Tournefolic acid B attenuates amyloid beta protein-mediated toxicity by abrogating the calcium overload in mitochondria and retarding the caspase 8-truncated Bid-cytochrome c pathway in rat cortical neurons

Dibenzo[b,f]oxepine Molecules Used in Biological Systems and Medicine

In this short review, including 113 references, issues related to dibenzo[b,f]oxepine derivatives are presented. Dibenzo[b,f]oxepine scaffold is an important framework in medicinal chemistry, and its derivatives occur in several medicinally relevant plants. At the same time, the structure, production, and therapeutic effects of dibenzo[b,f]oxepines have not been extensively discussed thus far and are presented in this review. This manuscript addresses the following issues: extracting dibenzo[b,f]oxepines from plants and its significance in medicine, the biosynthesis of dibenzo[b,f]oxepines, the active synthetic dibenzo[b,f]oxepine derivatives, the potential of dibenzo[b,f]oxepines as microtubule inhibitors, and perspective for applications of dibenzo[b,f]oxepine derivatives. In conclusion, this review describes studies on various structural features and pharmacological actions of dibenzo[b,f]oxepine derivatives.

Gram-Scale Total Synthesis of TAB with Cardioprotective Activity and the Structure-Activity Relationship of Its Analogs

Traditional Chinese medicine has been proven to be of great significance in cardioprotective effects. Clinopodium chinense (Lamiaceae) has unique advantages in the treatment and prevention of cardiovascular diseases. Tournefolic acid B (TAB) was proven to be a potent component against myocardial ischemia reperfusion injury (MIRI) from Clinopodium chinense (Lamiaceae). This article will attempt to establish a gram-scale synthesis method of TAB and discuss the structure-activity relationship of its analogs. The total synthesis of TAB was completed in 10 steps with an overall yield of 13%. In addition, analogs were synthesized, and their cardioprotective activity was evaluated on the hypoxia/reoxygenation of H9c2 cells. Amidation of the acid position is helpful to the activity, while methylation of phenolic hydroxyl groups greatly decreased the cardioprotective activity. The easily prepared azxepin analogs also showed cardioprotective activity. Most of the clogP values calculated by Molinspiration ranged from 2.5 to 5, which is in accordance with Lipinski's rule of 5. These findings represent a novel kind of cardioprotective agent that is worthy of further study.

Mitochondria and Calcium in Alzheimer's Disease: From Cell Signaling to Neuronal Cell Death

Mitochondrial dysfunction has been implicated in the pathogenesis of almost all neurological diseases, including Alzheimer's disease (AD). Historically, a primary focus in this context has been the link between mitochondrial dynamics and amyloid β toxicity. Recent evidence suggests that dysregulation of mitochondrial calcium homeostasis is also related to tau and other risk factors in AD, although an ongoing challenge in the field is that data collected from different models or experimental settings have not always been consistent. We examine recent literature on mitochondrial dysregulation in AD, with special emphasis on mitochondrial calcium. We include data from in vitro systems, genetic animal models, and AD-derived human tissue, and discuss whether mitochondrial calcium transporters should be proposed as therapeutic candidates for the development of neuroprotective drugs against AD.

Mitochondrial Peptide Humanin Protects Silver Nanoparticles-Induced Neurotoxicity in Human Neuroblastoma Cancer Cells (SH-SY5Y)

The extensive usage of silver nanoparticles (AgNPs) as medical products such as antimicrobial and anticancer agents has raised concerns about their harmful effects on human beings. AgNPs can potentially induce oxidative stress and apoptosis in cells. However, humanin (HN) is a small secreted peptide that has cytoprotective and neuroprotective cellular effects. The aim of this study was to assess the harmful effects of AgNPs on human neuroblastoma SH-SY5Y cells and also to investigate the protective effect of HN from AgNPs-induced cell death, mitochondrial dysfunctions, DNA damage, and apoptosis. AgNPs were prepared with an average size of 18 nm diameter to study their interaction with SH-SY5Y cells. AgNPs caused a dose-dependent decrease of cell viability and proliferation, induced loss of plasma-membrane integrity, oxidative stress, loss of mitochondrial membrane potential (MMP), and loss of ATP content, amongst other effects. Pretreatment or co-treatment of HN with AgNPs protected cells from several of these AgNPs induced adverse effects. Thus, this study demonstrated for the first time that HN protected neuroblastoma cells against AgNPs-induced neurotoxicity. The mechanisms of the HN-mediated protective effect on neuroblastoma cells may provide further insights for the development of novel therapeutic agents against neurodegenerative diseases.

Tournefolic acid B, derived from Clinopodium chinense (Benth.) Kuntze, protects against myocardial ischemia/reperfusion injury by inhibiting endoplasmic reticulum stress-regulated apoptosis via PI3K/AKT pathways

BACKGROUND

Protection the heart from ischemia/reperfusion (I/R) injury is an area of intense research, as myocardial infarction is a major cause of mortality and morbidity all around the world. Tournefolic acid B (TAB) is a relative new compound derived from Clinopodium chinense (Benth.) Kuntze (Chinese name: Feng Lun Cai). This traditional Chinese herbal medicine has been used for its activities on anti-inflammatory, lowering blood glucose, antitumor and antiradiation. However, the pharmacological effects of TAB were rarely studied.

PURPOSE

Pathways involving phosphoinositide 3-kinase (PI3K) and protein kinase b (Akt) are crucial in regulating the ER stress and associated apoptosis in the process of I/R injury. In the present study, we aim to investigate the cardioprotective effects of tournefolic acid B (TAB) against myocardial I/R injury and explore the molecular mechanisms involved.

STUDY DESIGN

H9c2 cadiomyocyte were incubated with TAB for 24 h and then exposed to hypoxia/reoxygenation. Isolated rat hearts were subjected to global ischemia and reperfusion in the absence or presence of TAB.

METHODS

The possible mechanisms were investigated in vitro and ex vivo by multiple detection methods including JC-1 staining, ROS detection, activities of caspases detection, TUNEL staining, and Western-blot analysis.

RESULTS

We found that TAB significantly improved the hemodynamic parameters (LVeDP, LVSP, + dP/dt_max, - dP/dt_min, and HR) of isolated rat hearts, and depressed the cardiomyocyte apoptosis. Besides, TAB inhibited the oxidative stress by adjusting the activities of antioxidant enzymes (SOD, CAT, and GSH-Px). The I/R injury triggered the endoplasmic reticulum (ER) stress by activating the ER proteins, such as Grp78, ATF6, PERK, and eIf2α. which are all refrained by TAB. TAB also enhanced the phosphorylation of PI3K and AKT, inhibited the expression of CHOP and Caspase-12, reduced the phosphorylation of JNK, and increased Bcl-2/Bax ratio.

CONCLUSION

TAB protects against myocardial I/R injury by suppressing PI3K/AKT-mediated ER stress, oxidative stress, and apoptosis, revealing a promising therapeutic agent against ischemic cardiovascular diseases.

Lithospermic acid attenuates 1-methyl-4-phenylpyridine-induced neurotoxicity by blocking neuronal apoptotic and neuroinflammatory pathways

Background

Parkinson’s disease is the second most common neurodegenerative disorders after Alzheimer’s disease. The main cause of the disease is the massive degeneration of dopaminergic neurons in the substantia nigra. Neuronal apoptosis and neuroinflammation are thought to be the key contributors to the neuronal degeneration.

Results

Both CATH.a cells and ICR mice were treated with 1-methyl-4-phenylpyridin (MPP⁺) to induce neurotoxicity in vitro and in vivo. Western blotting and immunohistochemistry were also used to analyse neurotoxicity, neuroinflammation and aberrant neurogenesis in vivo. The experiment in CATH.a cells showed that the treatment of MPP⁺ impaired intake of cell membrane and activated caspase system, suggesting that the neurotoxic mechanisms of MPP⁺ might include both necrosis and apoptosis. Pretreatment of lithospermic acid might prevent these toxicities. Lithospermic acid possesses specific inhibitory effect on caspase 3. In mitochondria, MPP⁺ caused mitochondrial depolarization and induced endoplasmic reticulum stress via increasing expression of chaperone protein, GRP-78. All the effects mentioned above were reduced by lithospermic acid. In animal model, the immunohistochemistry of mice brain sections revealed that MPP⁺ decreased the amount of dopaminergic neurons, enhanced microglia activation, promoted astrogliosis in both substantia nigra and hippocampus, and MPP⁺ provoked the aberrant neurogenesis in hippocampus. Lithospermic acid significantly attenuates all of these effects induced by MPP⁺.

Conclusions

Lithospermic acid is a potential candidate drug for the novel therapeutic intervention on Parkinson’s disease.

Mitochondria-Targeted Protective Compounds in Parkinson's and Alzheimer's Diseases

Mitochondria are cytoplasmic organelles that regulate both metabolic and apoptotic signaling pathways; their most highlighted functions include cellular energy generation in the form of adenosine triphosphate (ATP), regulation of cellular calcium homeostasis, balance between ROS production and detoxification, mediation of apoptosis cell death, and synthesis and metabolism of various key molecules. Consistent evidence suggests that mitochondrial failure is associated with early events in the pathogenesis of ageing-related neurodegenerative disorders including Parkinson's disease and Alzheimer's disease. Mitochondria-targeted protective compounds that prevent or minimize mitochondrial dysfunction constitute potential therapeutic strategies in the prevention and treatment of these central nervous system diseases. This paper provides an overview of the involvement of mitochondrial dysfunction in Parkinson's and Alzheimer's diseases, with particular attention to in vitro and in vivo studies on promising endogenous and exogenous mitochondria-targeted protective compounds.

Modulation of mitochondrial calcium as a pharmacological target for Alzheimer's disease

Perturbed neuronal calcium homeostasis is a prominent feature in Alzheimer's disease (AD). Mitochondria accumulate calcium ions (Ca(2+)) for cellular bioenergetic metabolism and suppression of mitochondrial motility within the cell. Excessive Ca(2+) uptake into mitochondria often leads to mitochondrial membrane permeabilization and induction of apoptosis. Ca(2+) is an interesting second messenger which can initiate both cellular life and death pathways in mitochondria. This review critically discusses the potential of manipulating mitochondrial Ca(2+) concentrations as a novel therapeutic opportunity for treating AD. This review also highlights the neuroprotective role of a number of currently available agents that modulate different mitochondrial Ca(2+) transport pathways. It is reasoned that these mitochondrial Ca(2+) modulators are most effective in combination with agents that increase the Ca(2+) buffering capacity of mitochondria. Modulation of mitochondrial Ca(2+) handling is a potential pharmacological target for future development of AD treatments.

Protective effects of [Gly14]-Humanin on beta-amyloid-induced PC12 cell death by preventing mitochondrial dysfunction

Mitochondrial dysfunction is a hallmark of beta-amyloid (Abeta)-induced neuronal toxicity in Alzheimer's disease (AD), and is considered as an early event in AD pathology. Humanin (HN) and its derivative, [Gly14]-Humanin (HNG), are known for their ability to suppress neuronal death induced by AD-related insults in vitro and in vivo. In the present study, we investigated the neuroprotective effects of HNG on Abeta(25-35)-induced toxicity and its potential mechanisms in PC12 cells. Exposure of PC12 cells to 25 microM Abeta(25-35) caused significant viability loss and cell apoptosis. In addition, decreased mitochondrial membrane potential and increased cytochrome c releases from mitochondria were also observed after Abeta(25-35) exposure. All these effects induced by Abeta(25-35) were markedly reversed by HNG. Pretreatment with 100 nM HNG 6h prior to Abeta(25-35) exposure significantly elevated cell viability, reduced Abeta(25-35)-induced cell apoptosis, stabilized mitochondrial membrane potential, and blocked cytochrome c release from mitochondria. Furthermore, HNG also ameliorated the Abeta(25-35)-induced Bcl-2/Bax ratio reduction and decreased caspase-3 activity in PC12 cells. These results demonstrate that HNG could attenuate Abeta(25-35)-induced PC12 cell injury and apoptosis by preventing mitochondrial dysfunction. Furthermore, these data suggest that mitochondria are involved in the protective effect of HNG against Abeta(25-35).