303-Hydroxyursolic acid

The configuration at C-2 of methyl 2-acetoxy-20/3-hydroxyursonate (162) from apple peel is a.121 Guaijavolic acid from the leaves of Psidium guaijava122 is identical with 2a-hydroxyursolic acid (163). The related triol (164) has been... 

Triterpenic Acids. The following pentacyclic mono- and dihydroxy triterpenic acids are present in virgin olive oil (35, 43, 44) 3p-hydroxy-17-carboxy-5-12-olea-nene (oleanolic acid) 3 3,2a-dihydroxy-17-carboxy-5-12-oleanene (maslinic acid) 3p-hydroxy-17-carboxy-8-12-ursene (ursolic acid) 2a,3p-dihydroxy-17-carboxy-5-12-ursene (2a-hydroxyursolic acid) and deoxyursolic acid (structure not fully elucidated). 

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. 

Details have been published of the biosynthesis of olean-12-ene and urs-12-ene type triterpenoids in tissue cultures of lsodon japonicus (Labiatae).10 The results are fully in accord with the original biogenetic postulates of Ruzicka and his colleagues.11 By using [5-13C, 5-2H2]MVA as substrate it was shown that, as expected, both squalene 2,3-epoxides [part structures (12) and (13)] are involved in the biosynthesis of 2a-hydroxyursolic acid (14), 3-epimaslinic acid (15), and j3-sitosterol in I. japonicus. The 13C n.m.r. spectra of (14) and (15) suggested... 

New ursene derivatives include acuminatic acid (192) (2a,3a,19a-trihydroxy-urs-12-en-28-oic acid) from Pygeum acuminatum, 2a,3a,19a,23-tetra-hydroxyursolic acid (193) from the leaves of Coleus ambionicus, and... 

Hydroxy-12-ursen-28-oic acid, H-10242 3)5-Hydroxy-ll-ursen-28,13-olide, in D-10258 20-Hydroxy-12-ursen-3-one, H-10243 21a-Hydroxyursolic acid, in D-10259 21)5-Hydroxyursolic acid, in D-10259 16a-Hydroxyverazine, see E-10206... 

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