Different classes of secondary metabolites have been identified from Lamiaceae, the majority of the isolated compounds are terpenoids (~71%), and additionally other classes of compounds like flavonoids, α-pyrone derivatives, phenolic acids, and alkaloids were reported. Mono-, sesqui-, and tri-terpenoids are relatively small in number (~15%) when compared to diterpenoids and it was reported that more than 100 of different diterpene skeletons were identified which indicate the high evolutionary index of Lamiaceae . According to the literature, the genera Leonotis(known as wild dagga) and Plectranthushave received the highest attention where 70 (Leonotis) and 94 (Plectranthus) compounds were identified so far, the majority of the isolated compounds are labdane diterpenes. In this chapter, the different genera have been listed alphabetically and the trivial names have been retained in the cases where they were given by authors and/or chemical abstracts.
Three species were recorded in SA. The triterpenes 3α,19α-dihydroxyurs-12-en-28-oic acid (18) and 3β-acetoxyoleanan-13β,28-olide (19), Me betulinate (20), oleanolic acid/acetate (21/22), and ursolic (11) and maslinic acids (23) were isolated from H. mutabilis.
From H. spicigera,seven labdane diterpenes; 19-acetoxy-2α,7α,15-trihydroxylabda-8(17),(13Z)-diene (24); 15,19-diacetoxy-2α,7α-dihydroxylabda-8(17),(13Z)-diene (25); 7α,15,19-triacetoxy-2α-hydroxylabda-8(17),(13Z)-diene (26); 19-acetoxy-2α,7α-dihydroxylabda-8(17),(13Z)-dien-15-al (27); 19-acetoxy-7α,15-dihydroxylabda-8(17),(13Z)-dien-2-one (28); 2α,7α,15,19-tetrahydroxy-ent-labda-8(17), (13Z)-diene (29); and 19-acetoxy-2R,7R-dihydroxylabda-14,15-dinorlabd-8(17)-en-13-one (30) were isolated from the aerial parts .
Seven species were recorded in SA and two of them were extensively studied. Traditionally, this genus is used to substitute hemp and called as wild dagga; however, there is no much scientific biological evidences supporting such claim. The chemistry was started in early 60s of the last century by South African researchers. Many labdane diterpenes have been isolated. The chemistry of the genus was covered previously by a review published by Piozzi et al..
2.7.1. Leonotis leonurus
The chemistry of Leonotiswas commenced in 1962 and some compounds were identified; marrubiin (31) compounds, X (32) and Y (33), the stereoisomers of premarrubiin (34) and (35) (the C-13 epimeric forms of premarrubiin). Leonurun (36) has been isolated and the relative stereochemistry was determined using single-crystal X-ray diffraction analysis [24, 25]. After two years, labdane (13S)-9α,13α-epoxylabda-6β(19),15(14)-dioldilactone (37) was isolated, this compound caused significant changes in blood pressure of anesthetized normotensive rats, and also was found to exhibit a negative chronotropic effect .
The organic extract of L. leonurusshowed 99% growth inhibition against M. tuberculosisat 1.0 mg/mL, subsequent phytochemical studies resulted in the identification of three labdane-type diterpenoids: 9,13:15,16-diepoxy-6,16-labdanediol (38), 6-acetoxy-9,13-epoxy-15-methoxy-labdan-16,15-olide (39), and 9,13-epoxy-6-hydroxylabdan-16,15-olide (40). None of the isolated compounds were active against M. tuberculosis.
Recently, Fang et al.  identified leonurenones A–C (41–43), in addition to 9,13:15,16-diepoxy-6,16-labdanediol (38) and nepetifolin (44). The leonurenones contain an uncommon α,β-unsaturated enone moiety in ring B. Compound 38was isolated as epimeric form, (at C-16, ratio 3:1). Compound 41was isolated from aqueous extract of the leaves and the authors proposed the possible formation of 43as an artefact viaoxidation and lactonization of the more polar intermediate (41) during the isolation process. The total aqueous extract, at concentration of 1.0 g/mL, showed an 81% inhibition in a binding assay at the GABAA site. Compounds 41and 43did not show activity (<50% inhibition) in this assay .
In the following year, Wu and co-workers (2013) were successful to isolate and identify eleven labdanoides, vizleoleorins D–J (41–43, 45–48) and 16-epi-leoleorin F (49), leoleorin A [corresponding to compound Y (33)], leoleorin B (50) (anhydro derivative of compound Y), and leoleorin C [9,13-epoxy-6-hydroxylabdan-15,16-olide (40)]. The absolute configurations of leoleorin A (33) and D (41) were established by X-ray crystallographic analyses. It is important to indicate that new compounds “leoleorins G-I”, which were isolated in this study, were reported in the previous work under the names of leonurenones A–C (41–43)(13C data showed exchange positions C12 and C14 for leonurenones C/leoleorin H between the two references) .
From L. leonurus’ flowers, an acyclic diterpene ester, 1,2,3-trihydroxy-3,7,11,15-tetramethylhexadecan-1-yl-palmitate (51), along with geniposidic acid (52) were isolated, the compounds exhibited neither cytotoxicity on mammalian kidney fibroblasts (Vero cells) nor antimicrobial activities .
2.7.2. Leonotis nepetaefolia
The chemistry of L. nepetaefoliastarted almost simultaneously with L. leonurus. Leonotin (53), nepetaefuran (54), nepetaefuranol (55), nepetaefolin (44) methoxynepetaefolin (56), nepetaefolinol (57) and leonotinin (58) the dilactone (8β,17,9,13-diepoxylabdane-16,15,19,6β-diolactone, 59) were characterized [31, 32, 33, 34, 35, 36].
From the species collected from India, nepetaefolinol (57), dehydrated nepetaefolinol (60) and isomeric tetrol (61) (15,16-epoxy-labda-13(16),14-diene-6β,9,17,19-tetrol: the reduction product of leonotinin) were identified . Leonitinic acid (62) with free C-17 carboxyl group was also isolated .
From a commercially material, originally collected from Peru, five inseparable epimeric mixtures of bis-spirolabdane diterpenoids, resulted from biosynthetic epimerization of three different structures around C-13 and C-15, have been isolated and identified as leonepetaefolin A (63) and its epimeric isomer 15-epi-leonepetaefolin A (64) (ratio 1:1), leonepetaefolin B(65)/15-epi-leonepetaefolin B (66) (2:3), leonepetaefolin C(67)/15-epi-leonepetaefolin C (68) (1,1), leonepetaefolin D (69)/15-epi-leonepetaefolin D (70) (7,10), leonepetaefolin E (71)/15-epi-leonepetaefolin E (72) (2,3) . Additionally, methoxynepataefolin (56), nepetaefolin (44), nepetaefuran (54), dubiin (73), 19 chlroro derivative of nepetaefolin (74), leonotinin (58), leonotin (53), and LS-1 (75) were isolated. The absolute configuration of the epimeric mixture 63and 64was determined by X-ray crystallographic analysis .
The isolated compounds were evaluated for their binding activities to a panel of CNS G-protein-coupled receptors including adrenergic, dopaminergic, histaminic, muscarinic, opioid, and serotonergic receptors and neurotransmitter transporters and showed no interesting activity.. From the material collected from Japan, five iridoid glycosides: 10-O-(trans-3,4-dimethoxycinnamoyl) geniposidic acid (76), 10-O-(p-hydroxybenzoyl) geniposidic acid (77), geniposidic acid (52), mussaenoside (78), and ixoside (79) were isolated .
2.7.3. Leonotis ocymifolia
L. ocymifoliawas studied under different synonyms viz; L. dubia(L. ocymifolia, var. ocymifolia),L. leonitis; L. leonitisvar. hirtfolia(L. ocymifolia, var. ocymifolia) and L. dysophyllaBenth. (L. ocymifoliavar. raineriana) and L. ocymifoliavar. raineriana(Burm f) Iwarsson var. raineriana(Visiani) Iwarsson. The chemical studies resulted in the isolation of dubiin (73), 9α,13(S)-epoxy-8β-hydroxylabdane-6β,19;16,15-diolide (80), and leonitin (81). 20-acetoxy-9α,l3-dihydroxy-15(16)-epoxylabd-14-en-6β(19)-lactone (82) and 6β-acetoxy-9α,l3α-epoxylabda-20(19),16(15)-diol-dilactone (83) are from the leaves, in addition to compound X (32)[24, 41] Finally, nepetaefolin (44), leonotinin (58), and leonotin (53) were identified from the material collected from Pretoria (South Africa) .
About 300 species distributed in tropical and warm regions of the old World, 45 species recorded in SA, from which 19 species were studied for their chemical and/or biological constituents. The genus is characterized by the presence of orange glands that distributed in the aerial parts and contain highly oxygenated (and modified) abietane-type diterpenoids. Others, e.g., kaurane, labdane, phyllocladane as well as the rare skeleton halimane diterpenoids were described.
2.12.1. Plectranthus ambiguus
Plectranthus ambiguusafforded a series of tetracyclic phyllocladane-type (= 13β-kaurane) diter-penoids: (16R)-2α-senecioyloxy-3α-acetoxyphyllocladan-16,17-diol (95), (16R)-2α-senecioyloxy-3α,17-diacetoxy-16-hydroxyphyllocladane (96), (16R)-2α-isovaleroyloxy-3α-acetoxyphyllocladan-16,17-diol (97), (16R)-2α-isovaleroyloxy-3α,17-diacetoxy-16-hydroxyphyllocladane (98), (16R)-3α-acetoxyphyllocladan-16,17-diol (99), (16R)-2α-senecioyloxy-16,17-dihydroxyphyllocladan-3-one (100), and (16R)-2α,3α-diacetoxyphyllocladan-16,17-diol (101). The authors discriminated between phyllocladane and ent-kaurane tetracyclic skeletons after extensive spectroscopic investigation as well as chemical transformations [48, 49].
2.12.2. Plectranthus amboinicus
Thymoquinone (105) was identified as an active nonpolar ingredient to suppress the expression of lipopolysaccharide-induced tumor necrosis factor-alpha (TNF-α) . The total extract showed cytotoxic activity against MCF-7, using HPLC-based metabolomics approach, and 7α-acetoxy-6β-hydroxyroyleanone (102) was identified as the main active constituent. Other minor compounds like coleon E (103) and royleanone (104) were also identified .
2.12.3. Plectranthus caninus
Plectranthus caninusafforded coleons M (106), N (107), P (108), Q(109), R (110), S (111), and T (112) and barbatusin (113) [52, 53].
2.12.4. Plectranthus ecklonii
Plectranthus eckloniiis traditionally used in South Africa for treating stomach aches, nausea, vomiting, and meningitis. Ecklonoquinone A (114) and B (115) and parviflorons D (116) and F (117) were isolated [54, 55]. Compound 117showed potent activity against Listeria monocytogenesand M. tuberculosisand both 116and 117were found to be very toxic against vero cell lines. The potency of parvifloron D (116) was further confirmed and showed fast and potent apoptotic inducer in leukemia cells .
2.12.5. Plectranthus ernstii
Two pimaranes rel-15(ζ),16-epoxy-7α-hydroxypimar-8,14-ene (118): rel-15(ζ),16-epoxy-7-oxopimar-8,14-ene (119) and a labdane 1R,11S-dihydroxy-8R,13R-epoxylabd-14-ene (120) were isolated. The three compounds showed activity against M. tuberculosisand different strains of S. aureus.
2.12.6. Plectranthus fruticosus
Plectranthus fruticosuscultivated in Porugal afforded 4 labdanes, ent-labda-8(17),12Z,14-trien-2β-ol (121),ent-2α-acetoxylabda-8(17),12Z,14-trien-3β-ol (122), ent-3β-acetoxylabda-8(17),12Z,14-trien-2α-ol (123),3β-acetoxylabda-8(17),12E,14-trien-2α-ol (124), 10 kauranes (ent-12β-acetoxy-15β,16β-epoxykauran-19-oic acid (125), ent-7β-hydroxy-15β,16β-epoxykauran-19-oic acid (126), ent-15β,16β-epoxykauran-19-oic acid (127), ent-15β,16β-epoxykauran-19-ol (128), ent-12β-acetoxy-15β-hydroxykaur-16-en-19-oic acid (129), ent-12β-acetoxy-7β-hydroxykaur-16-en-19-oic acid (130),methyl ent-12β-acetoxy-16-kauren-19-oate (131), ent-7β-hydroxykaur-15-en-19-oic acid (132), methyl ent-12β-acetoxy-7β-hydroxykaur-15-en-19-oate acid (133), ent-12β-acetoxy-17-oxokaur-15-en-19-oic acid (134), methyl ent-12β-acetoxy-15-kauren-19-oate (135), additionally, armendrance (136), caryophyllene α-oxide (137), ursolic/oleanolic acids (2,1 mixture) β-sitosterol, stigmasta-5,22E-dien-3β-ol, and β-amyrin. Some of the compounds showed moderate anti-staphylococcusactivity [58, 59]. P. fruticosusgrowing in India showed abietane diterpene pattern and 7α-acetoxy-6β-hydroxyroyleanone (102), 6,7-dehydroroyleanone (138) and 7α,6β-dihydroxyroyleanone (139) were isolated .
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)  were identified. Also, royleanone (103), 6,7-dehydroroyleanone (138), horminone (150), 6β-hydroxyroyleanone (151), and 7α-acetoxy-6β-hydroxyroyleanone (102) together with a mixture of fatty acid esters of 7α-acyloxy-6β,12-dihydroxy-abieta-8,12-diene-11,14-dione (152), 7α,6β,-dihydroxyroyleanone (139), and 9α-(2-oxopropyl)abietane derivative(156) were isolated [62, 63, 64, 65, 66, 67].
Fatty acid esters of 7α-acyloxy-6β-hydroxyroyleanone (152) showed moderate antibacterial activity ; 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 . Coleons U 141is considered as a promising compound and deserves further evaluation as an anti-cancer drug . Coleon U (141), 7α-acetoxy-6β-hydroxyroyleanone (102), and horminone (150) showed activity against methicillin-resistant S. aureus(MRSA) and vancomycin-resistant Enterococcus faecalis(VRE). Recently, the biological activity of 102was reported and showed selective cytotoxicity against MCF-7. Other derivatives of the same compound showed potent cytotoxic [69, 70] and antimicrobial  activities.
2.12.8. Plectranthus hereroensis
Plectranthus hereroensishorminone (150), 16-acetoxy-7α,12-dihydroxy-8,12-abietadiene-11,14-dione (153) and 7α-12-dihydroxy-17(15→16)-abieta-8,12,16-triene-11,14-dione (157);3β-acetoxy-6β,7α-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 , all compounds showed moderate antimicrobial activity [13, 66, 71, 72], while 158showed antiviral activity .
2.12.9. Plectranthus madagascariensis
Plectranthus madagascariensisis used as a traditional medicine in Southern Africa. Three constituents were isolated and identified as 6β,7β-dihydroxyroyleanone (154), 7β-acetoxy-6β-hydroxyroyleanone (155), and coleon U (141). The compounds exhibited inhibitory activity on α-glucosidase, S. aureusand Enterococcus faecalis.
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 (plec-trornatins A (160) , 11R*-acetoxykolavenic acid (161), 11R*-acetoxy-2-oxokolavenic acid (162), 11R*-acetoxy-3β-hydroxyneocleroda-4(18),13E-dien-15-oic acid (163) , ornatins A–E (164-168), 3β-hydroxyneocleroda-4(18),13E-dien-15-oic acid (169) ; 7 labdanes (plectrornatins B (170), C (171), ,6-O-acetylforskolin (172); 1,6-di-O-acetylforskolin (173), 1,6-di-O-acetyl-9-deoxyforskolin (174) [76, 78], rhinocerotinoic acid (175) , 8β-hydroxylabd-13-en-15-oic acid (176) ); 2 abietanes (14-O-acetyl-coleon U (177), coleon R (110)) and a halimane derivative, (11R*-acetoxyhalima-5,13E-dien-15-oic acid (178) ) in addition to β-sitosterol and stigmasterol, 3β-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 . 160, 161showed moderate antimicrobial. 178exhibited growth inhibitory activity against five Staphylococcusand five Enterococcusstrains . Ornatin C, D, E and three related diterpenes displayed marginal bactericidal or bacteriostatic effects against the Gram-positive strains .
2.12.11. Plectranthus porcatus
Plectranthus porcatus:(13S,15S)-6β,7α,12α,19-tetrahydroxy-13β,16-cyclo-8-abietene-11,14-dione (179) has been isolated and showed weak antibacterial activity against S. aureus.
2.12.12. Plectranthus saccatus
Plectranthus Saccatus ent-7α-acetoxy-15-beyeren-18-oic acid (180), ent-3β-(3-methyl-2-butenoyl) oxy-15-beyeren-19-oic acid (181), and ent-3β-(3-methylbutanoyl) oxy-15-beyeren-19-oic acid (182). Both 181and 182showed insect antifeedant activity against Spodopteralittoralis, while 180showed no antibacterial activity [81, 82].
2.12.13. Plectranthus strigosus
Plectranthus strigosus:9 abietanes (parviflorones A (183), B (184), C (185), D (114), E (186), F (115), G (187), and H (188) , and hinokiol (189)) ), 3 kauranes (ent-16-kauren-19-ol (190), ent-16-kauren-19-oic acid (191), xylopic acid (192), xylopinic acid (193)), and 2 sesquiterpens (4β,6β-dihydroxy-1α,5β(H)-guai-9-ene (194) 4β,6β-dihydroxy-1α,5β(H)-guai-10(14)-ene (195)), were isolated . A bioactivity study revealed herpetic inhibitory properties for (190) and (191) .
The genus Salviais known as sage and is the largest genus in Lamiaceae, comprising over 900 species distributed throughout the world. Salvia isrepresented by 30 species in SA, distributed mainly in great cape region. The chemistry of Salviais rich in diterpenoids and different skeletons have been reported, also, many members of this genus is well known for its curative and medicinal properties like S. officinalisand S. miltiorrhiza.
2.13.1. Salvia africana-lutea
Salvia africana-lutea:carnosol (196), rosmadial (197), and carnosic acid (198-characterized as its methyl ester) were isolated. Compound 198exhibited potent activity against M. tuberculosisand cytotoxic activity against a breast (MCF-7) human cancer cell line .
2.13.2. Salvia chamelaeagnea
Salvia chamelaeagnea:four compounds were isolated: carnosol (196), 7-O-methylepirosmanol (200), oleanolic and ursolic acids as the active principles against S. aureus.
2.13.3. Salvia coccinea
Salvia coccinea:momordic acid, methyl ester (201), salviacoccin (202) , dehydrouvaol (203), and uvaol (204)  were isolated.
2.13.4. Salvia disermas
Salvia disermasaerial parts afforded ocotillol II (205) .
2.13.5. Salvia radula
Salvia radula:betulafolientriol oxide (206) was isolated .
2.13.6. Salvia reflexa
Salvia reflexa:four neoclerodanes were isolated and identified as salviarin (207), 6β-hydroxysalviarin (208), 15,16-epoxy-8α-hydroxyneocleroda-2,13(16),14-triene-17,12R:18,19-diolide (209), and 5,6-secoclerodane, 7,8-didehydrorhyacophiline (210) .
2.13.7. Salvia repens
S. repenswhole plant extract yielded 12-methoxycarnosic acid (199) with antiprotozoal activity against Leishmania donovaniamastigotes and cytotoxicity against the L6-cells .
2.13.8. Salvia verbenaca
Salvia verbenacayielded β-sitosterol, ursolic acid, dehydroursolic acid, sitosteryl-3-β-D-glucoside , taxodione (211), horminone (150) and 7α-acetoxy-6β-hydroxyroyleanone (102) , verbenacine (212) and salvinine (213) .
Seven species were recorded in SA, one of them T. ripariais widely distributed in Africa and showed interesting chemical profile. Several compounds have been isolated from the leaves of this plant, including 8(14),15-sandaracopimaradiene-7α,18-diol (214) , 8(14),15-sandaracopimaradiene-2α,18-diol (215) , 9β,13β-epoxy-7-abietene (216), 6,7-dehydroroyleanone (136) , and ibozol (217) .
Compound (214) exhibited antimicrobial activity (213). Compound (215) showed papaverine-like antispasmodic activity on guinea pig ileum contracted by methacholine, histamine, or BaCl2 and on the noradrenaline-induced contractions of rabbit aorta . It also showed activities against Trichomonasvulgariswith MIC of 20–40 μg/mL , wheat rootlets inhibition activity (MIC7.81 μg/mL) , and M. tuberculosis.