Anti-Allergic and Antioxidant Potential of Polyphenol-Enriched Fractions from Cyclopia subternata (Honeybush) Produced by a Scalable Process

Abstract

Anti-allergic activity was previously demonstrated for extracts of Cyclopia subternata Vogel plant material, containing substantial amounts of xanthones, benzophenones, dihydrochalcones, flavanones and flavones. Fractionation of a hot water extract on macroporous resin was performed aiming to increase its potency. Operating conditions for scaled-up fractionation of the extract were determined, using small-scale static and dynamic sorption/desorption experiments. The anti-allergic potential of the fractions was assessed based on inhibition of β-hexosaminidase release from IgE-sensitized RBL-2H3 cells. Given the role of oxidative stress in allergic reactions, the extract and fractions were also tested for their ability to scavenge the superoxide anion radical and inhibit xanthine oxidase (XO), an enzyme involved in its generation. The routine DPPH and ORAC assays were used for determination of the antioxidant capacity of the fractions. 3-β-D-Glucopyranosyl-4-O-β-D-glucopyranosyliriflophenone (IDG) had the lowest affinity for the resin, dictating selection of the optimal separation conditions. The extract was separated into four fractions on XAD1180N, using step-wise gradient elution with EtOH-water solutions. The major phenolic compounds present in the fractions were IDG and 3-β-D-glucopyranosyliriflophenone (fraction 1), mangiferin, isomangiferin, 3′,5′-di-β-D-glucopyranosyl-3-hydroxyphloretin and vicenin-2 (fraction 2), 3′,5′-di-β-D-glucopyranosylphloretin, eriocitrin and scolymoside (fraction 3) and hesperidin and p-coumaric acid (fraction 4). Fractionation was only partially effective in increasing activity compared to the extract, i.e., fractions 2, 3 and 4 in the DPPH• and XO assays, fractions 1 and 2 in the ORAC assay and fraction 1 in the β-hexosaminidase release assay. In vivo testing will be required to determine whether the increased activity of fractions is worth the effort and expense of fractionation.

Anti-allergic effect of <i>Cyclopia</i> (honeybush) extracts via anti-degranulation activity in a murine allergy model for inhaled antigen

“…exhibiting consistency with the results of a previous in vitro study [12]. Additionally, an aqueous extract of C. subternata was found to inhibit β-hexosaminidase release from immunoglobulin (Ig)E-sensitized RBL-2H3 cells [13]. The phenolic content of the extract, especially its mangiferin content, could be increased by using an aqueous-ethanolic mixture for extraction [12].…”

“…Our previous study revealed that orally administered extracts (40% ethanol) of honeybush, in particular Cyclopia genistoides and Cyclopia subternata, significantly enhanced antibody production and regulatory T-cell induction in mice [ 11 ], exhibiting consistency with the results of a previous in vitro study [ 12 ]. Additionally, an aqueous extract of C. subternata was found to inhibit β-hexosaminidase release from immunoglobulin (Ig)E-sensitized RBL-2H3 cells [ 13 ]. The phenolic content of the extract, especially its mangiferin content, could be increased by using an aqueous–ethanolic mixture for extraction [ 12 ].…”