Evaluation of the photocatalytic degradation mechanism of methylene blue using nascent and Ag+ ions-modified TiO2.

In photocatalytic removal of organic pollutants, adsorption and degradation are two important processes that take place. Various instrumental techniques and trapping experiments have been used to identify the reactive species and the mechanism of photodegradation. The present work focuses on investigating the mechanism of photo-induced degradation from the comparative characterization of fresh and used samples, isotherm models, competitive adsorption, and desorption studies of pure and Ag+-modified TiO2 NPs. The comparative characterizations of fresh and used NPs were carried out with FT-IR, EDX, and XRF analyses after methylene blue (MB) degradation. The Ag+ doped TiO2 used in this study was fabricated using simple impregnation technique. The prepared NPs were characterized using techniques including XPS, XRD, SEM/EDX, XRF, UV-DRS, and pH point-zero charge analyses (pHPZC). The Ag+-modified TiO2 NPs showed improved efficiency compared to pure TiO2 NPs using normal compact fluorescent light (CFL). The Langmuir and Freundlich isotherm models were applied to test the adsorption behavior on the surface photocatalysts. The investigational data finest fitted to the Langmuir isotherms model compared to Freundlich model, suggesting the homogeneous monolayer adsorption followed by degradations. The competitive removal of MB in the presence of a photo-generated electrons trapper (Cd2+) was enhanced almost 3-folds (115 mg/L) compared to the removal from a single MB solution (40 mg/L). The characterization of the used samples as well as adsorption in the dark and negligible desorption of used samples support the involvement of the proposed photo-induced degradation mechanism.

Novel modeling and optimization framework for Navy Blue adsorption onto eco-friendly magnetic geopolymer composite.

The disproportionate potency of dyes in textile wastewater is a global concern that needs to be contended. The present study comprehensively investigates the adsorption of Navy-Blue dye (NB) onto bentonite clay based geopolymer/Fe3O4 nanocomposite (GFC) using novel statistical and machine learning frameworks in the following steps; (1) synthesis and characterization of GFC, (2) experimental testing and modelling of NB adsorption onto GFC following Box-Behnken design and three response surface prediction models namely stepwise regression analysis (SRA), Support vector regression (SVR) and Kriging (KR), (3) parametric, sensitivity, thermodynamic and kinetic analysis of pH, GFC dose and contact time on adsorption performance, and (4) finding global parametric solution of the process using Latin Hypercube, Sobol and Taguchi orthogonal array sampling and combining SRA-SVR-KR predictions with novel hybrid simulated annealing (SA)-desirability function (DF) approach. Under the given testing range, parametric/sensitivity analysis revealed the critical role of pH over others accounting ∼37% relative effect and primarily derived the NB adsorption. The statistical evaluation of models revealed that all models could be utilized for elucidating and predicting the NB removal using GFC, however, SVR accuracy was better among others for this particular work, as the overall computed root mean squared error was only 0.55 while the error frequency counts remained <1 for 90% predictions. GFC showed 86.29% NB removal for the given experimental matrix which can be elevated to 96.25% under optimum conditions. The NB adsorption was found to be physical, spontaneous, favorable and obeyed pseudo-2nd order kinetics. The results demonstrate the suitability of GFC as the promising cost-effective and efficient alternative for the decolourization of urban and drinking water streams and elucidate the potential of machine learning models for accurate prediction & elevation of adsorption processes with less experimentation in water purification applications.

Probing the chemical constituents of Cassia javanica and its in vitro analyses as a potent drug.

The phytochemical screening of the crude methanolic stem extracts of Cassia javanica plant showed the presence of different classes of organic compounds like alkaloids, tannins, flavonoids, saponins, phlobatanins, steroids, anthraquinone and cardiac glycoside. The starching frequencies of these functional groups were determined from FT-IR spectroscopic data. The crude and their fractions were examined for antibacterial potential against Klebsiella pneumoniae and Proteus mirabilis. The antibacterial assay showed maximum zone of inhibition for ethyl acetate fraction, i.e. 20 mm against Proteus mirabilis and 18 mm against Klebsiella pneumoniae in the comparison with Levofloxacin used as standard (40 mm). Meanwhile for methanolic crude extract, the inhibition zone was recorded 14 mm against Klebsiella pneumoniae and 22 mm against Proteus mirabilis. The minimum inhibitory concentrations and minimum bactericidal concentrations were recorded as 187.5 µg ml-1 against Proteus mirabilis and 93.75 µg ml-1 against Klebsiella pneumoniae. The scavenging free radical assay was noted as 69.61% at the concentration of 100 ppm.

Synthesis of AgNPs coated with secondary metabolites of Acacia nilotica: An efficient antimicrobial and detoxification agent for environmental toxic organic pollutants.

This study concentrates on biosynthesis of Silver Nanoparticles (AgNPs) from stem extract of Acacia nilotica (A. nilotica). The reaction was completed at a temperature ~40-45 °C and time duration of 5 h. AgNPs were thoroughly investigated via advanced characterization techniques such as UV-Vis spectrophotometry (UV-Vis), Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffractometry (XRD), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM), X-ray Photoelectron Spectroscopy (XPS), Thermo Gravimetric Analysis (TGA), Diffuse Reflectance Spectroscopy (DRS), Brunner-Emmett-Teller (BET), Dynamic Light Scattering (DLS), and Zeta potential analysis. AgNPs with average size below 50 nm were revealed by all the measuring techniques. Maximum surface area ~5.69 m2/g was reported for the as synthesized NPs with total pore volume ~0.0191 mL/g and average pore size ~1.13 nm. Physical properties such as size and shape have changed the surface plasmon resonance peak in UV-visible spectrum. Antimicrobial activity was reported due to denaturation of microbial ribosome's sulphur and phosphorus bond by silver ions against bacterium Methicillin Resistant Staphylococcus aureus (MRSA) and fungus Candida Albican (CA). Furthermore, AgNPs degraded toxic pollutants such as 4-nitrophenol (4-NP), 2-nitrophenol (2-NP) and various hazardous dyes such as Congo Red (CR), Methylene Blue (MB) and Methyl Orange (MO) up to 95%. The present work provided low cost, green and an effective way for synthesis of AgNPs which were utilized as potential antimicrobial agents as well as effective catalyst for detoxification of various pollutants and dyes.

Report: Protective effects of rice bran oil in haloperidol-induced tardive dyskinesia and serotonergic responses in rats.

Effect of administration of Rice bran oil (RBO) was evaluated on haloperidol elicited tardive dyskinesia in rats. Albino Wistar rats treated with haloperidol in drinking water at a dose of 0.2mg/kg/day and RBO by oral tubes at a dose of 0.4 mL/day for 5 weeks. Motor coordination, VCMs and 8-hydroxy-2-(di-n-propylamino) tetraline)[8-OH-DPAT] _syndrome were monitored. Striatal serotonin (5-hydroxytryptamine; 5-HT) and 5-hydroxyindolacetic acid (5-HIAA) levels were determined by high performance liquid chromatography (HPLC-EC). Rats treated with haloperidol orally at a dose of for a period of 5 weeks developed VCMs, which increased progressively as the treatment continued for 5 weeks. Motor coordination impairment started after the 1st week and was maximally impaired after 3 weeks and gradually returned to the 1st week value. Co-administration of RBO prevented haloperidol_induced VCMs as well impairment of motor coordination. The intensity of 8-OH-DPAT_induced syndrome and decreased 5-HT metabolism were greater in water + haloperidol treated animals than RBO + haloperidol treated animals. The present study suggested that involvement of free radical in the development of TD and point to RBO as a possible therapeutic option to treat this hyperkinetic motor disorder.

Behavioral, hormonal and central serotonin modulating effects of injected leptin.

Leptin is viewed as an important target for developing novel therapeutics for obesity, depression/anxiety and cognitive dysfunctions. The present study therefore concerns behavioral, hormonal and central serotonin modulating effects of systemically injected leptin. Pharmacological doses (100 and 500 µg/kg) of leptin injected systemically decreased 24h cumulative food intake and body weight in freely feeding rats and improved acquisition and retention of memory in Morris water maze test. Potential anxiety reducing, hormonal and serotonin modulating effects of the peptide hormone were determined in a separate experiment. Animals injected with 100 or 500 µg/kg leptin were tested for anxiety in an elevated plus maze test 1h later. A significant increase in the number of entries and time passed in open arm of the elevated plus maze in leptin injected animals suggested pronounced anxiety reducing effect. Moreover, circulating levels of leptin correlated significantly with anxiety reducing effects of the peptide hormone. Serum serotonin increased and ghrelin decreased in leptin injected animals and correlated, positively and negatively respectively, with circulating leptin. Corticosterone increased at low dose and levels were normal at higher dose. Serotonin metabolism in the hypothalamus and hippocampus decreased only at higher dose of leptin. The results support a role of leptin in the treatment of obesity, anxiety and cognitive dysfunctions. It is suggested that hormonal and serotonin modulating effects of leptin can alter treatment efficacy in particularly comorbid conditions.

Serum leptin and cortisol, related to acutely perceived academic examination stress and performance in female university students.

Leptin, identified as an antiobesity hormone, also has important role in responses to stress and processing of memory. This study was designed to determine effects of academic examination stress-induced changes in serum leptin and its impact on academic performance. Eighty five healthy female students (age 19-21 years; BMI 21.9 ± 1.6) were recruited for the study. Serum leptin and cortisol were monitored at base line (beginning of academic session) and on the day of examination; using a standardized ELISA kit. Acute perception of academic examination stress was determined with the help of a questionnaire derived from Hamilton Anxiety Scale and self report of stress perception. Academic performance was evaluated by the percentage of marks obtained in the examination. Serum cortisol levels were positively correlated (p < 0.01) with the subjective perception of examination stress but not with academic performance. There was an inverted U-shape relationship between level of stress and academic performance. Leptin increased in all stress groups and correlated (p < 0.01) positively with academic performance. There was an inverted U-shape relationship between level of stress and circulating leptin. The findings suggest the peptide hormone, leptin, is a biomarker of stress perception and a mediator of facilitating effects of stress on cognition.

Effects of clinically relevant doses of methyphenidate on spatial memory, behavioral sensitization and open field habituation: a time related study.

The psychostimulant methylphenidate (MPD) is a first-line drug for the treatment of attention deficit hyperactivity disorder (ADHD). Despite acceptable therapeutic efficacy, there is limited data regarding the long-term consequences of MPD exposure over extended periods. The present study concerns effects of clinically relevant doses of MPD, administered orally to rats for an extended period, on spatial memory, behavioral sensitization and habituation to an open field. Water maze test was used to monitor memory acquisition (2 h after training), retention (day next to training), extinction (1 week after training) and reconsolidation (weekly for 4 weeks). Administration of MPD at doses of 0.25-1.0 mg/kg improved memory acquisition, retention, reconsolidation and impaired memory extinction. Treatment with 0.25 and 0.5 mg/kg MPD for 6 weeks produced a sustained increase in motor activity but higher dose (1.0 mg/kg) elicited behavioral sensitization. High as well as low doses MPD impaired open field habituation. We conclude that clinically relevant doses of MPD enhance memory even if used for extended period. It is suggested that higher (1.0 mg/kg) clinically relevant doses of MPD, if used for extended period, may exacerbate hyperactivity and impulsivity associated with the disease.

Inhibition of apomorphine-induced conditioned place preference in rats co-injected with buspirone: relationship with serotonin and dopamine in the striatum.

Apomorphine is a non-narcotic derivative of morphine, which acts as a dopamine agonist to produce psychostimulant like effects. Currently, apomorphine is used in patients with advanced Parkinson׳s disease, for the treatment of persistent and disabling motor fluctuations, but a constellation of addictive syndromes such as excessive over use of medication, compulsive behaviors, and disturbances of impulse control are noticed in certain patients. Research on rodent models using conditioned place preference (CPP) paradigm also shows that the drug is rewarding. Previously we have shown that repeated administration of apomorphine produces behavioral sensitization which is prevented in rats co-injected with a low (1.0mg/kg) but not higher (2.0mg/kg) dose of buspirone. The present study shows that rewarding effects of apomorphine (1.0mg/kg) in a CPP paradigm are also blocked in rats co-injected with a low (1.0mg/kg) but not higher (2.0mg/kg) dose of buspirone. The levels of serotonin and its metabolite are decreased in the caudate as well as nucleus accumbens of rats exhibiting CPP and the decreases do not occur in animals co-injected with low or higher dose of buspirone. The levels of dopamine and its metabolites are not affected in animals exhibiting CPP; administration as well as co-administration of higher dose of buspirone decreased dopamine metabolism in the caudate as well as nucleus accumbens. The findings suggest a critical role of serotonin in the rewarding effects of apomorphine and imply that co-use of buspirone at low doses can help to control addictive syndromes in Parkinson׳s disease patients on apomorphine therapy.

Enhancement and inhibition of apomorphine-induced sensitization in rats exposed to immobilization stress: relationship with adaptation to stress.

Stress increases vulnerability to addiction while drugs of abuse impair coping responses and pre-dispose to depression. Pre-clinical research shows that stress exposure augments locomotor sensitization effects of drugs of abuse and impairs behavioral tolerance to repeated stress. The present study investigates relationship between behavioral tolerance to repeated immobilization stress and apomorphine-induced sensitization. Apomorphine was injected either before exposure or after the termination of immobilization, daily for 5 days, to monitor drug-induced behavioral sensitization and tolerance in immobilization stress-induced anorexia. We find that apomorphine-induced sensitization is enhanced and tolerance to repeated immobilization is impaired if the drug is administered before exposure to stress episode. Conversely, apomorphine-induced sensitization is inhibited and adaptation to stress is facilitated if the drug is administered after the termination of stress episode. It shows that apomorphine, if experienced during stress, produces greater sensitization and impairs stress tolerance. Conversely, sensitization effects of apomorphine are blocked and tolerance to stress is facilitated in animals receiving drug after the termination of stress episode. It is suggested that additive effects of stress and apomorphine on mesocorticolimbic dopamine neurotransmission and 5-HT-1A influences on dopamine neurotransmission may have a role in the modulation of apomorphine sensitization and tolerance to repeated immobilization stress. The results may help develop potential pharmacotherapies when substance abuse/dependence disorder and depression occur together.

Identification of Sulfamoylbenzamide derivatives as selective Cathepsin D inhibitors.

Aspartic proteases play very important role in post translational processing of proteins and several of them are essential for organism's viability. Here we present the enzyme inhibition activities of different Sulfamoylbenzamide derivatives against two aspartic proteases cathepsin D and plasmepsin II. Cathepsin D is an aspartic protease that degrades proteins at acidic pH in the lysosomes, or extracellular matrix. It is overexpressed by epithelial breast cancer cells and hence hyper-secreted. On the other hand plasmepsin II is an essential enzyme of Plasmodium falciperum. Cathepsin D and Plasmepsin II are pivotal drug targets for treatment of breast cancer and malaria respectively. Virtual screening of Sulfamoylbenzamide compounds followed by enzyme inhibition assays revealed these compounds as selective Cathepsin D inhibitors while inactive against Plasmepsin-II. IC50 values of five Sulfamoylbenzamide compounds tested are in range of 1.25-2.0 µM. N-(3-chlorophenyl)-2-sulfamoylbenzamide is identified as the most potent of all tested Sulfamoylbenzamide compounds with IC50 1.25 µM. It was also noted that the docking score of theses compounds was better in case of Cathepsin D as compared to Plasmepsin-II. Docking score ranges from -29.9±1.16 to -35.1±0.13 in case of Cathepsin D, while from -24.0±0.10 to -29.5±0.10 in case of Plasmepsin-II.

Neurochemical and behavioral effects of green tea (Camellia sinensis): a model study.

Being rich in polyphenolic compounds such as flavonoids, green tea is suggested to be a potential candidate for the treatment of obesity, stress, depression, Parkinson's and other disorders. Since serotonin has an important role in the pathophysiology of these disorders, present study was designed to monitor the effects of green tea in rats. Green tea extract was provided to the male Albino Wistar rats for 5 weeks, and effects on behaviors were monitored. Results show a decrease in food intake after 5th week but not before. An increase in locomotive activities of the animals was observed, as monitored in novel as well as in familiar environment. Anxiolytic effects were observed in elevated plus maze but not in light dark activity box. An increase in dopamine and serotonin turnover was observed. Our results suggest that beneficial effects of green tea drinking might be due to alteration of serotonin and/or dopamine metabolism. We thereby propose that in further experiments, green tea should be administered in animal model of learned helplessness and effects on the development of adaptation to stress should be monitored. Neurochemical estimations of catecholamine and indoleamine in these animal models of stress exposed to green tea would help in understanding the anxiolytic effects of green tea.

Dose-related effects of clozapine and risperidone on the pattern of brain regional serotonin and dopamine metabolism and on tests related to extrapyramidal functions in rats.

The present study was designed to evaluate the behavioral and neurochemical profiles of clozapine and risperidone in rats in a dose-dependent manner. Animals injected intraperitoneally (i.p.) with clozapine (2.5, 5.0 and 10.0 mg kg-1) or risperidone (1.0, 2.5 and 5.0 mg kg-1) were sacrificed 1 h later to collect brain samples. Hypolocomotive effects (home cage activity and catalepsy) were successively monitored in each animal after the drug or saline administration. Both drugs significantly (p < 0.01) decreased locomotor activity at high doses and in a dose-dependent manner. Maximum (100%) cataleptic potential was achieved at a high dose (5.0 mg kg-1) of risperidone. Neurochemical estimations were carried out by HPLC with electrochemical detection. Both drugs, at all doses, significantly (p < 0.01) increased the concentration of homovanillic acid (HVA), a metabolite of dopamine (DA), in the striatum. Dihydroxyphenylacetic acid (DOPAC) levels increased in the striatum and decreased in the rest of the brain, particularly in clozapine-injected rats. 5-Hydroxyindoleacetic acid (5-HIAA), the predominant metabolite of serotonin, significantly (p < 0.01) decreased in the striatum. 5-Hydroxytryptamine (5-HT) was significantly (p < 0.01) increased by risperidone and decreased by clozapine in the rest of the brain. Striatal tryptophan (TRP) was significantly (p < 0.01) decreased by risperidone and increased in the rest of the brain. The striatal HVA/DA ratio increased and the 5-HT turnover rate remained unchanged in the rest of the brain. Results suggest that the affinity of the two drugs towards D2/5-HT1A receptors interaction is involved in lower incidence of extrapyramidal side effects. Role of 5-HT1A receptors in the treatment of schizophrenia is discussed.

Reversal of haloperidol-induced tardive vacuous chewing movements and supersensitive somatodendritic serotonergic response by buspirone in rats.

Tardive dyskinesia (TD), a syndrome of involuntary hyperkinesias in the orofacial region that develops in patients chronically treated with neuroleptic agents is a major limitation of the therapy. Rats chronically treated with haloperidol exhibit vacuous chewing movements (VCMs) with the twitching of facial musculature and tongue protrusion. The syndrome is widely used as an animal model of TD. Evidence suggests a role of 5-hydroxytryptamine (5-HT; serotonin)-1A receptors in the pathogenesis and treatment of TD because repeated administration of haloperidol resulted in an increase in the effectiveness of 5-HT-1A receptors while drugs with agonist activity at 5-HT-1A receptors could attenuate haloperidol-induced VCMs. The present study was designed to test the hypothesis that a decrease in the responsiveness of somatodendritic 5-HT-1A receptors by the coadministration of buspirone could reverse the induction of VCMs and supersensitivity at 5-HT-1A receptors by haloperidol. Rats treated with haloperidol at a dose of 1 mg/kg twice a day for 2 weeks displayed VCMs with twitching of facial musculature that increased in a time dependent manner as the treatment continued to 5 weeks. Coadministration of buspirone attenuated haloperidol-induced VCMs after 2 weeks and completely prevented it after 5 weeks. The intensity of 8-hydroxy-2-di (n-propylamino) tetralin (8-OH-DPAT)-induced locomotion was greater in saline+haloperidol injected animals but not in buspirone+haloperidol injected animals. 8-OH-DPAT-induced decreases of 5-HT metabolism were greater in saline+haloperidol injected animals but not in buspirone+haloperidol injected animals. It is suggested that an impaired somatodendritic 5-HT-1A receptor dependent response is a major contributing factor in the pathophysiology of TD and a normalization of the somatodendritic response by drugs may help extending therapeutics in schizophrenia.

Reversal of haloperidol-induced extrapyramidal symptoms by buspirone: a time-related study.

Effects of coadministration of buspirone were investigated on the time course of haloperidol-induced extrapyramidal symptoms in rats. Rats treated with haloperidol at a dose of 1 mg/kg exhibited impaired motor coordination and a decrease in exploratory activity. Coadministration of buspirone at a dose of 1 mg/kg attenuated haloperidol-induced deficits of motor coordination but no effect was produced on the deficits of exploratory activity, possibly because of a 'floor effect'. Long-term administration of haloperidol (1 mg/kg) twice a day for 5 weeks did not produce tolerance to haloperidol-induced deficits of exploratory activity. The deficits of motor coordination were attenuated after 4-5 weeks of drug administration. Coadministration of buspirone for 3-5 weeks attenuated and reversed haloperidol-induced deficits of exploratory activity. Deficits of motor coordination were smaller in rats cotreated with buspirone after 1 week but not after 2-5 weeks. Administration of haloperidol for 2 weeks elicited vacuous chewing movements with twitching of facial musculature that increased in a time-dependent manner as the treatment continued to 5 weeks. Animals cotreated with buspirone exhibited a gradual reversal of the response during 2-5 weeks of treatment. The mechanism involved in the attenuation/reversal of haloperidol-induced extrapyramidal symptoms by buspirone is discussed. Prior administration of buspirone for 2 weeks may be of help in the improvement of extrapyramidal symptoms induced by antipsychotic drugs.