Are Isoursenol and γ-Amyrin Rare Triterpenes in Nature or Simply Overlooked by Usual Analytical Methods?
Wilson, William K.
Castillo, Dorianne A.
Matsuda, Seiichi P.T.
Among pentacyclic triterpenes commonly found in plants, γ-amyrin and isoursenol are seldom reported and considered rare in nature. It was hypothesized that these triterpenes are instead routinely overlooked due to inadequate spectral characterization. γ-Amyrin was prepared by HCOOH isomerization of α-amyrin, and isoursenol was isolated from products of a heterologously expressed oxidosqualene cyclase. With precise NMR and GC-MS data, a metabolomics strategy was used to identify isoursenol and γ-amyrin in a wide range of plants.