*2.12.2. Plectranthus amboinicus*

**2.8.** *Neophyptis* **genus**

20 Terpenes and Terpenoids

**2.9.** *Ocimum* **genus**

against five strains of *S. aureus* [43].

*Neophyptis* genus is represented by *N paniculata* in SA. Isoneocembrene-A (**84**), *β*-caryophyllene oxide(**85**), *α*-himachalene (**86**), the isolates showed weak to moderate antibacterial activity

*Ocimum* genus comprises 65 aromatic species, distributed in tropical and subtropical regions worldwide. Species belonging to this genus are popularly used in Africa and Asia for treating diabetic symptoms. The genus is represented by 16 species in SA and the phytochemical Thymoquinone (**105**) was identified as an active nonpolar ingredient to suppress the expression of lipopolysaccharide-induced tumor necrosis factor-alpha (TNF-*α*) [50]. The total extract showed cytotoxic activity against MCF-7, using HPLC-based metabolomics approach, and 7α-acetoxy-6*β*-hydroxyroyleanone (**102**) was identified as the main active constituent. Other minor compounds like coleon E (**103**) and royleanone (**104**) were also identified [51].

12*Z*,14-trien-2*α*-ol (**123**),3*β*-acetoxylabda-8(17),12*E*,14-trien-2*α*-ol (**124**), 10 kauranes (*ent*-12*β*acetoxy-15*β*,16*β*-epoxykauran-19-oic acid (**125**), *ent*-7*β*-hydroxy-15*β*,16*β*-epoxykauran-19-oic acid (**126**), *ent*-15*β*,16*β*-epoxykauran-19-oic acid (**127**), *ent*-15*β*,16*β*-epoxykauran-19-ol (**128**), *ent*-12*β*-acetoxy-15*β*-hydroxykaur-16-en-19-oic acid (**129**), *ent*-12*β*-acetoxy-7*β*-hydroxykaur-16-en-19-oic acid (**130**),methyl ent-12*β*-acetoxy-16-kauren-19-oate (**131**), *ent*-7*β*-hydroxykaur-15-en-19-oic acid (**132**), methyl *ent*-12*β*-acetoxy-7*β*-hydroxykaur-15-en-19-oate acid (**133**), *ent*-12*β*-acetoxy-17-oxokaur-15-en-19-oic acid (**134**), methyl *ent*-12*β*-acetoxy-15-kauren-19 oate (**135**), additionally, armendrance (**136**), caryophyllene *α*-oxide (**137**), ursolic/oleanolic acids (2,1 mixture) *β*-sitosterol, stigmasta-5,22*E*-dien-3*β*-ol, and *β*-amyrin. Some of the compounds showed moderate anti-*staphylococcus* activity [58, 59]. *P. fruticosus* growing in India showed abietane diterpene pattern and 7*α*-acetoxy-6*β*-hydroxyroyleanone (**102**), 6,7-dehy-

Chemistry of South African Lamiaceae: Structures and Biological Activity of Terpenoids

http://dx.doi.org/10.5772/intechopen.77399

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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

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

Horminone (**150**), 16-acetoxy-7*α*,12-dihydroxy-8,12-abietadiene-11,14-dione (**153**) and 7*α*-12 dihydroxy-17(15→16)-abieta-8,12,16-triene-11,14-dione (**157**);3*β*-acetoxy-6*β*,7*α*-12-trihydroxy-17(15→16)18(4→3)bisabeo-abieta-4(19)8,12,16-triene-11,14-dione (**158**) were isolated [13, 66, 71], on the other hand, the structure of an aristolane sesquiterpene aldehyde (**159**) have been revised [72], all compounds showed moderate antimicrobialactivity [13, 66, 71, 72], while **158**

*Plectranthus madagascariensis* is used as a traditional medicine in Southern Africa. Three constituents were isolated and identified as 6*β*,7*β*-dihydroxyroyleanone (**154**), 7*β*-acetoxy-6*β*hydroxyroyleanone (**155**), and coleon U (**141**). The compounds exhibited inhibitory activity

droroyleanone (**138**) and 7*α*,6*β*-dihydroxyroyleanone (**139**) were isolated [60].

compound showed potent cytotoxic [69, 70] and antimicrobial [66] activities.

9*α*-(2-oxopropyl)abietane derivative(**156**) were isolated [62–67].

*2.12.7. Plectranthus grandidentatus*

*2.12.8. Plectranthus hereroensis*

showed antiviral activity [73].

*2.12.9. Plectranthus madagascariensis*

on *α*-glucosidase, *S. aureus* and *Enterococcus faecalis* [74].
