Results: The methanolic extracts of G.glabra , M. chamomilla , S. triloba , R. palmatum inhibited the melanotic WM1361A proliferation in a dose-dependent manner revealing IC 50 values of 35.2, 25.2, 20.6, 17.8, μg/ml, respectively but not A375.S2 cell line. However, the extracts of T. foenum-graecum and S. ebulus did not exhibit any significant cytotoxic activity on both melanoma cell lines. Conclusion: The results of these experiments show that methanol extracts of licorice, chamomile, sage and rhubarb have significant antiproliferative activity onWM1361A cell line; a representative human melanotic melanocyte tumor cell line. This renders these plants as potential sources of new lead compounds for the development of new drugs for melanoma cancer. Keywords: Melanoma, Plant extract, tyrosinase, Licorice, Chamomile, Sage, Rhubarb, WM1361A