**2.6.** *Hyptis* **genus**

Three species were recorded in SA. The triterpenes 3*α*,19*α*-dihydroxyurs-12-en-28-oic acid (**18**) and 3*β*-acetoxyoleanan-13*β*,28-olide (**19**), Me betulinate (**20**), oleanolic acid/acetate (**21/22**), and ursolic (**11**) and maslinic acids (**23**) were isolated from *H. mutabilis* [22].

From *H. spicigera,* seven labdane diterpenes; 19-acetoxy-2*α*,7*α*,15-trihydroxylabda-8(17),(13*Z*)-diene (**24**); 15,19-diacetoxy-2*α*,7*α-*dihydroxylabda-8(17),(13*Z*)-diene (**25**); 7*α*,15,19-triacetoxy-2*α*-hydroxylabda-8(17),(13*Z*)-diene (**26**); 19-acetoxy-2*α*,7*α*-dihydroxylabda-8(17),(13*Z*)-dien-15-al (**27**); 19-acetoxy-7*α*,15-dihydroxylabda-8(17),(13*Z*)-dien-2-one (**28**); 2*α*,7*α*,15,19-tetrahydroxy-ent-labda-8(17), (13Z)-diene (**29**); and 19-acetoxy-2*R*,7*R*-dihydroxylabda-14,15-dinorlabd-8(17)-en-13-one (**30**) were isolated from the aerial parts [23].

isolated. The chemistry of the genus was covered previously by a review published by

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

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

17

The chemistry of *Leonotis* was 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 (13*S*)-9*α*,13*α*-epoxylabda-6*β*(19),15(14)-dioldilactone (**37**) was isolated, this compound caused significant changes in blood pressure of anesthetized normotensive rats,

The organic extract of *L. leonurus* showed 99% growth inhibition against *M*. *tuberculosis* at 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-methoxylabdan-16,15-olide (**39**), and 9,13-epoxy-6-hydroxylabdan-16,15-olide (**40**). None of the iso-

Recently, Fang et al. [28] 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 **38** was isolated as epimeric form, (at C-16, ratio 3:1). Compound **41** was isolated from aqueous extract of the leaves and the authors proposed the possible formation of **43** as an artefact *via* oxidation 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 **41** and **43** did not show activity (<50% inhibition)

In the following year, Wu and co-workers (2013) were successful to isolate and identify eleven labdanoides, *viz* leoleorins 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

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

and also was found to exhibit a negative chronotropic effect [26].

lated compounds were active against *M*. *tuberculosis* [27].

Piozzi et al.[24].

*2.7.1. Leonotis leonurus*

in this assay [28].

references) [29].

activities [30].

#### **2.7.** *Leonotis* **genus**

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.[24].
