Accummulation of mangiferin, isomangiferin, iriflophenone-3-C-β-glucoside and hesperidin in honeybush leaves (Cyclopia genistoides Vent.) in response to harvest time, harvest interval and seed source

•Xanthone and benzophenone content in leaves responded similarly to seasonal variation.•Xanthone and benzophenone content in leaves highest in summer.•Hesperidin content of leaves showed no seasonal variation.•Seed source determined the plant response to environmental factors.•Annual harvesting increased xanthone content of leaves.

Cyclopia species, commonly known as honeybush, have been identified as good sources of the xanthones, mangiferin and isomangiferin, the benzophenone, iriflophenone-3-C-β-glucoside, and the flavanone, hesperidin. Cyclopia genistoides Vent., containing the highest levels of mangiferin of commercially cultivated Cyclopia species, was chosen to study the accumulation of these compounds in the leaves of the plant in response to harvest time, harvest interval and seed source. Mostly similar trends were observed for the xanthones and benzophenone. Seed source and harvest time strongly affected mangiferin, isomangiferin and iriflophenone-3-C-glucoside levels. Harvesting during summer (high solar radiation, high temperature, high growing degree days and water deficit) resulted in the highest levels of these compounds in the leaves, while hesperidin showed no clear seasonal variation. Moreover, seed source determined the plant response to environmental factors in terms of composition. In addition, selection of seeds sourced from the Cape Peninsula wild population and annual harvesting as opposed to a longer interval between harvests can additionally improve the xanthone content of the leaves.

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