Estrogenic and anti-amnesic potential of Millettia griffoniana Baill. (Fabaceae) ethanolic extract on scopolamine-induced memory impairment in ovariectomized Wistar rats.

Abstract

Dementias including Alzheimer disease (AD) are three times higher in menopausal women than in men. Phytoestrogens, a group of plant-derived compounds are known to alleviate menopausal complaints including dementia. Millettia griffoniana Baill is a phytoestrogen-rich plant used to treat menopausal complaints and dementia. Evaluating the estrogenic and neuroprotective potential of Millettia griffoniana on ovariectomized (OVX) rats. The in vitro safety of M. griffoniana ethanolic extract was assayed by MTT in human mammary epithelial (HMEC) and mouse neuronal (HT-22) cells and its lethal dose 50 (LD50) was estimated following OECD 423 guidelines. For estrogenicity, in vitro the well known E-screen assay on MCF-7cells was performed and in vivo four groups of OVX rats were treated either with 75, 150 and 300mg/kg M. griffoniana extract doses or estradiol (1mg/kg BW) for three days; and changes in uterine and vagina were analyzed. Then, for neuroprotective effect, Alzheimer-type dementia induction was achieved by scopolamine (1.5mg/kg B.W., i.p.) injection four days/week and M. griffoniana extract as well as piracetam (standard) were administered daily for 2 weeks to evaluate the extract's neuroprotective potential. The endpoints were the assessment of learning and working memory, oxidative stress state (SOD, CAT, and MDA) in brain, acetylcholine esterase (AChE) activity and the histopathological changes in hippocampus. No toxic effect was observed when incubating mammary (HMEC) and neuronal (HT-22) cells with M. griffoniana ethanol extract for 24h and its LD50 was found >2000mg/kg. The extract also exhibited both in vitro and in vivo estrogenic activities, displayed by a significant (p<0.01) increment in MCF-7cells population in vitro and an increase in the epithelium height of the vagina and the wet weight of the uterus mainly with the 150mg/kg BW extract dose compared to untreated OVX rats. The extract also reversed scopolamine-induced memory impairment in rat by improving learning, working and reference memory. This was associated with an increment in CAT and SOD expression, alongside a decrement in MDA content and AChE activity in hippocampus. Further, the extract reduced neuronal cell loss in hippocampal structures (CA1, CA3 and dentate gyrus). High Performance Liquid Chromatography coupled with Mass Spectrometry (HPLC-MS) spectra, revealed the presence of numerous phytoestrogens in M. griffoniana extract. M. griffoniana ethanolic extract has estrogenic, anticholinesterase and antioxidant activities that could account for its anti-amnesic effects. These findings therefore sheds light on why this plant is commonly used in the therapy of menopausal complaints and dementia.