Thesis (M.Sc.)--Chulalongkorn University, 2008

In phytochemical investigation for antitumor compounds from Thai medicinal plants, the extracts of Goniothalamus laoticus stems were found to have a promising activity on KB and HeLa cell lines in preliminary evaluation. The dichloromethane and methanolic extracts were selected for further isolation, purification and structure elucidation. The chromatographic separation of these crude extracts led to the isolation of one new alkaloid, laoticuzanone A (9) and a synthetically known styryl-lactone (-)-goniofufurone (5), new natural compound, along with eleven known compounds, pinocembrin (1), altholactone (2), goniopypyrone (3), 5-hydroxy-3-amino-2-aceto-1,4-naphthoquinone (4), 2-epi-altholactone (6), 3-methyl-1H-1-azaanthracene-2,9,10-trione (7), griffithazanone A (8), methyl sinapate (10), 3-(4'-hydroxyphenyl)-(E) propenoic acid methyl ester (11), 2-(4-hydroxyphenyl) ethyl (E)-3-(4-hydroxyphenyl) prop-2-enoate (12) and (+)-goniofufurone (13). The structures of all isolated compounds were characterized by spectroscopic method, Single-Crystal X-ray analysis as well as comparison with the previous literature data. All of isolated compounds were evaluated for cytotoxicity against KB and HeLa cells. Compound 1, 9, 4 and 2 showed the significantly cytotoxicity against KB cell with IC₅₀ values 0.55, 0.68, 1.70 and 2.40 µg/ml, respectively. On the other hand, compound 9 also showed the highest cytotoxicity against Hela cell with IC₅₀ value 0.50 µg/ml, followed by compound 4, 1, 8, 2 and 7 with IC₅₀ values 0.50, 1.60, 3.00, 3.00, 3.10 and 4.00 µg/ml.