Browsing by Author "Jack, Babalwa Unice"
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- ItemAn investigation into the anti-obesity properties of Cyclopia(Stellenbosch : Stellenbosch University, 2016-12) Jack, Babalwa Unice; Pheiffer, Carmen; Malherbe, Christiaan; Huisamen, Barbara; Stellenbonsch university. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences : Medical Physiology.ENGLISH SUMMARY: Polyphenols have a range of health promoting effects against chronic diseases such as obesity and type 2 diabetes mellitus. Previous research in our group showed that Cyclopia species (honeybush), endemic South African plants, display anti-obesity effects. The aim of this study was to investigate the anti-obesity potential of polyphenol-enriched extracts of three Cyclopia spp. (C. subternata, C. intermedia and C. maculata) using bioactivity guided fractionation to facilitate the identification of anti-obesity polyphenols. Aqueous methanol extracts of C. subternata, C. intermedia and C. maculata were prepared and separated into their aqueous and organic fractions, which were tested for their anti-obesity effects in 3T3-L1 adipocytes using the Oil Red O, glycerol release (marker of lipolysis), and triglyceride assays. Cytotoxicity was evaluated using the 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and adenosine triphosphate (ATP) assays. The anti-obesity properties of the organic fraction of the aqueous methanol extract of C. intermedia were evaluated in obese Leprdb/db mice. Thereafter, the organic fraction was separated into four fractions (CCC F1 to CCC F4) using high performance counter-current chromatography (HPCCC), which were tested for their anti-obesity and cytotoxic effects in 3T3-L1 pre-adipocytes and in mature adipocytes. Liquid chromatography tandem mass spectrometry (LC-MS/MS) and quantitative high performance liquid chromatography diode array detection (HPLC-DAD) were used for determination of phenolic composition. The molecular mechanisms of action of the organic fraction and its CCC fractions were assessed with quantitative real-time PCR and western blot analysis. The polyphenol-enriched extracts of C. subternata, C. intermedia and C. maculata, and their aqueous and organic fractions exhibited differences in phenolic composition and bioactivity. The aqueous fractions of C. maculata and C. subternata, containing lower phenolic content than the organic fractions, decreased lipid content in 3T3-L1 adipocytes compared to their organic counterparts. However, the organic fraction of C. intermedia, with higher phenolic content than its aqueous fraction, decreased lipid content compared to its aqueous fraction in 3T3-L1 adipocytes. In Leprdb/db mice, the organic fraction of C. intermedia decreased body weight gain, without affecting food or water consumption. Further fractionation of the organic fraction of C. intermedia by HPCCC provided four fractions with differences in phenolic composition and anti-obesity effects. None of the extracts or fractions, except for the aqueous C. intermedia and organic C. maculata fractions which decreased ATP content, affected cell viability as measured with the MTT and ATP assays during acute treatment. The highest concentrations of CCC F1 and CCC F3 decreased ATP content during chronic treatment in pre-adipocytes. In 3T3-L1 adipocytes, the organic fraction of C. intermedia and CCC fractions modulated the expression of genes implicated in lipid and energy metabolism, whereas the organic fraction of C. intermedia had no effect on the expression of these genes in Leprdb/db mice. In conclusion, the organic fraction of C. intermedia exhibited anti-obesity properties in vitro and in vivo. A flavanone with anti-obesity potential, neoponcirin, was identified in C. intermedia, the first discovery of this compound in Cyclopia spp. Bioactivity guided fractionation of the organic fraction of C. intermedia resulted in CCC fractions retaining different polyphenols with varying anti-obesity effects. These results demonstrate that the anti-obesity potential of C. intermedia is due to the presence of more than one compound, with different mechanisms of action, or the synergistic effects of more than one compound, may contribute to the bioactivity of C. intermedia.