Liposoluble Components From Rice False Smut Balls And Their Bioactivities

False smut appeared in rice panicle was a fungal disease caused by Ustilaginoidea virens.This disease had occurred in all rice-producing areas of the world. It has showed an increasingtrend in recent years in China. It not only affected the quality and yield of rice, but also thetoxins produced by the pathogen were toxic to humans and animals. In this thesis, themethanol extract was prepared from the rice false smut balls, which were mainly composed ofthe chlamydospores of the pathogen. The oil part and three compounds were separated fromthe petroleum ether fraction of the methanol extract. Their antimicrobial and antioxidantactivities were evaluated. The main results were as follows.The crude methanol extract （1964g）, which was prepared from the rice false smut balls（6.0kg）, was suspended in water, and then extracted with petroleum ether, ethyl acetate, andn-butanol in turn to obtain petroleum ether fraction （310g）, ethyl acetate fraction （136g）,n-butanol fraction （318g） and aqueous fraction （1200g）.The oil part and three compounds （1,2and3） were separated from the petroleum etherfraction by various techniques such as silica gel column chromatography, Sephadex LH-20column chromatography, crystallization and recrystallization. Chemical compostions of the oilpart were analyzed by GC-MS. Three compounds were identified as octadecenoic acid （1）,tetracontane （2）, and ergosta-5,7,22-trien-3-ol （3） by the spectroscopic methods of HRMS,1H-NMR, and13C-NMR.The above liposoluble components were evaluated for their antibacterial activity by themethod of MTT-microplate spectrophotometry as well as for their antifungal activity byMagnaporthe oryzae spore germination assay. Both the oil part and compound3showed acertain inhibitory activity on Bacillus subtilis with their IC50values as148.29μg/mL and50.38μg/mL, respectively; which indicated that the antibacterial activity of compound3wasstronger that that of the oil part. Furthermore, compound3had its inbitory activity onPseudomonas lachrymans, Xanthomonas vesicatoria, and Agrobacterium tumefaciens to someextent. Compound2and the oil part had certain inbitory activity on Magnaporthe oryzae, butweaker than the positive control carbendazim.The liposoluble components were also evaluated for their antioxidant activity. The oilpart as well as the compounds1and2exhibited Fe²⁺chelating activity with the EC50valuesas37.88μg/mL,74.82μg/mL and23.58μg/mL, respectively. Both the oil part and compound2showed stronger antioxidant activity than compound1.This thesis first reported the chemical composition of the oil part of petroleum ether fraction of the methanol extract from rice false smut balls. Three compounds octadecenoicacid （1）, tetracontane （2）, and ergosta-5,7,22-trien-3-ol （3） were also reported from rice falsesmut balls for the first time. Their antimicrobial and antioxidant activities were evaluated atthe same time. The results could provide a basis to clarify the liposoluble components andtheir bioactivities from rice false smut balls.