Phytoestrogen in cowpea (Vigna unguiculata L. Walp) (Fabaceae) extract reduces vaginal oxidative stress and increases proliferation of fibroblast in ovariectomized rats

Abstract

Purpose: To evaluate the effects of a phytoestrogen extract of cowpea (Vigna unguiculata) on malondialdehyde (MDA) and superoxide dismutase (SOD) levels, mitogen-activated protein kinase (MAPK) activity, as well as proliferation of fibroblasts in ovariectomized rat vagina. This is with a view to identify the optimal dose of a phytoestrogen supplement for use during the menopausal period of women. Methods: Wistar rats (Rattus norvegicus) were divided into five groups: negative control, ovariectomy, and ovariectomy groups treated with 1.25, 2.5, or 5 mg/kg of cowpea extract, respectively. The three doses were used to identify the optimal dose required to reduce vaginal oxidative stress and increase fibroblast proliferation in ovariectomized rats. After treatment, the ovariectomized rat vagina was assessed for SOD and MDA levels, MAPK activity, and fibroblast proliferation. Results: Cowpea extract at a dose of 2.5 and 5 mg/kg caused significant reduction in SOD levels in the vaginal tissue of rats compared with control (p < 0.05). In contrast, cowpea extract at 1.25 mg/kg resulted in MDA levels similar to that of control rats (p < 0.05). Cowpea extract treatment had positive effects on SOD and MDA levels and on fibroblast proliferation. Increase in SOD levels in rat vagina was induced by increased MDA levels, which is characteristic of oxidative stress, while ovariectomy resulted in decreased MAPK activity. Conclusion: Overall, the cowpea extract has no significant effect on MAPK activity or fibroblast proliferation. However, it has a significant effect on SOD and MDA levels and on fibroblast proliferation at a dose of 2.5 mg/kg.