Reactive oxygen species mediate caspase activation and apoptosis induced by lipoic acid in human lung epithelial cancer cells through Bcl-2 down-regulation

The regulatory mechanisms for beef tenderization by the calcium-independent phospholipase A2 activity of Peroxiredoxin 6

This study investigated the effect of the inhibition of the activity of Ca2+-independent Phospholipase A2 (iPLA2) of Peroxiredoxin 6 (Prdx6) on beef tenderization in the early post-mortem period. Longissimus lumborum (LL) were incubated with or without the inhibitor of iPLA2 activity of Prdx6 (MJ33) for 1, 6, 12, 24, or 36 h, followed by incubation with or without the H2O2. iPLA2 activity, troponin T and desmin, Ca2+ concentration, calpain-1, caspases, apoptosis rate, and cell morphology were examined. It was found that the reduction of the iPLA2 activity of Prdx6 was found to promote degradation of cytoskeletal proteins (troponin T, desmin). The inhibition of the iPLA2 activity of Prdx6 suppressed the caspases activation. This reduced the apoptotic rate, but increased Ca2+ concentrations and calpain-1 activation, outcomes that promoted beef tenderization. This mechanistic characterization confirms the application of Prdx6 as a biomarker for beef of high quality and consumer acceptance.

Lipoic Acid/Choline Ionic Liquid Enhanced Intratumoral Heat/Mass Transfer for Suppressing Thermo-Mediated Tumor Relapse and Metastasis

Thermal ablation (TA) is widely used for clinical treatment of various cancers. However, TA often struggles to efficiently kill tumor cells without injuring adjacent normal tissues/cells, leading to thermo-mediated tumor relapse and metastasis, owing to the immunosuppressive microenvironment surrounding residual tumor cells. In this study, a temperature-sensitive ionic liquid composed of lipoic acid and choline (LACH/PNA) is developed as a multifunctional TA sensitizer to suppress tumor metastasis induced by incomplete microwave ablation. LACH/PNA exhibits a high diffusion coefficient by disrupting the tumor matrix and modulating cancer-associated fibroblasts, thereby facilitating heat and mass transfer in tumors. LACH/PNA demonstrates greater cytotoxicity toward hepatoma cells than on normal hepatocytes with this effect further intensified by thermal treatment. These findings highlight LACH/PNA as a promising multifunctional sensitizer for clinical chemoablation-microwave ablation synergy.

Insight into the molecular mechanism of anti-breast cancer therapeutic potential of substituted salicylidene-based compounds using cell-based assays and molecular docking studies

Targeting oxidative stress and inflammatory signaling pathways is an effective cancer prevention and therapy approach. The mechanism of action of synthesized salicylidene-based compounds was investigated in regulating key molecular targets of breast cancer development. Compounds (1), (4), (5), and (7) were found to be more cytotoxic to MCF-7 and 4T1 cells compared to non-cancerous Chang liver cells, while these compounds were cytotoxic to MDA-MB-231 cells, but with poor selectivity. The colony formation assay indicated that bioactive compounds induced significant damage to breast cancer cells, as observed by a reduction in the number of colonies compared to control cells. By inducing a concentration and time-dependent increase of luminescence and fluorescence of phosphatidylserine, and activating the expression of caspases-3, -7, -8, -9 in breast cancer cells, (1) and (7) have shown to induce caspase-dependent apoptosis. The downregulation of NF-kB-p65 and an upregulation of TP53 expression after exposure to bioactive compounds, demonstrated the suppression of two key targets of breast cancer development. Molecular docking studies revealed that selected protein targets strongly interact with bioactive compounds, and the estimated inhibition constants (Ki) of JAK2, STAT3, COX-2, HPV31 E6, EGFR1, TP53, and PARP1 were significantly decreased compared to acetylsalicylic acid. This could be a clear indication that these protein targets are implicated with antiproliferative efficacy, thereby warranting the potential of (1) and (7) to be used as anti-breast cancer drug candidates.

THERAPEUTIC USE OF ALPHA-LIPOIC ACID SUPPLEMENTATION: A REVIEW ON CURRENT USE AND FUTURE PROSPECTIVE

Alpha-lipoic acid (ALA, thioctic acid, 5-(1,2-dithiolan-3-yl) pentanoic acid) is an organosulfur compound produced by plants, humans, and animals. ALA plays a crucial role in mitochondrial bioenergetics reactions. It is a natural antioxidant and a dithiol compound. ALA is a coenzyme that plays a crucial role in the function of pyruvate and Alpha-ketoglutarate dehydrogenase complexes found in mitochondria. ALA has cytotoxic and antiproliferative effects on several cancers, including Polycystic Ovarian Syndrome (PCOS). Most of ALA's clinical applications come from its antioxidant properties, but it also shows potential in treating female and male infertility. Although ALA can potentially be a therapeutic agent, its pharmacokinetic profile limits its effectiveness. Research suggests that ALA has a short half-life and low bioavailability (around 30%) because it gets broken down in the liver, has reduced solubility, and is unstable in the stomach. Liquid formulations have higher bioavailability and plasma concentration than solid dose forms. This review covers the current clinical evidence on using ALA to prevent, manage, and cure numerous disorders, including diabetic neuropathy, obesity, central nervous system-related ailments, and pregnancy abnormalities.

Effects of oxidative stress and protein S-nitrosylation interactions on mitochondrial pathway apoptosis and tenderness of yak meat during postmortem aging

To reveal the interaction of oxidative stress and protein S-nitrosylation on mitochondrial pathway apoptosis and tenderness development in postmortem yak meat. Herein, we selected yak longissimus dorsi muscle as the research object and treated hydrogen peroxide (H2O2) with S-nitrosoglutathione agent (GSNO) as well as Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) in mixed injections with 0.9 % saline as a control group, followed by incubation at 4 °C for 12, 24, 72, 120 and 168 h. Results showed that this interaction significantly increased mitochondrial ROS and NO content (P < 0.05) while weakening the antioxidant capacity of GSH and TRX redox response systems or accelerating the Ca2+ release process, leading to mitochondrial functional impairment and increased apoptosis rate. Notably, the H2O2 + L-NAME group showed more pronounced apoptosis. Hence, we suggest that the interaction between oxidative stress and protein S-nitrosylation could positively regulate yak meat tenderization.

Dissecting the pleiotropic roles of reactive oxygen species (ROS) in lung cancer: From carcinogenesis toward therapy

Lung cancer is a major cause of morbidity and mortality. The specific pulmonary structure to directly connect with ambient air makes it more susceptible to damage from airborne toxins. External oxidative stimuli and endogenous reactive oxygen species (ROS) play a crucial role in promoting lung carcinogenesis and development. The biological properties of higher ROS levels in tumor cells than in normal cells make them more sensitive and vulnerable to ROS injury. Therefore, the strategy of targeting ROS has been proposed for cancer therapy for decades. However, it is embarrassing that countless attempts at ROS-based therapies have had very limited success, and no FDA approval in the anticancer list was mechanistically based on ROS manipulation. Even compared with the untargetable proteins, such as transcription factors, ROS are more difficult to be targeted due to their chemical properties. Thus, the pleiotropic roles of ROS provide therapeutic potential for anticancer drug discovery, while a better dissection of the mechanistic action and signaling pathways is a prerequisite for future breakthroughs. This review discusses the critical roles of ROS in cancer carcinogenesis, ROS-inspired signaling pathways, and ROS-based treatment, exemplified by lung cancer. In particular, an eight considerations rule is proposed for ROS-targeting strategies and drug design and development.

Dichloroacetate for Cancer Treatment: Some Facts and Many Doubts

Rarely has a chemical elicited as much controversy as dichloroacetate (DCA). DCA was initially considered a dangerous toxic industrial waste product, then a potential treatment for lactic acidosis. However, the main controversies started in 2008 when DCA was found to have anti-cancer effects on experimental animals. These publications showed contradictory results in vivo and in vitro such that a thorough consideration of this compound's in cancer is merited. Despite 50 years of experimentation, DCA's future in therapeutics is uncertain. Without adequate clinical trials and health authorities' approval, DCA has been introduced in off-label cancer treatments in alternative medicine clinics in Canada, Germany, and other European countries. The lack of well-planned clinical trials and its use by people without medical training has discouraged consideration by the scientific community. There are few thorough clinical studies of DCA, and many publications are individual case reports. Case reports of DCA's benefits against cancer have been increasing recently. Furthermore, it has been shown that DCA synergizes with conventional treatments and other repurposable drugs. Beyond the classic DCA target, pyruvate dehydrogenase kinase, new target molecules have also been recently discovered. These findings have renewed interest in DCA. This paper explores whether existing evidence justifies further research on DCA for cancer treatment and it explores the role DCA may play in it.

Betulinic acid inhibits the proliferation of human laryngeal carcinoma cells through reactive oxygen species-mediate mitochondrial apoptotic pathway

Betulinic acid (BA), a natural pentacyclic triterpene, was extracted from the white birch tree, Triphyophyllum peltatum and the jujube tree. In a variety of human cancer cell lines, this substance displays anticancer properties. In this study, we examined how BA works to inhibit human laryngeal cancer growth. We discovered that BA minimally exhibited cytotoxicity in normal cells (human normal cell line GES-1), while remarkably inhibiting viability of AMC-HN-8, TU212, HEp-2 and M4e cells in a concentration-dependent manner. In AMC-HN-8 cancer cells, BA induced apoptosis, activated caspase-3/9/PARP, significantly reduced mitochondrial membrane potential (MMP), increased the expression of cytochrome C in the cytoplasm, transported Bax to the mitochondria, increased the production of reactive oxygen species (ROS), and the ROS scavenger N-acetylcysteine can reduce apoptosis. All data showed that BA triggered apoptosis via the mitochondrial pathway, in which ROS production was likely involved. The findings support the development of BA as a viable drug for the treatment of human laryngeal carcinoma.

Synergistic inhibitory actions of resveratrol, epigallocatechin-3-gallate, and diallyl trisulfide against skin cancer cell line A431 through mitochondrial caspase dependent pathway: a combinational drug approach

The harmful effect of chemotherapeutic side effects has paid a way to discover a novel with curative way for skin cancer treatment. Skin cancer prevention is more viable with the use of combination of bioactive agents than using of single bioactive compounds. Present work was demonstrated to evaluate the interaction of Resveratrol (Res), Epigallocatechin-3-gallate (EGCG), and diallyl trisulfide (DATS) with each other as a binary combination on A431 cells. Nuclear fragmentation analysis of combination of bioactive agents using DAPI analysis, detection of apoptosis, analysis of cell cycle, ROS assay, antimigration assays, and western blotting were implemented to study the combination of bioactive compounds on A431 cell line. Among the selected combination EGCG + DATS had a synergetic effect reducing cellular migration, increased intercellular reactive oxygen species generation, condensation, cell phagocytosis induced by phosphatidylserine externalization, rise in sub-G1 DNA content, and S-phase were cell cycle arrest. The combinations EGCG + DATS induced apoptotic proteins in A431 cells by upregulation of proapoptotic Bax and Bad proteins, a downmodulation of anti-apoptotic proteins Bcl2 and caspases (caspase-3, and -9) activity got triggered by intrinsic pathway. The combination of EGCG + DATS showed good anticancer potential against A431 skin cancer cell line via the mitochondrial caspase dependent pathway with very strong synergism. This finding will help to produce a novel combination/chemoprevention using dietary bioactive agents (EGCG + DATS) for the treatment of skin cancer after clinical trial.

Alpha-Lipoic Acid Reduces Cell Growth, Inhibits Autophagy, and Counteracts Prostate Cancer Cell Migration and Invasion: Evidence from In Vitro Studies

Alpha-lipoic acid (ALA) is a natural antioxidant dithiol compound, exerting antiproliferative and antimetastatic effects in various cancer cell lines. In our study, we demonstrated that ALA reduces the cell growth of prostate cancer cells LNCaP and DU-145. Western blot results revealed that in both cancer cells, ALA, by upregulating pmTOR expression, reduced the protein content of two autophagy initiation markers, Beclin-1 and MAPLC3. Concomitantly, MTT assays showed that chloroquine (CQ) exposure, a well-known autophagy inhibitor, reduced cells' viability. This was more evident for treatment using the combination ALA + CQ, suggesting that ALA can reduce cells' viability by inhibiting autophagy. In addition, in DU-145 cells we observed that ALA affected the oxidative/redox balance system by deregulating the KEAP1/Nrf2/p62 signaling pathway. ALA decreased ROS production, SOD1 and GSTP1 protein expression, and significantly reduced the cytosolic and nuclear content of the transcription factor Nrf2, concomitantly downregulating p62, suggesting that ALA disrupted p62-Nrf2 feedback loop. Conversely, in LNCaP cells, ALA exposure upregulated both SOD1 and p62 protein expression, but did not affect the KEAP1/Nrf2/p62 signaling pathway. In addition, wound-healing, Western blot, and immunofluorescence assays evidenced that ALA significantly reduced the motility of LNCaP and DU-145 cells and downregulated the protein expression of TGFβ1 and vimentin and the deposition of fibronectin. Finally, a soft agar assay revealed that ALA decreased the colony formation of both the prostate cancer cells by affecting the anchorage independent growth. Collectively, our in vitro evidence demonstrated that in prostate cancer cells, ALA reduces cell growth and counteracts both migration and invasion. Further studies are needed in order to achieve a better understanding of the underlined molecular mechanisms.

Stereospecificity of Ginsenoside AD-1 and AD-2 Showed Anticancer Activity via Inducing Mitochondrial Dysfunction and Reactive Oxygen Species Mediate Cell Apoptosis

In this paper, the anti-cancer activity and molecular mechanisms of the isomers of AD-1 and AD-2 (20(R)-AD-1, 20(R)-AD-2, 20(S)-AD-1 and 20(S)-AD-2) were investigated. The results indicated that all of the four compounds obviously suppressed the viability of various cancer cells, and the anti-cancer activity of 20(R)-AD-1 and 20(R)-AD-2 was significantly better than 20(S)-AD-1 and 20(S)-AD-2, especially for gastric cancer cells (BGC-803). Then, the differences in the anti-cancer mechanisms of the isomers were investigated. The data showed that 20(R)-AD-1 and 20(R)-AD-2 induced apoptosis and decreased MMP, up-regulated the expression of cytochrome C in cytosol, transferred Bax to the mitochondria, suppressed oxidative phosphorylation and glycolysis and stimulated reactive oxygen species (ROS) production. Apoptosis can be attenuated by the reactive oxygen species scavenger N-acetylcysteine. However, 20(S)-AD-1 and 20(S)-AD-2 barely exhibited the same results. The results indicated that 20(R)-AD-1 and 20(R)-AD-2 suppressed cellular energy metabolism and caused apoptosis through the mitochondrial pathway, which ROS generation was probably involved in. Above all, the data support the development of 20(R)-AD-1 and 20(R)-AD-2 as potential agents for human gastric carcinoma therapy.

Alpha-lipoic acid induced apoptosis of PC3 prostate cancer cells through an alteration on mitochondrial membrane depolarization and MMP-9 mRNA expression

Cancer has become an important cause of mortality and morbidity in the world. Over the past decades, biomedical research revealed insights into the molecular events and signaling pathways involved in carcinogenesis and cancer progression. Matrix metalloproteinases (MMPs) are a diverse family of enzymes that can degrade various components of the extracellular matrix and are considered as potential diagnostic and prognostic biomarkers for many cancer types and cancer stages. Recently, studies on the role of natural-origin active substances in the prevention of cancer development gained importance. Among them, the α-lipoic acid, which is commonly found in plants, displayed potent anti-proliferative effects on cancer cell lines. However, the effect of the compound on the induction of apoptosis and mRNA expression of MMPs in human prostate cancer cells remains unclear. The present study aimed to evaluate the anti-proliferative and apoptotic activity of α-lipoic acid in human PC3 prostate carcinoma cells considering different concentrations and exposure durations. The findings showed that, α-lipoic acid significantly decreased PC3 cell viability with an IC₅₀ value of 1.71 mM at 48 h (p < 0.05). Additionally, the compound significantly increased Annexin-V binding in cells compared to control and induced a significant alteration in mitochondrial membrane potential and caspase levels (p < 0.05). Furhermore, the RT-PCR analyses have revealed that α-lipoic acid reduced MMP-9 mRNA expression in PC3 cells compared to the control (p < 0.05). In conclusion, this study highlights that α-lipoic acid induced apoptosis in human PC3 prostate cancer cells and inhibited the MMP-9 gene at the mRNA level, which is known to play a role in metastasis development.

The effects of non-functionalized polystyrene nanoparticles of different diameters on the induction of apoptosis and mTOR level in human peripheral blood mononuclear cells

Particles of various types of plastics, including polystyrene nanoparticles (PS-NPs), have been determined in human blood, placenta, and lungs. These findings suggest a potential detrimental effect of PS-NPs on bloodstream cells. The purpose of this study was to assess the mechanism underlying PS-NPs-induced apoptosis in human peripheral blood mononuclear cells (PBMCs). Non-functionalized PS-NPs of three diameters: 29 nm, 44 nm, and 72 nm were studied used in this research. PBMCs were isolated from human leukocyte-platelet buffy coat and treated with PS-NPs at concentrations ranging from 0.001 to 200 μg/mL for 24 h. Apoptotic mechanism of action was evaluated by determining the level of cytosolic calcium ions, as well as mitochondrial transmembrane potential, and ATP levels. Furthermore, detection of caspase-8, -9, and -3 activation, as well as mTOR level was conducted. The presence of apoptotic PBMCs was confirmed by the method of double staining of the cells with propidium iodide and FITC-conjugated Annexin V. We found that all tested NPs increased calcium ion and depleted mitochondrial transmembrane potential levels. The tested NPs also activated caspase-9 and caspase-3, and the smallest NPs of 29 nm of diameter also activated caspase-8. The results clearly showed that apoptotic changes and an increase of mTOR level depended on the size of the tested NPs, while the smallest particles caused the greatest alterations. PS-NPs of 26 nm of diameter activated the extrinsic pathway (increased caspase-8 activity), as well as intrinsic (mitochondrial) pathway (increased caspase-9 activity, raised calcium ion level, and decreased transmembrane mitochondrial potential) of apoptosis. All PS-NPs increased mTOR level at the concentrations smaller than those that induced apoptosis and its level returned to control value when the process of apoptosis escalated.

Pyrazolo[4,3-e]tetrazolo[1,5-b][1,2,4]triazine Sulfonamides as Novel Potential Anticancer Agents: Apoptosis, Oxidative Stress, and Cell Cycle Analysis

The current study continues the evaluation of the anticancer potential of three de novo synthesized pyrazolo[4,3-e]tetrazolo[1,5-b][1,2,4]triazine sulfonamides-MM129, MM130, and MM131-against human cancer cells of HeLa, HCT 116, PC-3, and BxPC-3 lines. The pro-apoptotic activity of the investigated sulfonamides was shown by observations of changes in the mitochondrial transmembrane potential of the tested cells, externalization of phosphatidylserine on the cellular membrane surface, and cell morphology in microscopic imaging. The computational studies have shown that MM129 exhibited the lowest binding energy values when docked against CDK enzymes. In addition, the highest stability was shown for complexes formed between MM129 and CDK5/8 enzymes. All examined compounds induced cell cycle arrest in the G0/G1 phase in the BxPC-3 and PC-3 cells and simultaneously caused the accumulation of cells in the S phase in the HCT 116 cells. In addition, the increase in the subG1 fraction was observed in PC-3 and HeLa cells. The application of a fluorescent H₂DCFDA probe revealed the high pro-oxidative properties of the tested triazine derivatives, especially MM131. In conclusion, the obtained results suggest that MM129, MM130, and MM131 exhibited strong pro-apoptotic properties towards investigated cells, mainly against the HeLa and HCT 116 cell lines, and high pro-oxidative potential as well. Moreover, it is suggested that the anticancer activity of the tested compounds may be associated with their ability to inhibit CDK enzymes activities.

Knockdown of heat shock protein family D member 1 (HSPD1) promotes proliferation and migration of ovarian cancer cells via disrupting the stability of mitochondrial 3-oxoacyl-ACP synthase (OXSM)

BACKGROUND

Heat shock protein 60 (HSP60) is essential for the folding and assembly of newly imported proteins to the mitochondria. HSP60 is overexpressed in most types of cancer, but its association with ovarian cancer is still in dispute. SKOV3 and OVCAR3 were used as experimental models after comparing the expression level of mitochondrial HSP60 in a normal human ovarian epithelial cell line and four ovarian cancer cell lines.

RESULTS

Low HSPD1 (Heat Shock Protein Family D (HSP60) Member 1) expression was associated with unfavorable prognosis in ovarian cancer patients. Knockdown of HSPD1 significantly promoted the proliferation and migration of ovarian cancer cells. The differentially expressed proteins after HSPD1 knockdown were enriched in the lipoic acid (LA) biosynthesis and metabolism pathway, in which mitochondrial 3-oxoacyl-ACP synthase (OXSM) was the most downregulated protein and responsible for lipoic acid synthesis. HSP60 interacted with OXSM and overexpression of OXSM or LA treatment could reverse proliferation promotion mediated by HSPD1 knockdown.

CONCLUSIONS

HSP60 interacted with OXSM and maintained its stability. Knockdown of HSPD1 could promote the proliferation and migration of SKOV3 and OVCAR3 via lowering the protein level of OXSM and LA synthesis.

The effects of lipoic acid on respiratory diseases

Respiratory diseases, including lung cancer, pulmonary fibrosis, asthma, and the recently emerging fatal coronavirus disease-19 (COVID-19), are the leading causes of illness and death worldwide. The increasing incidence and mortality rates have attracted much attention to the prevention and treatment of these conditions. Lipoic acid (LA), a naturally occurring organosulfur compound, is not only essential for mitochondrial aerobic metabolism but also shows therapeutic potential via certain pharmacological effects (e.g., antioxidative and anti-inflammatory effects). In recent years, accumulating evidence (animal experiments and in vitro studies) has suggested a role of LA in ameliorating many respiratory diseases (e.g., lung cancer, fibrosis, asthma, acute lung injury and smoking-induced lung injury). Therefore, this review will provide an overview of the present investigational evidence on the therapeutic effect of LA against respiratory diseases in vitro and in vivo. We also summarize the corresponding mechanisms of action to inspire further basic studies and clinical trials to confirm the health benefits of LA in the context of respiratory diseases.

Antibacterial Mode of Action of β-Amyrin Promotes Apoptosis-Like Death in Escherichia coli by Producing Reactive Oxygen Species

β-Amyrin is a pentacyclic triterpene widely distributed in leaves and stems worldwide. The ability of β-amyrin to induce the production of reactive oxygen species (ROS) in microorganisms suggests its potential as an antimicrobial agent. Thus, this study aimed to elucidate the antibacterial mode of action of β-amyrin. We treated Escherichia coli cells with β-amyrin and found that it triggered ROS accumulation. Excessive stress caused by ROS, particularly hydroxyl radicals, induces glutathione (GSH) dysfunction. GSH protects cells from oxidative and osmotic stresses; thus, its dysfunction leads to membrane depolarization. The resultant change in membrane potential leads to the release of apoptotic proteins, such as caspases. The activated caspases-like protein promotes the cleavage of DNA into single strands, which is a hallmark of apoptosis-like death in bacteria. Apoptotic cells usually undergo events such as DNA fragmentation and phosphatidylserine exposure, differentiating them from necrotic cells, and the cells treated with β-amyrin in this study were positive for annexin V and negative for propidium iodide, indicating apoptosis-like death. In conclusion, our findings suggest that the antibacterial mode of action of β-amyrin involves the induction of ROS, which resulted in apoptosis-like death in E. coli.

Effect of Alpha-Lipoic Acid Supplementation on Low-Grade Squamous Intraepithelial Lesions-Double-Blind, Randomized, Placebo-Controlled Trial

Low-grade squamous intraepithelial lesion (SIL) is a cytologic diagnosis etiologically related to human papilloma virus (HPV) infection that leads to the release of inflammation mediators, the formation of reactive oxygen species (ROS) and decreased levels of antioxidants in tissues, which is why antioxidants might be considered effective against SIL progression. This randomized double-blind placebo-controlled study aimed to investigate the effectiveness of alpha-lipoic acid (ALA) supplementation (600 mg/day) on the regression of low-grade SIL in 100 patients. Low-grade SIL was determined after the cytological screening, colposcopic examination and targeted biopsy and histological confirmation of cytological−colposcopic diagnosis. Inflammation parameters and the presence of HPV were determined by standard laboratory methods. Dietary and lifestyle habits were investigated using a standardized and validated semi-quantitative food questionnaire (FFQ). ALA supplementation significantly reduced the proportion of patients with low-grade cytological abnormalities, in comparison to placebo. Given the obtained level of significance (p < 0.001), the presented results indicate that short-term ALA supplementation shows a clinically significant effect on cervical cytology. Future studies should focus on the use of innovative formulations of ALA that might induce bioavailability and therapeutic efficiency against HPV infection and the investigation of synergistic effects of concurrent dietary/lifestyle modification and ALA supplementation in both low-grade and high-grade SIL.

Impaired energy metabolism and altered functional activity of alveolar type II epithelial cells following exposure of rats to nitrogen mustard

Nitrogen mustard (NM) is a cytotoxic vesicant known to cause acute lung injury which progresses to fibrosis. Alveolar Type II cells are primarily responsible for surfactant production; they also play a key role in lung repair following injury. Herein, we assessed the effects of NM on Type II cell activity. Male Wistar rats were administered NM (0.125 mg/kg) or PBS control intratracheally. Type II cells, lung tissue and BAL were collected 3 d later. NM exposure resulted in double strand DNA breaks in Type II cells, as assessed by expression of γH2AX; this was associated with decreased expression of the DNA repair protein, PARP1. Expression of HO-1 was upregulated and nitrotyrosine residues were noted in Type II cells after NM exposure indicating oxidative stress. NM also caused alterations in Type II cell energy metabolism; thus, both glycolysis and oxidative phosphorylation were reduced; there was also a shift from a reliance on oxidative phosphorylation to glycolysis for ATP production. This was associated with increased expression of pro-apoptotic proteins activated caspase-3 and -9, and decreases in survival proteins, β-catenin, Nur77, HMGB1 and SOCS2. Intracellular signaling molecules important in Type II cell activity including PI3K, Akt2, phospho-p38 MAPK and phospho-ERK were reduced after NM exposure. This was correlated with dysregulation of surfactant protein production and impaired pulmonary functioning. These data demonstrate that Type II cells are targets of NM-induced DNA damage and oxidative stress. Impaired functioning of these cells may contribute to pulmonary toxicity caused by mustards.

Acute and Subacute Toxicity of Fluorescent Gold Nanoclusters Conjugated with α-Lipoic Acid

Fluorescent gold nanoclusters conjugated with α-lipoic acid (FANC) is a promising biocompatible fluorescent nanomaterial with a high potential for drug development. However, there is still no FANC-related research on toxicology, which is very important for future research and the development of healthy food supplements or drugs. This study uses oral administration of FANC to determine the most appropriate dose range in ICR mice for further evaluation. The in vivo acute and subacute toxicity study was conducted by oral administration of FANC to male and female ICR mice. Animal survival, body weight, daily food consumption, hematological profile, organ coefficient, serum biochemistry profile, and histopathological changes were analyzed. FANC did not show any form of morbidity or mortality at acute and subacute toxicity in both male and female ICR mice. Animal behavior, daily food consumption, hematological profile, organ coefficient, and histopathology showed no treatment-related malignant changes at single and repeated doses. Furthermore, serum glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), lactate dehydrogenase (LDH), blood urea nitrogen (BUN), and creatinine (CRE) levels showed no significant malignant changes, which indicated that FANC does not cause liver and renal damage. The only change observed in this study was the change in body weight. The body weight of the FANC-treated group was slightly decreased in female mice but increased in male mice; however, the body weight decreases were below the threshold of concern, and there was no dose-response effect. In conclusion, no observed adverse effect level (NOAEL) in repeated doses was considered in 20 μM/100 μL/25 g male and female ICR mice.

Protective Effects of Alpha-Lipoic Acid against 5-Fluorouracil-Induced Gastrointestinal Mucositis in Rats

Alpha-lipoic acid (ALA) is extensively utilized in multivitamin formulas and anti-aging products. The purpose of this study was to investigate the potential protective benefits of ALA on 5-fluorouracil (5-FU)-induced gastrointestinal mucositis in Wistar albino rats. Tissues from the stomach, small intestine, and large intestine were excised, and blood sera were obtained to identify biochemical indices such as TNF-α, IL-1β, MDA, GPx, SOD, MMP-1, -2, -8, and TIMP-1. A histopathological study was also performed. The results revealed mucositis-elevated TNF-, IL-1, MDA, MMP-1, -2, -8, and TIMP-1 levels in both tissues and sera, and these values dropped dramatically following ALA treatment. Reduced SOD and GPx activities in mucositis groups were reversed in ALA-treated groups. The damage produced by mucositis in the stomach and small intestine regressed in the ALA-treated group, according to histopathological evaluation. Consequently, the implementation of ALA supplementation in 5-FU therapy may act as a protective intervention for cancer patients with gastrointestinal mucositis. In light of the findings, ALA, a food-derived antioxidant with pleiotropic properties, may be an effective treatment for 5-FU-induced gastrointestinal mucositus, and prevent oxidative stress, inflammation, and tissue damage in cancer patients receiving 5-FU therapy.

Design, Synthesis, and Biological Evaluation of Novel Dihydropyridine and Pyridine Analogs as Potent Human Tissue Nonspecific Alkaline Phosphatase Inhibitors with Anticancer Activity: ROS and DNA Damage-Induced Apoptosis

Small molecules with nitrogen-containing scaffolds have gained much attention due to their biological importance in the development of new anticancer agents. The present paper reports the synthesis of a library of new dihydropyridine and pyridine analogs with diverse pharmacophores. All compounds were tested against the human tissue nonspecific alkaline phosphatase (h-TNAP) enzyme. Most of the compounds showed excellent enzyme inhibition against h-TNAP, having IC₅₀ values ranging from 0.49 ± 0.025 to 8.8 ± 0.53 µM, which is multi-fold higher than that of the standard inhibitor (levamisole = 22.65 ± 1.60 µM) of the h-TNAP enzyme. Furthermore, an MTT assay was carried out to evaluate cytotoxicity against the HeLa and MCF-7 cancer cell lines. Among the analogs, the most potent dihydropyridine-based compound 4d was selected to investigate pro-apoptotic behavior. The further analysis demonstrated that compound 4d played a significant role in inducing apoptosis through multiple mechanisms, including overproduction of reactive oxygen species, mitochondrial dysfunction, DNA damaging, and arrest of the cell cycle at the G1 phase by inhibiting CDK4/6. The apoptosis-inducing effect of compound 4d was studied through staining agents, microscopic, and flow cytometry techniques. Detailed structure–activity relationship (SAR) and molecular docking studies were carried out to identify the core structural features responsible for inhibiting the enzymatic activity of the h-TNAP enzyme. Moreover, fluorescence emission studies corroborated the binding interaction of compound 4d with DNA through a fluorescence titration experiment.

Review of lipoic acid: From a clinical therapeutic agent to various emerging biomaterials

Lipoic acid (LA), an endogenous small molecule in organisms, has been extensively used for the highly efficient clinical treatment of malignant diseases, which include diabetes, Alzheimer's disease, and cancer over the past seven decades. Tremendous progresses have been made on the use of LA in nanomedicine for the development of various biomaterials because of its unique biological properties and highly adaptable structure since the first discovery. However, there are few reviews thus far, to our knowledge, summarizing this hot subject of research of LA and its derived biomaterials. For this purpose, we present herein the first comprehensive summary on the design and development of LA and its derived materials for biomedical applications. This review first discusses the therapeutic use of LA followed by the description of synthesis and preclinical study of LA-derived-small molecules. The applications of various LA and poly (lipoic acid) (PLA)-derived-biomaterials are next summarized in detail with an emphasis on the use of LA for the design of biomaterials and the diverse properties. This review describes the development of LA from a clinical therapeutic agent to a building unit of various biomaterials field, which will promote the further discovery of new therapeutic uses of LA as therapeutic agents and facile development of LA-based derivates with greater performance for biomedical applications.

Effects of nitric oxide synthase inhibitor on mitochondria apoptosis and meat quality in postmortem Gannan yak (Bos grunniens) meat

This research aimed to explore the effects of the nitric oxide synthase (NOS) inhibitor (L-NAME) on mitochondria apoptosis in postmortem Gannan yak (Bos grunniens) longissimus dorsi (LD) muscle and to explore its effect on meat quality further. The Gannan yak meat samples were treated with the control group (0.9% NaCl) and L-NAME (20, 60, and 100 mM) for 24 h and then stored for 0, 1, 3, 5, and 7 days at 4°C. NOS activity and NO content were investigated, and the parameters of mitochondrial apoptosis of the postmortem Gannan yak meat were determined. Meanwhile, the meat quality such as the centrifugation loss, meat color, and myofibril fragmentation index (MFI) was evaluated. The results indicated that after treatment with L-NAME, NOS activity and NO content decreased, causing mitochondrial membrane damage, Bax protein, and Cyt-c levels increased, and resulted in increased activities of caspase-9 and -3, promoting the occurrence of mitochondrial apoptosis. Furthermore, it increased the tenderness and water retention of Gannan yak meat. The results indicated that NOS inhibitor played a regulatory role in postmortem Gannan yak meat quality by regulating mitochondria apoptosis during postmortem aging. PRACTICAL APPLICATIONS: The meat's tenderness is often considered the most important factor affecting consumers' willingness to repurchase. The relationship of caspases and MFI suggested that L-NAME played a regulatory role in postmortem Gannan yak meat quality by regulating mitochondria apoptosis during postmortem aging. This study provides valuable information for the development of the Gannan yak economy in Tibetan areas.

The Intertwined Roles of Oxidative Stress and Endoplasmic Reticulum Stress in Glaucoma

Glaucoma is the leading cause of irreversible blindness worldwide, and the burden of the disease continues to grow as the global population ages. Currently, the only treatment option is to lower intraocular pressure. A better understanding of glaucoma pathogenesis will help us to develop novel therapeutic options. Oxidative stress has been implicated in the pathogenesis of many diseases. Oxidative stress occurs when there is an imbalance in redox homeostasis, with reactive oxygen species producing processes overcoming anti-oxidant defensive processes. Oxidative stress works in a synergistic fashion with endoplasmic reticulum stress, to drive glaucomatous damage to trabecular meshwork, retinal ganglion cells and the optic nerve head. We discuss the oxidative stress and endoplasmic reticulum stress pathways and their connections including their key intermediary, calcium. We highlight therapeutic options aimed at disrupting these pathways and discuss their potential role in glaucoma treatment.

Quercetin attenuates the proliferation of arsenic-related lung cancer cells via a caspase-dependent DNA damage signaling

Exposure to arsenic (As) mainly through contaminated drinking water enhances the lung tumor progression, invasion, and metastasis. The carcinogenic effect of As is due to the generation of reactive oxygen species (ROS) and DNA damage, and interference with DNA repair machinery. Herein, we investigated the potential therapeutic function of quercetin on As-treated lung cancer cells. Quercetin is a natural product with antioxidative, anti-inflammatory, and antiproliferative properties. We showed that quercetin induced cell death in the As-exposed lung cancer cells in a dose-dependent manner. Quercetin was able to significantly inhibit the proliferation of the As-treated cells over a period of 5 weeks. In addition, quercetin induced ROS-mediated DNA double-strand breaks in the As-treated lung cancer cells. We also showed that ROS generation induced by quercetin activated caspase-3 to a sufficient level to induce DNA damage but insufficient to induce death in As-treated lung cancer cells. Moreover, transient activation of caspase-2 was detected in quercetin- and As-cotreated cells. The flow cytometry-based cell cycle analysis showed that the antiproliferative function of quercetin was mediated by S-phase cell cycle arrest, which was associated with upregulation of the Ataxia Telangiectasia-mutated (ATM), but not ATM and RAD3-related. In conclusion, quercetin synergized the As-driven ROS generation and DNA damage, and induced the S-phase arrest, thus inhibiting the proliferation of As-exposed lung cancer cells. This data suggested that quercetin is an alternative reagent to chemo-drugs to prevent the growth of As-exposed lung cancer cells.

Cytotoxicity and 1H NMR metabolomics analyses of microalgal extracts for synergistic application with Tamoxifen on breast cancer cells with reduced toxicity against Vero cells

This study evaluated the cytotoxic activity of Tamoxifen (TMX), an anti-estrogen drug, with microalgal crude extracts (MCEs) in single and synergistic application (TMX-MCEs) on MCF-7 and 4T1 breast cancer cells, and non-cancerous Vero cells. The MCEs of Nannochloropsis oculata, Tetraselmis suecica and Chlorella sp. from five different solvents (methanol, MET; ethanol, ETH; water, W; chloroform, CHL; and hexane, HEX) were developed. The TMX-MCEs-ETH and W at the 1:2 and 1:3 ratios, attained IC50 of 15.84-29.51 μg/mL against MCF-7; 13.8-31.62 μg/mL against 4T1; and 24.54-85.11 μg/mL against Vero cells. Higher late apoptosis was exhibited against MCF-7 by the TMX-N. oculata-ETH (41.15 %); and by the TMX-T. suecica-ETH (65.69 %) against 4T1 cells. The TMX-T. suecica-ETH also showed higher ADP/ATP ratios, but comparable Caspase activities to control. For Vero cells, overall apoptotic effects were lowered with synergistic application, and only early apoptosis was higher with TMX-T. suecica-ETH but at lower levels (29.84 %). The MCEs-W showed the presence of alanine, oleic acid, linoleic acid, lactic acid, and fumaric acid. Based on Principal Component Analysis (PCA), the spectral signals for polar solvents such as MET and ETH, were found in the same cluster, while the non-polar solvent CHL was with HEX, suggesting similar chemical profiles clustered for the same polarity. The CHL and HEX were more effective with N. oculata and T. suecica which were of the marine origin, while the ETH and MET were more effective with Chlorella sp., which was of the freshwater origin. The synergistic application of microalgal bioactive compounds with TMX can maintain the cytotoxicity against breast cancer cells whilst reducing the toxicity against non-cancerous Vero cells. These findings will benefit the biopharmaceutical, and functional and healthy food industries.

Rg3-enriched red ginseng extract promotes lung cancer cell apoptosis and mitophagy by ROS production

Background

Red Ginseng has been used for many years to treat diseases. Ginsenoside Rg3 has documented therapeutic effects, including anticancer and anti-inflammatory activities. However, the anticancer effect of Rg3-enriched red ginseng extract (Rg3-RGE) and its underlying mechanisms have not been fully explored. We investigated whether Rg3-RGE plays an anti-tumor role in lung cancer cells.

Methods

To examine the effect of Rg3-RGE on lung cancer cells, we performed cell viability assays, flow cytometry, western blotting analysis, and immunofluorescence to monitor specific markers.

Results

Rg3-RGE significantly inhibited cell proliferation and induced mitochondria-dependent apoptosis. Furthermore, Rg3-RGE also increased expression of mitophagy-related proteins such as PINK1 and Parkin. In addition, treatment with Rg3-RGE and mitophagy inhibitors stimulated cell death by inducing mitochondria dysfunction.

Conclusions

Rg3-RGE could be used as a therapeutic agent against lung cancer.

AMP-activated protein kinase contributes to myofibrillar protein hydrolysis in bovine skeletal muscle through postmortem mitochondrial dysfunction-induced apoptosis

This study aimed to verify the role of AMP-activated protein kinase (AMPK) in mitochondrial dysfunction-induced apoptosis and postmortem bovine muscle tenderization. AMPK phosphorylation levels, mitochondrial dysfunction, mitochondrial apoptotic factors, and myofibrillar protein hydrolysis were assessed in the control group and Compound C (AMPK inhibitor) group over a 168 hr aging period. Compared with the Compound C group, the control group had an extremely significantly increased AMPK activity at 6-120 hr (p < .01) and a 62.3% and 42.1% higher mitochondrial Bax/Bcl-2 ratio at 6 and 12 hr, respectively (p < .05). Moreover, the control group had a significantly or extremely significantly higher mitochondrial dysfunction and cytoplasmic cytochrome c content at 6-72 and 12-72 hr, respectively (p < .05, p < .01); a 23.2%, 26.5%, and 26.1% increased caspase-3 expression levels at 12, 24, and 72 hr, respectively (p < .05); a significantly higher proportion of apoptotic nuclei at 24-168 hr (p < .05); and a 30.8%, 35.8%, 43.9%, and 39.5% increased production of 45-, 38-, 36-, 30-, and 28-kDa proteins at 168 hr, respectively (p < .05). Taken together, these results suggested that activated AMPK promoted mitochondrial apoptosis and bovine muscle tenderization during postmortem aging by increasing the Bax/Bcl-2 ratio on the mitochondrial membrane. PRACTICAL APPLICATIONS: Based on consumer preference, chilled fresh meat is gradually becoming the future trend of the meat industry. Poorly tenderized beef often affects consumers' desire to make secondary purchases and leads to large losses to the meat industry. Therefore, AMP-activated protein kinase, which regulates postmortem mitochondrial apoptosis and bovine muscle tenderization, is a valid research target.

α-Lipoic Acid Targeting PDK1/NRF2 Axis Contributes to the Apoptosis Effect of Lung Cancer Cells

As an antioxidant, α-lipoic acid (LA) has attracted much attention to cancer research. However, the exact mechanism of LA in cancer progression control and prevention remains to be unclear. In this study, we demonstrated that α-lipoic acid has inhibitory effects on the proliferation, migration, and proapoptotic effects of non-small-cell lung cancer (NSCLC) cell lines A549 and PC9. LA-induced NSCLC cell apoptosis was mediated by elevated mitochondrial reactive oxygen species (ROS). Further study confirmed that it is by downregulating the expression of PDK1 (the PDH kinase), resulted in less phospho-PDH phenotype which could interact with Keap1, the negative controller of NRF2, directly leading to NRF2 decrease. Thus, by downregulating the NRF2 antioxidant system, LA plays a role in promoting apoptosis through the ROS signaling pathway. Moreover, LA could enhance other PDK inhibitors with the proapoptosis effect. In summary, our study shows that LA promotes apoptosis and exerts its antitumor activity against lung cancer by regulating mitochondrial energy metabolism enzyme-related antioxidative stress system. Administration of LA to the tumor-bearing animal model further supported the antitumor effect of LA. These findings provided new ideas for the clinical application of LA in the field of cancer therapy.

Alpha-Lipoic Acid Attenuates Cadmium- and Lead-Induced Neurotoxicity by Inhibiting Both Endoplasmic-Reticulum Stress and Activation of Fas/FasL and Mitochondrial Apoptotic Pathways in Rat Cerebral Cortex

Although many studies have reported toxic effects of cadmium (Cd) and lead (Pb) in the central nervous system, few studies have investigated the combined toxicity of Cd and Pb. The mechanisms by which these combined heavy metals induce toxicity, as well as effective means to exert neuroprotection from these agents, remain poorly understood. To investigate the protective effects of alpha-lipoic acid (α-LA) on Cd- and/or Pb-induced cortical damage in rats, 48 Sprague-Dawley rats were exposed to drinking water containing 50 mg/L of Cd and/or 300 mg/L of Pb for 12 weeks, in the presence or absence of α-LA co-treatment (50 mg/kg) via gavage. We observed that exposure to Cd and/or Pb decreased the brain weight/body weight ratio and increased Cd and/or Pb contents as well as ultrastructural damage to the cerebral cortex. Cd and/or Pb also induced endoplasmic-reticulum (ER) stress and activated Fas (CD95/APO-1)/Fas ligand (FasL) and mitochondrial apoptotic pathways. Furthermore, co-treatment of Cd and Pb further exacerbated part of these phenotypes than treatment of Cd or Pb alone. However, simultaneous supplementation with α-LA attenuated Cd and/or Pb-induced neurotoxicity by increasing the brain weight/body weight ratio, reducing Cd and/or Pb contents, ameliorating both nuclear/mitochondrial damage and ER stress, and attenuating activation of Fas/FasL and mitochondrial apoptotic pathways. Collectively, our results indicate that the accumulation of Cd and/or Pb causes cortical damage and that α-LA exerts protection against Cd- and/or Pb-induced neurotoxicity. These findings highlight that α-LA may be exploited for the treatment and prevention of Cd- and/or Pb-induced neurotoxicity.

Reprogramming of glucose metabolism of cumulus cells and oocytes and its therapeutic significance

The aim of this review is to summarize our current understanding of the molecular mechanism for the glucose metabolism, especially pyruvate dehydrogenase (PDH), during oocyte maturation, as well as future perspectives of therapeutic strategies for aging focusing on metabolic regulation between aerobic glycolysis and the tricarboxylic acid (TCA) cycle/oxidative phosphorylation (OXPHOS). Each keyword alone or in combination was used to search from PubMed. Glucose metabolism is a dynamic process involving "On" and "Off" switches by the pyruvate dehydrogenase kinase (PDK)-PDH axis, which is crucial for energy metabolism and mitochondrial efficiency in cumulus cell differentiation and oocyte maturation. Activation of PDK suppresses the conversion of pyruvate to acetyl-coenzyme A (acetyl-CoA) through the inactivation of PDH, which allows the cumulus cells to supply sufficient amounts of pyruvate, lactate, and nicotinamide adenine dinucleotide phosphate (NADPH) to the oocytes. On the other hand, inactivation of PDK in oocytes can produce adenosine triphosphate (ATP) through a metabolic shift from aerobic glycolysis to the TCA cycle/OXPHOS. The metabolic balance between aerobic glycolysis and TCA cycle/OXPHOS presents us with a number of enzymes, ligands, receptors, and antioxidants that are potential therapeutic targets, some of which have already been successfully pursued to improve fertility outcomes. However, there are also many reports that question their efficacy. In conclusion, understanding the molecular mechanisms involved in the PDK-PDH axis is a crucial step to advance in novel therapeutic strategies to improve oocyte quality.

Potential mechanisms of uremic muscle wasting and the protective role of the mitochondria-targeted antioxidant Mito-TEMPO

BACKGROUND

Muscle wasting is common in patients with chronic kidney disease (CKD). Many studies report that mitochondrial dysfunction and endoplasmic reticulum (ER) stress are involved in the development of muscle wasting. However, treatment approaches to protect against muscle wasting are limited. In this study, we investigated the benefits and potential mechanism of Mito-TEMPO, a mitochondria-targeted antioxidant on uremic-induced muscle wasting.

METHODS

Mice were randomly divided into four groups as follows: control group, CKD group, CKD + Mito-TEMPO group, and Mito-TEMPO group. Renal injury was assessed by measurement of serum creatinine and BUN along with PAS and Masson's staining. Bodyweight, gastrocnemius muscle mass, grip strength, and myofiber cross-sectional areas were investigated to evaluate muscle atrophy. Muscle protein synthesis and proteolysis were evaluated by Western blot and real-time PCR. Inflammatory cytokines including TNF-α, IL-6, IL-1β, and MCP-1 were measured by ELISA kits. Oxidative stress markers such as SOD2 activity and MDA level in gastrocnemius muscle tissue were measured by colorimetric assay. Mitochondrial dysfunction was evaluated by transmission electron microscopy and real-time PCR. ER stress was evaluated by Western blot.

RESULTS

Impaired renal function was significantly restored by Mito-TEMPO treatment. Severe muscle atrophy was observed in muscle tissues of CKD mice along with increased inflammatory factors, oxidative stress markers, mitochondrial dysfunction, and ER stress. However, these effects were significantly attenuated with Mito-TEMPO treatment.

CONCLUSIONS

Mito-TEMPO improved muscle wasting in CKD mice possibly through alleviating mitochondrial dysfunction and endoplasmic reticulum stress, providing a potential new therapeutic approach for preventing muscle wasting in chronic kidney disease.

Activation of Caspase-3 by Terpenoids and Flavonoids in Different Types of Cancer Cells

BACKGROUND

Caspase-3 is accountable for the execution of apoptosis. Recently, it has gained attention as a promising target for the discovery of natural products as anticancer agents.

METHODS

We examined the efficacy of two different sets of natural products (terpenoids and flavonoids) towards caspase-3 activity adopting in silico, cell-free and cell-based activity and real-time gene expression analysis.

RESULTS

It was observed that terpenes activate caspase-3 activity in both the cell-free and cell-based systems, which was supported by the gene expression analysis, binding energy and activation constant. Flavonoids' action, however, was limited to the cell-based system and transcriptional regulation suggesting their indirect association, which enhanced the enzyme activity and up-regulated the expression of mRNA levels in the cells. Among the tested natural products, (+) carvone was observed to be the best activator of caspase-3 in K562 (34.4 μM), WRL-68 (22.3 μM), HeLa (18.7 μM), MCF-7 (39.4 μM) and MDA-MB-231 cell lines (45.1 μM).

CONCLUSION

Overall, terpenoids have a persistent activation of caspase-3 in all the investigated systems, while flavonoids circuitously affect the enzyme activity.

2-Pyrazine-PPD, a novel dammarane derivative, showed anticancer activity by reactive oxygen species-mediate apoptosis and endoplasmic reticulum stress in gastric cancer cells

20 (R)-Dammarane-3β, 12β, 20, 25-tetrol (25-OH-PPD), a ginsenoside, was derived from Panax ginseng (C. A. Meyer) and inhibited growth of several cancer cell lines. To improve the anti-cancer activity, we introduced the pyrazine ring to 25-OH-PPD and obtained the compound 20(R)-[2,3-β]-Pyrazine-dammarane-12β,20,25-triol (2-Pyrazine-PPD). we evaluated the anti-cancer activity of 2-Pyrazine-PPD and investigated the main anti-cancer mechanisms of 2-Pyrazine-PPD in gastric cancer cells. We found that 2-Pyrazine-PPD remarkably suppressed the proliferation of gastric cancer cells in a concentration-dependent, and showed little toxicity to the normal cell (human gastric epithelial cell line-GES-1). Further study indicated that 2-Pyrazine-PPD induced apoptosis by mitochondria pathway in BGC-803 cancer cells, and activated unfolded protein response and the protein kinase RNA-activated (PKR)-like ER kinase (PERK)/Eukaryotic translation initiation factor-2α (eIF-2α)/Activating transcription factor 4 (ATF4) axis, the expression level of the protein C/EBP homologous protein (CHOP), the marker of endoplasmic reticulum stress, and the apoptosis inducing by 2-Pyrazine-PPD can partly be inhibited by siRNA-mediated knockdown of CHOP. Moreover, the production of reactive oxygen species was remarkably up-regulated in BGC-803 cancer cells treated with 2-Pyrazine-PPD. N-acetylcysteine (NAC, a reactive oxygen species scavenger) can attenuate 2-Pyrazine-PPD-induced apoptosis and endoplasmic reticulum stress. Taken together, we suggested that 2-Pyrazine-PPD exhibited remarkable anti-cancer activity by reactive oxygen species-mediate cell apoptosis and endoplasmic reticulum stress in gastric cancer cells. Our results uncovered the mechanism of 2-Pyrazine-PPD as a promising anti-tumor candidate for gastric cancer therapy.

An Overview of the Antioxidant Effects of Ascorbic Acid and Alpha Lipoic Acid (in Liposomal Forms) as Adjuvant in Cancer Treatment

Antioxidants are known to minimize oxidative stress by interacting with free radicals produced as a result of cell aerobic reactions. Oxidative stress has long been linked to many diseases, especially tumours. Therefore, antioxidants play a crucial role in the prevention or management of free radical-related diseases. However, most of these antioxidants have anticancer effects only if taken in large doses. Others show inadequate bioavailability due to their instability in the blood or having a hydrophilic nature that limits their permeation through the cell membrane. Therefore, entrapping antioxidants in liposomes may overcome these drawbacks as liposomes have the capability to accommodate both hydrophilic and hydrophobic compounds with a considerable stability. Additionally, liposomes have the capability to accumulate at the cancer tissue passively, due to their small sizes, with enhanced drug delivery. Additionally, liposomes can be engineered with targeting moieties to increase the delivery of chemotherapeutic agents to specific tumour cells with decreased accumulation in healthy tissues. Therefore, combined use of liposomes and antioxidants, with or without chemotherapeutic agents, is an attractive strategy to combat varies tumours. This mini review focuses on the liposomal delivery of selected antioxidants, namely ascorbic acid (AA) and alpha-lipoic acid (ALA). The contribution of these nanocarriers in enhancing the antioxidant effect of AA and ALA and consequently their anticancer potentials will be demonstrated.

Lipoic acid-induced oxidative stress abrogates IGF-1R maturation by inhibiting the CREB/furin axis in breast cancer cell lines

The beneficial effects of lipoic acid (LA) in cancer treatment have been well documented in the last decade. Indeed, LA exerts crucial antiproliferative effects by reducing breast cancer cell viability, cell cycle progression and the epithelial-to-mesenchymal transition (EMT). However, the mechanisms of action (MOA) underlying these antiproliferative effects remain to be elucidated. Recently, we demonstrated that LA decreases breast cancer cell proliferation by inhibiting IGF-1R maturation via the downregulation of the proprotein convertase furin. The aim of the present study was to investigate the MOA by which LA inhibits furin expression in estrogen receptor α (ERα) (+) and (-) breast cancer cell lines. We unveil that LA exerts a pro-oxidant effect on these cell lines, the resulting reactive oxygen species (ROS) generated being responsible for the reduction in the expression of the major (CREB) protein. This transcription factor is overexpressed in many types of cancers and regulates the expression of furin in breast cancer cells independently of ERα, as evidenced herein by the inhibition of furin expression following CREB silencing. Consequently, our findings expose for the first time the complete MOA of LA via the CREB/furin axis leading to inhibition of breast cancer cell proliferation.

Battling Glioblastoma: A Novel Tyrosine Kinase Inhibitor with Multi-Dimensional Anti-Tumor Effect (Running Title: Cancer Cells Death Signalling Activation)

Glioblastoma (GB), a grade IV glioma, with high heterogeneity and chemoresistance, obligates a multidimensional antagonist to debilitate its competence. Considering the previous reports on thioesters as antitumor compounds, this paper investigates on use of this densely functionalized sulphur rich molecule as a potent anti-GB agent. Bio-evaluation of 12 novel compounds, containing α-thioether ketone and orthothioester functionalities, identified that five analogs exhibited better cytotoxic profile compared to standard drug cisplatin. Detailed toxicity studies of top compound were evaluated in two cell lines, using cell viability test, apoptotic activity, oxidative stress and caspase activation and RNA-sequencing analysis, to obtain a comprehensive molecular profile of drug activity. The most effective molecule presented half maximal inhibitory concentration (IC₅₀) values of 27 μM and 23 μM against U87 and LN229 GB cells, respectively. Same compound effectively weakened various angiogenic pathways, mainly MAPK and JAK-STAT pathways, downregulating VEGF. Transcriptome analysis identified significant promotion of apoptotic genes, and genes involved in cell cycle arrest, with concurrent inhibition of various tyrosine kinase cascades and stress response genes. Docking and immunoblotting studies suggest EGFR as a strong target of the orthothioester identified. Therefore, orthothioesters can potentially serve as a multi-dimensional chemotherapeutic possessing strong cytotoxic, anti-angiogenic and chemo-sensitization activity, challenging glioblastoma pathogenesis.

Insights on the Use of α-Lipoic Acid for Therapeutic Purposes

α-lipoic acid (ALA, thioctic acid) is an organosulfur component produced from plants, animals, and humans. It has various properties, among them great antioxidant potential and is widely used as a racemic drug for diabetic polyneuropathy-associated pain and paresthesia. Naturally, ALA is located in mitochondria, where it is used as a cofactor for pyruvate dehydrogenase (PDH) and α-ketoglutarate dehydrogenase complexes. Despite its various potentials, ALA therapeutic efficacy is relatively low due to its pharmacokinetic profile. Data suggests that ALA has a short half-life and bioavailability (about 30%) triggered by its hepatic degradation, reduced solubility as well as instability in the stomach. However, the use of various innovative formulations has greatly improved ALA bioavailability. The R enantiomer of ALA shows better pharmacokinetic parameters, including increased bioavailability as compared to its S enantiomer. Indeed, the use of amphiphilic matrices has capability to improve ALA bioavailability and intestinal absorption. Also, ALA's liquid formulations are associated with greater plasma concentration and bioavailability as compared to its solidified dosage form. Thus, improved formulations can increase both ALA absorption and bioavailability, leading to a raise in therapeutic efficacy. Interestingly, ALA bioavailability will be dependent on age, while no difference has been found for gender. The present review aims to provide an updated on studies from preclinical to clinical trials assessing ALA's usages in diabetic patients with neuropathy, obesity, central nervous system-related diseases and abnormalities in pregnancy.

4-XL-PPD, a novel ginsenoside derivative, as potential therapeutic agents for gastric cancer shows anti-cancer activity via inducing cell apoptosis medicated generation of reactive oxygen species and inhibiting migratory and invasive

(20R)-Dammarane-3β, 12β, 20, 25-tetrol (25-OH-PPD) is a ginsenoside isolated from Panax ginseng (C. A. Meyer). Previous research shows that the compound exhibits anti-cancer activities on many human cancer cell lines. In an attempt to enhance 25-OH-PPD activity, some derivatives were synthesized. Through screening of the derivative compounds for anti-cancer activity against gastric carcinoma cells, 12β-O-(L-Chloracetyl)-dammar-20(22)-ene-3β, 25-diol (4-XL-PPD) was selected as a strong anti-cancer agent. In this study, the anti-cancer mechanisms of 4-XL-PPD were investigated. The results showed that compound 4-XL-PPD resulted in a concentration-dependent inhibition of cells viability in gastric cancer cells, without affecting the viability of normal cell (human gastric epithelial cell line-GES-1). In BGC-803 cancer cells, 4-XL-PPD triggered apoptosis, and stimulated reactive oxygen species production. Apoptosis can be attenuated by the reactive oxygen species scavenger N-acetylcysteine. Meantime, 4-XL-PPD effectively suppressed the migratory and invasive capabilities of BGC-803 cancer cell and inhibited the expression levels of proteins associated with migratory and invasive capabilities (MMP-2, MMP-9, E-cadherin and CD34). All the results suggest that 4-XL-PPD exhibited remarkable anticancer activity base on inducing apoptosis via generating reactive oxygen species and inhibiting migratory and invasive, which support development of 4-XL-PPD as a potential agent for cancer therapy.

Lipoic Acid Synergizes with Antineoplastic Drugs in Colorectal Cancer by Targeting p53 for Proteasomal Degradation

Lipoic acid (LA) is a redox-active disulphide compound, which functions as a pivotal co-factor for mitochondrial oxidative decarboxylation. LA and chemical derivatives were shown to target mitochondria in cancer cells with altered energy metabolism, thereby inducing cell death. In this study, the impact of LA on the tumor suppressor protein p53 was analyzed in various colorectal cancer (CRC) cell lines, with a focus on the mechanisms driving p53 degradation. First, LA was demonstrated to trigger the depletion of both wildtype and mutant p53 protein in all CRC cells tested without influencing its gene expression and preceded LA-triggered cytotoxicity. Depletion of p53 coincided with a moderate, LA-dependent ROS production, but was not rescued by antioxidant treatment. LA induced the autophagy receptor p62 and differentially modulated autophagosome formation in CRC cells. However, p53 degradation was not mediated via autophagy as shown by chemical inhibition and genetic abrogation of autophagy. LA treatment also stabilized and activated the transcription factor Nrf2 in CRC cells, which was however dispensable for p53 degradation. Mechanistically, p53 was found to be readily ubiquitinylated and degraded by the proteasomal machinery following LA treatment, which did not involve the E3 ubiquitin ligase MDM2. Intriguingly, the combination of LA and anticancer drugs (doxorubicin, 5-fluorouracil) attenuated p53-mediated stabilization of p21 and resulted in synergistic killing in CRC cells in a p53-dependant manner.

Soluble epoxide hydrolase inhibitor, APAU, protects dopaminergic neurons against rotenone induced neurotoxicity: Implications for Parkinson's disease

Epoxyeicosatrienoic acids (EETs), metabolites of arachidonic acid, play a crucial role in cytoprotection by attenuating oxidative stress, inflammation and apoptosis. EETs are rapidly metabolised in vivo by the soluble epoxide hydrolase (sEH). Increasing the half life of EETs by inhibiting the sEH enzyme is a novel strategy for neuroprotection. In the present study, sEH inhibitors APAU was screened in silico and further evaluated for their antiparkinson activity against rotenone (ROT) induced neurodegeneration in N27 dopaminergic cell line and Drosophila melanogaster model of Parkinson disease (PD). In the in vitro study cell viability (MTT and LDH release assay), oxidative stress parameters (total intracellular ROS, hydroperoxides, protein oxidation, lipid peroxidation, superoxide dismutase, catalase, glutathione peroxidise, glutathione reductase, glutathione, total antioxidant status, mitochondrial complex-1activity and mitochondrial membrane potential), inflammatory markers (IL-6, COX-1 and COX-2), and apoptotic markers (JNK, phospho-JNK, c-jun, phospho-c-jun, pro and active caspase-3) were assessed to study the neuroprotective effects. In vivo activity of APAU was assessed in Drosophila melanogaster by measuring survival rate, negative geotaxis, oxidative stress parameters (total intracellular ROS, hydroperoxides, glutathione levels) were measured. Dopamine and its metabolites were estimated by LC-MS/MS analysis. In the in silico study the molecule, APAU showed good binding interaction at the active site of sEH (PDB: 1VJ5). In the in vitro study, APAU significantly attenuated ROT induced changes in oxidative, pro-inflammatory and apoptotic parameters. In the in vivo study, APAU significantly attenuates ROT induced changes in survival rate, negative geotaxis, oxidative stress, dopamine and its metabolites levels (p < 0.05). Our study, therefore, concludes that the molecule APAU, has significant neuroprotection benefits against rotenone induced Parkinsonism.

Decane-1,2-diol derivatives as potential antitumor agents for the treatment of glioblastoma

Glioblastoma remains the most common and aggressive type of malignant brain tumor among adults thus, considerable attention has been given to discovery of novel anti-tumor drugs for its treatment. This study reports the synthesis of a series of twelve novel decane-1,2-diol derivatives and evaluation of its anti-tumor activity in mammalian glioblastoma cell lines, U87 and LN229. Starting from decane-1,2-diol, several derivatives were prepared using a diversity oriented synthesis approach through which a small library composed of esters, silyl ethers, sulfonates, sulfites, sulfates, ketals, and phosphonates was built. The decane-1,2-diol ditosylated derivative, DBT, found to have higher cytotoxicity than the standard drug cisplatin, has IC₅₀ value of 52 µM in U87 and 270 µM in LN229. Migration analysis of U87 cell line treated with the DBT indicated its ability to effectively suppress proliferation during initial hours of treatment and decrease anti-proliferative property over time. Additionally, DBT was assessed for its role in apoptosis, oxidative stress and caspase 3/7 activation in U87. Interestingly, our experiments indicated that its cytotoxicity is independent of Reactive oxygen species induced caspase 3/7 activity. The compound also exhibited caspase independent apoptosis activity in U87. DBT treatment led to G1/S cell cycle arrest and apoptosis induction of glioma cell lines. In addition, we identified 1533 genes with significant changes at the transcriptional level, in response to DBT. A molecular docking study accounting for the interaction of DBT with NMDA receptor disclosed several hydrogen bonds and charged residue interactions with 17 amino acids, which might be the basis of the DBT cytotoxicity observed. We conclude that this molecule exerts its cytotoxicity via caspase 3/7 independent pathways in glioblastoma cells. Concisely, simple decane-1,2-diol derivatives might serve as scaffolds for the development of effective anti-glioblastoma agents.

Synergistic interaction of β-caryophyllene with aromadendrene oxide 2 and phytol induces apoptosis on skin epidermoid cancer cells

BACKGROUND

Pamburus missionis (Wight) Swingle (Rutaceae) is traditionally used in the treatment of swellings, chronic rheumatism, paralysis and puerperal diseases. In a previous study the authors demonstrated apoptotic activity of Pamburus missionis essential oil (EO) on A431 and HaCaT cells. The major components of EO were β-caryophyllene (25.40%), 4(14),11- eudesmadiene (7.17%), aromadendrene oxide 2 (14.01%) (AO-(2) and phytol (6.88%).

PURPOSE OF STUDY

To investigate the role as well as the interactions among EO components inducing apoptosis in A431 and HaCaT cells.

METHODS

Isobolographic analysis and combination index methods were used to detect the type of interactions among the essential oil (EO) components. Cell viability was used to detect cytotoxic activity. Mechanism of cell death was studied using Annexin V-FITC/PI binding assay, cell cycle analysis, measurement of MMP and ROS generation by flow cytometry. Expression of apoptosis associated proteins was investigated by western blot.

RESULTS

Combination of P. missionis EO components: β-caryophyllene/ aromadendrene oxide 2 (β-C/AO-(2)), β-caryophyllene/phytol (β-C/P) and aromadendrene oxide 2 /phytol (AO-(2)/P) inhibited growth and colony formation ability of skin epidermoid A431 and precancerous HaCaT cells. Synergistic interaction was observed between β-C/AO-(2) and β-C/P combination while AO-(2)/P exhibited an additive effect. Combination of components induced chromatin condensation, phosphatidylserine externalisation, increase in sub-G1 DNA content, cell cycle arrest at G0/G1 phase and intracellular ROS accumulation. Inhibition of intracellular ROS by N-acetyl cysteine treatment blocked apoptosis induced by the combinations. The combinations induced apoptosis in A431 and HaCaT cells mediated by loss of mitochondrial membrane potential (ΔΨm), increase in Bax/Bcl-2 ratio, release of cytosolic cytochrome c and activation of caspases (cleaved form of caspase-3, caspase-8, caspase-9) and by PARP cleavage.

CONCLUSION

The present study demonstrates interactions among β-C, AO-(2) and P in the induction of apoptosis on A431 and HaCaT cells. These data suggest the combination of β-caryophyllene with aromadendrene oxide 2 and phytol could be potential therapeutics for the treatment of skin epidermoid cancer and precancerous cells.