Anthocyanins of Wild Rhododendron simsii Planch. Flowers in Vietnam and Japan

Fourteen anthocyanins were detected in the flowers of R. simsii distributed in Vietnam and Japan. The anthocyanin constituents of R. simsii flowers seem to be more complex in the Japanese than Vietnamese population. The percentage of each flower anthocyanin was very low except for two major anthocyanins found in all Vietnamese and Japanese accessions. It was not possible to classify the Vietnamese and Japanese populations by flower anthocyanin constituents. The two major anthocyanins found in all accessions of R. simsii flowers in Vietnam and Japan were isolated and purified by column and high-performance liquid chromatography. Their structures were elucidated by H-1-NMR spectroscopic analyses and either acid or alkaline hydrolysis, and they were identified as cyanidin 3-galactoside and cyanidin 3-arabinoside. These two anthocyanins seem to be common to red-flowered evergreen azaleas, such as R. indicum, R. kaempferi, R. oldhamii, and R. scabrum.