Abstract
The genus Cyclopia, an indigenous South African fynbos plant used to prepare honeybush tea, contains phytoestrogenic compounds. An extract from C. subternata, SM6Met, displays three desirable estrogenic attributes for future development of a phytoestrogenic nutraceutical, namely, ERα antagonism, ERβ agonism, and also antagonism of E2-induced breast cancer cell proliferation. Activity-guided fractionation of SM6Met was used in an attempt to isolate and identify compounds conferring the desirable estrogenic profile to SM6Met. Initial liquid-liquid fractionation of SM6Met yielded a polar fraction (PF) and a non-polar fraction (NPF), with the desirable estrogenic attributes retained in the NPF. Subsequent high performance counter-current chromatography (HPCCC) fractionation of the NPF yielded three fractions (F1-F3). Interestingly, the fractions revealed separation of the previously demonstrated positive estrogenic attributes of the NPF into separate fractions, with F1 and F2 acting as ERα antagonists, only F2 inducing antagonism of E2-induced breast cancer cell proliferation and only F3 retaining robust ERβ agonist activity. In terms of major polyphenols, quantitative HPLC and liquid chromatography tandem mass spectrometry (LC-MS/MS) indicated that HPCCC fractionation resulted in a divergence of polyphenolic classes, with F1 emerging as the dihydrochalcone-rich fraction and F2 as the flavanone- and benzophenone-rich fraction, while the xanthones, flavones and phenolic acids were retained in F3. F3 was re-engineered into F3R by reassembling the major polyphenols identified in the fraction. F3R could, however, not replicate the effect of F3. In conclusion, although activity-guided fractionation results suggest that retention of all the desirable estrogenic attributes of the original SM6Met in one fraction is not an attainable goal, fractionation is a useful tool to enhance specific desirable estrogenic attributes.
Highlights
Nutraceuticals, i.e. food extract supplements with health benefits [1], have become a multi-billion dollar global industry [2]
In the case of SM6Met the desired positive estrogenic attributes are more complex in that ERβ agonism, ERα antagonism and antagonism of E2-induced breast cancer cell proliferation were simultaneously targeted
Our results from liquid-liquid fractionation of SM6Met into the polar fraction (PF) and the non-polar fraction (NPF) seemed promising as the three desirable estrogenic attributes were retained in the NPF (S2 Table)
Summary
Nutraceuticals, i.e. food extract supplements with health benefits [1], have become a multi-billion dollar global industry [2]. Renewed interest in Cyclopia in the 1990’s led to the production of green or ‘unfermented’ honeybush tea, in order to prevent breakdown of potentially health-promoting polyphenols during the high temperature oxidation process. This ‘unfermented’ plant material could serve as a source for nutraceutical extracts [11]. As consumers worldwide demonstrated an increased demand for health-promoting foods, the honeybush industry has benefitted through a growing export market [9]. Several in vitro and in vivo studies have already shown that several Cyclopia species have antimutagenic [12], antioxidant [13], anticancer [14,15,16] and phytoestrogenic properties [10]
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