The Inhibition Mechanism Of Osthol To Phytopathogenic Fungi

97.5% purity of osthol was achieved by gradient resolvement and crystallization with ethanol and ethyl acetate. When osthol was treated with Acidum Peroxyaceticum, two main products were achieved, but the antifungal activity of the two products did not increase compared with osthol.In vitro studies,osthol displayed a wide range of antifungal activity to phytopathogenic fungi such as Rhizoctonia solani and Macrophoma kawatsukai. Osthol inhibited hyphal growth and spores germination of F.graminearuym. At 50 g mL-1 osthol,Spores germination was completely inhibited and hyphal branches increased. Treated with 100 g mL-1osthol for 24 hour, the hyphae growing in aliquous culture fragmented greatly.In 100 g mL-1 osthol-treated F.graminearuym, N-GlcNAc required for synthesis of cell wall as well as cell wall lysis-related chitinase activity increased whereas -1.6-glucanase activity remain unchanged. When F. graminearuym fed with 14C glucose was treated with 100 g mL-1 osthol, glucose content decreased rapidly and reduced to the lowest level i.e. 51% of control in 3h, while chitinase activity,soluable proteins content and protease activity increased rapidly,which suggested glucose starvation might induce the expression of chitinase. It was proposed that osthol treatment increased chitinase activity leading to the degradation of chitinsome required for biosynthesis of fungus cell wall and led to hyphae fragment.When F. gramineantymg was treated with 100 g mL-1 osthol for 12h, calcium in F. graminearuym decreased by 40%. Such suggesteded that osthol inhibited uptake of calcium required for Ca2+ dependent vacuole transportation and growing hyphae tip. PAGE indicated that osthol also inhibited ATPase, and it was likely that osthol could inhibit energy metabolism by inhibiting ATPase.