Isodonic acid

Ursolic acid Isodon excisus, Salvia triloba AROM (31)... 

Ursolic acid 3-O-acetate Isodon excisus (Lamiaceae) AROM (86)... 

Some resonances in the ursene series have been reassigned.The labelling pattern in ursolic acid and 2a-hydroxyursolic acid isolated from tissue cultures of Isodon japonicus fed with sodium [l,2- C]acetate conforms with the original Ruzicka hypothesis for the biogenesis of pentacyclic triterpenoids. 

Investigations with tissue cultures of Isodon japonicus using [l,2- C]acetate have been extended to the study of the formation of ring E of ursolic acid. Ruzicka s hypothesis for the cyclization of 2,3-oxidosqualene appears to hold for the ursanes (103) and (104) as indicated in Scheme 17, and routes involving the carbonium ion (105) can be excluded. 

A qualitative theory on the relationship between bitterness and chemical structures of bitter Rabdosia diterpenoids has been proposed 143). To be bitter a substance must have at least one bitter unit it consists of a hard acid and a hard base which are located within 1.5 A of each other so that intramolecular hydrogen-bonding is possible. Cleavage of this hydrogen bond and concomitant formation of a new hydrogen bond to the receptor site are responsible for bitterness 150). For instance, isodonal (71) which possesses an a-orientated 11-OH is very bitter, while trichodonin (70), its 11 P-epimer, is not. In bitter isodonal, the distance between the 11-hydroxy proton, the donor proton, and the 6-aldehydic oxygen, the proton acceptor, is ca. 1 A, while in tasteless trichodonin it is ca. 3 A. 

In the oleanane-ursane group of triterpenes, postulated hydride shifts [as proposed by Eschenmoser and co-workers (1955)] have now been demonstrated. Incorporation of [4- C]MVA into oleanolic acid (56), ursolic acid (63), and several other metabolites was accomplished with tissue cultures of Isodon japonicus (Lamiaceae). Following introduction of [4- C]mevalonate and [l,2- C2]acetate, the pentacyclic triterpene compounds were examined by C-NMR spectroscopy. Rings D and E were formed by the routes predicted by Eschenmoser et al. (1955). The labeling pattern at carbons 4,23, and 24 of 3- p/-maslinic acid (64) indicates that this series is formed from (35)-squalene epoxide, rather than from the (3R)-epimer. 

In search of molecules that selectively induce apoptosis in cancer cells, Hergenrother and coworkers synthesized a combinatorial library based on the A(-acylated aromatic amine 211, isolated from Isodon excisus, which displayed activity in either pro- or antiapoptotic assays (Figure 11.97). ° - ° The library was created from the parallel coupling of 8 acids and 11 amine building blocks, using... 

Isodocarpin, T33 Isodonal, T33 Ivorensic acid, T52 tate, T39 Laudanosine, K3... 

Seo, S., Y. Tomita, and K. Tori Biosynthesis of Oleanene- and Ursene-type Triterpenes from [4- C]Mevalonic Acid in Tissue Cultures of Isodon japonicus Hara. Chem. Commun. 1975, 270. 

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