Mechanisms of action of formononetin, an extract from Astragalus membranaceus medicinal plant, in ameliorating Alzheimer’s disease

Alzheimer’s disease (AD), the term “dementia”, describes a specific neuropathology together with the development and progression of age-related cognitive and functional loss. Formononetin is naturally occurring isoflavone recognized for its potential health benefits, anti-oxidant, anti-inflammatory, anti-cancer, and anti-apoptotic properties. Neurodegenerative disorders arise from the gradual loss of function and eventual death of nerve cells in the brain or peripheral nervous system. Astragalus membranaceus is a traditional plant with a variety of pharmacological and biochemical properties, including antiviral, anti-hyperglycaemic, and immunomodulatory effects. Moreover, the expression of membrane-bound and soluble receptor for advanced glycation end products (RAGE) is enhanced in the AD brain due to increased levels of soluble and insoluble amyloid-beta (Aβ) peptides. Additionally, in inflammatory circumstances, leukocytes’ firm attachment and transmigration to endothelial cells are regulated by intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1). Formononetin also possesses anti-bacterial, anti-inflammatory, anti-cancer, anti-oxidant, and estrogenic activity. Formononetin has emerged as a promising agent in the modulation of mediators involved in neurodegenerative disease. Formononetin might modulate nuclear factor erythroid 2-related factor 2 (Nrf-2) signaling pathway to potentiate the anti-Alzheimer’s activity. Additionally, formononetin might inhibit the Aβ/RAGE interaction which further inactivates the activity of extracellular signal regulated kinase (ERK), Janus kinase (JNK) signaling pathway that results in the reduction of nuclear translocation of nuclear factor kappa B (NF-κB) and also reduces the cytokines level to ameliorate AD. It might inhibit the ICAM, VCAM, and THP-1 proteins. Therefore, this compound offers potential therapeutic benefits by reducing cytokine levels to ameliorate AD. This review article is designed to explore the mechanistic interplay underlying the anti-Alzheimer’s effect of A. membranaceus, especially formononetin.