Rooibos (Aspalathus linearis) and its constituent quercetin can suppress ovarian cell functions and their response to FSH

Abstract

Rooibos (Aspalathus linearis Brum. f) can directly influence female reproduction, but whether rooibos can influence the response of ovarian cells to FSH and whether the rooibos effects are due to the presence of quercetin remain unknown. We compared the influence of rooibos extract and quercetin (both at 10 µg/ml-1) on porcine ovarian granulosa cells cultured with and without FSH (0, 1, 10 or 100 ng/ml(-1)). The expression of intracellular proliferation (PCNA, cyclin B1) and apoptosis (bax, caspase 3) markers in the cells was detected by immunocytochemistry. The release of progesterone (P), testosterone (T) and estradiol (E) were evaluated with ELISAs. Administration of both rooibos and quercetin reduced the accumulation of proliferation markers and promoted the accumulation of apoptosis markers and the release of T and E. Rooibos stimulated, but quercetin inhibited, P output. Administration of FSH increased the accumulation of proliferation markers, decreased the accumulation of apoptosis markers, promoted the release of P and T, and had a biphasic effect on E output. The addition of both rooibos and quercetin mitigated or prevented the main effects of FSH. The present observations suggest a direct influence of both rooibos and quercetin on basic ovarian functions – proliferation, apoptosis, steroidogenesis and response to FSH. The similarity in the major effects of rooibos and its constituent quercetin indicates that quercetin could be the molecule responsible for the main rooibos effects on the ovary. The potential anti-reproductive effects of rooibos and rooibos constituent quercetin, should be taken into account in animal and human nutrition.