Toxic Free Radicals Research Articles

Oxidative Stress and Age-Related Tumors.

Oxidative stress is the result of the imbalance between reactive oxygen and nitrogen species (RONS), which are produced by several endogenous and exogenous processes, and antioxidant defenses consisting of exogenous and endogenous molecules that protect biological systems from free radical toxicity. Oxidative stress is a major factor in the aging process, contributing to the accumulation of cellular damage over time. Oxidative damage to cellular biomolecules, leads to DNA alterations, lipid peroxidation, protein oxidation, and mitochondrial dysfunction resulting in cellular senescence, immune system and tissue dysfunctions, and increased susceptibility to age-related pathologies, such as inflammatory disorders, cardiovascular and neurodegenerative diseases, diabetes, and cancer. Oxidative stress-driven DNA damage and mutations, or methylation and histone modification, which alter gene expression, are key determinants of tumor initiation, angiogenesis, metastasis, and therapy resistance. Accumulation of genetic and epigenetic damage, to which oxidative stress contributes, eventually leads to unrestrained cell proliferation, the inhibition of cell differentiation, and the evasion of cell death, providing favorable conditions for tumorigenesis. Colorectal, breast, lung, prostate, and skin cancers are the most frequent aging-associated malignancies, and oxidative stress is implicated in their pathogenesis and biological behavior. Our aim is to shed light on the molecular and cellular mechanisms that link oxidative stress, aging, and cancers, highlighting the impact of both RONS and antioxidants, provided by diet and exercise, on cellular senescence, immunity, and development of an antitumor response. The dual role of ROS as physiological regulators of cell signaling responsible for cell damage and diseases, as well as its use for anti-tumor therapeutic purposes, will also be discussed. Managing oxidative stress is crucial for promoting healthy aging and reducing the risk of age-related tumors.

Free Radicals in Little Cigar Mainstream Smoke and the Potential Influence of Flavoring Chemicals on Free Radical Production.

Implementation of the Tobacco Control Act in 2009 banned characterizing flavors in cigarettes (except menthol and tobacco), but substitution has occurred by the continued availability of alternative flavored products (i.e., flavored little cigars). Little is known about how flavorants in noncigarette tobacco products impact human health. Thus, we investigated the impact of flavorants on free radical production in the mainstream smoke of little cigars. Gas- and particulate-phase free radical yields in mainstream smoke generated from 12 commercial little cigar brands and research little cigars and cigarettes were measured via electron paramagnetic resonance spectroscopy using the International Organization of Standardization (ISO) smoking protocol. Flavorants were extracted from unsmoked little cigars and analyzed by gas chromatography-mass spectroscopy. Gas- and particulate-phase radical yields from little cigars ranged from 13.5 to 97.6 and 0.453-1.175 nmol/unit, respectively. Comparatively, research cigarettes yielded an average of 4.9 nmol gas-phase radicals/unit and 0.292 nmol particulate-phase radicals/unit. From the products, 66 flavorants were identified, with each brand containing 4-24 individual flavorants. The free radical content was strongly correlated with the number of flavorants present in each cigar (r = 0.74, p = 0.01), indicating that highly flavored little cigars may produce higher levels of toxic free radicals. The presence of the flavorant ethyl methylphenylglycidate (strawberry) was associated with >2-fold higher levels of GP radicals (p = 0.001). Our results show that free radical delivery from little cigars is greater than that from research cigarettes and provide empirical evidence for the harmfulness of flavored tobacco products. Additionally, it demonstrates that flavorants present in combustible tobacco products can influence the levels of free radicals produced. Therefore, future tobacco product standards should consider little cigars.

Photoaged nanoplastics with multienzyme-like activities significantly shape the horizontal transfer of antibiotic resistance genes

Nanoplastics (NPs), identified as emerging pollutants, pose a great risk to environment and global public health, exerting profound influences on the prevalence and dissemination of antibiotic resistance genes (ARGs). Despite evidence suggesting that nano-sized plastic particles can facilitate the horizontal gene transfer (HGT) of ARGs, it is imperative to explore strategies for inhibiting the transfer of ARGs. Currently, limited information exists regarding the characteristics of environmentally aged NPs and their impact on ARGs propagation. Herein, we investigated the impact of photo-aged NPs on the transfer of ARG-carrying plasmids into Escherichia coli (E. coli) cells. Following simulated sunlight irradiation, photo-aged nano-sized polystyrene plastics (PS NPs) exhibited multiple enzyme-like activities, including peroxidase (POD) and oxidase (OXD), leading to a burst of reactive oxygen species (ROS). At relatively low concentrations (0.1, 1 μg/mL), both pristine and aged PS NPs facilitated the transfer of pUC19 and pHSG396 plasmids within E. coli due to moderate ROS production and enhanced cell membrane permeability. Intriguingly, at relatively high concentrations (5, 10 μg/mL), aged PS NPs significantly suppressed plasmids transformation. The non-unidirectional impact of aged PS NPs involved the overproduction of ROS (•OH and •O2−) via nanozyme activity, directly degrading ARGs and damaging plasmid structure. Additionally, oxidative damage to bacteria resulted from the presence of much toxic free radicals, causing physical damage to cell membranes, reduction of the SOS response and restriction of adenosine-triphosphate (ATP) supply, ultimately leading to inactivation of recipient cells. This study unveils the intrinsic multienzyme-like activity of environmentally aged NPs, highlighting their potential to impede the transfer and dissemination of ARGs.

Mft1, identified from a genome-wide screen of the yeast haploid mutants, mediates cell cycle arrest to counteract quinoxaline-induced toxicity.

Quinoxaline is a heterocyclic compound with a two-membered ring structure that undergoes redox cycling to produce toxic free radicals. It has antiviral, antibacterial, antifungal, and antitumor activities. However, the biological functions that are involved in mounting a response against the toxic effects of quinoxaline have not been investigated. Herein, we performed a genome-wide screen using the yeast haploid mutant collection and reported the identification of 12 mutants that displayed varying sensitivity towards quinoxaline. No mutant was recovered that showed resistance to quinoxaline. The quinoxaline-sensitive mutants were deleted for genes that encode cell cycle function, as well as genes that belong to other physiological pathways such as the vacuolar detoxification process. Three of the highly sensitive gene-deletion mutants lack the DDC1, DUN1, and MFT1 genes. While Ddc1 and Dun1 are known to perform roles in the cell cycle arrest pathway, the role of Mft1 remains unclear. We show that the mft1Δ mutant is as sensitive to quinoxaline as the ddc1Δ mutant. However, the double mutant ddc1Δ mft1Δ lacking the DDC1 and MFT1 genes, is extremely sensitive to quinoxaline, as compared to the ddc1Δ and mft1Δ single mutants. We further show that the mft1Δ mutant is unable to arrest in the G2/M phase in response to the drug. We conclude that Mft1 performs a unique function independent of Ddc1 in the cell cycle arrest pathway in response to quinoxaline exposure. This is the first demonstration that quinoxaline exerts its toxic effect likely by inducing oxidative DNA damage causing cell cycle arrest. We suggest that clinical applications of quinoxaline and its derivatives should entail targeting cancer cells with defective cell cycle arrest.

Food packaging based on biodegradable polymers from seaweeds: a systematic review

As a result of its brief lifespan, food packaging contributes significantly to environmental contamination through the rapid accumulation of plastic in the environment. In order to mitigate these impacts and provide a food packaging solution that is more environmentally sustainable, researchers have created biodegradable and biobased polymers, which are presently being introduced to the market. The current state of research regarding the incorporation of seaweed into food packaging and active packaging is summarized in this study. In order to emphasize the benefits of polysaccharides and draw attention to the constraints of current research, this study also presents a synopsis of the effects of seaweed incorporation on a range of properties, including chemical, physical, thermal, antioxidant, antimicrobial, and mechanical attributes, in addition to the release of active compounds. A multitude of polysaccharides, including those found in seaweed, have the potential to enhance the antibacterial, thermal, and mechanical properties of these polymers, among other attributes. In addition to increasing hydrophilicity and mechanical properties such as tensile strength and elongation at break, they suggest employing it as active packaging. This is feasible as a result of the antioxidant properties of seaweed, which inhibit lipid oxidation and decrease toxic, mutagenic, or carcinogenic free radicals, thereby extending the nutritional value and shelf life of food. Certain varieties of seaweed have exhibited the capacity to impede the proliferation of bacteria classified as gram-positive and gram-negative. Thus, their prospective application as antimicrobial packaging is indicated.

Effect of Pimpinella tirupatiensis Extract on Brain Free Radical Toxicity in STZ Induced Diabetic Rats

The objective of this study was to investigate the effects of Pimpinella tirupatiensis on oxidative stress markers in different regions of the brain (cerebral cortex, cerebellum, hippocampus, and Pons medulla) in rats with diabetes. Diabetes was induced in wistar rats by injecting them with STZ (40 mg/kg). The rats were then administered Pimpinella tirupatiensis aqueous extract (750 mg/kg / b.w. /day) and glibenclamide (Glb) (20 mg/ kg / b.w. /day) orally for 30 days. After 4 weeks of high blood sugar, the activity of antioxidant enzymes was measured in both the diabetic and control groups. Diabetes can worsen nerve damage and cause oxidative damage due to high blood sugar levels. The diabetic rats displayed a significant decrease in levels of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase) and reduced glutathione. However, when ginger was administered orally, it enhanced the activity of antioxidant enzymes in the diabetic rats. This suggests that Pimpinella tirupatiensis has a protective effect on the brain by enhancing antioxidant defense mechanisms in diabetic rats. Furthermore, it has a neuroprotective effect by enhancing the brain's antioxidant defense mechanisms and thereby attenuating the progression of hyperglycemia and some complications caused by diabetes in the rat brain.

Biochar-Associated Free Radicals Reduce Soil Bacterial Diversity: New Insight into Ecoenzymatic Stoichiometry.

The toxicity of environmentally persistent free radicals (EPFRs), often generated during biochar production, on soil bacteria is still not truly reflected when considering the conditions in real soil. Herein, the influence of free radicals within biochar on soil bacteria was investigated from the perspectives of enzyme activity, community structure, and ecoenzymatic stoichiometry. Biochar addition enhanced the contents of EPFRs and derived hydroxyl radicals (•OH) in the soil, while it reduced bacterial alpha diversity by 5.06-35.44%. The results of redundancy analysis and inhibition experiments collectively demonstrated the key role of EPFRs and •OH in reducing the bacterial alpha diversity. Specifically, EPFRs and •OH increased the stoichiometric imbalance by promoting the release of dissolved organic carbon and ammonium N, thus aggravating the P limitation in soil. This was further confirmed by increased alkaline phosphatase activity from 702 to 874 nmol g-1 h-1. The P limitation induced by EPFRs and •OH decreased the bacterial alpha diversity, as evidenced by the negative correlation between P limitation and bacterial alpha diversity (r2 = -0.931 to -0.979, P < 0.01) and the structural equation model. The obtained results demonstrate a ubiquitous but previously overlooked mechanism for bacterial toxicity of biochar-associated free radicals, providing scientific guidance for safe utilization of biochar.

Aluminium chloride-induced prefrontal cortex toxicity in Wistar rats: evidence from pretreatment with aqueous &lt;i&gt;Psidium guajava&lt;/i&gt; leaf extract

Aluminium is reported to be a very common element and one of the most abundant metals on Earth. Although aluminium is neurotoxic and linked to several brain disorders, reports indicate that antioxidants from natural sources can neutralise the toxic free radicals generated by aluminium. Consequently, this study evaluated the protective and antioxidative effects of Psidium guajava (GV) aqueous leaf extract on Aluminium-induced prefrontal cortex toxicity. Thirty (30) adult Wistar rats in six (6) groups were used for this experiment (n=5): Group A (control); Group B rats (Al) were given 100 mg/kg body weight (BW) of Aluminium alone; Group C (Al + GV1) rats were given 100 mg/kg BW of Aluminium and 200mg/kg BW/day of aqueous GV leaf extract; Group D (Al + GV2) was administered 100 mg/kg BW of Al and 400 mg/kg BW of aqueous GV leaf extract; Group E (GV1) was administered 200 mg/kg BW of aqueous GV leaf extract alone and Group F (GV2) was administered 400 mg/kg BW of aqueous GV leaf extract alone. Following the end of administration, neurobehavioral, antioxidant enzymes, and prefrontal cortex histology assessments were done. Findings showed that Group B rats had a significant (p&lt;0.05) decrease in final body and absolute brain weights, and antioxidant enzymes activity when compared to control. Likewise, a significant (p&lt;0.05) decrease was observed in spontaneous alternation in rats treated with Al alone, thus indicating cognitive dysfunction. Conversely, following pretreatment with Psidium guajava, the alterations induced by Al were mitigated. Taken together, Psidium guajava showed a potent capability as a possible neuroprotective agent that can be useful for inhibiting Al-induced neurotoxicity and cognitive dysfunctions. Further investigations and development of this plant could offer a worthwhile substitute to other orthodox drugs currently used in the treatment and/or management of aluminium-related disorders.

Biotin receptor and mitochondria dual targeted AIE photosensitizer for fluorescence imaging guided photodynamic anticancer therapy

Rational design of organelle targeted therapeutic platform in where the drug can be targeted to destroy tumor cells as much as possible, is one of the effective ways to improve the therapeutic outcomes and minimize the cytotoxicity to normal cells. Here, photosensitizer TSPy-B with aggregation-induced emission (AIE) feature, biotin receptor and mitochondria dual-targeted capability, and high reactive oxygen species (ROS) generation efficiency was designed for fluorescence imaging guided photodynamic therapy (PDT) by linking biotin group to D-π-A type AIE dyes via ester bonds. Notably, cell imaging experiments showed that TSPy-B could selectively target tumor cells with biotin receptor overexpression and further exhibit mitochondria targeting ability. The in vitro anticancer mechanism confirmed that after cell internalization, TSPy-B localized in the mitochondrial site and produced ROS resulting in mitochondrial dysfunction and cell death. ROS generation experiments showed that TSPy-B could simultaneously produce 1O2 and highly toxic free radicals which not depended on the oxygen level of solid tumor. The cell killing effect of TSPy-B was also confirmed in hypoxic culture model. In vivo photodynamic therapy experiments demonstrated that TSPy-B could effectively inhibit tumor growth and had good biological safety. This work provides a choice for development of highly targeted photosensitizers for clinical fluorescence imaging guided PDT.

A chemodynamic nanoenzyme with highly efficient Fenton reaction for cancer therapy

Chemodynamic therapy (CDT) is a rising technology for cancer therapy by converting intracellular hydrogen peroxide (H2O2) into hydroxyl radical (•OH) via transition-metal-containing nanoparticles (NPs) catalysis reaction (i.e. Fenton reaction) to kill tumor cells. Highly efficient Fenton reaction and favorable delivery of the catalytic NPs ‘nanoenzyme’ are the key for successful treatment of cancer. In this work, we developed a novel nanoenzyme MnFe2O4@GFP for in vitro and in vivo antitumor therapy. A new MnFe2O4 nanoparticle containing two transition-metal-element Fe and Mn was synthesized for enhanced Fenton reaction and used to co-deliver protein with high biocompatibility through post-modification with dopamine polymerization, green fluorescent protein adsorption, and PEG coating. The enrichment of H2O2 and glutathione (GSH) in tumor tissue provided a favorable microenvironment for in situ generation of toxic free radicals. Fe3+ and GSH triggered a redox reaction to produce Fe2+, which in turn catalyzed H2O2 into •OH, with the consumption of antioxidant GSH. By combining Fe3+ with another catalyzer, the catalytic efficiency of the nanoenzyme were greatly improved. Consequently, the nanoenzyme showed efficient antitumor ability both in vitro and in vivo. Thus, the multifunctional CDT nanoenzyme platform shows great promising for antitumor therapy through the combination of catalyzers Fe3+ and Mn2+ and codelivery of protein cargo.

Near-IR-Regulated Composite Hydrogel with Real-Time Infection Monitoring and a Combined Antibacterial Effect for Efficient Wound Management.

Chronic wounds induced by bacterial infection have seriously affected the health of people in the world. So, it is meaningful to develop a novel strategy with real-time infection monitoring and excellent antibacterial performance for enhancing wound management. Herein, we constructed a composite hydrogel by loading the pH indicator bromothymol blue (BTB) and gold nanocages containing 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (Au NCs@AIPH) into a polyacrylamide-co-poly(acrylic anhydride-modified oxidized sodium alginate) (PAM-co-PAOSA) hydrogel. In vitro and in vivo experimental results demonstrated that the composite hydrogel could effectively detect bacteria and diagnose the infection status of a wound in real time by showing visible color changes. In addition, the composite hydrogel containing Au NCs@AIPH possessed an excellent photothermal effect under near-IR (NIR) laser irradiation. The photothermal effect further activated AIPH to generate toxic free radicals to form combined antibacterial therapy for accelerating wound healing. Moreover, the composite hydrogel showed great biocompatibility. Therefore, the multifunctional hydrogel provided a novel wound management strategy for bacterial infection diagnosis and combined therapy in an infected wound.

A Molecular Mechanism of Stress-Induced Alzheimer’s Disease; Part 1

Alzheimer’s disease (AD) is a chronic but deadly neurodegenerative disorder. A significant burden on global public health, a cure for AD is still elusive. Recent clinical trials based on pathogenic theories of extra/intracellular protein aggregation resulting from oxidative stress or other environmental insults have encountered setbacks. In this first part of a series, we report a significant and serendipitous case of an AD patient. It is the first time, to our knowledge, to follow a single patient over 33 plus years (1985–2018), where AD symptoms were presented and remised repeatedly. The effects of stress resulting in numerous ailments, e.g., memory loss, brain atrophy, high blood pressure, inflammations, decrease of immunity, etc., were observed in four ‘episodes’ of severe stress, confirming that the disease is stress-induced. An anti-stress lifestyle, involving seven daily anti-stress practices, was implemented which, remarkably, led to the recovery of memory and retardation of disease progression. We discovered a relationship between stress/stress hormones, the strain effects on these stress hormones and the pathways leading to a stress-induced macro-molecular mechanism that accounts for the origin of toxic free radical species (oxidants) which derive from Amyloid beta (Aβ) and Tau proteins (antioxidants). We suggest our mechanism may also be applied to other neurodegenerative diseases related to stress effects on proteins, such as alpha-synuclein in Parkinson’s disease, superoxide dismutase in amyotrophic lateral sclerosis, IAPP amyloid in type 2 diabetes, etc. As chronic traumatic encephalopathy and post-traumatic stress disorder both lead to AD, the anti-stress program proposed here may also very well be of assistance to those impacted by the said ailments described above. Consequently, the proposed stress-induced molecular mechanism deduced from the Alzheimer disease patient’s experience, we suggest, represents a significant step forward in understanding the origins of Alzheimer’s disease and many other neurodegenerative diseases. In part 2, we will discuss the patients further AD development from 2018 to the current-time and expand our discussion of the physics of stress/strain on the macromolecules.

Enhanced chemodynamic therapy and immunotherapy by hypoxia augmentation for tumor ablation

Chemodynamic therapy (CDT) produces highly toxic hydroxyl free radicals (•OH) to achieve selective tumor treatment based on Fenton reaction. However, the insufficient intracellular H2O2 level in tumor cells severely limits the therapeutic efficacy of Fenton reaction. Here, we report a synergistic enhancement strategy for amplifying Fenton reaction and relieving the tumor immunosuppressive microenvironment. In this work, a targeted PCL-PEG-cRGD (PCE-cRGD) micelle was developed for delivering apatinib (APA) to tumor vessels, promoting vascular normalization and relieving tumor hypoxia. On one hand, the hypoxia relief promoted the chemodynamic therapy of ascorbyl palmitate-loaded FePOs, where ascorbyl palmitate generates endogenous H2O2 in the presence of oxygen, and FePOs catalyze Fenton reaction to produce more potent •OH, which can be reduced to Fe2+ by ascorbyl palmitate. The continued involvement of Fe2+ in the Fenton reaction enhances tumor therapy efficiency through cyclic catalysis and self-enhanced catalysis. On the other hand, the increased oxygen content induced the polarization of M2 macrophage to antitumor M1 phenotype, which secreted TNF-α and IL-6 to activate CD4+ and CD8+ T cells, enhancing antitumor immune response. Combining enhanced chemodynamic therapy and immunotherapy, this strategy establishes the high feasibility of the synergistic treatment concept.

N-acetylcysteine and Reduction of Ischemia-reperfusion Injury in Liver Transplantation.

In the current issue of Transplantation, Jia et al perform a systemic review and meta-analysis looking at the utilization of N-acetylcysteine (NAC) in the donor and recipient in liver transplantation.1,2 It has been suggested that NAC may have a role in mitigating ischemia-reperfusion injury that occurs during the various stages of organ donation. The pathophysiology of ischemia-reperfusion injury is mainly due to the oxidative stress and cytotoxicity arising from the imbalance between oxidants and antioxidants. NAC is a rich source of sulfhydryl groups, which are important for replenishing glutathione (GSH) stores. GSH acts as a free radical scavenger to decrease damage caused by the toxic free radicals. GSH is the main endogenous antioxidant, and the liver is the main organ producing GSH under normal conditions.2 The present meta-analysis demonstrates a lower incidence of primary nonfunction, a reduction in posttransplant peak aspartate transaminase and alanine transaminase, and reduced postoperative complications in the NAC treatment groups compared with the control groups. As a long-time proponent of the use of NAC in the transplant setting, the overall results of this meta-analysis are encouraging. At Mayo Clinic Florida, we routinely use a NAC infusion for donation after circulatory death (DCD) liver transplant recipients. Our protocol involves a bolus of 150 mg/kg given over 1 h before reperfusion followed by an infusion of 150 mg/kg given for 72 h. Our current rate of ischemic cholangiopathy is <4%; however, whether NAC provides any direct benefit in the reduction of ischemic cholangiopathy remains unproven.3 More recently, we have also started using NAC in the perfusate when performing abdominal normothermic regional perfusion in DCD donors ([6 g/30 mL] × 3 vials). Negative effects of NAC administration are minimal. Although the meta-analysis demonstrated a slightly increased need for packed red blood cells and cryoprecipitate in NAC treatment groups, the magnitude of difference was <1 unit. This may imply that although a statistically significant difference was seen, such a small difference may not be clinically significant. There are some limitations to the present study that should be mentioned. One of the challenges with combining the data from the different studies in the present analysis is that some of the studies gave NAC to the donors at the time of donor procurement, some gave NAC to the recipients at the time of transplant, and others gave NAC to both the donor and recipient. Dosing and timing of dosing was also very heterogeneous between the different studies. Given this heterogeneity, developing a comprehensive protocol utilizing NAC is problematic. In the subanalysis, the authors did suggest that NAC administration to the recipient appeared to produce better clinical effects than administration to the donor. Another unanswered question based on the present analysis is how the benefits of NAC may vary by donor type? Some of the studies looked at living donors while others looked at donation after brain death donors and others looked at DCD donors. Could there be a more significant effect in marginal liver grafts with a suspected higher degree of ischemia-reperfusion injury or should NAC be utilized in all cases? Finally postoperative complications were treated as a binary variable (yes/no) for the analysis. Given the vastly different implications of complications based on their severity, using a classification system such as Clavien-Dindo would be more meaningful when comparing study groups. Despite the limitations of the present meta-analysis, the results are encouraging and suggest that NAC does have some potentially beneficial effects in reducing ischemia-reperfusion injury when used in the setting of liver transplantation. The adequate safety of NAC, in addition to its low costs, makes it an appealing intervention. Further studies are needed before evidence is strong enough to recommend a specific protocol describing both optimal timing and dosage for administration. Moreover, the donor type that may achieve the greatest benefit remains unknown.

Computational studies of toxicity and properties of β-diketones through topological indices and M/NM-polynomials

β-diketones are promising scaffolds for drug discovery and drug delivery because of their diketo moiety separated by a CH2 group that results in facile keto-enol tautomerism. Consequently, the loosely bound proton at the diketo bridge undergoes facile replacement by toxic metal ions, thus making them attractive scavengers of toxic ions and free radicals as well as candidates for transporting drugs. Therefore, it is of paramount importance to gain computational insights into their physicochemical properties and toxicity parameters (LD50). In this paper we compute a number of distance and degree based topological indices through M-polynomials and NM-polynomials of 76 β-diketones in order to develop QSAR relations through statistical regressions for several important toxicity and property parameters such as LD50, LogP, and XLogP3. We show several distance based indices including Szeged like indices to offer promising avenue in predicting the properties and somewhat less accurate in predicting toxicity parameters of these molecules.

AN EXPERIMENTAL STUDY ON ALBINO RATS TO COMPARE THE HEPATOPROTECTIVE EFFECT OF ORALLY ADMINISTERED DL-METHIONINE AND N-ACETYLCYSTEINE ON THE LIVER INJURY CAUSED BY POSITIVE CONTROL DRUG DICLOFENAC SODIUM

Introduction: Liver, main organ for biotransformation of drugs, during which most of the drugs which are lipophilic in nature are made hydrophilic by the biochemical processes in the liver cells resulting into water-soluble products which get excreted in urine or bile. Adverse drug reactions (ADRs) pertaining to liver, can be of mainly two types, predictable or dose dependent and idiosyncratic. To counter the oxidative stress and cellular damage, several antioxidant enzymes have been developed including superoxide dismutase (SOD), Glutathione peroxidase and catalase, that detoxify the reactive oxygen species and the cells contained endogenous antioxidants that scavenge the free radicals and reduces the cellular damage of which glutathione plays a major role. Synthesis of glutathione is regulated at the substrate level by cysteine, which is synthesized from homocysteine via the trans-sulfuration pathway N-Acetylcysteine used as a specific drug in the treatment of Paracetamol overdose, serves as a prodrug to L-Cysteine, which is a precursor to the antioxidant Glutathione. L-methionine, a precursor of L-cysteine, which is considered to have antioxidant activity, is found to be a precursor to glutathione as well. Methionine is particularly important in opposing the toxicity of free radicals generated by various toxins. Hence, supplementation of the same has been proposed to have a greater role in reducing the toxic effect on liver. The aim was to study the comparative hepatoprotective effect of orally administered DL-Methionine and N-Acetylcysteine on the liver injury induced by positive control Diclofenac Sodium. Materials and Methods: The healthy albino rats were grouped for the experimental study, in various groups (n=6). After overnight fasting, rats belonging to Group I Vehicle treated Group (n=6) were administered Distilled Water 10 ml/kg orally Group II to V were administered single oral dose concomitantly with Diclofenac sodium (96 mg/kg &amp; 240 mg/kg p.o.) and DL-Methionine (700 mg/kg p.o. &amp; 1400 mg/kg p.o.) respectively. Group VI and VII were administered single oral dose concomitantly with Diclofenac sodium (96 mg/kg &amp; 240 mg/kg p.o.) and N-Acetylcysteine 450 mg/kg p.o., respectively. Serum samples from each rats were collected after 24-hours of post-treatment, to study the comparative effects of DL-Methionine and N-Acetylcysteine on the liver injury induced by positive control Diclofenac Sodium through Haemato-biochemical changes. Results: The vehicle-treated group showed no significant alteration in the level of liver function tests and liver morphology. On concomitant administration of DL-Methionine 700 mg/kg with Diclofenac sodium 96 mg/kg and 240 mg/kg it was observed that there occurred significant reduction (p &lt; 0.001) in the serum SGOT and SGPT levels as compared to control and positive control group. The hepatoprotective effect of DL-Methionine 700 mg/kg and N-Acetylcysteine 450 mg/kg on concomitant administration with positive control drug Diclofenac sodium 96 mg/kg were compared for their effect on serum SGPT levels and was observed that there was no statistically significant decrease in the levels of SGPT when compared between the two groups of hepatoprotective agents. The hepatoprotective effect of DL-Methionine 700 mg/kg and N-Acetylcysteine 450 mg/kg on concomitant administration with positive control drug Diclofenac sodium 240 mg/kg, were compared for their effect on serum SGPT levels. It was observed that there was a significant reduction (p &lt;0.05) in SGPT levels, with DL-Methionine 700 mg/kg and N-Acetylcysteine 450 mg/kg. However, in both the doses of DL-Methionine, there were no statistically significant changes in the Total Serum Bilirubin, serum Alkaline Phosphatase &amp; serum Gamma-Glutamyl Transpeptidase (GGTP) levels. Conclusion: We have compared for the effectiveness of DL-Methionine and N-Acetylcysteine for their hepatoprotective effect against Diclofenac-induced hepatotoxicity, where we have observed, both DL-Methionine and N-Acetylcysteine reduces the serum transaminases levels, that were elevated due to the hepatotoxic effect of diclofenac sodium. However, there was no much of a difference of hepatoprotective effect of both DL-Methionine and N-Acetylcysteine. In summary, our present study reinforced the concept that hepatotoxicity induced by drug can be protected by administering NAC even in cases of non-paracetamol induced liver injury.

Mechanistic Framework of Herbs and Phytoconstituents used Against Experimentally Induced Urolithiasis

Urolithiasis, the term is referred to as the process of formation of stones in the urinary system and is a complex process that results in the development of a succession of several physicochemical steps i.e., supersaturation, nucleation, growth, aggregation, and retention within the kidneys. Urolithiasis is a multi-factorial etiopathogenesis involving anatomical, metabolic, genetic, nutritional, infections, environmental and socio-economic factors. Different types of calculi (calcium oxalate, struvite, uric acid and cystine stones etc.,) have been identified and among which the common type of stone found is calcium oxalate-type crystals. A person with urolithiasis may experience nausea, vomiting, severe pain in the side and back and in the process of urination. The medical management of urolithiasis is mainly caused by procedures like percutaneous nephrolithotomy and Extracorporeal Shock Wave Lithotripsy (ESWL) techniques. But these procedures can cause undesirable side effects such as the development of tubular necrosis, hypertension, haemorrhage, and later fibrosis of the kidney leading to cellular injury and the reappearance of the formation of renal stones. Thus, there is an essential for more effective alternative therapy, which corrects the events of stone formation. Treatment with synthetic drugs has shown many side effects. Some synthetic drugs may cause nephrotoxicity. In India, medicinal plants/herbs have been in use to treat various diseases since ancient times. These plant-based derivatives are stated to be effective in decreasing the recurrence rate of renal stones without any side effects and minimizing toxic free radical generation by radical scavenging action. This review discussed the mechanisms of various medicinal plants and their phytoconstituents in experimentally induced urolithiasis in preclinical models.

Local delivery of artesunate dimer liposomes incorporated injectable hydrogel for H2O2 and pH-independent chemodynamic therapy

Chemodynamic therapy (CDT) has emerged as a powerful tumor treatment option by inducing the imbalance of redox homeostasis in cancer cells. Nevertheless, the therapeutic outcomes were greatly limited because of insufficient endogenous H2O2 and upregulated cellular antioxidant defense in the tumor microenvironment (TME). Herein, a liposome-incorporated in-situ alginate hydrogel locoregional treatment strategy was developed, which involves using hemin-loaded artesunate dimer liposomes (HAD-LP) as redox-triggered self-amplified C-center free radical nanogenerator to enhance CDT. First, HAD-LP based on artesunate dimer glycerophosphocholine (ART-GPC) was prepared by a thin film method. Their spherical structure was manifested by dynamic light scattering (DLS) and transmission electron microscope (TEM). The generation of C-center free radicals from HAD-LP was carefully evaluated by using methylene blue (MB) degradation method. The results suggested that the hemin was reduced to heme under the action of glutathione (GSH), which could catalyze the breakage of endoperoxide of ART-GPC derived dihydroartemisinin (DHA) to generate toxic C-centered free radicals in a H2O2 and pH-independent manner. Moreover, the change of intracellular GSH and free radical level was monitored through ultraviolet spectroscopy and confocal laser scanning microscope (CLSM). It was revealed that the hemin reduction induced GSH depletion and elevated free radical level, disrupting cellular redox homeostasis. After co-incubation with MDA-MB-231 or 4 T1 cells, HAD-LP was found to be highly cytotoxic. In order to prolong retention and improve antitumor efficacy, HAD-LP was mixed with alginate and injected intratumorally into 4 T1 tumor bearing mice. The injected HAD-LP and alginate mixture formed in-situ hydrogel and achieved best antitumor effect with the growth inhibition rate of 72.6%. Together, the hemin-loaded artesunate dimer liposome-incorporated alginate hydrogel possessed effective antitumor activity through redox-triggered C-center free radical generation induced apoptosis in a H2O2 and pH-independent manner, which might be a promising candidate in the application of chemodynamic anti-tumor therapy.

Pyruvate and lactate based hydrogel film inhibits UV radiation-induced skin inflammation and oxidative stress

Solar skin damage is one of the most common diseases among outdoor workers. An important cause for the damage is the ultraviolet and infrared rays in sunlight, which are absorbed by the skin in large amounts, leading to severe skin inflammation and oxidative stress. Therefore, physical prevention by shielding the light from harmful wavelengths can be an effective method of skin protection from radiation. However, for existing skin lesions, prompt treatment is essential to avoid the aggravation of the injury and promote repair. Therefore, to improve the therapeutic effect on sun-damaged skin, we attempted to design a system with a dual purpose of eliminating toxic free radicals and modulating tissue inflammatory response. Here, we designed and synthesized a poly-acryloyl lysine (P-Ac-Lys) and polyvinyl alcohol-dihydroxyphenylalanine (PVA-DOPA) composite hydrogel (PAL@PVA-DOPA Hydrogel) loaded with lactate and pyruvate, that exhibites a good free radical scavenging activity and an excellent ability to modulate the inflammatory response. Experimental results showe that this hydrogel film could effectively reduce the UV-induced skin inflammation response, alleviate pathological damage and promote the recovery of the damaged skin.

Enzyme/inorganic nanoparticle dual-loaded animal protein/plant protein composite nanospheres and their synergistic effect in cancer therapy.

It is a viable strategy to develop a safer and tumor-specific method by considering the tumor microenvironment to optimize the curative effect and reduce the side effects in cancer treatment. In this study, glucose oxidase (GOx) and Fe3O4 nanoparticles were successfully loaded inside regenerated silk fibroin/zein (RSF/zein) nanospheres to obtain dual-loaded Fe3O4/GOx@RSF/zein nanospheres. The unique structure of the RSF/zein nanospheres reported in our previous work was favorable to loading sufficient amounts of GOx and Fe3O4 nanoparticles in the nanospheres. For Fe3O4/GOx@RSF/zein nanospheres, GOx depletes endogenous glucose via an enzyme-catalyzed bioreaction, simultaneously generating plenty of H2O2in situ. It was further catalyzed through a Fe3O4-mediated Fenton reaction to form highly toxic hydroxyl free radicals (˙OH) in the acidic tumor microenvironment. These two successive reactions made up the combination of starvation therapy and chemodynamic therapy during cancer treatment. The catalytic activity of GOx loaded in the RSF/zein nanospheres is similar to that of the pristine enzyme. It was maintained for more than one month due to the protection of the RSF/zein nanospheres. The methylene blue degradation results confirmed the sequential reaction by GOx and Fe3O4 from Fe3O4/GOx@RSF/zein nanospheres. The in vitro experiments demonstrated that the Fe3O4/GOx@RSF/zein nanospheres entered MCF-7 cells and generated ˙OH free radicals. Therefore, these Fe3O4/GOx@RSF/zein nanospheres exhibited a considerable synergistic therapeutic effect. They showed more efficient suppression in cancer cell growth than either single-loaded GOx@RSF/zein or Fe3O4@RSF/zein nanospheres, achieving the design goal for the nanospheres. Therefore, the Fe3O4/GOx@RSF/zein nanospheres cut off the nutrient supply due to the strong glucose dependence of tumor cells and generated highly toxic ˙OH free radicals in tumor cells, effectively enhancing the anticancer effect and minimizing side effects. Therefore, in future clinical applications, the Fe3O4/GOx@RSF/zein nanospheres developed in this study have significant potential for combining starvation and chemodynamic therapy.