Selective extraction of Cyclopia for enhanced in vitro phytoestrogenicity
Thesis (MSc (Biochemistry))--University of Stellenbosch, 2008.
Phytoestrogens are plant compounds whose ability to mimic the action of estrogens has resulted in their usage for the treatment of menopausal symptoms. Despite uncertainties about the safety and effectiveness of phytoestrogens in humans, the use of market phytoestrogenic nutraceuticals and botanicals is on the increase. Positive epidemiological study findings coupled to an entrenched belief in many societies about the superiority of what they view as “natural” remedies, as well as the reluctance of women to use the traditional hormone replacement therapy due to its association with detrimental health effects as reported by studies such as the World Health Initiative, the Million Women and the Kronos Early Estrogen Prevention studies, are thought to be instrumental in the growth of the phytoestrogen market. As the subject of the current thesis, we investigated the candidacy of extracts of the honeybush plant (genus Cyclopia), which is used for the manufacture of popular tea beverages, for use in the formulation of a high quality phytoestrogenic nutraceutical with a competitive market edge. We evaluated four harvestings of Cyclopia (M6-9) available in bulk and selected 2 harvestings (M6 and M7) for further extraction using solvents of differing polarity and also mimicking the preparation of a cup of tea. Our findings clearly demonstrate that of the resultant 22 extracts the SM6Met and SM6EAc extracts had the highest in vitro potency and efficacy, respectively. Another exciting finding from our study is the unequivocal demonstration of phytoestrogenic activity by extracts prepared in the same manner as the traditional cup of honeybush tea. Additionally, our study has highlighted the importance and the influence of experimental variables such as the specific harvesting evaluated and the characteristics of the extraction solvent (e.g. polarity and temperature) on the yield and the estrogenic activity of the extracts. In addition, the advantage of certain in vitro assays over others for discriminating between estrogenic substances based on their efficacies and potencies was demonstrated with the alkaline phosphatase assay being most suitable for discriminating efficacy and the E-screen most suitable for discriminating potency. Furthermore, our study has imparted a valuable lesson about the pharmacological behavior of estrogenic substances by presenting a conundrum in the form of the two desirable pharmacological parameters (potency and efficacy) occurring in different extracts, an outcome that complicates the central aim of our study, which is the preparation of an extract that embodies both parameters. Additionally, the low quantity of known putative phytoestrogens and the presence of unidentified polyphenols in M6, the source of our choice extracts (SM6Met and SM6EAc), makes the high estrogenic potency and efficacy of the choice extracts that much more intriguing. Nonetheless, benchmarking against four market phytoestrogen extracts indicate that the Cyclopia extracts have comparable estrogenicity suggesting potential as marketable phytoestrogenic preparations. The combination of the achievement of aims and the birth of new questions from that very achievement, which are the hallmark of scientific endeavors, have made this study a rewarding experience and we hope to share the feeling in its entirety with the reader.