Isodon japonicus

The 13C resonances of a series of urs-12-enes have been assigned"7 to facilitate biosynthetic studies on the metabolites of tissue cultures of Isodon japonicus. 

Tissue cultures of Isodon japonicus could biosynthesize oleanane- and ursane-type triterpenoids from [4-13C]MVA with sufficient incorporation of tracer to allow the elucidation of the labelling pattern by 13C n.m.r. spectroscopy.356 The results verify the hypothesis of Ruzicka involving cyclization of 2,3-oxidosqualene in a chair-chair-boat form, followed by specific 1,2-hydride shifts, and the rearrangement of... 

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. 

Fujita, E., and T. Fujita The Constituents of Enmei-so Isodon japonicus Hara and /. trichocarpus Kudo). Proc. Symp. Wakan-Yaku 9, 1 (1975). 

Takahashi, M., T. Fujita, and Y. Koyama Studies on the Components of Isodon japonicus (Burm.) Hara and I. trichocarpus (Maxim.) Kudo. Yakugaku Zasshi 78, 699 (1958). 

Components of Isodon japonicus (Burm.) Hara and I. trichocarpus (Maxim.)... 

Fujita, E., T. Fujita, and M. Shibuya Diterpenoids Constituents of Isodon trichocarpus and Isodon japonicus. Tetrahedron Letters 1977, 3153. 

Fujita, E., M. Taoka, M. Shibuya, T. Fujita, and T. Shingu Terpenoids. Part XXVII. Structure and Stereochemistry of Ponicidin, a Diterpenoid of Isodon japonicus. J. Chem. Soc., Perkin Trans. I 1973, 2277. 

Fujita, E., T. Fujita, and M. Shibuya The Structures of Isodocarpin, Nodosin, Oridonin and Other Constituents of Isodon Trichocarpus and Isodon Japonicus. Abstract Papers of the 10th Symposium on the Chemistry of Natural Products. (Tokyo) P. 224 (1966). 

Kubo, I., T. Kamikawa, and T. Kubota Studies on Constituents of Isodon japonicus Kara. The Structures and Absolute Stereochemistry of Isodonal, Trichodonin and Epinodosin. Tetrahedron 30, 615 (1974). 

Kubota, T., and I. Kubo A New Bitter Principle of Isodon japonicus Hara. Tetrahedron Letters 1967, 3781. 

Seo, S., Y. Tomita, and K. Tori Biosynthesis of Oleanene- and Ursene-Type Triterpenes from [4- C]Mevalonolactone and [1,2- C2]Acetate in Tissue Cultures of Isodon japonicus Hara. J. Am. Chem. Soc. 103, 2075 (1981). 

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. 

ORGANISM Isodon japonicus and Isodon trichocarpus (Labiatae) reference 151... 

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