Phaeocaulines H and I, Two New Sesquiterpenoids from Curcuma phaeocaulis with Unprecedented Skeletons and Antiangiogenic Activity.

Sesquiterpenoids are a highly diverse group of natural compounds, known for their wide range of biological effects. Among them, the derivatives in the genus Curcuma have garnered significant interest for their intricate structures and potential pharmacological benefits. Curcuma phaeocaulis Val. (Peng Ezhu), a geo-authentic medicinal plant native to Sichuan Province, has been traditionally employed to enhance blood circulation and relieve pain. This study reports the isolation of two new sesquiterpenoids, phaeocauline H (1) and phaeocauline I (2), from C. phaeocaulis rhizomes. Compound 1 exhibits a novel dicyclo[4.3.1]-decane structure, whereas compound 2 contains an uncommon 5/7-fused bicyclic ring system. Detailed spectroscopic analyses and ECD data were employed to ascertain their structures, including absolute configurations. Plausible biosynthetic pathways for both compounds are proposed. Preliminary bioactivity evaluation revealed that both compounds exhibit antiangiogenic activity by preventing the proliferation of HUVECs induced by VEGF.