Phytochemical Investigation and Cytotoxic Characterization of Bioactive Constituents from Conyza dioscoridis

A follow-up chemical investigation to methanol extract of Conyza dioscoridis (Family Asteraceae) led to the isolation of seven compounds (1-7). The isolated compounds identified as 2-(3,4-dihydroxyphenyl)ethyl-2-O-[6-deoxy-α-Lmannopyranosyl-4-(3,4-dihydroxyphenyl)-2-propenoate]-β-D-glucopyranoside (1), rutin (2), isoquercetin (3), E-caffeic acid (4), gallic acid (5), quercetin (6), β-Sitosterol-3-O-β-D-glucpyranoside (7). The methanol and chloroform extracts of the plant showed cytotoxic activity against brine shrimp in a preliminary assay and inhibitory activity against colon carcinoma cells (HCT-116) with LC50 value 20, 32 μg/ml and IC50 value 25, 35.3 μg/ml, respectively. Brine shrimp lethality test was conducted on the seven isolated compounds at six different concentrations 400, 200, 100, 20, 10 and 5 μg/ml; compounds 1, 2, 3, 5, 6 and 7 showed significant cytotoxicity with LC50 value 9, 10, 11, 22, 8 and 19 μg/ml, respectively. Compounds 1, 2, 3 and 6 exhibited inhibitory activity against colon carcinoma cells with IC50 value 25, 30, 34.2 and 10 μg/ml, respectively. These results indicate that; Conyza dioscoridis has biochemical activity as potential pharmaceuticals. The chemical structures of active constituents were unambiguously determined by analysis of HNMR, CNMR, ESI-MS, as well as by comparison with literature data and physical methods.