Biosynthesis of Triterpenes, Ursolic Acid, and Oleanolic Acid in Tissue Cultures of Rabdosia japonica Hara Fed Mevalonolactone and Acetate

Article abstract of DOI:10.1021/ja00214a013

<5-(13)C(2)H2>Mevalonolactone and sodium <2-(13)C(2)H3>acetate were fed to suspension cultures of Rabdosia japonica Hara.The (13)C-(2)H labeling patterns analysed by (13)C-<(1)H><(2)H>NMR spectroscopy for methyl ursolate (13) and methyl oleanolate (15) give the biosynthetic information for all the hydrogen atoms composing mevalonic acid incorporated into these two triterpenes.The combination of the labeling patterns on C(11)-C(12) in one molecule of ursolate from <5-(13)C(2)H2>MVA being (13)C(11)(2)H2-(13)C(12)(2)H and (13)C(11)(2)H(1)H-(13)C(12)(2)H differ from those of oleanolate <(13)C(11)(2)H2-(13)C(12)(1)H and (13)C(11)(2)H(1)H-(13)C(12)(2)H>.This indicates that ursolic acid (12) and oleanolic acid (14) are formed from both oxidosqualenes 8 and 9 and the 12(13) double bond of 12 is formed by elimination of the 12-pro-R hydrogen atom of 10 and 11 in a cis mode.Three signals shifted by β-deuterium atoms verify the 1,2-hydride shifts (20-H from C-19,19-H from C-18, and 18-H from C-13) in the biosynthesis of ursolic acid (12) from <2-(13)C(2)H3>acetate.Two β-deuterium-shifted signals confirm the 1,2-hydride shifts (19-H from C-18 and 18-H from C-13) in the biosynthesis of oleanolic acid (14) from <2-(13)C(2)H3>acetate.