ISOLATION AND PHYTOTOXIC EFFECTS OF HELVOLIC ACID FROM PLANT-PATHOGENIC FUNGUS SAROCLADIUM-ORYZAE

In this study, we isolate helvolic acid, an antibiotic metabolite, fro m the rice sheath rot pathogen Sarocladium oryzae. The fungus is cultu red in potato-sucrose broth. The metabolite is extracted by ethyl acet ate, and its antibiotic activity is tested with Bacillus subtilis. Hel volic acid is soluble in chloroform, acetone, ethyl acetate, methanol, ethanol, and alkali water. The substance is stable at an active tempe rature of 22 degrees C-100 degrees C and is also active at various hyd rogen ion levels (pH 3-11). Also, helvolic acid is identified with thi n-layer chromatography and further characterized by UV, IR, NMR, and M ass spectroscopy. The toxic effects of helvolic acid on seedlings of G raminae include growth retardation and chlorosis. These effects are re duced about 40% by treating with Hoagland's solution and can be reduce d to around 30% by treating with magnesium solution.