Current Progress on Neuroprotection Induced by Artemisia, Ginseng, Astragalus, and Ginkgo Traditional Chinese Medicines for the Therapy of Alzheimer's Disease

Cordycepin mediates neuroprotection against apoptosis via ERK/CREB signaling activation in Aβ1-42-induced neuronal cell models

The aggregation of β-amyloid (Aβ) peptides has been associated with the onset of Alzheimer's disease (AD) by causing neurotoxicity due to oxidative stress and apoptosis. Cordycepin is a natural derivative of the nucleoside adenosine that displays potent antioxidant, antitumor, anti-inflammatory, and neuroprotective properties. However, the mechanism of the neuroprotective effect of cordycepin toward Aβ-induced neurotoxicity, as well as underlying mechanisms, is still unclear. In this study, we found that cordycepin conferred neuroprotection to catecholaminergic PC12 neuronal cell cultures exposed to Aβ1-42-insult by reducing the production of reactive oxygen species, restoring the mitochondrial membrane potential, and inhibiting apoptosis. Cordycepin stimulated the phosphorylation of extracellular signal-regulated kinase (ERK) and cyclic AMP-responsive element-binding protein (CREB) in a time- and concentration-dependent manner. Inhibition of the ERK pathway reduced the neuroprotective effect of cordycepin. Similar results were obtained with hippocampal HT22 neuronal cell cultures. Cumulatively, these findings suggest that cordycepin-induced neuroprotection toward Aβ1-42 neurotoxic insult may involve activation of the ERK/CREB pathway. This study expands our knowledge of the neuroprotective function of cordycepin and suggests that it holds promise as a natural lead compound for drug development in AD.

Physalin H ameliorates LPS-induced acute lung injury via KEAP1/NRF2 axis

Physalin H (PH), a withanolide isolated from Physalisangulata L. has been reported to have anti-inflammatory effect. However, its impact on acute lung injury (ALI) remains unexplored. In this study, we observed that PH significantly alleviated inflammation in LPS-stimulated macrophages by suppressing the release of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and down-regulating the expression of the inflammation-related genes. RNA sequencing analysis revealed a significant up-regulation of the NRF2 pathway by PH. Further investigation elucidated that PH attenuated the ubiquitination of NRF2 by impeding the interaction between NRF2 and KEAP1, thereby facilitating NRF2 nuclear translocation and up-regulating the expression of target genes. Consequently, it regulated redox system and exerted anti-inflammatory effect. Consistently, PH also significantly alleviated pathological damage and inflammation in LPS-induced ALI mice model, which could be reversed by administration of an NRF2 inhibitor. Collectively, these results suggest that PH ameliorates ALI by activating the KEAP1/NRF2 pathway. These findings provide a foundation for further development of pH as a new anti-inflammatory agent for ALI therapy.

Critical analysis of ginkgo preparations: comparison of approved drugs and dietary supplements marketed in Germany

Demographic change is taking place in the population of western industrialized countries, and the population is aging constantly. As a result, the mortality rate of patients due to dementia is rising steadily. To counteract this, the relevance of neuroprotective agents is increasing. Preparations from the medicinal tree species Ginkgo biloba ("gingko") are becoming increasingly popular. In this study, 63 ginkgo preparations marketed in Germany were analyzed. The following data were collected from the package inserts of the preparations: Country of manufacture, approval as a drug, compliance to target values of flavone glycosides, compliance to target values of terpene lactones, compliance to target values of ginkgolic acids, dosage per unit in milligrams (mg), duration of use, interactions with other drugs, contraindications, adverse effects and daily defined dose costs. In the next step, these data were compared in the following form: Total preparations versus preparations with drug approval versus dietary supplements. Almost without exception, the results indicate a pharmaceutical reliability of the preparations with drug approval and a dubious reliability of the preparations marketed as dietary supplements. Thus, ginkgo preparations marketed as dietary supplements appear to have an economic rather than a medical focus. We discuss the evidence of efficacy, and other criteria mentioned above, to evaluate the adequacy of the costs for the statutory health insurance that pay for preparations with drug approval in Germany. From the analysis of our results it is very doubtful that ginkgo biloba extract preparations of the food industry have any health benefit. It must be evaluated whether prohibition of selling ginkgo biloba extract as a dietary supplement is an option.

Aging and aging-related diseases: from molecular mechanisms to interventions and treatments

Aging is a gradual and irreversible pathophysiological process. It presents with declines in tissue and cell functions and significant increases in the risks of various aging-related diseases, including neurodegenerative diseases, cardiovascular diseases, metabolic diseases, musculoskeletal diseases, and immune system diseases. Although the development of modern medicine has promoted human health and greatly extended life expectancy, with the aging of society, a variety of chronic diseases have gradually become the most important causes of disability and death in elderly individuals. Current research on aging focuses on elucidating how various endogenous and exogenous stresses (such as genomic instability, telomere dysfunction, epigenetic alterations, loss of proteostasis, compromise of autophagy, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, deregulated nutrient sensing) participate in the regulation of aging. Furthermore, thorough research on the pathogenesis of aging to identify interventions that promote health and longevity (such as caloric restriction, microbiota transplantation, and nutritional intervention) and clinical treatment methods for aging-related diseases (depletion of senescent cells, stem cell therapy, antioxidative and anti-inflammatory treatments, and hormone replacement therapy) could decrease the incidence and development of aging-related diseases and in turn promote healthy aging and longevity.

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.