Effects of Pueraria lobata root and Glycine max (L.) Merrill extracts fermented with Lactiplantibacillus plantarum on the depressive-like behavior in ovariectomized mice via upregulation of hippocampal BDNF

Abstract

Pueraria lobata roots and Glycine max (L.) Merrill are rich in isoflavones, which are phytoestrogens known to alleviate menopausal and some disease symptoms. However, the high molecular weight and poor bioavailability of isoflavones, owing to the glucose moieties attached to these glycosides, limit their practical use. Fermentation with lactic acid bacteria has been reported to convert glycosides into their aglycone forms. In this study, we investigated the health-promoting effects of fermented P. lobata root extract (FPE) and G. max (L.) Merrill extract (FGE) using ovariectomized mice. The extract was fermented with lactic acid bacteria. Lactiplantibacillus plantarum strains that convert glycosides to aglycones were selected, and in vitro and in vivo experiments were conducted to confirm various functionalities resulting from fermentation. FPE and FGE exhibited estrogen-like activities. In particular, fermentation increased the expression of estrogen receptor beta (ERβ), as a result of which the fermented extracts should probably not be associated with increasing the incidence of various female cancers—a common side effect of hormone replacement therapy. In addition, oral administration of FPE, FGE, or a mixture of the two extracts (FPE-FGE) to ovariectomized mice improved depressive symptoms by upregulating hippocampal brain-derived neurotrophic factor (BDNF). The expression of ERβ was the highest in the FPE-FGE group. These results indicate that FPE-FGE can be used as a raw material for the development of dietary supplements for menopausal women because it increases ERβ expression and alleviates the depressive-like behavior through the regulation of BDNF and neurotransmitters.