Involvement Of Free Radicals Research Articles

10-(6-Plastoquinonyl) decyltriphenylphosphonium imparts anti-colitogenic protection through recovery of mitochondrial dysfunction in ulcerated murine colon: Implications in ulcerative colitis

AimsTo elucidate the impact of 10-(6-plastoquinonyl) decyltriphenylphosphonium (SkQ1) as an anti-colitogenic agent for maintenance of colon epithelial tract in ulcerated mice through recovery of mitochondrial dysfunction and mitochondrial stress by virtue of its free radical scavenging properties. Main methodsDSS induced ulcerated BALB/c mice were treated with SkQ1 for 14 days @ 30 nmol/kg/body wt./day/mice. Post-treatment, isolated colonic mitochondria were utilized for spectrophotometric and spectrofluorometric biochemical analysis of various mitochondrial functional variables including individual mitochondrial respiratory enzyme complexes. Confocal microscopy was utilized for measuring mitochondrial membrane potential in vivo. ELISA technique was adapted for measuring colonic nitrite and 3–nitrotyrosine (3-NT) content. Finally in vitro cell line study was carried out to substantiate in vivo findings and elucidate the involvement of free radicals in UC using antioxidant/free radical scavenging regimen. Key findingsTreatment with SkQ1 in vivo reduced histopathological severity of colitis, induced recovery of mitochondrial respiratory complex activities and associated functional variables, improved oxidative stress indices and normalized mitochondrial cardiolipin content. Importantly, SkQ1 lowered nitrite concentration and 3–nitrotyrosine formation in vivo. In vitro SkQ1 restored mitochondrial functions wherein the efficacy of SkQ1 proved equal or better compared to SOD and DMSO indicating predominant involvement of O2− and OH in UC. However, NO and ONOO− also seemed to play a secondary role as MEG and L-NAME provided lesser protection as compared to SOD and DMSO. SignificanceSkQ1 can be considered as a potent anti-colitogenic agent by virtue of its free radical scavenging properties in treating UC.

Reactive species identification in KCl activated biochar/persulfate system under different pH condition: Theoretical calculation and column experiments

The challenges of remediating polluted water in mine areas are exacerbated by low emission dispersion and long-lasting pollution, particularly the significant fluctuations in pH value. Notably, the treatment of flotation reagent polluted water with variable pH scenarios remains a challenge. In this study, metal-free biochar-based materials (KBBC)/persulfate system was used for flotation reagent contaminated wastewater treatment with a wide pH range. Regarding the intrinsic nature of the biochar-based materials, ball milling enhanced the degree of graphitization, while introducing a hard template of KCl increased the proportion of carbonyl functional groups on their surface, thereby facilitating persulfate activation. Experimental findings revealed that the KBBC/PS system displayed efficient degradation of aniline aerofloat (AAF) as a representative flotation reagent across a wide pH range (pH = 3.6–10.4 with buffer). Investigations on the mechanism indicated that, under acidic and neutral conditions, superoxide radicals and direct electron transfer processes constituted primary pathways for pollutant degradation. Meanwhile, various active species contributed under alkaline conditions with increased involvement of free radicals (•OH and SO4•−) and singlet oxygen. Furthermore, continuous flow experiments were set up to prove the potential applicability of the KBBC/PS process. This study not only deepens the understanding of persulfate activation by metal-free carbon-based materials across a wide pH range but also expands their potential applications in mine-polluted water purification.

Cobalt‐Catalyzed Oxytrifluoromethylation of N‐Allylamides toward Trifluoromethyl‐Containing Oxazolines

AbstractWe herein report a cobalt‐catalyzed intramolecular oxytrifluoromethylation of N‐allylamides for the efficient synthesis of trifluoromethyl‐containing oxazolines with Togni's reagent II as the trifluoromethyl precursor. The protocol features mild reaction conditions and good functional group compatibility. Preliminary mechanistic investigations suggest the involvement of free radicals in this transformation.

Mechanistic Study of Reaction between 5-Sulfosalicylic Acid and Colloidal MnO2

The reaction between 5-sulfosalicylic acid (5-SSA) and colloidal MnO2 has been studied kinetically in acidic medium. During the reaction the concentration of 5-SSA was kept highly excess than the concentration of colloidal MnO2 to maintain the pseudo-first-order condition. The reaction was studied by following decrease in absorbance of colloidal MnO2 at 390 nm and the first order rate constants were determined from linear log (Abs.) against time plots. The linearity of the first-order plots did not involve any autocatalytic part. The oxidation of 5-sulfosalicylic acid (5-SSA) by colloidal MnO2 involves intervention of free radicals and Mn(III). The product of reaction in colloidal MnO2 was p-hydroxy benzene sulfonate ion as confirmed by LCMS-MS analysis. The oxidation by colloidal MnO2 consists of acid dependent and independent mechanisms. The results of added Mn(II), Na4P2O7 and acrylonitrile indicate involvement of Mn(III) and free radical during oxidation by colloidal MnO2. The probable mechanisms for acid dependent and independent paths were predicted and the rate expressions were also obtained. The activation parameters also support the proposed mechanisms.

Phytochemical Evaluation and Determination of the Content of Some Natural Antioxidants (Polyphenols and Flavonoids) from Ficus Capensis, Newbouldia laevis and Carpolobia lutea

Scientific interest in the search for natural antioxidants (secondary metabolites) from medicinal plants has increased considerably in recent years, due to the involvement of free radicals in the genesis of many diseases. The aim of the present study is to determine qualitatively and quantitatively the secondary metabolites of aqueous and hydroethanol extracts from the leaves of the medicinal plants under investigation. Qualitative determination is based on staining and/or precipitation reactions, while quantitative determination is based on the assay of secondary metabolites. The results of their qualitative determinations revealed an abundance of polyphenols and saponins, a significant presence of flavonoids and anthocyanins, and a moderate presence of alkaloids, terpenes and catechic tannins in the aqueous extract. In the hydroethanol extract, on the other hand, there is an abundance of flavonoids, a significant presence of polyphenols, saponins and anthocyanins, and a moderate presence of alkaloids, terpenes and catechic tannins. Gallic tannins and quinones are absent in both extracts. While their quantitative assay revealed an abundance of flavonoids (314.51±5.14 mgEAG/g extract) and total polyphenols (66.19±2.44 mgEQ/g extract). Thus, the high flavonoid and polyphenol content of the various extracts (aqueous and hydroethanolic) of the leaves of the plants studied would justify their use in traditional medicine in the care of sickle-cell patients.

Pterodon emarginatus Seed Preparations: Antiradical Activity, Chemical Characterization, and In Silico ADMET Parameters of β-caryophyllene and Farnesol.

The study of medicinal plants and their active compounds is relevant to maintaining knowledge of traditional medicine and to the development of new drugs of natural origin with lower environmental impact. From the seeds of the Brazilian plant Pterodon emarginatus, six different preparations were obtained: essential oil (EO), ethanol extract (EthE) prepared using the traditional method, and four extracts using solvents at different polarities, such as n-hexane, chloroform, ethyl acetate, and methanol (HexE, ChlE, EtAE, and MetE). Chemical characterization was carried out with gas chromatography, allowing the identification of several terpenoids as characteristic components. The two sesquiterpenes β-caryophyllene and farnesol were identified in all preparations of Pterodon emarginatus, and their amounts were also evaluated. Furthermore, the total flavonoid and phenolic contents of the extracts were assessed. Successively, the antiradical activity with DPPH and ORAC assays and the influence on cell proliferation by the MTT test on the human colorectal adenocarcinoma (HT-29) cell line of the preparations and the two compounds were evaluated. Lastly, an in silico study of adsorption, distribution, metabolism, excretion, and toxicity (ADMET) showed that β-caryophyllene and farnesol could be suitable candidates for development as drugs. The set of data obtained highlights the potential medicinal use of Pterodon emarginatus seeds and supports further studies of both plant preparations and isolated compounds, β-caryophyllene and farnesol, for their potential use in disease with free radical involvement as age-related chronic disorders.

Effect of initial solution pH on 4-nitrophenol oxidation through homogeneous/heterogeneous photo-Fenton process using goethite/H2O2 system

The photodegradation of 4-nitrophenol (4-NP) through homogeneous/heterogeneous photo-Fenton process was examined in the presence of goethite (α-FeOOH)/H2O2/UV system in solution at different pH values. The degradation of 4-NP was achieved with excellent performance. Conversion reached 100%, 92% and 83% in the first 120 min of irradiation for acidic, point of zero charge (pzc) and weakly alkaline pH, respectively. Meanwhile, 69% of degradation was reached under strong alkaline pH conditions and this resulted in the weakest removal percentage under comparable experimental conditions. The rate of photocatalytic degradation followed pseudo-first order kinetics with kinetic constants of 6.30 × 10−2 min−1, 2.37 × 10−2 min−1, 1.73 × 10−2 min−1 and 0.70 × 10−2 min−1 at pH = 3.0, 5.5, 9.0 and 11.0, respectively. The iron(II) species dissolved in the solution enhanced the photocatalytic degradation and the hydroxyl radicals (OH) production. The involvement of free radicals was evidenced by using scavengers and the results revealed that OH is the main active species. The stability of goethite to repeated uses was investigated too and, after five runs, the removal efficiency of 4-NP was still complete, with values attaining 100%.

Oxygen vacancies enhanced natural manganese sand activation by PMS for CBZ degradation: Intermediate toxicity and DFT calculations

The preparation of sulfate-based advanced oxidation catalysts is usually both complex and expensive. In this study, natural manganese sand enriched with oxygen vacancies was prepared by NaBH4 reduction of natural manganese sand for activating peroxymonosulfate (PMS) to remove carbamazepine (CBZ). 70% of carbamazepine was degraded at 120 min when natural manganese sand enriched with oxygen vacancies and PMS were dosed at 0.4 g/L and 0.3 g/L respectively, and the reaction rate constant of the natural manganese sand system with rich oxygen vacancies was 7 times that of the common system. The mineralization of total organic carbon (TOC) reached 41.9%. Combined EPR and radical quenching assays revealed that degradation of pollutants relied on the involvement of free radicals and non-free radicals, in which singlet oxygen was dominant. The XPS results showed that the redox cycles of Fe3+/Fe2+ and Mn4+/Mn3+/Mn2+ promoted the generation of free radicals. Density functional theory results also showed that the energy required for PMS to adsorb on natural manganese sand with many oxygen vacancies was decreased, and the OO bond was elongated, which was beneficial to the catalytic reaction. According to LC-MS and Fukui function, the degradation route of CBZ was predicted, and the toxicity of the breakdown products was calculated. The research provides a reference for introducing oxygen vacancies in natural catalysts to improve degradation performance for “green (source) to green (application)”.

Organic matrix-entrapped methylene blue as a photochemical reactor applied in chemical synthesis and nanotechnology

Aggregation modulates the photochemical and photophysical properties of methylene blue (MB+). MB+ adsorbed by the anionic polymer Chelex® 100 was characterized by UV–visible absorption spectroscopy and sulfur K-edge X-ray absorption near edge structure (XANES) as H- and J-aggregates. Nuclear magnetic resonance (NMR) indicates that dye molecules bind to the unprotonated carboxylic groups of the polymer via electrostatic interactions and are bridged by water molecules. MB+ also stacks with phenyl rings appended in the Chelex® 100 chain, leading to a gain in the mobility of ordered water displaced around the aromatic rings. Like the blue bottle experiment, MB+ in Chelex® 100 was entirely photoconverted for the leuco form (LMB) by visible and red light and reoxidized by molecular oxygen. Electron paramagnetic resonance (EPR) of MB+ in Chelex® 100 demonstrated the formation of a sulfur-centered free radical during photobleaching. The free radical involvement in MB+ photobleaching is consistent with a type I mechanism in which the stabilization of the products MB2+• and MB• in dye aggregates allows the formation of LMB by MB• dismutation or a second electron abstraction. Chelex® 100 beds loaded with MB+ solutions prepared in H2O and D2O produce H2O2 and D2O2, respectively, after successive cycles of photobleaching and recycling by O2 dissolved in the liquid phase. The formation of hydrogen peroxide is attributed to spontaneous superoxide ion disproportionation in the microenvironment of the polymer lattice. The LMB produced in Chelex® 100 was also able to act as a reducing agent for the synthesis of anisotropic iridescent gold nanoparticles (GNPs). The LMB/Chelex system allows the modulation of the shape and size of GNPs using different dye/Au3+ ratios. GNPs produced using LMB as a reducing agent are also efficient cell delivery systems. The specific properties of LMB confined in solid hosts LMB/Chelex also have potential applications in new solid-state optoelectronic devices such as sensing and imaging.

Sulfmyoglobin production by free cysteine during thermal treatment: Involvement of heme iron in the production of free radicals

The meat greening is an abnormal pigmentation related to microbiological contamination and lipid oxidation during storage. This color change results from sulfmyoglobin (SulfMb) production promoted by the reaction between metmyoglobin (MetMb), H2O2, and thiol compounds. Spectral studies on cooked meat suggested the production of SulfMb, probably due to the increment of free radicals during thermal treatment. Thus, we evaluated the involvement of free radicals and heme iron in the SulfMb production from horse MetMb and free cysteine (Cys) during thermal treatment. The results confirm that the reaction of SulfMb production at meat muscle pH (5.7–7.2) during heat treatment is a product of free radicals formed from Cys oxidation (SH) and reactive oxygen species (O2−, H2O2). This is catalyzed by the release of heme iron, thus promoting a consecutive reaction having MbFe(IV)O as a reaction intermediate.

Electrochemically Induced Regio‐ and Stereoselective (E)‐β‐C(sp2)−H Trifluoromethylation and Arylsulfonylation of Enamides

AbstractHerein, we disclosed an electrochemically induced method for the regio‐ and stereoselective (E)‐β‐C(sp2)−H trifluoromethylation of enamides by employing readily available and inexpensive Langlois’ reagent (CF3SO2Na). Preliminary mechanistic studies indicate the involvement of free radicals in the process. The exogenous oxidant‐free reaction proceeds in an undivided electrochemical cell under mild conditions and allows for the accomplishment of the trifluoromethylation products with exclusive E‐selective control. The methodology is featured by catalyst‐free, simple setup, and broad substrate scopes of enamides with good functional group tolerance. Using ArSO2Na as the coupling partner, the corresponding (E)‐β‐C(sp2)−H arylsulfonylated enamides products are obtained under standard reaction conditions.magnified image

Redox reaction of bis-(2-pyridinealdoximato)dioxomolybdate(IV) complex with thiosulphate ion in aqueous acidic and surfactant media

• The order of reaction, the stoichiometric, the salt effect, and the involvement of free radical are imperative in rationalizing the mechanistic route of the reaction. • The probing of the electrostatic and hydrophobic interactions of the substrates with the micelle is vital in understanding medium effect on redox reactions. • The activation parameters portray the occurrence of energized precursor complex and activated complex. The redox reaction of bis-(2-pyridinealdoximato)dioxomolybdate(IV) complex, [Mo IV O 2 (paoH) 2 ] 2− with thiosulphate ion (S 2 O 3 2− ) is conducted spectrophotometrically, and it follows a reductive-oxidative route which is medium dependent. The aqueous acidic and surfactant media were studied in order to understand the mobility and the rate of the reacting species with regard to their chemical nature. The aqueous acidic medium is characterised by a slow rate compared with the surfactant (CTAB) medium and with the second order rate constant of 0.1299 ± 0.004 and 0.294 ± 0.02 dm 3 mol −1 s −1 respectively. The general order of the reaction was first order with respect to the concentration of both reactants and second order overall. The stoichiometry trend of 1:1 is observed with the full participation of free radicals (atoms), which led to the formation of Mo II ion and tetrathionate ion as the products. The effect of salt concentration on the reaction rate is not positively pronounced, which implies a reaction occurring with dissimilar charge species at the slow phase of the reaction. The decrease in the medium polarity influences the reaction rate positively with a significant acceleration in the rate of reaction. The prevalence of ion catalysis is expected due to the interaction of unlike charged species at the rate-limiting step. The activation parameters, Δ H ‡ and Δ G ‡ (41.60 ± 0.02 and 78.44 ± 0.03) kJ mol −1 show that reasonable energy is needed to overcome the energy barrier of the transition state of the reaction. Further probing of the effect of surfactant medium led to the generation of a kinetic model from Piszkiewicz’s model of bimolecular reaction.

Tissue Sodium Accumulation: Pathophysiology and Clinical Implications.

Excessive sodium intake has been well established as a risk factor for the development and progression of cardiovascular and renal diseases. Its adverse effects are achieved by renal sodium retention and related volume expansion and by inducing low-grade inflammation and oxidative stress (OS) in the target tissues. This review presents the recent concept of nonosmotic sodium storage in the skin interstitium, the subsequent dissociation of sodium and volume homeostasis, and the cellular response to the increased tissue sodium concentration. Furthermore, data are shown on the sodium barrier and buffering potential of the endothelial glycocalyx that may protect the functional integrity of the endothelium when it is challenged by an increased sodium load. Finally, examples will be given of the involvement of oxygen free radicals (OFR) in sodium-induced tissue damage, and some clinical entities will be mentioned that are causally associated with sodium/volume retention and OS.

Free radical biology in neurological manifestations: mechanisms to therapeutics interventions.

Recent advancements and growing attention about free radicals (ROS) and redox signaling enable the scientific fraternity to consider their involvement in the pathophysiology of inflammatory diseases, metabolic disorders, and neurological defects. Free radicals increase the concentration of reactive oxygen and nitrogen species in the biological system through different endogenous sources and thus increased the overall oxidative stress. An increase in oxidative stress causes cell death through different signaling mechanisms such as mitochondrial impairment, cell-cycle arrest, DNA damage response, inflammation, negative regulation of protein, and lipid peroxidation. Thus, an appropriate balance between free radicals and antioxidants becomes crucial to maintain physiological function. Since the 1brain requires high oxygen for its functioning, it is highly vulnerable to free radical generation and enhanced ROS in the brain adversely affects axonal regeneration and synaptic plasticity, which results in neuronal cell death. In addition, increased ROS in the brain alters various signaling pathways such as apoptosis, autophagy, inflammation and microglial activation, DNA damage response, and cell-cycle arrest, leading to memory and learning defects. Mounting evidence suggests the potential involvement of micro-RNAs, circular-RNAs, natural and dietary compounds, synthetic inhibitors, and heat-shock proteins as therapeutic agents to combat neurological diseases. Herein, we explain the mechanism of free radical generation and its role in mitochondrial, protein, and lipid peroxidation biology. Further, we discuss the negative role of free radicals in synaptic plasticity and axonal regeneration through the modulation of various signaling molecules and also in the involvement of free radicals in various neurological diseases and their potential therapeutic approaches. The primary cause of free radical generation is drug overdosing, industrial air pollution, toxic heavy metals, ionizing radiation, smoking, alcohol, pesticides, and ultraviolet radiation. Excessive generation of free radicals inside the cell R1Q1 increases reactive oxygen and nitrogen species, which causes oxidative damage. An increase in oxidative damage alters different cellular pathways and processes such as mitochondrial impairment, DNA damage response, cell cycle arrest, and inflammatory response, leading to pathogenesis and progression of neurodegenerative disease other neurological defects.

Redox reactions of tris-(1,10-phenanthroline)iron(III) complex with thiourea and N-methylthiourea in an aqueous acidic medium: Kinetics and mechanism

Spectrophotometrically, the redox reactions of tris-(1,10-phenanthroline)iron(III) complex with thiourea (TSH) and N-methylthiourea (MSH) in an aqueous acidified medium have been investigated at maximum absorption of 510 nm and 301 K. The reactions were first order with respect to [FeIII(phen)33+], [MSH] and [TSH]. The stoichiometric mole ratio investigations of [FeIII(phen)3]3+ with [MSH] is 1:1, and with that of [TSH] is 2:1. An enhancement of observed reaction rates by protonation of hydrogen ion was insignificant for both reactions of TSH and MSH with the complex. The variation of the salt concentration (NaCl) and solvent polarity (acetone/water mixture) of the [FeIII(phen)3]3+ / TSH reaction medium has no substantial effect on the observed reaction rate (kobd), while there was retardation and enhancement of reaction rate on the change in the salt concentration and solvent polarity of the [FeIII(phen)3]3+ / MSH system respectively. The participation of added anion (NO3−) and cation (NH4+) aided the reaction of the complex with MSH, and the cation (NH4+) and anion (NO3−) showed no significant effect on the observed reaction rates of the [FeIII(phen)3]3+ / TSH system. The involvement of free radicals was eminent for the reactions, and it contributed to a meaningful product formation. The investigation of the thermodynamic activation parameters; ΔS‡ (−152.63 Jmol−1 K−1), ΔH‡ (+33.19 kJmol−1), Ea (+35.69 kJmol−1), and ΔG‡ (+79.13 kJmol−1) showed that the reaction of the complex with TSH proceeds via an endothermic process as well as the reaction of the complex / MSH with ΔS‡ (−145.03 Jmol−1 K−1), ΔH‡ (+36.07 kJmol−1), Ea (+38.57 kJmol−1) and ΔG‡ (+79.72 kJmol−1). The results of ΔS‡ indicate that the reactions followed an associative route, and although, it was not established by Michaelis Menten’s plot for the reaction of the complex with MSH. The observation of a determinable intermediate complex reinforced the associative route noticed in the reaction of the TSH with the complex, whereas, the absence of a significant intermediate complex in the reaction of the MSH with the complex ruled it out. An inner-sphere mechanistic pathway is implicated for [FeIII(phen)3]3+/ TSH reaction with a stable intermediate complex formation as shown below;

Metal-free visible-light-catalyzed synthesis of 3-methyl-3,4-dihydroisoquinolin-1(2H)-one: mechanism, DFT calculation and optical properties

We had developed a visible light-catalyzed green synthesis method of 3-position substituted 3,4-dihydroisoquinoline-1(2H)-one compounds without metal participation, and initially proposed the reaction mechanism of visible light-catalyzed free radical involvement. In order to further verify the reliability of the proposed mechanism, density functional theory was used to analyze the structures involved in the reaction process. The theoretical results rationalized the experimental observations well and provided deeper insight into the mechanism. In addition, the photocatalytic reaction was further recognized by measuring the emission spectrum and absorption spectrum of the reaction system.

Study of the Development of Carotid Artery Atherosclerosis upon Oxidative Stress using Infrared Spectroscopy and Scanning Electron Microscopy

In the present study, Fourier-transform infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) were used to investigate the formation and development of carotid artery atherosclerosis. The FTIR spectra showed that with the progression of atheromatic plaque formation, the collagen changed its native structure from ɑ-helix to random coil, amyloid, and cross-links. The infrared spectra and SEM analysis of carotid arteries showed that higher than 65% of the atheromatic plaque in patients with stenosis consisted of calcium carbonate, which lies inside foam cells. However, as the stenosis progresses, these deposits of calcium phosphate become more prevalent. A thorough analysis of the SEM images highlighted that mineral deposits preferred the carboxyl groups of amino acids. The intensity and shape changes in FT-IR spectra in the region of 1200-900 cm<sup>-1</sup> were related to elevated serum glucose and uric acid levels, the formation of advanced glycation end products (AGEs), and the involvement of free radicals during atherosclerosis.

Drug Repurposing Patent Applications October-December 2020.

Drug Repurposing Patent Applications October-December 2020.

Role of free radical scavenging activity of vasoactive intestinal peptide in the attenuation of mitochondrial dysfunction to ameliorate dextran sulphate sodium‐induced colitis in mice: Implications in ulcerative colitis

To evaluate the efficacy of vasoactive intestinal peptide (VIP) in treating ulcerative colitis (UC), targeting colonic mitochondrial dysfunction by virtue of its free radical scavenging properties for maintenance of colon mucosal integrity. A murine model was administered with dextran sodium sulfate (DSS) to induce colitis in C57BL/6J mice at 3.5%/g bodyweight for 3 cycles of 5 days each, followed by an intraperitoneal dose of VIP at 0.5 nmol/L per mouse per day for 10 days. The post-treatment mice were sacrificed and their colon samples were utilized for further analysis. To substantiate the in vivo findings and identify the reactive species involved in progression of UC, Caco-2 cells were subjected to DSS (5%) for 24 hours at 37 °C with or without VIP (10 nmol/L) in the presence or absence of specific free radical scavengers and antioxidants. Treatment with VIP reduced histopathological severity of colitis and cell death markers in murine model, leading to partial recovery of inhibited mitochondrial respiratory complexes, altered mitochondrial membrane potential and lowered adenosine triphosphate generation. Interestingly, in vitro treatment with VIP restored mitochondrial functions and its efficacy was equal to super oxide dismutase and dimethyl sulfoxide, indicating involvement of superoxide free radical (O2 •-) and hydroxyl radical (•OH) in progression of UC. However, catalase, Nω-nitro-l-arginine methyl ester and mercaptoethylguanidine were ineffective, indicating non-involvement of hydrogen peroxide, nitric oxide and ONOO- in UC. By virtue of its free radical scavenging properties VIP can act as a potent anti-colitogenic agent, reversing colonic mitochondrial dysfunction for treating UC.

Restraint stress abates the antioxidant potential of melatonin on dimethyl benz (a) anthracene (DMBA) induced carcinogenesis.

Free radical involvement in initiation, promotion and progression of carcinogenesis, implicates that scavengers of free radicals may act as inhibitors in the carcinogenic process. Melatonin, an antioxidant was used in the present study to evaluate its effectiveness on skin carcinogenesis induced by DMBA both with and without chronic restraint stress (CRS). Fifty Swiss albino young male rats were divided into five groups of 10 rats each as controls, topical DMB alone, Pre CRS-DMBA, melatonin DMBA and Pre-CRS-DMBA-melatonin treated groups. After 18 weeks blood was collected along with liver and skin samples. These were used for antioxidant enzyme assay, DNA damage and fluorescent spectra analysis. Melatonin showed antioxidant potential in combatting DMBA induced skin carcinogenesis measured by free radical scavenging enzymes and in vivo antioxidant status, DNA damage. Sensitive detection of the DMBA induced micro biochemical changes was possible by fluorescent spectroscopy from the transformed ratio of fluorescent intensity (F1 530 nm/630 nm) otherwise found constant for normal tissues. By melatonin treatment this ratio was similar to control values. The decreased antioxidant biochemical parameters depicting oxidative stress were comparable to comet assay and fluorescent studies, endorsing the chemo-preventive efficacy of melatonin against skin carcinogenesis caused by DMBA. CRS pre-exposure diminished the chemo-preventive/antioxidant ability of melatonin and the results were same as DMBA alone treatment, showing stress affected both cancer development and chemoprevention. CRS decreased the antioxidant potential of melatonin. Hence, managing stress could be perceived in cancer chemoprevention. Further studies focusing on stress reduction are needed.