Studies On The Secondary Metabolites Of Two Strains Of Plant Endophytic Xylaria Sp.

The unmet need for new and effective drugs to provide assistance in all aspects of the human health is ever growing.Drug resistance in bacteria,the appearance of lifethreading viruses,the recurring problems with disease in persons with organ transplants,and the tremendous increase in the incidence of fungal infections in the world's population all underscore our inadequacy to cope with medical problems.Endophytes,especially endophytic fungi,are relatively unstudied and potential sources of novel natural products for applications in medicine,agriculture,and industry.In this study,the secondary metabolites of two endophytic fungal strainswere studied.Using column chromatography over silica gel, middle-pressure column chromatography over reversed-phase C-18 silical gel and Sephadex LH-20,10 compounds including 4 new ones,namely DCB2, DCB6,DCB8 and DCB9,were isolated.The secondary metabolites of the strain NCY2 were studied and structures of 3 compounds were elucidated by extensive spectroscopic data analyses.They are named YYD1,YYD2 and YYD3,respectively.These three compounds are which have been isolated and studied previously.The secondary metabolites of the strain 290 were studied and structures of 7 compounds were elucidated by extensive spectroscopic data analyses. They are named DCB1,DCB2,DCB3,DCB6,DCB7,DCB8 and DCB9, respectively.There are four new compounds which are isolated for the first time.They are DCB2,DCB6,DCB8 and DCB9.DCB6 is named 4-n-butanyl-2-(E)-pentylidene-3-methylbutanedioate;DCB9 is named Phenethyl-L-rhamnoside;What's the most interesting is that DCB2 and DCB8, together with DCB7,belong to a series of derivatives named pimarane diterpenoids. The strains NCY2 and 290 were identified by morphological and molecule biological methods.The result indicated that the strain NCY2 and 290 belonged to Xylaria sp..In conclusion,our study indicated that endophytic fungi were valuable resources for novel metabolites with antimicrobial,antitumor and antioxidant activities.