A Systematic Review on the Role of Natural Products in Modulating the Pathways in Alzheimer's Disease.

Alzheimer's disease (AD) is the most common neurodegenerative disorder to date, with no cure or preventive therapy. Histopathological hallmarks of AD include deposition of β-amyloid plaques and formation of neurofibrillary tangles in brain. Despite extensive research, only five approved drugs are available for the management of AD. Hence, there is a need to look for alternative therapies and new drugs. Use of natural products in medicine has gained popularity in recent years and several natural compounds with neuroprotective effects have been studied in detail. Some of them target the disease pathways and improve cognition by directly affecting amyloidogenesis, programmed cell death and increase neuronal cell survival. Currently, phytochemicals like polyphenols, alkaloids, terpenes, flavonoids, tannins, saponins and vitamins from plants have received a special attention from the scientific community against the pathological processes in conditions like cancer, cardiovascular diseases and neurodegenerative diseases. Many efforts have been made to unravel the molecular mechanisms and the specific interactions of phytochemicals, which targets disease pathways in the AD. Further studies on these natural products and their mechanism of action, target specific effect in disease pathology parallel with the use of novel pharmaceutical drug design and delivery techniques, enable us to offer an addition to conventional medicine in treatment of AD. This review presents detailed information on natural products like polyphenols, alkaloids and terpenes with their potential effects in Alzheimer's disease.