Xanthone, benzophenone and bioflavonoid accumulation in Cyclopia genistoides (L.) Vent. (honeybush) shoot cultures grown on membrane rafts and in a temporary immersion system

Abstract

In vitro shoots of the commercially important South-African legume Cyclopia genistoides were grown in different liquid culture systems [membrane rafts (MR) and a temporary immersion bioreactor (TIB)] and evaluated for the accumulation of phenolic secondary metabolites. The major constituents of the investigated cultures were medicinally relevant xanthones [mangiferin (M) and isomangiferin (IM)] and benzophenone derivatives [iriflophenone 3-C-β-glucoside (IG)]. The highest concentrations of M, IM and IG in MR-grown shoots were 1,843.59, 712.02 and 594.29 mg 100 g−1 dry wt, respectively. Bioreactor cultivation provided higher peak concentrations of M (2,622.70 mg 100 g−1 dry wt), IM (757.40 mg 100 g−1 dry wt) and IG (648.30 mg 100 g−1 dry wt) which corresponded to the respective productivities of 5.48, 1.58 and 3.04 mg l−1 d−1. The results indicate that TIB cultures of C. genistoides may be utilized as an alternative source of the above constituents, particularly IM and IG, which are relatively expensive and so far hardly available from commercial sources.