Alzheimer's disease: Molecular aspects and treatment opportunities using herbal drugs.

Alzheimer's disease (AD), also called senile dementia, is the most common neurological disorder. Around 50 million people, mostly of advanced age, are suffering from dementia worldwide and this is expected to reach 100-130 million between 2040 and 2050. AD is characterized by impaired glutamatergic and cholinergic neurotransmission, which is associated with clinical and pathological symptoms. AD is characterized clinically by loss of cognition and memory impairment and pathologically by senile plaques formed by Amyloid ß deposits or neurofibrillary tangles (NFT) consisting of aggregated tau proteins. Amyloid ß deposits are responsible for glutamatergic dysfunction that develops NMDA dependent Ca2+ influx into postsynaptic neurons generating slow excitotoxicity process leading to oxidative stress and finally impaired cognition and neuronal loss. Amyloid decreases acetylcholine release, synthesis and neuronal transport. The decreased levels of neurotransmitter acetylcholine, neuronal loss, tau aggregation, amyloid ß plaques, increased oxidative stress, neuroinflammation, bio-metal dyshomeostasis, autophagy, cell cycle dysregulation, mitochondrial dysfunction, and endoplasmic reticulum dysfunction are the factors responsible for the pathogenesis of AD. Acetylcholinesterase, NMDA, Glutamate, BACE1, 5HT6, and RAGE (Receptors for Advanced Glycation End products) are receptors targeted in treatment of AD. The FDA approved acetylcholinesterase inhibitors Donepezil, Galantamine and Rivastigmine and N-methyl-D-aspartate antagonist Memantine provide symptomatic relief. Different therapies such as amyloid ß therapies, tau-based therapies, neurotransmitter-based therapies, autophagy-based therapies, multi-target therapeutic strategies, and gene therapy modify the natural course of the disease. Herbal and food intake is also important as preventive strategy and recently focus has also been placed on herbal drugs for treatment. This review focuses on the molecular aspects, pathogenesis and recent studies that signifies the potential of medicinal plants and their extracts or chemical constituents for the treatment of degenerative symptoms related to AD.

Application of nanotechnology to herbal antioxidants as improved phytomedicine: An expanding horizon.

Phytotherapy, based on medicinal plants, have excellent potential in managing several diseases. A vital part of the healthcare system is herbal medicines, consisting of therapeutic agents with high safety profile and no or least adverse effects. Herbs or medicinal plants show anticancer, antioxidant, and gene-protective activity, which is useful for pharmaceutical industries. In vitro, the extract of antioxidant compounds prevents the growth of colon and liver cancer cells, followed by a dose-dependent method. The screening of extracts is done by using in vitro models. Reactive oxygen species (ROS) and free radicals lead to diseases based on age which promotes oxidative stress. Different types of ROSs available have central roles in the normal physiology and functioning of processes. Herbal or traditional plant medicines have rich antioxidant activity. Despite the limited literature on the health effect of herbal extract or spices. There are many studies examining the encouraging health effects of single phytochemicals instigating from the medicinal plant. This review provides a detailed overview on herbal antioxidants and how application of nanotechnology can improve its biological activity in managing several major diseases, and having no reported side effects.