Anoectochilus chapaensis Gagnep. （Orchidaceae） was named as the ＂king of medicine＂ because of its excellent efficacy for the treatment of diabetes. However, the bioactive constituents are unknown. An ethanol extract from A. chapaensis showed significant stimulating effect on glucose consumption in HepG2 cells. The chemical composition was investigated by UPLC-MS/MS in negative electrospray ionization （ESI） mode, and 63 compounds including flavonoids, triterpenoids, and aliphatic acids were tentatively identified by accurate mass and characteristic fragments. Moreover, the method of hypoglycemic screening with insulin resistant HepG2 cells and UPLC-MS/MS might be potentially useful in rapid and efficient characterization and primary prediction of natural products prior to traditional isolation.
Anoectochilus chapaensis Gagnep. （Orchidaceae）, an indigenous and valuable Chinese folk medicine, has been widely used in China to treat diabetes. However, few reports are available about its constituents and activity. The present experiment was conducted to investigate the active fractions from A. chapaensis in diabetic rat model induced by high-fat diet plus streptozotocin. The total EtOH extract from the whole herbs ofA. chapaensis, half of which was partitioned in sequence with petrol ether （PE）, ethyl acetate （EtOAc）, n-BuOH and H2O, thus yielding four fractions, all of them were orally administered with an identical dose amount to 4 g/kg dried crude herbs once a day for consecutive two weeks to further investigate the antihyperglycemic activity. The EtOAc fraction caused a significant fall in the non-fasting blood glucose level of diabetic rats from （402.66±82.26） to （226.26±62.10） mg/dl, which may be attributed to ameliorating insulin resistance, modulating the activity of enzymatic antioxidants, reducing the content of NO, etc. Much more intact β cells in the islets of Langerhans in EtOAc fraction-treated groups than the negative control were observed, which greatly supported the morphological and functional elucidation. The OGTT evidenced that EtOAc fraction could promote the endurance capacity of acute glucose increase in diabetic rats. The EtOAc fraction of A. chapaensis contains some hypoglycemic and antioxidant principles with the potential to be developed further for the treatment of diabetes specifically associated with an insulin resistance state.
