Reversed-phase HPLC determination of mangiferin, isomangiferin and hesperidin in Cyclopia and the effect of harvesting date on the phenolic composition of C. genistoides

摘要

A reversed-phase HPLC method for separation of polyphenols in honeybush tea (Cyclopia spp.) is presented. Separation of eriodictyol, luteolin, medicagol, formononetin, mangiferin, isomangiferin, hesperetin and hesperidin was investigated. A C12 stationary phase was required to separate mangiferin and isomangiferin. The method was used to quantify the three major polyphenols (mangiferin, isomangiferin and hesperidin) in C. genistoides, C. intermedia, C. maculata and C. sessiliflora and to study the effect of harvesting date on these compounds in two types of C genistoides. The highest levels of the xanthones, mangiferin (3.61 g/100 g) and isomangiferin (0.54 g/100 g), and the flavanone, hesperidin (1.74 g/100 g), were found for C genistoides (both xanthones) and C. intermedia, respectively. Cyclopia sessiliflora contained the lowest levels of mangiferin (1.04 g/100 g) and hesperidin(0.29 g/100 g). The mangiferin content of both the Overberg and West Coast types decreased with harvesting date (P<0.05). The Overberg type contained more mangiferin, but hesperidin was more prominent in the West Coast type.