**2.10.** *Orthosiphon* **genus**

*Orthosiphon* genus comprises 40 species recorded from the old world: in tropical and subtropical regions including Southern Africa and Madagascar. Three species were found in SA. Three labdanoids (+)-*trans*-ozic acid (**91**), labda-8(17),12*E*,14-trien-2α,18-diol (**92**), and 2α-hydroxylabda-8(17),12*E*,14-trien-18-oic acid (**93**) have been isolated from an ethanol extract. Compound **93** exhibited activity against *M. tuberculosis*, while **92** showed cytotoxic activity against MCF-7 and decreased the production of all the pro-inflammatory cytokines. From the same source, pheophytin a, the acidic degradation product of chlorophyll a, was isolated and showed inhibition of HIV-1 protease [45, 46].
