Bioactive alkaloids from the aerial parts of Houttuynia cordata

Ethnopharmacological relevance: Houttuynia cordata is an important traditional Chinese medicine used in heat-clearing and detoxifying, swelling and discharging pus, promoting diuresis and relieving stranguria which recorded in Pharmacopoeia of the people's Republic of China (2015 Edition). H. cordata has been recorded in the book Bencaogangmu which was written by Shizhen Li for the treatment of pyretic toxicity, carbuncle swelling, haemorrhoids, and rectocele diseases. Aim of the study: Phytochemical investigation of the aerial parts of H. cordata and evaluation of their PTP1B inhibitory activities and hepatoprotective activities. Materials and methods: The dried aerial parts of H. cordata were fractionated by liquid-liquid extraction to obtain CHCl3, ethyl acetate, and n-butanolic fractions. The CHCl3 fraction was confirmed active fraction by the bioactivity-guided investigation, which was isolated and purified by chromatographing over silica gel, Sephadex LH-20, MPLC, and preparative HPLC. The chemical structures of the purified compounds were identified by their spectroscopic data and references. Results: Eight new compounds (1-8), together with fourteen known compounds (9-22) were isolated from the aerial parts of H. cordata. The known compounds (9-22) were obtained from this plant for the first time. Among them, some compounds exhibited moderate bioactivities. Conclusion: Compounds (1-8) were identified as new alkaloids, and the known alkaloids (9-22) were isolated from this plant for the first time. Compounds 1, 4, 14, and 19 showed significant PTP1B inhibitory activities with IC50 values of 1.254, 2.016, 2.672, and 1.862 mu m, respectively. Compounds 1, 3, 6, 11, 17, and 20 (10 mu m) exhibited moderate hepatoprotective activities against D-galactosamine-induced WB-F344 cells damage.