*2.12.7. Plectranthus grandidentatus*

In addition to 14-hydroxytaxodione (**140**), coleons U (**141**) and V (**142**), a series of abietane dimers namely grandidone A (**143**), B(**145**), and D(**147**) and their epimers 7-epigrandidone A(**144**), B(**146**), and D (**148**) and grandidone C (**149**) [61] were identified. Also, royleanone (**103**), 6,7-dehydroroyleanone (**138**), horminone (**150**), 6*β*-hydroxyroyleanone (**151**), and 7*α*acetoxy-6*β*-hydroxyroyleanone (**102**) together with a mixture of fatty acid esters of 7*α*-acyloxy-6*β*,12-dihydroxy-abieta-8,12-diene-11,14-dione (**152**), 7*α*,6*β*,-dihydroxyroyleanone (**139**), and 9*α*-(2-oxopropyl)abietane derivative(**156**) were isolated [62–67].

Fatty acid esters of 7*α*-acyloxy-6*β*-hydroxyroyleanone (**152**) showed moderate antibacterial activity [62]; coleon U exhibited potent cytotoxicity against a panel of human cancer cell lines [63, 65] also showed potent inhibition of mouse splenocyte proliferation induced by ConA or LPS mitogens [64]. Coleons U **141** is considered as a promising compound and deserves further evaluation as an anti-cancer drug [68]. Coleon U (**141**), 7*α*-acetoxy-6*β*-hydroxyroyleanone (**102**), and horminone (**150**) showed activity against methicillin-resistant *S. aureus* (MRSA) and vancomycin-resistant *Enterococcus faecalis* (VRE). Recently, the biological activity of **102** was reported and showed selective cytotoxicity against MCF-7. Other derivatives of the same compound showed potent cytotoxic [69, 70] and antimicrobial [66] activities.
