Chemical Composition, Cytotoxic and Antioxidant Activities of Celosia trigyna L. Grown in Saudi Arabia

The methanol extract of the aerial parts of Celosia trigyna (Amaranthaceae) was successively fractionated using n-hexane, dichloromethane, ethyl acetate and n-butanol. The cytotoxic activity of the obtained fractions was investigated using sulphorhodamine-B (SRB) assay against three carcinoma cell lines; breast adenocarcinoma (MCF-7), colorectal carcinoma (HCT-116) and hepatocellular carcinoma cells (HepG2). The dichloromethane fraction showed significant in vitro cytotoxic activities against the human cancer cell lines HCT-116 and HEP-G2 with IC50 values of 10.9 and 11.2 µg/mL, respectively, while all fractions revealed weak antioxidant activity using DPPH free radical scavenging method. The GC-MS analysis of the most cytotoxic dichloromethane fraction has resulted in the identification of 12 compounds. The main constituents were tetrahydroisoquinoline derivative (31.44%), 2,3-dimethylheptadecane (16.71%) and 3-octadecanone (15.56%). Moreover, the phytochemical study of the dichloromethane and n-butanol fractions led to the isolation and identification of five known compounds identified as β-amyrin acetate (1), acacetin 8-C-α-rhamnosyl-(1→2)-β-glucopyranoside (2), apigenin 8-C-α-rhamnosyl-(1→2)-β-glucopyranoside (3), quercetin 3-O-α-rhamnosyl-(1→6)-β-glucopyranoside (4) and 3-hydroxyglutaric acid (5).