Puqienine E: An angiotensin converting enzyme inhibitory steroidal alkaloid from Fritillaria puqiensis

Abstract Eight steroidal alkaloids, puqienine A, puqienine B, puqienine C, puqienine D, puqienine E, puqietinone, puqiedine and peimisine were isolated from Fritillaria puqiensis G. D. Yu et. G. Y. Chen, and their anti-hypertensive effect were assessed in vitro based on the inhibition of the purified angiotensin converting enzyme (ACE) using high-performance liquid chromatography assay. The results showed that puqienine E, puqienine B and puqienine A exhibited better inhibitory activity against ACE than others, with inhibition ratios of 70.2 ± 0.5%, 24.7 ± 0.5% and 20.4 ± 2.8%, respectively at the concentration of 200 μM. The 50% inhibiting concentration of puqienine E was determined to be 68 µM.