Neuroprotective effects of carvacrol against Alzheimer's disease and other neurodegenerative diseases: A review

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Linking the Amyloid, Tau, and Mitochondrial Hypotheses of Alzheimer's Disease and Identifying Promising Drug Targets

Damage or loss of brain cells and impaired neurochemistry, neurogenesis, and synaptic and nonsynaptic plasticity of the brain lead to dementia in neurodegenerative diseases, such as Alzheimer's disease (AD). Injury to synapses and neurons and accumulation of extracellular amyloid plaques and intracellular neurofibrillary tangles are considered the main morphological and neuropathological features of AD. Age, genetic and epigenetic factors, environmental stressors, and lifestyle contribute to the risk of AD onset and progression. These risk factors are associated with structural and functional changes in the brain, leading to cognitive decline. Biomarkers of AD reflect or cause specific changes in brain function, especially changes in pathways associated with neurotransmission, neuroinflammation, bioenergetics, apoptosis, and oxidative and nitrosative stress. Even in the initial stages, AD is associated with Aβ neurotoxicity, mitochondrial dysfunction, and tau neurotoxicity. The integrative amyloid-tau-mitochondrial hypothesis assumes that the primary cause of AD is the neurotoxicity of Aβ oligomers and tau oligomers, mitochondrial dysfunction, and their mutual synergy. For the development of new efficient AD drugs, targeting the elimination of neurotoxicity, mutual potentiation of effects, and unwanted protein interactions of risk factors and biomarkers (mainly Aβ oligomers, tau oligomers, and mitochondrial dysfunction) in the early stage of the disease seems promising.

Alzheimer's Disease: Understanding Its Novel Drug Delivery Systems and Treatments

Around the world, there are no fewer than 24 million people who suffer from dementia. Through 2040, this number is expected to rise steadily every 20 years. Alzheimer's disease (AD), the most prevalent kind of dementia, is characterised by a steady deterioration in cognitive function that most often begins with memory loss. Alzheimer's disease (AD) is considered to be one of the leading causes of morbidity in the elderly. Around 5 million people in the United States have Alzheimer's disease. Still, because AD is common in the older and greying population, its prevalence is expected to rise dramatically in the coming decades. As the disease progresses, people with Alzheimer's disease frequently become dependent on caregivers. The Alzheimer's-diseased brain is characterised neuropathologically by diffuse and neuritic extracellular amyloid plaques, which are often ringed by dystrophic neurites and intracellular neurofibrillary tangles. This particular disease is characterised by the presence of reactive microgliosis and the destruction of neurons, white matter, and synapses. The present review is done to study and learn about new treatments and novel drug delivery systems that may provide benefits to patients with AD. With the new drugs, treatments, constant care requirements, and lost productivity, Alzheimer's has a substantial financial impact on society. Therefore, better management and therapy are crucial. In this overview, we will briefly go through the current knowledge base about AD, covering the functions of beta-amyloid, tau proteins, and stem cell therapy, and elaborating on novel diagnostic and therapeutic interventions.