Six New neo-Clerodane Diterpenoids from Aerial Parts of Scutellaria barbata and Their Cytotoxic Activities.

Six new neo-clerodane diterpenoids (1: -6: ), scutebatas X - Z, A-C, along with twelve known ones (7: -18: ) were obtained via the phytochemical investigation of the aerial parts of . Their structures were established by detailed spectroscopic analysis. The absolute configurations of 1: and 2: , as the representative members of this type, were identified based on a circular dichroic exciton chirality method. Moreover, in vitro cytotoxicity of compounds 1: -6: were evaluated against three human cancer cell lines (SGC-7901, MCF-7, and A-549) using the MTT method. Compound 6: showed cytotoxic activities against all the three cell lines with IC values of 17.9, 29.9, and 35.7 µM, respectively.