Natural Products as Bioactive Agents in the Prevention of Dementia.

Dementia is a complex syndrome of neurological disorders which is associated with cognitive functions of the body. The present review focuses on the role and application of natural products in the treatment of dementia and related diseases. The studies highlight that there exist some potent synthetic/semisynthetic drugs that can effectively target dementia and related diseases. In contrast, despite the existence of a large library of natural products, only a few of them (galantamine, huperzine A, etc.) have been approved as drugs against dementia. This fact is not discouraging because a large number of natural products, including classes of polyphenols, alkaloids, isothiocyanates, phytocannabinoids, and terpenoids, are in the process of drug development stages against dementia and related diseases. It is because they display some promising and diverse biological activities, including antioxidant, acetylcholinesterase inhibitory activity, and anti-amyloidogenic properties, which are significantly associated with the prevention of dementia syndrome. The studies reported in the literature reveal that bioactive natural products particularly target Alzheimer's and Parkinson's diseases by suppressing the risks responsible for dementia. Huperzine A has been identified as a potent natural product against Alzheimer's disease. Despite the efficient role of natural products in preventing dementia, their direct application as drugs is still limited due to some controversial results obtained from their clinical trials; however, bioassay-guided drug development studies can prove them potential drugs against dementia and related diseases. This review provides useful information for researchers, pharmacologists, and medical doctors.