Commercial Honeybush (Cyclopia spp.) Tea Extract Inhibits Osteoclast Formation and Bone Resorption in RAW264.7 Murine Macrophages—An in vitro Study
The stems, leaves and flowers of Cyclopia have been consumed as a herbal tea 'honeybush tea' to treat various medical ailments since the 19th century. Plant polyphenols are reported to inhibit adipogenesis in cell and animal models of obesity. The aim of this study was to assess the effect of hot water extracts of two Cyclopia species, C. maculata and C. subternata on obesity in an in vitro model. The total polyphenol content of unfermented C. subternata, unfermented C. maculata and fermented C. maculata extracts was 25.6, 22.4 and 10.8g GAE/100g, respectively. The major compounds present in the extracts were: the flavonoid, phloretin-3',5'-di-C-glucoside in C. subternata, the xanthone, mangiferin in unfermented C. maculata and the flavanone, hesperidin in fermented C. maculata. All of the plant extracts inhibited intracellular triglyceride and fat accumulation, and decreased PPARγ2 expression. The higher concentrations of unfermented C. maculata (800 and 1600μg/ml) and C. subternata (1600μg/ml) were cytotoxic in terms of decreased mitochondrial dehydrogenase activity. Both fermented and unfermented C. maculata, at concentrations greater than 100μg/ml, decreased cellular ATP content. Cyclopia maculata and C. subternata inhibit adipogenesis in vitro, suggesting their potential as anti-obesity agents.