In vitro effects of aqueous extract of aspalathus linearis (rooibos) on human sperm cells

Abstract

This study investigated the effect of rooibos tea on human sperm in vitro. Semen samples from 50 healthy men and 50 patients were treated with aqueous extracts of fermented rooibos (0 µg/ml, 0.10 µg/ml, 1.0 µg/ml, 10 µg/ml, 100 μg/ml) and unfermented rooibos (0 µg/ml, 0.15 µg/ml, 1.5 µg/ml, 15 µg/ml, 150 μg/ml) for one hour at 37ºC. Thereafter, sperm parameters were analysed. Exposure to unfermented rooibos had no effect on sperm motility, vitality and DNA fragmentation in both groups (P>0.05). However, this treatment significantly increased the production of reactive oxygen species, thus influencing the acrosome reaction, and demonstrated a decrease in mitochondrial membrane potential in the donor group (P<0.05). Treatment with fermented rooibos increased progressive motility in the donor group (P<0.05) but had no effect on sperm vitality, reactive oxygen species and the acrosome reaction in either group (P>0.05). A decrease in mitochondrial membrane potential and DNA fragmentation was observed in the donor group and the patient group (P<0.05). Rooibos tea maintains certain sperm functional parameters, and this may positively affect fertility rate.