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

The investigation for chemical constituents and their biological activities from the CH2Cl2, EtOAc and MeOH crude extracts of the roots of Nauclea orientalis (L.) L. led to the isolation of three new indole alkaloids, naucleaorien (3), naucleaoral A (5) and B (6) along with nine known compounds, naucleficine (1), naucleactonin A (2), vanillic acid (4), naucleidinal (7), 19-epi-naucleidinal (8), strictosamide (9), alpigenoside (10), sweroside (11) and pumiloside (12). The structures of all isolated compounds were elucidated by physical properties and spectroscopic methods as well as comparison with previous literature data. Most of isolated compounds were tested for cytotoxicity on HeLa and KB cell lines. Compounds 1, 3, 6 and 7 showed very modest cytotoxicity against both HeLa and KB cell lines (IC50 values of 6.8 and 6.8, 9.5 and 5.0, 7.8 and 9.5 and 5.5 and 4.8 µg/mL, respectively). Compound 5 exhibited significant cytotoxic activity against only HeLa cells (IC50 value of 4.0 µg/mL), while compound 8 showed only very modest cytotoxic activity against KB cells (IC50 value of 6.8 µg/mL). On the contrary, compounds 2, 9 and 11-12 were inactive (IC50 >30.0 µg/mL). The results of testing for antimalarial activity of non-glycosidic indole alkaloids (compounds 1-2 and 5-8) showed that these compounds could be regarded as inactive (IC50 >10.00 µg/mL)