A histomorphometric study on the hepatoprotective effects of a green rooibos extract in a diet-induced obese rat model.

Obesity, type two diabetes mellitus and insulin resistance are associated with increased oxidative stress and inflammation. Unfermented green rooibos is an aspalathin rich variant of traditional fermented rooibos (Aspalathus linearis) and has a high polyphenol content. The present study aimed to determine the histologically observable effects of a commercially produced, aspalathin-rich green rooibos extract, Afriplex GRT™ (GRE) in a diet-induced obese rat model. Male Wistar rats (N = 28) were randomly assigned to four study groups (n = 7): control (C), green rooibos (GRT), high-fat diet (HFD) and experimental (HFD-GRT) group. Body mass was determined prior to euthanasia and liver mass was determined after death. The left lateral lobe of the liver was processed to wax and stained using haematoxylin and eosin (H & E), Masson's trichrome stain, Gordons and Sweet's reticulin impregnation and periodic acid-Schiff stain. Frozen liver tissue sections were used for Oil red O staining. Morphometric quantification of steatosis, semiquantitative pathology grading and scoring were performed and verified by a veterinary histopathologist. A significant increase in body and liver mass was observed in the HFD groups while co-treatment with green rooibos significantly reduced both. The volume and area of steatosis were significantly increased in the HFD groups while the area of steatosis significantly reduced with green rooibos co-treatment. The percentage, location and type of steatosis as well as presence of inflammation and hepatocellular injury were reduced in the HFD group co-treated with GRE. These findings suggest that a GRE has potential as an anti-steatotic, anti-inflammatory and weight reducing agent in vivo.

A toxicological assessment of Athrixia phylicoides aqueous extract following sub-chronic ingestion in a rat model.

Athrixia phylicoides is an aromatic, indigenous shrub used to brew "bush tea." Surveys have shown that the consumption of bush tea is widespread and commercialization of the extract holds economic and developmental potential. Aqueous extracts of A. phylicoides are non-toxic to brine shrimp and renal cell lines; however, verification in a mammalian model is needed. In this study, daily ingestion of high doses of aqueous A. phylicoides extract by mature Wistar rats was tested for potential toxicity over a 3-month period. Three-month-old Wistar rats were randomized into a control group (receiving no extract) and three experimental groups receiving 30, 90, or 180 mg dried aqueous A. phylicoides extract/kg body mass/day. After 90 days of daily extract ingestion, blood and tissue were harvested. There was no morbidity or mortality during the study. Food and water intake, as well as body mass and stool production, were unaffected by the consumption of the extract. Urine production was increased in the 90 and 180 mg/kg groups suggesting that A. phylicoides is mildly diuretic. Serum alkaline phosphatase, creatinine, and urea levels were normal for all groups. Histopathology showed no signs of any extract induced toxicity in the liver, kidneys, gastrointestinal tract, and other tissues studied.

An in vitro assessment of the effect of Athrixia phylicoides DC. aqueous extract on glucose metabolism.

Athrixia phylicoides DC. is an aromatic shrub indigenous to the eastern parts of Southern Africa. Indigenous communities brew "bush tea" from dried twigs and leaves of A. phylicoides, which is consumed as a beverage and used for its medicinal properties. Plant polyphenols have been shown to be beneficial to Type 2 diabetes mellitus (T2D) and obesity. Aqueous extracts of the plant have been shown to be rich in polyphenols, in particular phenolic acids, which may enhance glucose uptake and metabolism. The aim of this study was to determine the phenolic composition of a hot water A. phylicoides extract and assess its in vitro effect on cellular glucose utilisation. The most abundant phenolic compounds in the extract were 6-hydroxyluteolin-7-O-glucoside, chlorogenic acid, protocatechuic acid, a di-caffeoylquinic acid and a methoxy-flavonol derivative. The extract increased glucose uptake in C2C12, Chang and 3T3-L1 cells, respectively. Intracellular glucose was utilised by both oxidation (C2C12 myocytes and Chang cells; p < 0.01 and p < 0.05, respectively) and by increased glycogen storage (Chang cells; p < 0.05). No cytotoxicity was observed in Chang cells at the concentrations tested. The effects of the extract were not dose-dependent. A. phylicoides aqueous extract stimulated in vitro glucose uptake and metabolism, suggesting that consumption of this phenolic-rich extract could potentially ameliorate metabolic disorders related to obesity and T2D.