Microbial Transformation Strains Screening Of Five Natural Products And Study Of Solvent-induced Secondary Metabolites

Most natural products possess distinct biological activities and significant research value because of their complex cyclic structure. However, it is difficult to modify at some positions using the traditional chemical methods, particularly for inactive sites. Microbial cells can be employed to modify the strucures of some complex substrates, which is complementary with the traditional synthesis method especially in the reaction of inactive site.In this paper,23 different fungi were used to screen the biotransformed products of several natural products including naringenin, naringin, quinine, quinindium and camptothecin, the result showed that fungus Aspergillus niger 3.3928 can biotransform naringenin, Primary separation was carried out by Slica column chromatography, high preparative liquid chromatography and recrystallization.23 different fungi were used to induce by DMSO and DMF, DMSO was found to be able to induce a new secondary metabolite of No.10 fungus. (The fungus was identified as Eupenicillium sp.)The metabolite was isolated by column Chromatography, the structure of this product was confirmed as 6,8-dihydroxy-3-(4-hydroxy-2-oxopentyl)-1H-isochromen-l-one (compound 1) this is the first time to obtain this purified metabolite. According to NMR spectra and HR-ESI-MS. The fungus was identified as Eupenicillium sp. Further research revealed that acetone possess the same impact on No.10 fungus as that of DMSO and can induce the production of the same metabolite. However, DMF and ethanol exhibited no induction. This is the first time to obtain this purified metabolite and this solvent-induced secondary metabolite formation is much more convienent than that of original reported biotransform with the gene engineering fungus.The influence of different concentrations of DMSO on the production of this compound was invisgated by HPLC, the results suggested that 1‰ DMSO has the strongest induction.The biological activities of this induced product were evaluated, the test result showed that it could inhibit the growth of phytophthom vignae Purss but exhibited no significant antitumor and antioxidation activities.