A new abietane diterpene, 16-acetoxy-7 alpha,12-dihydroxy-8,12-abietad
iene-11,14-dione, has been isolated from the acetone extract of the ro
ot of Plectranthus hereroensis and its structure established by spectr
oscopic means. This compound showed antibacterial activity against Sta
phylococcus aureus and Vibrio cholerae, and antiviral activity against
Herpes simplex type II.