Selective extraction of Cyclopia for enhanced in vitro phytoestrogenicity and benchmarking against commercial phytoestrogen extracts

Previous work established the phytoestrogenicity of "unfermented"Cyclopia (honeybush) extracts. The current study investigated the phytoestrogenicity of four Cyclopia harvestings (M6-9) for preparation of extracts with enhanced phytoestrogenicity for benchmarking against commercial preparations. Two extracts, from M6 (C. subternata) and M7 (C. genistoides), were identified as most phytoestrogenic using estrogen receptor binding, an estrogen receptor response element containing promoter reporter assay, alkaline phosphatase activity, and E-screen. M6 and M7 were sequentially and non-sequentially extracted with five solvents of differing polarities. Additionally, two extracts were prepared in the traditional way of preparing a cup of honeybush tea. The resultant 22 extracts were evaluated for estrogenicity. Select extracts were analysed by high-pressure liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC-MS). The sequentially extracted M6 methanol extract (SM6Met) had the highest potency and the sequentially extracted M6 ethyl acetate extract (SM6EAc) had the highest efficacy of all the extracts. The HPLC results suggested enrichment of luteolin in SM6EAc and enrichment of an unidentified polyphenol in SM6Met. Benchmarking against four commercial phytoestrogenic preparations suggest that in terms of the assays used, Cyclopia extracts have comparable potency and efficacy to the commercial extracts and thus have potential as marketable phytoestrogenic nutraceuticals.