Effect of rooibos (Aspalathus linearis) on the female rat reproductive tract and liver and kidney functions in vivo

Looking for an animal model to investigate the potential estrogenic effect of indigenous rooibos (Aspalathus linearis) on females with functional ovaries, we used ovary-intact mature female Wistar rats. Rats were exposed to unfermented (Ur) or fermented (Fr) rooibos (2% and 5%, respectively) as sole source of drinking for 21 days. Unfermented rooibos (5%) significantly increased relative uterus weight while fermented tea (5%) caused a significant decrease in relative ovary weight. Although statistically not significant, all rooibos treatments caused a trend to increased serum FSH but decreased LH level. Histological sections revealed no adverse changes in the ovary, uterus, kidney and liver of all treated groups. Endometrium thickness was enhanced, whereas myometrium was unchanged. No signs of inflammation were observed. In serum, ferric reducing antioxidant power (FRAP) did not change whereas 2% Ur caused a significant drop in ALT activity. Fermented rooibos, however, induced an increase in AST activity (P < 0.01; 5%) and creatinine level (P < 0.05; 5%). No effects on total body weight gain or relative kidney weight were observed while relative liver weight was significantly increased by Ur. Antioxidant activities of CAT, SOD and GSH and MDA levels in the kidney and liver remained unchanged (P > 0.05) while liver CAT activity was significantly improved by 5% Ur. In conclusion, Aspalathus linearis might exhibit some estrogenic property and may thus be beneficial to boost female fertility. Rooibos is able to maintain antioxidant levels in the serum, kidney and liver. No major adverse in vivo effects could be observed. However, it seems that especially fermented rooibos may affect kidney and liver tissue as there is a significant increase in AST and creatinine values and a trend to dose-dependent rises in ALT activity. Though, the potential clinical relevance needs further investigations.