Biotransformation of salvianolic acid B by Fusarium oxysporum f. sp. Cucumerinum and its two degradation routes.

Resting cells of Fusarium oxysporum f. sp. Cucumerinum (F. oxsporum) were used for the biotransformation of salvianolic acid B (Sal B). Three transformed products, isolithospermic acid, prolithospermic acid and danshensu, were identified on the basis of chemical and spectroscopic data. The stability of the two ester bonds of Sal B was studied and two degradation routes were found. In the biotransformation system, Sal B was transformed into isolithospermic acid first which was then converted into prolithospermic acid. In alkaline solutions, Sal B was transformed into lithospermic acid first which was then converted into prolithospermic acid. This is the first reports of the NMR spectra of isolithospermic acid and this result may indicate the metabolic pathways of Sal B in vivo.