Studies On Microbial Transformation Of Toosendanin And The Activities

Toosendanin is a kind of tetracyclic triterpene compounds which isolated from meliaceaeplants. It has extensive pharmacological action and the insecticidal activity. Such asantifeedant acitivity, toxic, stomach poisoning and growth inhibition effect on insects.There is no people that has done toosendanin microbial conversion so far. In ourresearch we use endophytes from meliaceae plants to modify the tetracylic triterpenetoosendanin and finally we isolated and identified7coumpounds.There are42strain endophytic fungi isolated and purified from the root and bark of thesichuan neem tree, and we found the stem points genus Phomopsis sp K-J-11has best percentconversion to toosendanin. After large scale fermentation we got11compounds which wereisolated from ethyl acetate extract by methods including macroporous resin absorption,reversed-phase column RP-18and HPLC. And seven compounds were isolated and identifiedby1D、2DNMR and MS（:1）3-hydroxyl toosendanin、（2）3,4-dihydro-3,4,8-trihydroxiy(-2H)-naphthalenon、（3）alternariol（aoh）、（4）djalonensone、（5）C-24epimer of the24-methylepidioxysterol、（10）5a,6a-epoxy-24(R)-methylcholesta-7,22-dien-3b-ol、（11）(22E,24R)-24-methyl-5a-cholesta-7,22-diene-3f,3b,P5-triol。 The compound1is anunreported compound and the insecticidal activity of it has been tested. The result shows thatthe LC50of toosendanin is3.15±0.17μmol/L and the activity of3-hydroxy toosendanin is91.82±5.04μmol/L. The allelopathic activity of other six copounds has been assayed, and theresults suggest they have inapparent stimulation and inhibiting effects.