Editorial: Natural products-based drugs: Potential therapeutics against Alzheimer's disease and other neurological disorders

Abstract

Editorial on the Research Topic Natural Products-Based Drugs: Potential Therapeutics Against Alzheimer's Disease and Other Neurological Disorders Alzheimer's disease (AD) and dementia are disorders of the aging population and becoming major health care burden worldwide due to unavailability of complete therapy. AD is the most frequent cause of dementia among 60% to 80% patients and has effected 45 million people globally which is estimated to triple by 2050 (Alzheimer's, 2015). AD is a progressive, neurodegenerative disorder, characterized by behavioral turbulence, cognitive dysfunctions, imperfection in routine life activities, thus putting a huge socioeconomic burden on the health care system (Ahmad et al., 2015; Ali et al., 2017; Ayaz et al., 2017b). Among the pathophysiological hallmarks of the disease are the deficiency of vital neurotransmitter acetylcholine (ACh), deposition of amyloid plaques (Aβ), highly phosphorylated tau proteins, and imbalance in gluatamatergic system (Ayaz et al., 2017a; Khalil et al., 2018; Ovais et al., 2018a). Only five drugs are clinically approved for use, among which tacrine, galantamine, donepezil, and rivastigmine are cholinesterase inhibitors whereas the fifth one memantine is glutamatergic system modulator (Ayaz et al., 2015; Kamal et al., 2015). These drugs have limited efficacy and are associated with side effects like tacrine is hepatotoxic (Watkins et al., 1994). Currently, results from clinical trials performed in mild to moderate AD dementia have directed researchers to find more effective yet safe alternatives from natural sources (Yiannopoulou and Papageorgiou, 2013; Cummings et al., 2014; Ovais et al., 2018b). The plant kingdom consists of a huge number of species with tremendous diversity of bioactive metabolites with different chemical scaffold (Ramawat et al., 2009; Ahmad et al., 2016; Mir et al., 2019). According to reports, only 6% and 15% of medicinal plants have been systematically investigated for pharmacological and phytochemical potentials respectively (Choudhary, 2001). Since, natural products are synthesized by living organisms, they have naturally optimized properties for various biological functions including binding to specific bimolecules or target proteins. Comparison of the structural features of natural and compounds synthetic revealed that the major difference between the two sources originates from starting points which makes synthesis more easy. For instance, separation of chiral compounds is a big challenge, so usually molecules with less number of chiral centers is synthesized and favored (Jan et al., 2019; Hussain et al., 2019). Besides the less number of chiral centers, synthetic molecules have low molecular weight, high chain lengths, less number of Lipinski type H-bond receptors and donors, less oxygen, and more halogen, nitrogen and sulfer.