Metformin beyond an anti-diabetic agent: A comprehensive and mechanistic review on its effects against natural and chemical toxins

In addition to the anti-diabetic effect of metformin, a growing number of studies have shown that metformin has some exciting properties, such as anti-oxidative capabilities, anticancer, genomic stability, anti-inflammation, and anti-fibrosis, which have potent, that can treat other disorders other than diabetes mellitus. We aimed to describe and review the protective and antidotal efficacy of metformin against biologicals, chemicals, natural, medications, pesticides, and radiation-induced toxicities. A comprehensive search has been performed from Scopus, Web of Science, PubMed, and Google Scholar databases from inception to March 8, 2023. All in vitro, in vivo, and clinical studies were considered. Many studies suggest that metformin affects diseases other than diabetes. It is a radioprotective and chemoprotective drug that also affects viral and bacterial diseases. It can be used against inflammation-related and apoptosis-related abnormalities and against toxins to lower their effects. Besides lowering blood sugar, metformin can attenuate the effects of toxins on body weight, inflammation, apoptosis, necrosis, caspase-3 activation, cell viability and survival rate, reactive oxygen species (ROS), NF-κB, TNF-α, many interleukins, lipid profile, and many enzymes activity such as catalase and superoxide dismutase. It also can reduce the histopathological damages induced by many toxins on the kidneys, liver, and colon. However, clinical trials and human studies are needed before using metformin as a therapeutic agent against other diseases.

Cytotoxic impacts of treated electroplating industrial effluent and the comparative effect of their metal components (Zn, Hg, and Zn+Hg) on Danio rerio gill (DrG) cell line

Effluent produced during the electroplating process can contain high concentrations of heavy metals that can enter the environment and induce toxicity to aquatic organisms. Relatively high concentrations of zinc (Zn) and mercury (Hg) have been detected in treated electroplating industrial effluent (TEPIE), though the cytotoxic potential of these compounds has not been well assessed in fish gills. A novel cell line, Danio rerio gill (DrG), were exposed to TEPIE and concentrations of Zn, Hg, and Zn + Hg previously measured in treated effluent to evaluate the use of the DrG cell line following exposure to environmental pollutants. Several cytotoxic assays were employed to assess the effect of TEPIE, Zn, and Hg on this cell line. The percent cell viability was significantly reduced in a concentration-dependent manner following exposure to TEPIE, Zn, Hg, and Zn + Hg (p < 0.05) for 24 h, with additional morphological changes observed in exposure treatments relative to controls. Additionally, there was a significant induction of DNA damage detected in all exposure treatments determined through comet assay tail length. An increase in intracellular ROS generation was also observed in cells exposed to TEPIE, Zn, Hg, and Zn + Hg, corresponding to dose-dependent increases in apoptosis. Our study confirmed that TEPIE and the metals present in it induced cytotoxicity in the DrG cell line, demonstrating its usefulness as a model to explore relationships between pollutants and fish gills.

A combination of herbal compound (SPTC) along with exercise or metformin more efficiently alleviated diabetic complications through down-regulation of stress oxidative pathway upon activating Nrf2-Keap1 axis in AGE rich diet-induced type 2 diabetic mice

BACKGROUND

SPTC is a mix of four herbal components (Salvia officinalis, Panax ginseng, Trigonella foenum-graeceum, and Cinnamomum zeylanicum) which might be prevented the development of AGE rich diet-induced diabetic complication and liver injury through activated the nuclear factor erythroid-2-related-factor-2 (Nrf2) pathway. Nrf2, as a master regulator of antioxidant response elements by activating cytoprotective genes expression, is decreased oxidative stress that associated with hyperglycemia and increases insulin sensitivity. the aim of this study was to assess whether the combination therapy of SPTC along with exercise or metformin moderate oxidative stress related liver injurie with more favorable effects in the treatment of AGE rich diet-induced type 2 diabetic mice.

METHODS

We induced diabetes in C57BL/6 mice by AGE using a diet supplementation and limitation of physical activity. After 16 weeks of intervention, AGE fed mice were compared to control mice. Diabetic mice were assigned into seven experimental groups (each group; n = 5): diabetic mice, diabetic mice treated with SPTC (130 mg/kg), diabetic mice treated with Salvia Officinalis (65 mg/kg), diabetic mice treated with metformin (300 mg/kg), diabetic mice with endurance exercise training, diabetic mice treated with SPTC + metformin (130/300 mg/kg), diabetic mice treated with SPTC + exercise training.

RESULTS

SPTC + exercise and SPTC + metformin reduced diabetic complications like gain weight, water and calorie intake, blood glucose, insulin, and GLUT4 content more efficiently than each treatment. These combinations improved oxidative stress hemostasis by activating the Nrf2 signaling pathway and attenuating keap1 protein more significantly.

CONCLUSION

Eventually, combined treatment of SPTC with exercise or metformin as a novel approach had more beneficial effects to prevent the development of diabetes and oxidative stress associated with hyperglycemia.

Metabolic and mitochondrial treatments for severe paracetamol poisoning: a systematic review

BACKGROUND

Paracetamol (acetaminophen) remains a leading cause of poisoning in Europe, North America, and Australia. For over four decades, acetylcysteine has been the antidote of choice. However, despite the use of acetylcysteine, some patients who ingest very large doses of paracetamol or who reach hospital late in the course of their poisoning, develop acute liver failure. Some will develop metabolic acidosis indicating mitochondrial toxicity.

OBJECTIVE

We review the experimental and clinical data reported with the use of cimetidine, fomepizole, and calmangafodipir in the treatment of paracetamol toxicity to determine if these treatments alone or in combination with acetylcysteine might be of benefit.

METHODS

We searched Ovid Medline 1946-2020, Embase 1947-2020, Scopus 2004-2020, Cochrane Databases of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), and clinicaltrials.gov 1997-2020 for records including the concepts of paracetamol poisoning and cimetidine, fomepizole, calmangafodipir, and acetylcysteine. We included basic science studies in animals and all available study types in humans. We reviewed the reference lists of included articles to search for references missed in the original search. We registered the protocol in PROSPERO.

RESULTS

We completed all search strategies on 20 August 2019, 27 January 2020, and 15 June 2020. These produced 6,826 citations. We identified and deleted 2,843 duplicate resulting in a total of 3,856 unique citations. After applying inclusion and exclusion criteria, 89 studies remained. The largest numbers of studies described the past use of cimetidine, and the more recent use of fomepizole.Cimetidine: There is good animal evidence that cimetidine blocks CYP 2E1 with the potential to inhibit the toxic metabolism of paracetamol. Early case reports were inconclusive regarding the benefit to humans in paracetamol poisoning. Two comparative trials found no benefit of cimetidine in paracetamol poisoning, but few patients had severe poisoning.Fomepizole: There is good animal evidence that fomepizole blocks CYP 2E1 with the potential to inhibit the toxic metabolism of paracetamol. There are no comparative trials of fomepizole for acute paracetamol poisoning. Case reports are inconclusive due to multiple other interventions including the use of acetylcysteine in all cases. The benefit of fomepizole as adjunct treatment has not been demonstrated.Calmangafodipir: Calmangafodipir, a drug mimicking superoxide dismutase, has emerged as a potential treatment for severe paracetamol toxicity because the formation of superoxide free radicals appears to explain part of the mitochondrial toxicity of extremely large paracetamol overdoses. Calmangafodipir has reached Phase I/II trial of safety in humans with acute paracetamol overdose. Planning for a Phase III study of efficacy is currently underway.

CONCLUSIONS

The vast majority of patients with acute paracetamol overdose enjoy excellent outcomes with acetylcysteine alone. Although cimetidine and fomepizole inhibit CYP 2E1 in animals, there is insufficient evidence to recommend their use either as a primary treatment or adjunct therapy in paracetamol poisoning. Calmangafodipir remains investigational.

Metformin as a protective agent against natural or chemical toxicities: a comprehensive review on drug repositioning

BACKGROUND

Metformin is the first prescribed drug for hyperglycemia in type 2 diabetes mellitus. Mainly by activating AMPK pathway, this drug exerts various functions that among them protective effects are of the interest.

PURPOSE

Herein, we aimed to gather data about the protective impacts of metformin against various natural or chemical toxicities.

RESULTS

An extensive search among PubMed, Scopus, and Google Scholar was conducted by keywords related to protection, toxicity, natural and chemical toxins and, metformin. Our literature review showed metformin alongside its anti-hyperglycemic effect has a wide range of anti-toxic effects against anti-tumour and routine drugs, natural and chemical toxins, herbicides and, heavy metals.

CONCLUSION

It is evident that metformin is a potent drug against the toxicity of a broad spectrum of natural, chemical toxic agents which is proved by a vast number of studies. Metformin mainly through AMPK axis can protect different organs against toxicities. Moreover, metformin preserves DNA integrity and can be an option for adjuvant therapy to ameliorate side effect of other therapeutics.

Attenuation of hydrogenperoxide-induced oxidative damages in L929 fibroblast cells by sulfated polysaccharides isolated from the edible marine algae Padina tetrastromatica

Sulfated polysaccharides are polymers with potent biological roles such as antioxidant, anticancer, anti-inflammatory, and immunomodulatory activities. They are gaining significance in advanced healthcare research, since they can control oxidative cellular damages by arresting the reactive oxygen species. Hence, this study aims to evaluate the cellular antioxidant potential of sulfated polysaccharides isolated from the marine algae Padina tetrastromatica in L929 cells. The monosaccharide composition of sulfated polysaccharides was determined using high-performance liquid chromatography. The protective effect of sulfated polysaccharides on L929 fibroblast cells under H2O2-induced oxidative stress has been evaluated using MTT assay, acridine orange/ethidium bromide staining, flow cytometry, comet assay, DCFH-DA staining, fluorometry, and biochemical assays. Sulfated polysaccharides were found to contain glucose, fucose, xylose, and uronic acid. It was non-toxic to L929 cells and effectively increased the viability of mouse fibroblast cells under induced oxidative stress. Various cellular damages such as apoptosis, plasma membrane alterations, DNA damage, and lipid peroxidation induced by H2O2 have been attenuated by sulfated polysaccharides. This might be due to the reduction of intracellular reactive oxygen species level by sulfated polysaccharides as observed in DCFH-DA staining. Sulfated polysaccharides improved the activity of intracellular antioxidant status and glutathione system. The augmentation of endogenous antioxidant enzymes and glutathione system by sulfated polysaccharides can be the possible reason for the reduction of intracellular reactive oxygen species, prevention of apoptosis, and betterment of viability in L929 cells. The study confirms the potent antioxidant activity of the sulfated polysaccharides in addition to their structural and nutritional roles.

Hepatoprotective activity of metformin: A new mission for an old drug?

Metformin, as a dimethyl biguanide prescribed as the first-line medication for treatment of type 2 diabetes mellitus, is one of the most frequently used drugs, worldwide. However, the beneficial effects of metformin are not limited to insulin sensitizing and blood glucose lowering effects as recent clinical trials deciphered lower cancer risk in metformin users. In addition, metformin protected the liver against chemical or viral hepatotoxicants through various mechanisms including activation of AMPK via inhibition of mitochondrial complex I, inhibition of mitogen activated protein kinase (MAPK) and inhibition of Smads phosphorylation. Clinical trials are under way to assess possible additive effects of metformin when co-administered along with the standard regimen for hepatocellular carcinoma (HCC) treatment. This review outlines the molecular mechanisms behind protective activity of metformin against different liver diseases.

Augmented anticancer activity of naringenin-loaded TPGS polymeric nanosuspension for drug resistive MCF-7 human breast cancer cells

Naringenin (NAR) is a naturally occurring plant flavonoid, found predominantly in citrus fruits, possesses a wide range of pharmacological properties. However, despite the therapeutic potential of NAR, its clinical development has been hindered due to low aqueous solubility and inefficient transport across biological membranes resulting in low bioavailability at tumor sites. In our previous studies, nanosuspension of naringenin (NARNS) was prepared using high pressure homogenization method using different polymers. D-α-Tocopheryl polyethylene glycol succinate 1000 (TPGS) was added as a co-stabilizer. All formulation characterization studies were performed. As a continuation of our previous research, current study has further evaluated the ability of the TPGS-coated NARNS, to reverse drug-resistance of P-gp-over expressing MCF-7 human breast adenocarcinoma cell line and animal model. MTT-based colorimetric assay revealed higher cytotoxic efficacy of NARNS than free NAR in MCF-7 cells. NARNS treatment significantly increased intracellular ROS level, mitochondrial membrane potential, caspase-3 activity, lipid peroxidation status (TBARS) and decreased GSH levels when compared to free NAR treatment in MCF-7 cells. It has been also noticed that the presence of apoptotic indices (membrane blebbing, nuclear fragmentation) in NARNS treated cancer cells. Further, NARNS exhibited dose-dependent in vitro antitumor activity with DLA cells. A significant increase in the life span and a decrease in the cancer cell number and tumor weight were noted in the tumor-induced mice after treatment with NARNS.

Terminalia bellirica (Gaertn.) Roxb fruit exerts anti-inflammatory effect via regulating arachidonic acid pathway and pro-inflammatory cytokines in lipopolysaccharide-induced RAW 264.7 macrophages

Terminalia bellirica (Gaertn.) Roxb. (Family: Combretaceae), known as Bhibhitaki in Sanskrit and locally known as Behera in India, has been used for centuries in Ayurveda, a universal system of medicine in India. The dried fruit of T. bellirica is used for the treatment of several disorders. The present study aims to explore the anti-inflammatory effects of aqueous acetone extracts isolated from T. bellirica (AATB) in RAW 264.7 cell lines. The AATB was prepared from the fruits of T. bellirica. Different concentrations of AATB (6.25-100 μg/ml) were used for MTT assay. The anti-inflammatory effect of AATB was evaluated by using different assays such as total cyclooxygenase (COX), 5-lipoxygenase (5-LOX) activity, nitrate and reactive oxygen species (ROS) production. The mRNA level expression of COX-2, tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) were studied in LPS stimulated RAW 264.7 cells. AATB treatment significantly diminished the elevated levels of inflammatory markers. Moreover, AATB downregulated the mRNA level expression of TNF-α, IL-6 and COX-2 genes. The result of our study suggest the use of AATB and is able to reduce inflammatory conditions associated with various diseases.

Assessing the treatment of acetaminophen-contaminated brewery wastewater by an anaerobic packed-bed reactor

The treatment of high-strength organic brewery wastewater with added acetaminophen (AAP) by an anaerobic digester was investigated. An anaerobic packed-bed reactor (APBR) was operated as a continuous process with an organic loading rate of 1.5-g COD per litre per day and a hydraulic retention time of three days. The results of steady-state analysis showed that the greatest APBR performances for removing COD and TOC were as high as 98 and 93%, respectively, even though the anaerobic digestibility after adding the different AAP concentrations of 5, 10 and 15 mg L(-1) into brewery wastewater can affect the efficiency of organic matter removal. The average CH4 production decreased from 81 to 72% is counterbalanced by the increased CO2 production from 11 to 20% before and after the injection of AAP, respectively. The empirical kinetic models for substrate utilisation and CH4 production were used to predict that, under unfavourable conditions, the performance of the APBR treatment process is able to remove COD with an efficiency of only 6.8%.

Conceptual approaches for treatment of phosgene inhalation-induced lung injury

Toxic industrial chemicals are used throughout the world to produce everyday products such as household and commercial cleaners, disinfectants, pesticides, pharmaceuticals, plastics, paper, and fertilizers. These chemicals are produced, stored, and transported in large quantities, which poses a threat to the local civilian population in cases of accidental or intentional release. Several of these chemicals have no known medical countermeasures for their toxic effects. Phosgene is a highly toxic industrial chemical which was used as a chemical warfare agent in WWI. Exposure to phosgene causes latent, non-cardiogenic pulmonary edema which can result in respiratory failure and death. The mechanisms of phosgene-induced pulmonary injury are not fully identified, and currently there is no efficacious countermeasure. Here, we provide a proposed mechanism of phosgene-induced lung injury based on the literature and from studies conducted in our lab, as well as provide results from studies designed to evaluate survival efficacy of potential therapies following whole-body phosgene exposure in mice. Several therapies were able to significantly increase 24h survival following an LCt50-70 exposure to phosgene; however, no treatment was able to fully protect against phosgene-induced mortality. These studies provide evidence that mortality following phosgene toxicity can be mitigated by neuro- and calcium-regulators, antioxidants, phosphodiesterase and endothelin receptor antagonists, angiotensin converting enzymes, and transient receptor potential cation channel inhibitors. However, because the mechanism of phosgene toxicity is multifaceted, we conclude that a single therapeutic is unlikely to be sufficient to ameliorate the multitude of direct and secondary toxic effects caused by phosgene inhalation.