Scuteparvin, a new neoclerodane diterpenoid from Scutellaria parvula.

The diterpenoid fraction occurring in the acetone extract of the aerial parts of Scutellaria parvula has been investigated. Only one neoclerodane diterpenoid, scuteparvin, was isolated and its structure elucidated as 4α,18-epoxy-6α-trans-cinnamoyloxy-neoclerod-13-en-15,16-olide, a new natural product. Scuteparvin is quite similar to the already known ajugarin V from Ajuga remota, the only difference being the occurrence of a trans-cinnamoyl ester system instead of an acetate on the 6α-OH group. This finding confirms that the genera Scutellaria and Ajuga are closely related taxonomically.