Thesis (M.Sc.)--Chulalongkorn University, 2009

The investigation for chemical constituents and their biological activities from acetone crude extract of the roots of Shorea roxburghii G. Don led to the isolation of a new stilbenoid, roxburghiol A (5), along with fourteen known compounds, melanoxylin A (1), caragaphenol A (2), epsilon-viniferin (3), hopeahainanphenol (4), vitisinol G (6), vaticanol A (7), hopeaphenol (8), isohopeaphenol (9), apigenin 7-O-glucoside (10), trans-piceid (11), trans-3,5,4'-trihydroxystilbene 2-C-glucoside (12), neoisohopeaphenol A (13), balanocarpol (14) and gnemonol K (15). The structures of all isolated compounds were elucidated by physical properties and spectroscopic methods as well as comparison with previous literature data. The evaluation for antioxidant activity (DPPH radical scavenging) and cytotoxic activity against HeLa and KB cell lines found that most of isolated compounds showed antioxidant activity toward DPPH radical with IC[subscript 50] values in the range of 0.23-0.41 mM, and these compounds also exhibited cytotoxicity against KB cell line more than HeLa cell line. Compounds 8 and 9 showed the most effective cytotoxicity against KB cell line with IC[subscript 50] = 6.47 and 8.50 µ/mL, and HeLa cell line with IC[subscript 50] = 8.66 and 10.12 µ/mL, respectively. Compounds 4, 7, 10 and 11 were inactive toward both cell lines (IC[subscript 50] > 80.0 µ/mL).