Isolation of major phenolics from Launaea spinosa and their protective effect on HepG2 cells damaged with t-BHP

Context: Some Launaea species (Asteraceae) are used traditionally to treat liver oxidative stress. Objective: The present study investigates the protective effects of isolated compounds from Launaea spinosa Sch. Bip. (Asteraceae) against oxidative stress on t-BHP-induced HepG2 cells. Materials and methods: Major phenolic content from flowering aerial parts of L. spinosa was isolated and identified. The protective effects of isolated compounds (10 and 20 mu M) against oxidative stress induced by tert-butyl hydroperoxide (t-BHP) in HepG2 cells were investigated through the measurement of aspartate aminotransferase (AST), alanine transaminase (ALT), and superoxide dismutase (SOD) levels. Results: A new phenolic compound identified as 2,3-diferulyl R,R-(+) methyl tartrate (6), in addition to five known metabolites, esculetin (1), esculetin-7-O-D-glucoside (cichoriin) (2), fertaric acid (3), acacetin-7-O-D-glucoside (4), and acacetin-7-O-D-glucuronic acid (5), were isolated. Oxidant-induced damage by 200 mu M t-BHP in HepG2 cells was inhibited by compounds 1, 4, and 5 (10 and 20 mu M), or quercetin (10 mu M; positive control). The protective effects of compounds 1, 4, and 5 were associated with decreasing in AST, ALT, and SOD levels. Compound 4 (20 mu M) decreased the AST level from 128.5 +/- 13.9 to 7.9 +/- 1.8U/mL. Meanwhile, compound 1 (20 mu M) decreased ALT activity from 20.3 +/- 7.0 to 7.6 +/- 2.4U/mL, while compound 5 decreased SOD levels from 41.6 +/- 9.0 to 28.3 +/- 3.4mU/mg. Conclusion: The major phenolic compounds isolated from L. spinosa displayed a significant cytoprotective effect against oxidative stress, leading to maintenance of the normal redox status of the cell.