Browsing by Author "Malherbe, Christiaan J."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Adipose tissue as a possible therapeutic target for polyphenols : a case for Cyclopia extracts as anti-obesity nutraceuticals
    (Elsevier, 2019) Jack, Babalwa U.; Malherbe, Christiaan J.; Mamushi, Mokadi Peggy; Muller, Christo J. F.; Joubert, Elizabeth; Louwa, Johan; Pheiffer, Carmen
    ENGLISH ABSTRACT: Obesity is a significant contributor to increased morbidity and premature mortality due to increasing the risk of many chronic metabolic diseases such as type 2 diabetes, cardiovascular disease and certain types of cancer. Lifestyle modifications such as energy restriction and increased physical activity are highly effective first-line treatment strategies used in the management of obesity. However, adherence to these behavioral changes is poor, with an increased reliance on synthetic drugs, which unfortunately are plagued by adverse effects. The identification of new and safer anti-obesity agents is thus of significant interest. In recent years, plants and their phenolic constituents have attracted increased attention due to their health-promoting properties. Amongst these, Cyclopia, an endemic South African plant commonly consumed as a herbal tea (honeybush), has been shown to possess modulating properties against oxidative stress, hyperglycemia, and obesity. Likewise, several studies have reported that some of the major phenolic compounds present in Cyclopia spp. exhibit anti-obesity effects, particularly by targeting adipose tissue. These phenolic compounds belong to the xanthone, flavonoid and benzophenone classes. The aim of this review is to assess the potential of Cyclopia extracts as an anti-obesity nutraceutical as underpinned by in vitro and in vivo studies and the underlying cellular mechanisms and biological pathways regulated by their phenolic compounds.
  • Thumbnail Image
    Item
    Food ingredient extracts of Cyclopia subternata (Honeybush) : variation in phenolic composition and antioxidant capacity
    (MDPI, 2012) De Beer, Dalene; Schulze, Alexandra E.; Joubert, Elizabeth; De Villiers, Andre; Malherbe, Christiaan J.; Stander, Maria A.
    Cyclopia subternata plants are traditionally used for the production of the South African herbal tea, honeybush, and recently as aqueous extracts for the food industry. A C. subternata aqueous extract and mangiferin (a major constituent) are known to have anti-diabetic properties. Variation in phenolic composition and antioxidant capacity is expected due to cultivation largely from seedlings, having implications for extract standardization and quality control. Aqueous extracts from 64 seedlings of the same age, cultivated under the same environmental conditions, were analyzed for individual compound content, total polyphenol (TP) content and total antioxidant capacity (TAC) in a number of assays. An HPLC method was developed and validated to allow quantification of xanthones (mangiferin, isomangiferin), flavanones (hesperidin, eriocitrin), a flavone (scolymoside), a benzophenone (iriflophenone-3-C-β-glucoside) and dihydrochalcones (phloretin-3',5'-di-C-β-glucoside, 3-hydroxyphloretin-3',5'-di-C-hexoside). Additional compounds were tentatively identified using mass spectrometric detection, with the presence of the 3-hydroxyphloretin-glycoside, an iriflophenone-di-O,C-hexoside, an eriodictyol-di-C-hexoside and vicenin-2 being demonstrated for the first time. Variability of the individual phenolic compound contents was generally higher than that of the TP content and TAC values. Among the phenolic compounds, scolymoside, hesperidin and iriflophenone-3-C-β-glucoside contents were the most variable. A combination of the measured parameters could be useful in product standardization by providing a basis for specifying minimum levels.
  • Thumbnail Image
    Item
    In vitro a-glucosidase inhibition by honeybush (Cyclopia genistoides) food ingredient extract-potential for dose reduction of acarbose through synergism
    (Royal Society of Chemistry, 2020-06-29) Miller, Neil; Malherbe, Christiaan J.; Joubert, Elizabeth
    Extracts of Cyclopia species are used as food ingredients. In vitro α-glucosidase (AG) inhibition by ultrafiltered C. genistoides extract, fractions enriched in xanthones (XEF) and benzophenones (BEF), as well as mangiferin, isomangiferin, 3-β-D-glucopyranosyliriflophenone (I3G) and 3-β-D-glucopyranosyl-4-O-β-D-glucopyranosyliriflophenone (IDG) was determined with acarbose as positive control. XEF was more potent than the extract and BEF (IC50 = 43.3, 95.5 and 205.7 μg mL−1, respectively). Compounds demonstrated potency in the descending order: acarbose (IC50 = 44.3 μM) > mangiferin (102.2 μM) > isomangiferin (119.8 μM) > I3G (237.5 μM) > IDG (299.4 μM). The combination index (CI) was used to determine synergism (CI < 0.7) as demonstrated for combinations of acarbose with XEF, BEF or the respective compounds at 50% and 75% effect levels. The greatest potential acarbose dose reductions (>six-fold) across all effect levels were calculated for combinations of acarbose with mangiferin or isomangiferin, explaining the greater acarbose dose reduction potential of XEF vs. BEF. The effect of batch-to-batch variation (n = 10) of raw plant material on AG inhibition was quantified at a fixed concentration (160 μg mL−1). XEFs (xanthone content = 223–481 g kg−1) achieved AG inhibition of 63–72%, whereas BEFs (benzophenone content = 114–251 g kg−1) achieved AG inhibition of 26–34%, with weak linear correlation (R2 < 0.43) between target compound content of the fractions and their achieved AG inhibition. Thus, extract fractions of C. genistoides, enriched in xanthones and benzophenones, show potential in reducing the effective dose of acarbose required to prevent postprandial hyperglycaemia.