This study describes synthesis of a series of piperazine-triazole derivatives and their ex vivo evaluation for preliminary muscarinic acetylcholine receptor (mAChR) blocking activity on rat ileum model. A molecule based on benzonitrile piperazine triazole scaffold showed good tissue relaxation and blocking of neurotransmitter ACh in the ex vivo experiment.

This study describes screening of muscarinic acetylcholine receptors (mAChR) antagonist by pharmacophore modeling and optimization by molecular docking. A series of molecules was synthesized and evaluated for preliminary pharmacological activity on rat ileum. A molecule based on benzonitrile piperazine scaffold showed good tissue relaxation and blocking of neurotransmitter ACh in the ex vivo experiment.

Synthesis and bioefficacy of fentanyl and its 8 new 1-substituted analogs (1-8) were earlier reported by us. Of these 8 compounds, N-(1-(2-phenoxyethyl)-4-piperidinyl)propionanilide (2), N-isopropyl-3-(4-( N-phenylpropionamido)piperidin-1-yl)propanamide (5), and N- t-butyl-3-(4-( N-phenylpropionamido)piperidin-1-yl) propanamide (6) were found to be more effective and less toxic compared to fentanyl. The present study reports the acute effect of fentanyl (0.50 Median Lethal Dose (LD50); intraperitoneal) and its 3 analogs (2, 5, and 6) on various biochemical and oxidative parameters in mice and various physiological parameters in rats. Blood alkaline phosphatase (1 hour and 7 days) and urea levels (1 hour) were significantly elevated by fentanyl, while alanine aminotransferase levels (1 hour) were increased by both fentanyl and analog 2 compared to the corresponding control. Increase in partial pressure of carbon dioxide and decrease in partial pressure of oxygen were also caused by fentanyl and analog 2 (1 hour). Analog 6 alone elevated malondialdehyde levels in the brain, liver, and kidney tissues (7 days). The LD50 of fentanyl and analogs 2, 5, and 6 were found to be 0.879, 87.88, 69.80, and 55.44 mg/kg, respectively, in rats. Significant decrease in heart rate, mean arterial pressure, respiratory rate (RR), and neuromuscular transmission was produced by fentanyl and analog 2, while analog 5 decreased the RR alone. The changes, particularly the respiratory depression, were found to be reversed by naloxone, a μ-receptor antagonist. Thereby, indicating involvement of μ-receptor mediated effects of the compounds. To conclude, all the analogs were found to be less toxic compared to fentanyl, suggesting their possible role in pain management.

Cyanogens are widely used in industries and their toxicity is mainly due to cyanogenesis. The antidotes for cyanide are usually instituted for the management of cyanogen poisoning. The present study reports the protective efficacy of 14 carbonyl compounds and their metabolites, and nutrients (1.0 g/kg; oral; +5 min) against acute oral toxicity of acetonitrile (ATCN), acrylonitrile (ACN), malononitrile (MCN), propionitrile (PCN), sodium nitroprusside (SNP), succinonitrile (SCN), and potassium ferricyanide (PFCN) in rats. Maximum protection index was observed for alpha-ketoglutarate (A-KG) against MCN and PCN (5.60), followed by dihydroxyacetone (DHA) against MCN (2.79). Further, MCN (0.75 LD50) caused significant increase in cyanide concentration in brain, liver and kidney and inhibition of cytochrome c oxidase activity in brain and liver, which favorably responded to A-KG and DHA treatment. Up-regulation of inducible nitric oxide synthase by MCN, PCN and SNP, and uncoupling protein by PCN and SNP observed in the brain was abolished by A-KG administration. However, no DNA damage was detected in the brain. MCN and SNP significantly decreased the mean arterial pressure, heart rate, respiratory rate and neuromuscular transmission, which were resolved by A-KG. The study suggests a beneficial effect of A-KG in the treatment of acute cyanogen poisoning.

Abstract Objective: The present study was planned to investigate the prophylactic efficacy of S-2(2-aminoethylamino)ethyl phenyl sulfide (DRDE-07), against topically applied SM induced pulmonary toxicity in mouse. Materials and methods: Animals were pretreated with S-2(2-aminoethylamino)ethyl phenyl sulfide (DRDE-07) (249.4 mg/kg by oral gavage) 30 minutes before SM exposure. The SM (6.48 mg/kg) was applied on hair clipped dorsocaudal region (percutaneous) of the animal. The animals were sacrificed on day 1, 3, 5 and 7. The biochemical changes those were observed in the bronchoalveolar lavage (BAL) fluid and lung tissue included protein, LDH, MPO, β-glucuronidase, MMP-2, MMP-9, activated macrophages, reduced glutathione and lipid peroxidation level. Results and discussion: Pretreatment with DRDE-07 (0.2 LD50) attenuated SM-induced changes at all time point tested. BAL fluid biochemical endpoints indicated epithelial and endothelial cell damages as evidenced by increase in BAL protein, LDH level and increased number of activated macrophages. The increased myeloperoxidase activity and β-glucuronidase level exhibited the degranulation of neutrophils due to SM toxicity in lung. The zymogrphy analysis of BAL fluid showed a significant increase in matrix metalloproteases (MMP) activity due to inflammatory cells accumulation. Conclusion: Thirty minutes pretreatment with DRDE-07 decreased vascular permeability reduced the inflammation and oxidative stress, hence may be recommended as a potential prophylactic agent for SM intoxication.

Organophosphorus compounds (OPCs) are highly toxic being used in pest control. Some of the OPCs are lethal chemical warfare agents and their toxicity is due to inhibition of acetylcholine esterase (AChE), the enzyme that hydrolyses neurotransmitter acetylcholine (ACh). Due to over accumulation of ACh at muscarinic acetylcholine receptors (mAChRs) several cholinergic functions increase uncontrollably like salivation, lacrimation, urination, defecation, gastrointestinal upset, and emesis. Atropine is used to treat OPC poisoning because it is a mAChR antagonist. But atropine has several unwanted side effects including dryness of mucous membrane, hot and dry skin, tachycardia, and restlessness. Our goal was to find out molecules having antimuscarinic activity which may be developed as potential alternatives for atropine in future. In this work pharmacophore-based screening, structure identification, synthesis and ex vivo evaluation of a new class of muscarinic receptor antagonist are described. The antagonists are based on dihydropyrimidinone scaffold with a tertiary or quaternary amine side group. A series of molecules were evaluated for preliminary pharmacological activity on rat ileum out of which three molecules found active.

Objective: The study focuses on time-dependent comparative evaluation of various biomarkers of acute cyanide poisoning in rats.Methods: Blood gas (analyzer), lactate, pyruvate, cyanide, thiocyanate (spectrophotometer) and 2-amino-2-thiazoline-4-carboxylic acid (ATCA; gas chromatography-mass spectrometry) in plasma or urine, and various physiological parameters (polygraph) were measured.Results: Cyanide poisoning was characterized by elevated lactate, cyanide, thiocyanate and ATCA concentrations in plasma up to 15 min, 4, 16 and 24 h, respectively, while high urinary thiocyanate and ATCA levels were measured between 4 and 24 h.Conclusion: ATCA concentration in plasma and urine was found to be more reliable indicator of cyanide poisoning.

Atropine sulphate and pralidoxime chloride are considered as essential antidotes in the treatment of nerve agent poisoning. Now in India these antidotes are available in the form of self injectable autoinjectors. This study is designed with aim to replace two individual autoinjectors with single one. Stability of the components plays a vital role in the development of any dosage form, in this study we investigated the stability of the antidotes in combination (atropine sulphate+2 PAMCl) in single drug cartridges. In the present work shelf life of pralidoxime chloride (300 mg/ml) and atropine sulphate (1 mg/ml) solution in combination was evaluated by accelerated studies. The derived model is based on the rate equation and Arrhenius equation was used for extrapolation. Further, antidotal efficacy of atropine sulphate in vitro, using rat's isolated ileum and pralidoxime chloride by survival studies in vivo against dichlorvas in mice were evaluated, for further confirmation of analytical findings. The constituted formulation was found to be stable for 24 months.

Previous studies have reported an enhancement of central cholinergic signal cascade by shilajit. For the present study, it was hypothesized that parasympathomimetic effect of shilajit accounting for relaxation of rat corpus cavernosum may be one of the major mechanisms attributing to its traditional role as an aphrodisiac. To test this hypothesis, the acute peripheral effect of standard acetylcholine (ACh), shilajit, and their combination was evaluated on cardiorespiratory parameters such as mean arterial blood pressure (MABP), heart rate (HR), respiratory rate (RR), and neuromuscular transmission (NMT). Furthermore, in vitro effect of standard ACh, shilajit, and their combination was tested on the rat corpus cavernosum. Six groups were used for the in vivo study ( N = 5): Group I (control-saline), Group II (ACh), Group III (Sh), Group IV (Sh followed by ACh), Group V (Atropine followed by ACh), and Group VI (Atropine followed by Sh). The in vitro study included four groups: Group I (control-saline), Group II (ACh), Group III (Sh), and Group IV (Sh followed by ACh). The results of the in vivo study confirmed the peripheral parasympathomimetic effect of shilajit (400 µg/mL). The in vitro results revealed that shilajit (400 and 800 µg/mL) relaxed cavernous strips’ concentration dependently and enhanced ACh-mediated relaxations. The peripheral parasympathomimetic effects of shilajit were confirmed by blockade of shilajit-induced relaxations (in vitro) and shilajit-induced lowering of MABP and HR (in vivo) by atropine.

Epidemiological evidence demonstrates positive correlation between environmental and occupational arsenic or fluoride exposure and risk to various cardio-respiratory disorders. Arsenic-exposure has been associated with atherosclerosis, hypertension, cerebrovascular diseases, ischemic heart disease, and peripheral vascular disorders, whereas Fluoride-exposure manifests cardiac irregularities and low blood pressure (BP). Present study aims to study the combined effects of these toxicants on various cardio-respiratory variables in male rats. Single intravenous (i.v.) dose of arsenic (1, 5, 10 mg/kg) or fluoride (5, 10, 20, 36.5 mg/kg) either alone or in combination were administered. Individual exposure to arsenic or fluoride led to a significant depletion of mean arterial pressure, heart rate (HR), respiration rate and neuromuscular (NM) transmission in a dose-dependent manner. These changes were accompanied by increased levels of blood reactive oxygen species (ROS) and decreased glutathione (GSH) concentrations. An increase in the blood acetyl cholinesterase (AChE) activity was observed in both arsenic or fluoride exposed rats. These changes were significantly more pronounced in arsenic-exposed animals than in fluoride. During combined exposure to arsenic (5 mg/kg) + fluoride (20 mg/kg) or arsenic (10 mg/kg) + fluoride (36.5 mg/kg) the toxic effects were more pronounced compared to individual toxicities of arsenic or fluoride alone. However, combined exposure to arsenic (5 mg/kg) + fluoride (36.5 mg/kg) resulted in antagonistic effects on variables suggestive of altered cardio-respiratory function and oxidative stress. The results from the present study suggest that arsenic or fluoride individually demonstrate cardio-respiratory failure at all doses whereas during combination exposure these toxins show variable toxicities; both synergistic and antagonistic effects depending upon the dose. Moreover, it may be concluded that arsenic and/or fluoride cardio-respiratory toxicity may be mediated via oxidative stress. However, these results are new in the discipline thus requires further exploration.

The antidotal effectiveness of atropine sulfate and pralidoxime chloride delivered by autoinjectors against sarin toxicity was evaluated in rabbits. Sarin, diluted in saline was administered at a dose of 5, 10 or 20 µg/kg, topically to one eye of the rabbits. Anticholinesterase activity was assessed by measurements of ocular pupillary diameter and plasma cholinesterase activity. Atropine sulfate (1.8 ± 0.1 mg) and/ or pralidoxime chloride (36 ± 2 mg) were administered by autoinjectors to evaluate their antidotal efficacy individually and as combined treatment. The pupillary diameter was decreased to less than 50% of pretreatment values in the sarin-treated eyes within 5 minutes, without any change in the contralateral eye. Sarin given by topical application to the eye caused a significant inhibition of plasma cholinesterase activity. Tremor and paralysis of the limbs were observed at 20 µg/kg dose. When the antidotes were given alone, the effects of sarin on pupillary diameter and plasma cholinesterase activity were only marginally protective. More significant protection was obtained when atropine sulfate and pralidoxime chloride were given as a combined antidote. These findings confirm that the administration of atropine sulfate and pralidoxime chloride by the autoinjectors is an effective way of protecting nerve agent toxicity.

OBJECTIVE:To investigate the effects of pre-treatment of alpha-ketoglutarate (alpha-KG) on cyanide-induced lethality and changes in various physiological parameters in rodents.METHODS:The LD50 of potassium cyanide (KCN) given orally (po), intraperitoneally (ip), subcutaneously (sc) or intravenously (iv) was determined in male mice, in the presence or absence alpha-KG given po, ip or iv. alpha-KG was administered 10, 20 or 40 min prior to KCN at 0.50, 1.0 or 2.0 g/kg by po or ip route, and at 0.10, 0.20 or 0.40 g/kg by iv route. Protection index (PI) was calculated as the ratio of LD50 of KCN in the presence of alpha-KG (protected animals) and LD50 of KCN in the absence of alpha-KG (unprotected animals). In a separate experiment, several physiological variables viz. mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), neuromuscular transmission (NMT) and rectal temperature (RT) were measured in anesthetized female rats pre-treated (-10 min) with po (2.0 g/kg) or iv (0.125 g/kg) alpha-KG and then administered sub-lethal (0.75 LD50) or lethal (2.0, 4.0 or 8.0 LD50) doses of KCN (po).RESULTS:PI of 4.52, 6.40 and 7.60 at -10 min, 3.20, 5.40 and 6.40 at -20 min, and 1.40, 3.20 and 5.40 at -40 min of po administration with a-KG was observed for 0.50, 1.0 and 2.0 g/kg doses, respectively, against KCN given by po route. When KCN was given ip, a PI of 3.38, 4.79 and 5.70 was observed for 0.50, 1.0 and 2.0 g/kg alpha-KG given ip (-10 min), respectively. A lower PI of 3.37, 2.83 and 2.38 was observed when KCN given sc was challenged by 2.0 g/kg alpha-KG given ip at -10, -20 or -40 min, respectively. Similarly, a PI of 3.37, 2.83 and 2.0 was noted when KCN given sc was antagonized by 2.0 g/kg alpha-KG given po at -10, -20 or -40 min, respectively. No appreciable protection was observed when lower doses of alpha-KG (ip or po) challenged KCN given by sc route. Pre-treatment of iv or po administration of alpha-KG did not afford any protection against KCN given po or iv route. Oral treatment of 0.75 LD50 KCN caused significant decrease in MAP and HR after 15 min, RR after 30 min and NMT after 60 min. There was no effect on RT. No reduction in MAP, HR, RR and RT was observed when rats received 2.0 or 4.0 LD50 KCN after pre-treatment of alpha-KG (po; 2.0 g/kg). However, no protection was observed on NMT. Protective efficacy of alpha-KG was not observed on MAP, HR, RR, and NMT decreased by 8.0 LD50 KCN. Decrease in MAP and NMT caused by 2.0 LD50 KCN (po) was resolved by iv administration of alpha-KG.CONCLUSIONS:Cyanide antagonism by alpha-KG is best exhibited when both alpha-KG and KCN are given by po route. The protective effect of a-KG on cyanide-induced changes in several physiological parameters also indicates a promising role of alpha-KG as an alternative cyanide antidote.

OBJECTIVE: To study the cardio-respiratory effects of DRDE-07, a new prophylactic agent for sulphur mustard. MATERIAL AND METHODS: The effect of DRDE-07 was studied in anesthetized male rats (Wistar), by administering it either by intraperitoneal or oral routes. Different doses (0.25, 0.5, 1.0 and 2.0 LD50) were used and various cardio-respiratory parameters viz., mean arterial blood pressure, heart rate, respiratory rate and tidal volume were monitored on an oscillograph. RESULTS: Intraperitoneal administration of 0.5 and 1.0 LD50 and oral administration of 0.25 LD50 of DRDE-07 did not produce any effect on the cardio-respiratory variables. Oral administration of 0.5 and 1.0 LD50 showed a significant decrease in mean arterial blood pressure after 60 min. None of the animals died in the two-hour monitoring period. Two (2.0) LD50 administration of DRDE-07 either by intraperitoneal or oral routes induced a sudden decrease in the mean arterial blood pressure and the animals died within one hour. CONCLUSION: DRDE-07 did not show any significant effect on the cardio-respiratory variables at a dose of 0.25 LD50 by oral route and 1.0 LD50 by intraperitoneal route. The death after intraperitoneal or oral administration (2.0 LD50) of DRDE-07 is due to the sudden fall in the mean arterial blood pressure.

Recently we have shown that cyanide poisoning by the oral (p.o.) route could be antagonized significantly by pretreatment or simultaneous treatment of a-ketoglutarate (alpha -KG), administered p.o. in rodents. The protective effect of alpha -KG was dose dependent (0.125-2.0 g kg(-1)) and the effect was significant at a dose above 1.0 g kg(-1). In order to establish the safety of alpha -KG, various haematological, biochemical and histological parameters were studied following p.o. administration of 2.0 g kg(-1) alpha -KG in female rats, and various physiological parameters were studied following p.o. administration of 2.0 or 4.0 g kg(-1) alpha -KG in anaesthetized male rats. The p.o. LD50 of alpha -KG in male and female rats was >5.0 g kg(-1) and no toxic signs were observed in the surviving animals. Except for an increase in plasma alkaline phosphatase and urea levels after 1 h and a decrease in inorganic phosphorus levels after 7 days of treatment, no significant change in haematology, biochemistry or histology of the vital organs were observed. Mean arterial pressure and neuromuscular transmission were decreased at 4.0 g kg(-1) alpha -KG but other physiological variables such as heart rate, respiratory rate, rectal temperature, left ventricular pressure (systolic), arterial pressure (systolic) and arterial pressure (diastolic) were not altered. The changes observed at 4.0 g kg(-1) alpha -KG are unlikely to be of toxicological concern. The results indicate that alpha -KG at 2.0 g kg(-1) (p.o.)-a dose offering maximum antidotal efficacy-is non-toxic and therefore can be considered suitable for cyanide poisoning. Copyright (C) 2001 John Wiley & Sons, Ltd.

Anatoxin-a, recognised as a potent toxin warfare agent, is considered as a weapon of mass destruction due to its lethal anticholinesterase activity. The intravenous administration of cell-free extract of Anabena flosaquae UTEX-2383(anatoxin-a) produced a transient vasodepressor response followed by a sustained rise in blood pressure. The vasodepressor effect was potentiated by physostigmine and antagonised by atropine and bilateral vagotomy, suggesting the involvement of cholinergic system. On the contrary, the vasopressor response was antagonised by hexamethonium prazosin and hemicholinium-3, indicating that the toxin stimulates the sympathetic system through the release of catecholamines from nerve endings. Prolonged apnoea with attendant bronchoconstriction was observed corresponding to bradycardia and vasppressor response which remained unaltered by atropine while antagonised by bilateral vagotomy. The extract when administered intra-arterially did not modify the apnoea induced by veratridine; but phenyldiguanide potentiated the bronchoconstriction, indicating the involvement of pulmonary vagal afferents. The extract produced a dose- and time-dependent blockade of indirect muscle twitch recorded from gastrocnemius muscle. The neuromuscular blockade was potentiated by neostigmine but unaltered by DTC.

The ability of zinc, methionine or their combination given by gavage to prevent or treat experimental oral lead intoxication in rats was investigated. Simultaneous oral supplementation with zinc plus methionine was found to be most effective in reducing lead induced inhibition of delta-aminolevulinic acid dehydratase (ALAD) activity in blood, elevation of urinary delta-aminolevulinic acid (ALA) excretion and in enhancing the hepatic glutathione (GSH) contents. The combination was also most effective in reducing the accumulation of lead in blood, liver and kidney compared to zinc or methionine alone. Prevention was more effective than treatment after lead exposure which may be caused by a decrease in the absorption of lead in the gastrointestinal tract in the presence of zinc and/or methionine.

The effect of daily oral administration of ethanol (2.5, 5, or 10% in drinking water for 8 wk), lead (10 mg/kg, po, once daily for 8 wk), or their combination on tissue trace-metal concentration and hematopoietic and hepatic biochemical indices was investigated in male rats. Ethanol (10%) ingestion enhanced the hepatic lipid peroxidation and decreased the calcium and magnesium content of blood and liver. Coexposure to lead and ethanol (5 and 10%) produced a more pronounced elevation of blood zinc protoporphyrin (ZPP) and hepatic lipid peroxidation. Combined lead-ethanol exposure also lowered the concentration of blood and hepatic magnesium and calcium and increased the amount of lead in the blood, liver, and brain compared to a group treated with lead alone. The results suggest that chronic alcohol ingestion results in calcium and magnesium loss. However, coexposure to lead and ethanol could result in more serious depletion of calcium and magnesium, and this could be the cause of suspected synergism between alcohol consumption and lead poisoning.