Commercial interest in the genus, Cyclopia (family Fabaceae), endemic to South Africa has led to concerted efforts to develop
an industry [1]. Key issues included cultivation to lessen dependence on natural populations
and primary processing for herbal tea production. Investigation of the phenolic composition
and biological activities indicated potential for production of pharmaceutical and/or
nutraceutical extracts [2, 3]. The aim of the present paper is to describe the integrated
strategy followed by the Agricultural Research Council of South Africa to enable production
of high-value products, in particular extracts high in the anti-diabetic xanthones,
mangiferin and isomangiferin. Several Cyclopia species were evaluated with highest xanthone levels demonstrated in C. genistoides Vent and C. longifolia Vogel. As C. longifolia was thought to be extinct and cultivation is still in an experimental stage, further
focus fell on C. genistoides. Promising individual plants (16 genotypes), based on biomass yield, were selected
from natural populations and three seedling plantations, one situated in the Southern
Cape and two in the Overberg, and cuttings planted at one location for further selection.
Apart from primary criteria such as growth habit, growth vigour, leaf-shoot ratio,
etc., advanced selection criteria include phytochemical content. PCA showed clear
separation between genotypes with high hesperidin content and those with high content
of other major compounds. Whilst hesperidin levels of the leaves were not affected
by harvesting date, highest xanthone levels accumulated during summer (high solar
radiation, high temperature, and water deficit), while lowest levels were observed
during winter [4]. Mangiferin levels in the leaves were 5 to 10 times higher than
that of isomangiferin. Post-harvest product improvement entailed development of “green”
honeybush, as well as optimisation of xanthone extraction using a food-grade solvent
and membrane-enrichment.
Keywords: Mangiferin, isomangiferin, benzophenones, genotypes, harvest date, processing
References:
1 Joubert E, Joubert ME, Bester C, de Beer D, De Lange JH. Honeybush (Cyclopia spp.):
From local cottage industry to global markets – the catalytic and supporting role
of research. S Afr J Bot 2011; 77: 887 – 907
2 Joubert E, Gelderblom WC, Louw A, de Beer D. South African herbal teas: Aspalathus
linearis, Cyclopia spp. and Athrixia phylicoides – a review. J Ethnopharmacol 2008;
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3 Louw A, Joubert E, Visser K. Phytoestrogenic potential of Cyclopia extracts and
polyphenols. Planta Med 2013; 79: 580 – 590
4 Joubert E, de Beer D, Hernández I, Munné-Bosch S. Accumulation of mangiferin, isomangiferin,
iriflophenone-3-C-β-glucoside and hesperidin in honeybush leaves (Cyclopia genistoides
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