Isolation and Identification of Secondary Metabolites in L.fil. Growing in Kazakhstan and Surveying of Its Anticancer Potential.

L.fil., known for its high tolerance to drought, salinity, and nutritional deficiency, is the least studied species of wild rhubarb. Extract of roots and rhizomes of has been traditionally used for the treatment of different diseases such as liver, kidney, womb, and bladder diseases and also relapsing fever. An ethanol extract of the roots of was prepared and further successively fractionated by extraction with -butyl methyl ether () and ethyl acetate (). The obtained extract fractions were subjected to a series of chromatographic separations on silica gel for the isolation of its individual compounds. A total of 12 individual compounds, 2--β--glucopyranoside of -(4-hydroxyphenyl)-2-butanol (rhododendrin) , gallic acid , 2--β--glucopyranoside of -4-(4-hydroxyphenyl)-2-butanol (-rhododendrin) , their aglycones (-)-(2)-rhododendrol and (+)-(2)-rhododendrol , gallotannin β-glucogallin , chlorogenic acids (3,5-di--caffeoylquinic acid and 5--caffeoyl-3--(-coumaroyl) quinic acid ), 4-(4-hydroxyphenyl)-2-butanon (raspberry ketone) and three stilbenes (rhaponticin , desoxyrhaponticin and resveratroloside ), were isolated and characterized. The structure of desoxyrhaponticin was confirmed by X-ray diffraction analyses. The results of in vitro biological assays (the MTT test) showed that ethanol extract was non-toxic against the normal epithelial VERO cells. The isolated compounds , , and exhibited cytotoxicity against a cervical cancer cell line (CaSki), breast adenocarcinoma (MCF7) and glioblastoma cell line (SNB-19) at low micromolar concentrations. Polyhydroxystilbenes and showed the best potency against adenocarcinoma cells (GI = 7-8 μM). The inhibition activity towards cancer cells was comparable to those of the standard drug doxorubicin. The available from secondary metabolites may serve as new leads for the discovery of anticancer drugs.