Preclinical Evidence of Withania somnifera and Cordyceps spp.: Neuroprotective Properties for the Management of Alzheimer's Disease

: Alzheimer's disease (AD) is considered one of the main pathologies of our time, whose incidence and prevalence are suggested to be strongly underestimated. AD presents as a complex neurodegenerative condition characterized by marked neuroinflammation and a significant decline in the cognitive and mnemonic functions of affected patients. Recognized AD pathological hallmarks include amyloid beta plaque and neurofibrillary tangle formation, synaptic dysfunction with considerable apoptosis of cholinergic and dopaminergic neurons, and high levels of oxidative stress and neuroinflammation. The available pharmacological treatments are represented by acetylcholinesterase inhibitors to treat the mild to moderate form of the disease and N-methyl-D-aspartate inhibitors alone or in combination with the previously cited ones in the late stage of the neurodegenerative condition. Furthermore, emerging drug therapies such as monoclonal antibodies are promising agents in AD management. Although scientific evidence highlights these chemicals as effective in slowing down disease progression, significant limitations behind their employment derive from the notable dose-dependent side effects and the single-target mechanism of action. In this context, two well-studied phytotherapeutics, W. somnifera (W. somnifera) and fungi belonging to the genus Cordyceps, have gained attention for their chemical composition regarding their neuroprotective and anti-inflammatory effects. Ashwagandha (obtained principally from the roots of W. somnifera) is an adaptogen that relieves stress and anxiety. It contains several ergostane-type steroidal lactones-such as withanolides and withaferin A-and various alkaloids, contributing to its antioxidant and neuroprotective effects. Likewise, cordycepin is the main bioactive principle found in Cordyceps fungi. This natural nucleoside has been reported to possess therapeutic potential as an anti-cancer, immunomodulatory, and anti-inflammatory agent, with some studies suggesting a beneficial role in AD treatment. The purpose of the present review is to investigate the pharmacological properties of W. somnifera and Cordyceps species in the context of AD treatment and explore the therapeutic potential of the constitutive bioactive molecules in preclinical models mimicking this neurodegenerative condition.