Thesis (Ph.D.)--Chulalongkorn University, 2009

Exserohilum rostratum, an endophytic fungus, from Stemona sp. produced a novel compound, 11-hydroxymonocerin (2), and two known compounds -- monocerin (1) and 12-hydroxymonocerin (3). Compounds 1 and 2 were derivatized to obtain 8 new compounds: 8-acetylmonocerin (4), diacetylmonocerin (5), 8-benzoylmonocerin (6), 8-methylmonocerin (7), 5-bromomonocerin (8), 8-hydroxy-6,7-dimethoxy-3-(pentan-2´-yl-acetate)-isocoumarin (9), 11-Oxomonocerin (10) and 11-carbonylmonocerin (11). Compounds 1, 2, 4, 5, 6 and 10 have specific activity against Plasmodium falciparum K1 strain with IC₅₀ = 0.69, 7.42, 0.82, 9.1, 7.85 and 13.4 µM, respectively. Endophytic fungal strains from Andrographis paniculata produced three known compounds: N-Phenetyl-acetamide (12), and tryptophol (13) and indole-3-acetamide (14). Endophytic fungal strains from Chromolaena odoratum, produced two known compounds: cytochalasin D (15) and cytochalasin H (16)