Thesis (M.Sc.)--Chulalongkorn University, 2006

Plant pathogenic and soil fungi have been the source of a wide range of bioactive compounds. Trichoderma virens and Alternaria porri were selected for further investigation. The chromatographic separation of dichloromethane extract of liquid culture from T. virens led to the isolation of a novel furnaosteroid, 90epi-viridiol (4), along with three known compounds, viridin (1), 4-methylmevalonic acid (2) and viridiol (3). On the other hand, the isolation of ethyl acetate extract from A. porri afforded three new compounds, alterporriol F (9), zinnimide (10), deprenylzinnimide (16), together with ten known compounds, zinnimidine (5), alterporriol D or E (6), alterporriol A (7), alterporriol C (8), macrosporin (11), 3’, 3’-dimethylallyloxy)-3-methoxy-6-methylphthalide (12), porriolide (13), alternariol monomethyl ether (14), alternariol (15) and demethylmacrosporin 917). The structures of all isolated compounds were elucidated by spectroscopic methods as well as comparison with the previous literature data. All compounds were evaluated ofr cytotoxicity on HeLa and KB cell lines and inhibitory activity of acetylcholinesterase. Compound 14 showed highest cytotoxicity against HeLa cell line with IC [subscript 50] at 4.3 grams/millilitre, while compound 15 exhibited highest cytotoxicity with IC [subscript 50] at 4.5 grams/millilitre for KB cell line. In addition, Compound 3, 5, 10 and 12 displayed significant inhibitory activity of acetylcholinesterase with MIC values of 0.125, 0.250, 0.500 and 1,000 milligrams/ milloloL, respectively.