Stereo and region-selective biosynthesis of two new dihydroartemisinic acid glycosides by suspension-cultured cells of Artemisia annua

BACKGROUND: The system of plant-cultured cells is one of the optimal systems to investigate biosynthesis pathway and their bioactive intermediates. OBJECTIVE: To study the biosynthesis of dihydroartemisinic acid (1) by suspension-cultured cells of Artemisia annua. MATERIALS AND METHODS: Substrate (compound 1) was administered into the suspension-cultured cells of A. annua and co-cultured for 2 days. The methanol extract was separated on various column chromatography methods and the structures of two biosynthesis products were elucidated based on the analysis of (1)H NMR, (13)C NMR, 2D NMR, and ESI-MS. Time-course curve was also established. Furthermore, in vitro antitumor activities of compounds 1-3 against HepG2, K562, and A549 cell lines were evaluated by MTT assay. RESULTS: Two new compounds were obtained, namely 3α-hydroxy-dihydroartemisinic acid-α-D-glucopyranosyl ester (2) and 15-hydroxy-cadin-4-en-12-oic acid-β-d-glucopyranosyl ester (3). The results demonstrated that the cultured cells of A. annua possessed the abilities to stereo-selective hydroxylate and region-selective glycosylate sesquiterpene compounds in a highly efficient manner. Inhibitory effects of compounds 1-3 on proliferation of HepG2, K562, and A549 cell lines in vitro were also investigated. CONCLUSION: Two new dihydroartemisinic acid glycosides were obtained by stereo- and region-selective biosynthesis with cultured cells of A. annua.