Separation and Biological Activities of the Main Compounds from the Bark of Myrica rubra Siebold & Zucc

Myrica rubra (Lour.) Siebold & Zucc bark is a traditional natural medicine used by the people of the Dong minority in western Hunan in China. In this study, the main compounds in Myrica rubra bark including epigallocatechin gallate, myricetrin, myricetin, taraxerol, myricanol, and 11-O-acetylmyricanol were separated using both silica gel column chromatography and high-speed countercurrent chromatography (HSCCC). Notably, it is the first report of discovering 11-O-acetylmyricanol from Myrica rubra bark. The results of the bioactivity studies suggested that epigallocatechin gallate showed the highest α-glucosidase inhibitory activity, while myricetin exhibited the highest reactive oxygen species (ROS) scavenging ability in zebrafish embryos. Intriguingly, myricanol exhibited strong apoptosis-inducing activity on HepG2 cells, and further studies revealed that myricanol was capable of promoting the cleavage of caspase 3, 8, and 9, then resulting in the apoptosis in HepG2 cells. The findings of the present study have important implications for the separation of the main compounds in Myrica rubra and will provide credence to the ethnomedicinal application of the isolated compounds against cardiovascular disease and cancer.