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.