Chemotaxonomic Significance of Taxifolin-3-O-arabinopyranoside in Vietnamese Rhododendron genus

Abstract

The Rhododendron species have traditionally been used to treat inflammation, pain, colds, and skin diseases. Some species have been reported to exhibit various biological activities, including antioxidant, anti-inflammatory, and antibacterial properties, indicating their significant potential for use as functional materials. These activities are largely attributed to the secondary metabolites found in the Rhododendron species. Notably, taxifolin-3-O-arabinopyranoside, a flavanone glycoside, has garnered attention for its various biological activities, such as antioxidant, anti-inflammatory, skin whitening, anti-wrinkle effects, and improvement of hair loss. It is increasingly recognized as a specific indicator compound for the Rhododendron species. This study conducted a chemotaxonomic screening of the 15 species of Rhododendron native to Vietnam using taxifolin-3-O-arabinopyranoside as an indicator compound. The compound was detected in samples of R. kontumense, R. maddenii, and R. triumphans through HPLC and LC-MS/MS analyses, and the highest content (26.64±4.06 ppm) was shown in the leaves of R. maddenii. On the other hand, when analyzing the roots and the branches extract of Korean R. mucronulatum, it exhibited significantly higher contents than those of the Vietnamese species, measuring 156.73±19.32 ppm and 76.87±2.60 ppm, respectively. Since the indicator compound was not detected in more than half of the Rhododendron species used in the experiment, it is suggested that the Vietnamese species may be chemically differentiated lineages. Therefore, this study provides a new perspective on the classification of the Rhododendron genus. Furthermore, this study is valuable as the first to report taxifolin-3-O-arabinopyranoside in R. kontumense, R. maddenii, and R. triumphans, and a chemotaxonomic study on the Vietnamese Rhododendron species, which has been previously insufficient.