Hypopurolides A – G, Labdane Diterpenoids from Hypoestes purpurea and Their Nitric Oxide Inhibitory Activity

Abstract

Seven new labdane diterpenoids, hypopurolides A -G (1 -7) were discovered from the aerial part of Hypoestes purpurea, along with one known analog, hypopurin D (8). The structures of 1-7 were characterized based on 1 H-, 13 C-, and 2D-NMR, and HR-ESI-MS spectra. The absolute configurations of 1-7 were defined by single-crystal X-ray diffraction and electronic circular dichroism (ECD) data. Compounds 1-8 were tested for their nitric oxide (NO) inhibitory and cytotoxic effects. Compound 6 displayed moderate inhibitory effect toward LPS-induced NO release in RAW 264.7 cells with an IC 50 value of 41.50 μM.