The first three of these
compounds and erythrodiol are known secondary metabolites
produced by Rhododendron species.1115 In addition, the isolation
of 2,3-hydroxyursolic acid from the stem bark of Cussonia
bancoensis16,17 and the leaves of Lagerstroemia speciosa18 has been
reported, while farrerol and scopoletin were extracted from the
leaves of R. ferrugineum5 and the stems of R. mucronulatum,19
respectively. Corosolic acid has been isolated previously from the
leaves of Prunus zippeliana, Eriobotrta japonica, and Tiarella
polyphylla.2022