Biosynthesis of Novel Shikonin Glucosides by Enzymatic Glycosylation.

Shikonin, a natural naphthoquinone, has attracted much attention due to its various biological activities. Two shikonin glucosides, shikonin-1',8-di-O-β-D-glucopyranoside (1) and shikonin-1'-O-β-D-glucopyranoside (2), were biosynthesized through in vitro enzymatic glycosylation and their structures were elucidated using spectroscopic techniques. The water-solubility and stability of compounds 1 and 2 were significantly higher than those of the parent compound. Furthermore, compound 2 showed moderate cytotoxicity against six cancer cell lines, with IC ₅₀ values ranging from 36.10 to 67.47 µM. This research indicated that in vitro enzymatic glycosylation of shikonin is an effective strategy to improve it water solubility and chemical stability.