Naringin in a combined therapy with phenytoin on pentylenetetrazole-induced kindling in rats.

Phenytoin (Dilantin) is an orally active, use-dependent voltage-gated sodium channel inhibitor and is a potent, economical, and widely used anticonvulsant agent. The objective of the present study was to investigate the effect of the combined treatment of naringin (40 mg/kg and 80 mg/kg) and phenytoin on prevention of seizure attacks, development of kindling, oxidative stress, cognitive impairment, and neurochemicals in the frontal cortex, temporal cortex, and hippocampus, and morphological changes in the hippocampus. Treatment with the high dose of naringin (80 mg/kg) along with phenytoin has shown to offer protection against seizures, development of kindling, and cognition enhancement through Y-maze test and improved % conditioned avoidance response (% CAR) through pole climbing test in pentylenetetrazole (PTZ)-induced kindling model. It has also been shown to improve neurochemical balance by elevating levels of Gamma amino butyric acid (GABA) and dopamine, decreasing levels of glutamate, oxidative biomarker (malondialdehyde (MDA)), and increasing levels of antioxidants (glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and total thiol and offered neuroprotection in the hippocampus. So, coadministration of naringin with phenytoin offers a potential treatment option for drug-resistant epilepsy and associated comorbidities. Interpretable research on flavonoids will support the clinical evidence for the recommendation of flavonoids as supplements with antiepileptic drugs (AEDs) for curtailing pharmacoresistant epilepsy and AED-associated comorbidities.

Protective effect of naringin on pentylenetetrazole (PTZ)-induced kindling; possible mechanisms of antikindling, memory improvement, and neuroprotection.

The present study investigated the effects of Naringin on seizure severity, progress of kindling, memory impairment, oxidative stress, neurochemicals, and neural damage in Pentylenetetrazole (PTZ)-induced kindling. Alternate intra-peritoneal injections of PTZ induced kindling at 22 injections of PTZ. In comparison with the PTZ group, pretreatment with Naringin 30 min prior to PTZ administration and on a PTZ-free day was found to lead to a decreased seizure score, a mitigated progress of kindling, decreased transfer latency, and increased total number of arm entries, % alternation behavior in Y maze, and % conditioned avoidance response in a pole climbing apparatus. Biochemical analysis of the frontal and temporal cortexes and the hippocampus of the brain showed that Naringin attenuated the level of lipid peroxidation (MDA) and augmented the reduced glutathione, superoxide dismutase, catalase, and total thiol results in decreased oxidative stress compared with the PTZ group and control group. Investigation of neurochemicals revealed a minute change in gamma amino butyric acid (GABA), glutamate and dopamine, and decreased AChE in the three regions. Increased CA1 neuronal density in the hippocampus and increased cell density in the frontal and temporal regions indicate the potential of naringin to act against PTZ-induced kindling, memory impairment, oxidative stress, neurochemical changes, and histological aberrations.

Cerebroprotective potential of resveratrol through anti-oxidant and anti-inflammatory mechanisms in rats.

Oxidative stress and inflammation are two important pathological mechanisms involved in cerebral ischemia and reperfusion injury. In pathological conditions such as cerebral infarction, the free radical production is greater than that of elimination by endogenous anti-oxidant system, by this undesirable effect brain is highly injured. Resveratrol is reported to have anti-oxidant and anti-inflammatory, athero-protective activities. Therefore, the aim of the present study is to evaluate the therapeutic potential of resveratrol against cerebral infarction induced by ischemia and reperfusion injury in Wistar rats. Bi-common carotid occlusion followed by 4 h reperfusion model was used to induce cerebral infarction. Percent infarction, oxidative stress markers (malondialdehyde, catalase, superoxide dismutase) and inflammatory markers (myeloperoxidase, TNF-α, IL-6, ICAM-1 and IL-10) were measured. TNF-α, IL-6, IL-10, and intracellular adhesive molecule-I (ICAM-1) levels were quantified by enzyme-linked immunosorbent assay (ELISA). Resveratrol produced significant dose-dependent reduction in percent cerebral infarct volume. At resveratrol 20 mg/kg dose, there was a significant reduction in oxidative stress and inflammatory markers like malondialdehyde, TNF-α, IL-6, myeloperoxidase and ICAM-I and in contrast there was a significant increase in anti-oxidants and anti-inflammatory markers like superoxide dismutase, catalase and IL-10 levels. Resveratrol showed significant cerebroprotective action mediated by anti-oxidant and anti-inflammatory mechanisms.

Synthesis, characterization and biological evaluation of some novel 2,4-thiazolidinediones as potential cytotoxic, antimicrobial and antihyperglycemic agents.

A series of some novel 2,4-thiazolidinediones (TZDs) (2a-x) have been synthesized and characterized by FTIR, (1)H NMR, (13)C NMR and LC mass spectral analysis. All the synthesized compounds were evaluated for their cytotoxicity, antimicrobial and in vivo antihyperglycemic activities. Among the tested compounds for cytotoxicity using Brine Shrimp Lethality assay, compound 2t ((Z)-5-(4-((E)-3-oxo-3-(thiophen-2-yl)prop-1-enyl)benzylidene)-1,3-thiazolidine-2,4-dione) exhibited significant inhibitory activity at ED(50) value 4.00±0.25 µg/mL and this level of activity was comparable to that of the reference drug podophyllotoxin with ED(50) value 3.61±0.17 µg/mL. Antimicrobial activity was screened using agar well diffusion assay method against selected Gram-positive, Gram-negative and fungal strains and the activity expressed as the minimum inhibitory concentration (MIC) in µg/mL. From the results of antimicrobial activity compound 2s ((Z)-5-(4-((E)-3-(3,5-bis(benzyloxy)phenyl)-3-oxoprop-1-enyl)benzylidene)-1,3-thiazolidine-2,4-dione) was found to be the most active against all the tested strains of microorganisms with MIC value 16 µg/mL. In vivo antihyperglycemic effect of twenty four TZDs (2a-x) at different doses 10, 30 and 50mg/kg b.w (oral) were assessed using percentage reduction of plasma glucose (PG) levels in streptozotocin-induced type II diabetic rat models. From the results, the novel compound 2x ((Z)-5-(4-((E)-3-(9H-fluoren-2-yl)-3-oxoprop-1-enyl)benzylidene)-1,3-thiazolidine-2,4-dione) exhibited considerably potent blood glucose lowering activity than that of the standard drug rosiglitazone and it could be a remarkable starting point to evaluate structure-activity relationships and to develop new lead molecules with potential cytotoxicity, antimicrobial and antihyperglycemic activities. In addition molecular docking studies were carried out against PPARγ molecular target using Molegro Virtual Docker v 4.0 to accomplish preliminary confirmation of the observed in vivo antihyperglycemic activity.

Potential anti-hepatocellular carcinoma properties and mechanisms of action of clerodane diterpenes isolated from Polyalthia longifolia seeds.

Diterpenes are secondary metabolites that have attracted much attention due to their potential biological activities including anti-cancer potential. The aim of the current study is to assess the anticancer potential of the six known clerodane diterpenes (1-6) isolated from Polyalthia longifolia seeds and their underlying molecular mechanisms. These compounds were evaluated for their cytotoxicity in vitro by using MTT assays. The "two-phase model" with NDEA and PB ad libitum was used for induction of HCC and sorafenib was used as the standard drug. Prophylactic studies were carried out for compounds 4/6 at both low (5 mg/kg b.w) and high (10 mg/kg b.w) doses. Based on the MTT assay results, the two best compounds, 4 and 6, were selected for in vivo studies. The results showed that treatment with compound 4/6 significantly restored the changes in biochemical parameters and liver morphology observed in (NDEA + PB)-induced HCC rats. Additionally, the docking studies showed that compound 4/6 interacted with several key proteins such as MDM2, TNF-α, FAK, thereby inhibiting these proteins and reversing the negative impacts of NDEA. In conclusion, our results suggested that compounds 4 and 6 are potential therapeutic agents for HCC, mostly due to their ability to control typical cancer pathways.

Partial role of nitric oxide in infarct size limiting effect of quercetin and rutin against ischemia-reperfusion injury in normal and diabetic rats.

Reperfusion injury is remarkable clinical issue that needs to be resolved as ischemia-reperfusion is a common phenomenon encountered in numerous clinical situations. The present communication report the involvement of nitric oxide (NO) in cardioprotection offered by flavonoids (rutin and quercetin) against myocardial ischemia reperfusion. Rutin produced better cardioprotection than quercetin in normal and diabetic rats. The observed cardioprotection offered with quercetin and rutin was partially abolished by prior administration of nitric oxide synthase inhibitor, L-NAME (N-nitro-L-arginine methyl ester) in both normal and diabetic rats. L-NAME abolished the cardioprotective actions of rutin more strongly than the cardioprotective actions of quercetin. However, mechanistic study with NOS inhibitor implied the possible partial role of nitric oxide in infarct size limiting effect of quercetin and rutin

Benincasa hispida alleviates amyloid pathology by inhibition of Keap1/Nrf2-axis: Emphasis on oxidative and inflammatory stress involved in Alzheimer's disease model.

OBJECTIVES: Alzheimer's disease is a progressive neurodegenerative disorder with cognitive and memory impairment. Benincasa hispida is being used in the treatment of various neurological diseases in Ayurveda system of medicine. The objective of the study was to investigate the effect of Benincasa hispida fruit extract in the Alzheimer's disease rats. METHODS: Benincasa hispida fruits extract was administered orally for 16 weeks at doses of 250 and 500-mg/kg/day. The cognitive deficits were examined by behavioural tests like Morris water maze test, Y-maze and rota-rod test. Biochemical and neurochemical analysis of Acetylcholine, dopamine, serotonin levels and anti-oxidant, anti-inflammatory markers were evaluated and the mRNA expression of Keap/Nrf2 axis was analysed by RT-PCR. RESULTS: Aluminum chloride (AlCl3) induction altered the behavioural profile and produced significant alterations in the cortical and hippocampal regions of the brain and the treatment with Benincasa hispida extract at doses of 250-mg/kg/day (p<0.05) and 500mg/kg/day (p<0.05) alleviated the acetylcholine, dopamine and serotonin neurotransmitter levels. The antioxidant enzyme markers such as superoxide dismutase (SOD), Catalase (CAT), glutathione (GSH) were increased and the oxidative stress marker malondialdehyde(MDA) was decreased. The inflammatory cytokine levels of TNF-α, IL-1ß were decreased in Alzheimer's disease induced rats. We further estimated Keap/Nrf2/HO-1 genes these anti-oxidant genes were upregulated(p < 0.001) in treatment groups. Further, the neuroprotective activity of Benincasa was further confirmed by histopathological studies of hippocampal CA3 fields. CONCLUSIONS: The findings of the current study indicates Benincasa hispida as a possible neuroprotective alternative for Alzheimer's disease.

Assessment of Circulating Biomarkers in Relation to Various Stages of Diabetic Retinopathy in Type 2 Diabetic Patients-A Cross Sectional Study.

AIM: The aim of this study is to examine the relationship between inflammatory markers, and diabetic retinopathy in type II diabetic patients. METHODS: The study was a cross-sectional study included 150 type 2 diabetic patients who were divided into 3 groups. 50 in each group are divided as Diabetic patients without retinopathy (DM, n=50), nonproliferative diabetic retinopathy patients (NPDR, n=50), proliferative diabetic retinopathy patients (PDR, n=50). All the patients were subjected to complete clinical examination and laboratory investigations, such as fasting and postprandial blood glucose, serum creatinine, lipid profile tests, glycosylated haemoglobin (HbA1c), fasting insulin, serum inflammatory markers (TNF-alpha, C-reactive protein) and serum VEGF. RESULTS: The study revealed from the multivariate analysis that age, duration and WHR (waist-hip ratio) are potent risk factors responsible for the risk of Diabetic retinopathy. Similarly, serum creatinine, CRP, TNF- alpha and VEGF are significantly higher in diabetic patients with retinopathy compared to diabetic patients without retinopathy. CONCLUSION: The study concluded that inflammation was associated with severe diabetic retinopathy in patients with well-controlled diabetes. A possible relationship was provided between the risk factors and biomarkers which are responsible for Diabetic retinopathy. Hence, modifying the risk factors risk and development of severe diabetic retinopathy can be reduced.

Vitis vinifera acts as anti-Alzheimer's agent by modulating biochemical parameters implicated in cognition and memory.

BACKGROUND: Aluminum a known neuro and cholinotoxin has been implicated in the pathogenesis of Alzheimer's disease. Its exposure is associated with impairment of the memory and cognition. OBJECTIVE: The present study was undertaken to evaluate the anti-Alzheimer's activity of Vitis vinifera in aluminum induced Alzheimer's disease. MATERIALS AND METHODS: In this study, we investigated the behavioral and biochemical effects of aluminum in Sprague-Dawley rats. Animals were exposed to aluminum chloride (100 mg/kg/day) orally for a period of 8 weeks. Vitis was given in doses of 250 mg/kg and 500 mg/kg for 16 weeks and the possible effects of Vitis vinifera on the expression of Tau and amyloid precursor protein were evaluated by PCR analysis and the possible activities of lipid peroxidation, inflammation and anti-cholinesterase activity were evaluated. RESULTS: Aluminum intoxication was associated with significant impairment in learning and memory in Morris water maze test. A significant improvement was observed with Vitis vinifera in a dose dependent manner. CONCLUSION: The findings of the present study revealed the significant neuroprotective actions of Vitis vinifera by modifying the biochemical parameters and inhibited the mRNA expression of Amyloid Precursor Protein and Tau, which are the key pathological hallmarks of Alzheimer's disease, which was further confirmed by histopathological observations.

Bioinformatics analysis of diabetic retinopathy using functional protein sequences.

Diabetic retinopathy is the leading cause of blindness among patients with diabetes mellitus. We evaluated the role of several proteins that are likely to be involved in diabetic retinopathy by employing multiple sequence alignment using ClustalW tool and constructed a phylogram tree using functional protein sequences extracted from NCBI. Phylogram was constructed using Neighbor-Joining Algorithm in bioinformatics approach. It was observed that aldose reductase and nitric oxide synthase are closely associated with diabetic retinopathy. It is likely that vascular endothelial growth factor, pro-inflammatory cytokines, advanced glycation end products, and adhesion molecules that also play a role in diabetic retinopathy may do so by modulating the activities of aldose reductase and nitric oxide synthase. These results imply that methods designed to normalize aldose reductase and nitric oxide synthase activities could be of significant benefit in the prevention and treatment of diabetic retinopathy.

Anticancer Potential of Nutraceutical Formulations in MNU-induced Mammary Cancer in Sprague Dawley Rats.

BACKGROUND: Nutraceuticals help in combating some of the major health problems of the century including cancer, and 'nutraceutical formulations' have led to the new era of medicine and health. OBJECTIVE: To develop different nutraceutical formulations and to assess the anticancer potential of nutraceutical formulations in N-methyl-N-nitrosourea (MNU)-induced mammary cancer in Sprague Dawley rats. MATERIALS AND METHODS: Different nutraceutical formulations were prepared using fine powders of amla, apple, garlic, onion, papaya, turmeric, and wheat grass with and without cow urine distillate. Total phenolic content, acute oral toxicity, and microbial load of nutraceutical formulations were assessed. The anticancer potential of nutraceutical formulations was evaluated against MNU-induced mammary cancer in female Sprague Dawley rats. RESULTS: Improvement in total phenolic content was significant (P < 0.001) after self-fortification process. Toxicity studies showed that the nutraceutical formulations were safe to use in animals. Microbial load was within the limits. Significant longer tumor-free days (P < 0.01), lower tumor incidence (P < 0.01), lower tumor multiplicity (P < 0.05) and tumor burden (P < 0.01) were observed for nutraceutical formulation-treated groups. CONCLUSION: Combination of whole food-based nutraceuticals acted synergistically in the prevention of mammary cancer. Further, the process of fortification is novel and enhanced the anticancer potential of nutraceutical formulations. SUMMARY: Nutraceuticals help in combating some of the major health problems of the century including cancer, and 'nutraceutical formulations' have led to the new era of medicine and health. In this study, different nutraceutical formulations using fine powders of amla, apple, garlic, onion, papaya, turmeric, and wheat grass with and without cow urine distillate. Total phenolic content, acute oral toxicity, and microbial load of nutraceutical formulations were assessed. The anticancer potential of nutraceutical formulations was evaluated against MNU-induced mammary cancer in female Sprague Dawley rats. Improvement in total phenolic content was observed after self-fortification process. Toxicity studies showed that the nutraceutical formulations were safe to use in animals. Microbial load was within the limits. Longer tumor-free days, lower tumor incidence, lower tumor multiplicity and tumor burden were observed for nutraceutical formulation-treated groups. This suggests that combination of whole food-based nutraceuticals acted synergistically in the prevention of mammary cancer. Further, the process of fortification enhanced the anticancer potential of nutraceutical formulations. Abbreviations used: HMNU: N-methyl-N-nitrosourea, CAM: Complementary and Alternative Medicine, NF: Nutraceutical Formulation, SFNF: Self-Fortitfied Nutraceutical Formulation, NFCUD: Nutraceutical Formulation fortified with Cow Urine Disstillate, SFNFCUD: Self-Fortified Nutraceutical Formulation fortified with Cow Urine Disstillate, CPCSEA: Committee for the Purpose of Control and Supervision of Experiments on Animals, OECD: Organisation for Economic Co-operation and Development, TPC: Total Phenolic Content, ANOVA: Analysis of Variance, GAE: Gallic Acid Equivalent, cfu/g: Colony forming unit per g.

Prediabetes and Alzheimer's Disease.

Aging patients with diabetes are at higher risk of developing Alzheimer's disease. Emerging evidences demonstrate the role of brain insulin resistance, which is a key mediator in prediabetes and diabetes mellitus that may lead to Alzheimer's disease. Insulin and insulin-like growth factors regulate many biological processes such as axonal growth, protein synthesis, cell growth, gene expression, proliferation, differentiation, and development. Among these, the energy metabolism and synaptic plasticity are the major transduction processes regulated by insulin, which are the core objectives for learning and memory. It was also proposed that hyper insulinemia induced insulin resistance results in injury to the central nervous system by the activation of glycogen synthase kinase 3ß which is the key ailment in the cognitive decline. Hence, the endogenous brain specific insulin impairments and signaling account for the majority of Alzheimer's abnormalities.

Effect of wheat grass powder on aluminum induced Alzheimer's disease in Wistar rats.

OBJECTIVE: To find out the effect of wheat grass on aluminum induced Alzheimer's disease in Wistar rats. METHODS: Memory impairment was induced by aluminum chloride (4.2 mg/kg, i.p.) for 28 d. Memory function was assessed by Morris water maze test. To study the activity of wheat grass (100 mg/kg, p.o.), Wistar rats were administered it for 28 d along with aluminum chloride. Biochemical parameters of oxidative stress were estimated in brain after the treatment. RESULTS: The major finding of this study is that aluminum enhanced oxidative stress. Wheat grass showed a significant improvement in reduction of this oxidative stress by reduction of malondialdehyde levels and enhancement of superoxide dismutase and catalase levels. CONCLUSIONS: The present study clearly demonstrated the beneficial effects of wheat grass that shows good antioxidant properties, and this remarkable effect of wheat grass may act as a key to treat Alzheimer's disease.

Vitis vinifera acts as anti-Alzheimer's agent by modulating biochemical parameters implicated in cognition and memory

Background: Aluminum a known neuro and cholinotoxin has been implicated in the pathogenesis ofAlzheimer’s disease. Its exposure is associated with impairment of the memory and cognition.Objective: The present study was undertaken to evaluate the anti-Alzheimer’s activity of Vitis vinifera inaluminum induced Alzheimer’s disease.Materials and methods: In this study, we investigated the behavioral and biochemical effects ofaluminum in Sprague-Dawley rats. Animals were exposed to aluminum chloride (100 mg/kg/day) orallyfor a period of 8 weeks. Vitis was given in doses of 250 mg/kg and 500 mg/kg for 16 weeks and thepossible effects of Vitis vinifera on the expression of Tau and amyloid precursor protein were evaluated byPCR analysis and the possible activities of lipid peroxidation, inflammation and anti-cholinesterase activity were evaluated.Results: Aluminum intoxication was associated with significant impairment in learning and memory inMorris water maze test. A significant improvement was observed with Vitis vinifera in a dose dependentmanner.Conclusion: The findings of the present study revealed the significant neuroprotective actions of Vitisvinifera by modifying the biochemical parameters and inhibited the mRNA expression of Amyloid Precursor Protein and Tau, which are the key pathological hallmarks of Alzheimer’s disease, which wasfurther confirmed by histopathological observations.© 2017 Transdisciplinary University, Bangalore and World Ayurveda Foundation. Publishing Services byElsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Protective effects of rutin and naringin in testicular ischemia-reperfusion induced oxidative stress in rats.

INTRODUCTION: Testicular torsion and detorsion causes reperfusion injury which damages the testicular tissue and affects the quality of sperm. Deterioration in the quality of sperm worldwide is the recent scenario and one of its reasons is testicular ischemic/ reperfusion (IR) injury. Therefore the present study aims at producing new drugs for the treatment of testicular IR injury. METHODS: 42 animals were selected for the study and divided into 7 groups, each containing 6 rats. Bioflavonoids were tested for their efficacy in reversing the damage done to the testicular tissue by causing testicular torsion and detorsion in rats. As oxidative stress produced in the above condition causes tissue damage, MDA level was measured and antioxidant enzymes SOD and catalse were evaluated. Histological examination was conducted to find the extent of damage and the protective effect of rutin and naringin. One-way ANOVA and Tukey's post-hoc test were used for data analysis. A p-value<0.001 was considered statistically significant. RESULTS: MDA levels increased and antioxidant enzymes decreased drastically in the group of rats with testicular torsion and detorsion which clearly indicates a rise in oxidative stress (68% rise in the case of MDA and 20% and 16% decrease in SOD and catalase concentrations, respectively). Rutin and naringin-treated groups showed the beneficial effects of the medicinal drugs, particularly in higher doses. Rutin, 10 mg/kg, was effective when compared to naringin in providing protection. Compared to the animals in the control group, there was a 30% reduction in MDA levels and a 20% increment in SOD levels plus a five-fold increase in catalse in the rutin-treated group (10 mg/kg). Histological examination supported the above claims. CONCLUSION: Oxidative stress in testicular injury affects the quality of sperm. Rutin and naringin in higher doses protected testicular tissue effectively. Further studies in this direction may prove beneficial.

Proteomic analysis in diabetic cardiomyopathy using bioinformatics approach.

Diabetic cardiomyopathy is a distinct clinical entity that produces asymptomatic heart failure in diabetic patients without evidence of coronary artery disease and hypertension. Abnormalities in diabetic cardiomyopathy include: myocardial hypertrophy, impairment of contractile proteins, accumulation of extracellular matrix proteins, formation of advanced glycation end products, and decreased left ventricular compliance. These abnormalities lead to the most common clinical presentation of diabetic cardiomyopathy in the form of diastolic dysfunction.We evaluated the role of various proteins that are likely to be involved in diabetic cardiomyopathy by employing multiple sequence alignment using ClustalW tool and constructed a Phylogenetic tree using functional protein sequences extracted from NCBI. Phylogenetic tree was constructed using Neighbour-Joining Algorithm in bioinformatics approach. These results suggest a causal relationship between altered calcium homeostasis and diabetic cardiomyopathy that implies that efforts directed to normalize calcium homeostasis could form a novel therapeutic approach.

Partial role of nitric oxide in infarct size limiting effect of quercetin and rutin against ischemia-reperfusion injury in normal and diabetic rats.

Reperfusion injury is remarkable clinical issue that needs to be resolved as ischemia-reperfusion is a common phenomenon encountered in numerous clinical situations. The present communication report the involvement of nitric oxide (NO) in cardioprotection offered by flavonoids (rutin and quercetin) against myocardial ischemia reperfusion. Rutin produced better cardioprotection than quercetin in normal and diabetic rats. The observed cardioprotection offered with quercetin and rutin was partially abolished by prior administration of nitric oxide synthase inhibitor, L-NAME (N-nitro-L-arginine methyl ester) in both normal and diabetic rats. L-NAME abolished the cardioprotective actions of rutin more strongly than the cardioprotective actions of quercetin. However, mechanistic study with NOS inhibitor implied the possible partial role of nitric oxide in infarct size limiting effect of quercetin and rutin.

Nitric oxide- and prostaglandin-mediated cardioprotection by bradykinin in myocardial ischemia and reperfusion injury.

The aim of the present study was to investigate the involvement of nitric oxide and prostaglandin pathways in the cardioprotective actions mediated by bradykinin via the combined inhibition of angiotensin converting enzyme and aminopeptidase P in an in vivo rat model of acute ischemia (30 min) and reperfusion (4 h). Myocardial infarction was produced by occlusion of the left anterior descending coronary artery for 30 min followed by 4 h of reperfusion. Infarct size was measured by using the staining agent TTC (2,3,5-triphenyl-tetrazolium chloride). Lipid peroxide levels in serum and in heart tissue were estimated spectrophotometrically. A lead II ECG was monitored at various intervals throughout the experiment. Infarct size expressed as percent of left ventricle was found to be 50.5 +/- 3.5 in control animals and was reduced to 19.4 +/- 1.1 and 15.0 +/- 2.1 with the combined treatment of enalapril or lisinopril and 2-mercaptoethanol, respectively. There was no significant difference in the infarct size of control animals and in the animals treated with HOE140 prior to the combined treatment. Infarct size reduction obtained with the combined inhibition with enalapril and 2-mercaptoethanol or lisinopril and 2-mercaptoethanol was blocked partially but significantly with the prior administration of L-NAME (Nomega-nitro-L-arginine methyl ester) or aspirin, suggesting the involvement of both nitric oxide and prostaglandin pathways in the cardioprotective actions mediated by bradykinin.