*2.12.9. Plectranthus madagascariensis*

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

calculation [80]. **160**, **161** showed moderate antimicrobial. **178** exhibited growth inhibitory activity against five *Staphylococcus* and five *Enterococcus* strains [75]. Ornatin C, D, E and three related diterpenes displayed marginal bactericidal or bacteriostatic effects against the Gram-positive

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

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

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(13*S*,15*S*)-6*β*,7*α*,12*α*,19-tetrahydroxy-13*β*,16-cyclo-8-abietene-11,14-dione (**179**) has been iso-

*Ent*-7*α*-acetoxy-15-beyeren-18-oic acid (**180**), *ent*-3*β*-(3-methyl-2-butenoyl) oxy-15-beyeren-19-oic acid (**181**), and ent-3*β*-(3-methylbutanoyl) oxy-15-beyeren-19-oic acid (**182**). Both **181** and **182** showed insect antifeedant activity against *Spodopteralittoralis*, while **180** showed no

lated and showed weak antibacterial activity against *S. aureus* [81].

strains [77].

*2.12.11. Plectranthus porcatus*

*2.12.12. Plectranthus saccatus*

antibacterial activity [81, 82].

*2.12.10. Plectranthus ornatus*

Traditionally, the plants were used for treatment of stomach and liver diseases and as a substitute of *P. barbatus*. The phytochemical studies resulted in the isolation of 11 neoclerodanes (plectrornatins A (**160**) [75], 11*R*\*-acetoxykolavenic acid (**161**), 11*R*\*-acetoxy-2-oxokolavenic acid (**162**), 11*R\**-acetoxy-3*β*-hydroxyneocleroda-4(18),13*E*-dien-15-oic acid (**163**) [76], ornatins A–E (**164**-**168**), 3*β*-hydroxyneocleroda-4(18),13*E*-dien-15-oic acid (**169**) [77]; 7 labdanes (plectrornatins B (**170**), C (**171**), [75],6-*O*-acetylforskolin (**172**); 1,6-di-*O*-acetylforskolin (**173**), 1,6-di-*O*-acetyl-9-deoxyforskolin (**174**) [76, 78], rhinocerotinoic acid (**175**) [66], 8*β*-hydroxylabd-13-en-15-oic acid (**176**) [77]); 2 abietanes (14-*O*-acetyl-coleon U (**177**), coleon R (**110**)) and a halimane derivative, (11R\*-acetoxyhalima-5,13E-dien-15-oic acid (**178**) [79]) in addition to *β*-sitosterol and stigmasterol, 3*β*-acetyl-α-amyrin, and friedelin. Inversion at C-13 of 1,6-di-*O*-acetyl-9-deoxyforskolin (**174**) was carried out based on correlations between 13C NMR experimental data and HF/6-31G\* calculation [80]. **160**, **161** showed moderate antimicrobial. **178** exhibited growth inhibitory activity against five *Staphylococcus* and five *Enterococcus* strains [75]. Ornatin C, D, E and three related diterpenes displayed marginal bactericidal or bacteriostatic effects against the Gram-positive strains [77].

*2.12.11. Plectranthus porcatus*

*2.12.10. Plectranthus ornatus*

Traditionally, the plants were used for treatment of stomach and liver diseases and as a substitute of *P. barbatus*. The phytochemical studies resulted in the isolation of 11 neoclerodanes (plectrornatins A (**160**) [75], 11*R*\*-acetoxykolavenic acid (**161**), 11*R*\*-acetoxy-2-oxokolavenic acid (**162**), 11*R\**-acetoxy-3*β*-hydroxyneocleroda-4(18),13*E*-dien-15-oic acid (**163**) [76], ornatins A–E (**164**-**168**), 3*β*-hydroxyneocleroda-4(18),13*E*-dien-15-oic acid (**169**) [77]; 7 labdanes (plectrornatins B (**170**), C (**171**), [75],6-*O*-acetylforskolin (**172**); 1,6-di-*O*-acetylforskolin (**173**), 1,6-di-*O*-acetyl-9-deoxyforskolin (**174**) [76, 78], rhinocerotinoic acid (**175**) [66], 8*β*-hydroxylabd-13-en-15-oic acid (**176**) [77]); 2 abietanes (14-*O*-acetyl-coleon U (**177**), coleon R (**110**)) and a halimane derivative, (11R\*-acetoxyhalima-5,13E-dien-15-oic acid (**178**) [79]) in addition to *β*-sitosterol and stigmasterol, 3*β*-acetyl-α-amyrin, and friedelin. Inversion at C-13 of 1,6-di-*O*-acetyl-9-deoxyforskolin (**174**) was carried out based on correlations between 13C NMR experimental data and HF/6-31G\*

(13*S*,15*S*)-6*β*,7*α*,12*α*,19-tetrahydroxy-13*β*,16-cyclo-8-abietene-11,14-dione (**179**) has been isolated and showed weak antibacterial activity against *S. aureus* [81].
