Oleanolic acid biological activities

P-Sitosterol, betulin, and betulinic, ursolic and oleanolic acids, common metabolites in the plant kingdom, are also present in species of the Celastraceae, and have been reported to exhibit a wide range of biological activities. 

In summary, microbial hydroxylation of p-amyrin and oleanolic acids may lead to new hydroxylations mainly in positions -7p, -15a but also frequently in other positions -lip, -11a, -2a, -29, -30, -13p, -2ip, -16a, -23, -24, -ip, -6p, and -7a (in order of priority, see Figure 28.28). With already hydroxylated olean derivatives such as echinocystic acid, phytolaccagenin, maslinic acid, or glycyrrhetinic acid as substrates, the corresponding complementary positions can be hydroxylated, obtaining a wide combinatorial variety of new multihydroxy derivatives, which should be difficult to achieve by classical chemical means and, potentially possess new or increased biological activities. Several of them have been previously isolated in plants as natural products. A summary of these results and yields is presented in Table 28.2. 

---