Bioactive diterpenes from Orthosiphon labiatus and Salvia africana-lutea

Abstract

The known (+)-trans-ozic acid (1) and two new labdane diterpenoids (2 and 3) have been isolated from an ethanol extract of Orthosiphon labiatus. The structures of 2 and 3 were established mainly by 1D and 2D NMR spectroscopic means. The ethanolic extract of SalVia africana-lutea afforded the known abietane diterpenoids carnosol (4), rosmadial (5), and carnosic acid (characterized as its derivative 6). Compounds 3 and 6 exhibited MICs of 157 and 28 íM, respectively, against Mycobacterium tuberculosis, while 2 and 6 showed cytotoxic activity with IC50 82 and 69 íM, respectively, against a breast (MCF-7) human cancer cell line.The authors thank Dr. E. Retief, National Biodiversity Institute, South Africa, for the classification of plant materials. This work was supported by funds from the Spanish “Comisio´n Interministerial de Ciencia y Tecnologı´a” (CICYT, grant no. CTQ2005-05653/BQU).Peer reviewe