This study was conducted to investigate the protective effect of Asteracantha longifolia Linn (Acanthaceae) plant extract on carbon tetrachloride (CCl4)- and paracetamol-induced acute hepatotoxicity in mice. Hepatotoxicity was induced by the administration of a single intraperitoneal dose of CCl4 (0.5 mL kg(-1) CCl4 in olive oil) in one model and in the other by administration of paracetamol (300 mg kg(-1) in saline) orally, after a 16-h fast. An aqueous extract of the whole plant (0.9 g kg(-1)) was used on a pre- and post-treatment basis. Asteracantha reduced the alanine aminotransferase (ALT) level by 69.32% (P < 0.001) and increased the liver reduced glutathione level by 64.65% (P < 0.001) in the pre-treated group, 4 days after the administration of CCl4. A similar pattern was observed in the pre-treated group 4 h after the administration of paracetamol with a reduction in serum levels of ALT, aspartate aminotransferase and alkaline phosphatase enzymes by 65.04, 55.79 and 45.75% respectively (P < 0.001). Plant extract also increased the glutathione concentration of the liver significantly (P < 0.001). Histopathological studies also provided supportive evidence for results from the biochemical analysis with marked improvement in liver architecture being observed in the Asteracantha-treated groups. Pre-treatment showed better results than post-treatment in both hepatotoxic models. Overall results indicate that the aqueous extract of Asteracantha longifolia possesses hepatoprotective effects on CCl4- and paracetamol-induced hepatotoxicity in mice.

Introduction. Antibiotic resistance is one of the greatest threats of the 21st century. Scientists search for potential antimicrobial sources that can cope with antibiotic resistance. Plants used in traditional medicine can be identified as potential candidates for the synthesis of novel drug compounds to act against antibiotic-resistant bacteria. Objective. To determine the potential antimicrobial effects of ethanol, aqueous, and hexane extracts of five Sri Lankan medicinal plants against four human pathogens. Methods. Asparagus falcatus (tubers), Asteracantha longifolia (whole plant), Vetiveria zizanioides (roots), Epaltes divaricata (whole plant), and Coriandrum sativum (seeds) were used in the study. Plant extracts were screened against four clinically important Gram-positive and Gram-negative bacterial strains, Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), and Klebsiella pneumoniae (ATCC 700603). Antibacterial activity of plant extracts were monitored using the agar disc diffusion method. Eight concentrations of each positive plant extract were used to determine the minimum inhibitory concentration (MIC) by 5-fold dilution of plant extracts yielding a serial dilution of the original extract. Results. Ethanol, aqueous, and hexane extracts of E. divaricata gave the maximum zones of inhibition of 16.3 mm, 7.4 mm, and 13.7 mm and MIC values of 0.48 mg/ml, 1.2 mg/ml, and 1.6 mg/ml, respectively, against S. aureus. Ethanol and hexane extracts of V. zizanioides gave the maximum zones of inhibition of 12.1 mm and 11.4 mm and MIC values 2.4 mg/ml and 0.003 mg/ml, respectively, against S. aureus. None of the other plants were effective against any microorganism used for the study. Conclusions. It can be concluded that E. divaricata and V. zizanioides crude ethanol, aqueous, and hexane extracts exhibited significant in vitro antibacterial activity against S. aureus, and the active compounds isolated from them can be potential sources for the synthesis of antibacterial drugs.

Dose-dependent cardiotoxicity of doxorubicin may lead to irreversible congestive heart failure. Although multiple mechanisms are involved, generation of free radicals is the most commonly postulated mechanism. erefore, free radical scavengers are considered as potential therapeutic agents. As Murraya koenigii leaves are a rich source of flavonoids and phenols, they have the ability to scavenge free radicals effectively. erefore, the objective of this study was to investigate the cardioprotective potential of Murraya leaf extract against doxorubicin-induced cardiotoxicity in rats. Rats were randomly divided into five groups with 10 animals in each group. Doxorubicin was administered intraperitonially at 18 mg/kg while lyophilized plant extract was administered orally at 2 g/kg. Dexrazoxane, at 180 mg/kg, was used as the positive control. Cardiac damage of doxorubicin control was evident with a significant increase (p < 0.05) in cardiac troponin I, NT-pro BNP, AST, and LDH compared to the normal control. Plant-treated group showed cardioprotective effect by significantly reducing (p < 0.05) all of the above parameters compared to doxorubicin control (p < 0.05). Increased oxidative stress in doxorubicin control was evident with a significant reduction in reduced glutathione, glutathione reductase, glutathione peroxidase, total antioxidant capacity, superoxide dismutase, and catalase activity and a significant increase in lipid peroxidation compared to the control. Interestingly, treatment with Murraya leaf extract showed a significant increase in all of the above antioxidant parameters and a significant reduction in lipid peroxidation by showing an antioxidant effect. A significant increase in myeloperoxidase activity confirmed the increased inflammatory activity in doxorubicin control group whereas plant-treated group showed a significant reduction (p < 0.05) which expressed the anti-inflammatory effect of Murraya leaf extract. Doxorubicin-treated group showed histological evidence of extensive damage to the myocardium while plant-treated group showed a preserved myocardium with lesser degree of damage. Pretreatment with Murraya leaf extract may replenish cardiomyocytes with antioxidants and promote the defense against doxorubicin-induced cardiotoxicity.

Glutathione transferases (GSTs) are generally recognized for their role in phase II detoxification reactions. However, it is becoming increasingly apparent that members of the GST family also have a diverse range of other functions that are, in general, unrelated to detoxification. One such action is a specific inhibition of the cardiac isoform of the ryanodine receptor (RyR2) intracellular Ca(2+) release channel. In this review, we compare functional and physical interactions between members of the GST family, including GSTO1-1, GSTA1-1, and GSTM2-2, with RyR2 and with the skeletal isoform of the ryanodine receptor (RyR1). The active part of the muscle-specific GSTM2-2 is localized to its nonenzymatic C-terminal α-helical bundle, centered around α-helix 6. The GSTM2-2 binding site is in divergent region 3 (DR3 region) of RyR2. The sequence differences between the DR3 regions of RyR1 and RyR2 explain the specificity of the GSTs for one isoform of the protein. GSTM2-2 is one of the few known endogenous inhibitors of the cardiac RyR and is likely to be important in maintaining low RyR2 activity during diastole. We discuss interactions between a nonenzymatic member of the GST structural family, the CLIC-2 (type 2 chloride intracellular channel) protein, which inhibits both RyR1 and RyR2. The possibility that the GST and CLIC2 proteins bind to different sites on the RyR, and that different structures within the GST and CLIC proteins bind to RyR channels, is discussed. We conclude that the C-terminal part of GSTM2-2 may provide the basis of a therapeutic compound for use in cardiac disorders.

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The muscle specific glutathione transferase GSTM2-2 inhibits the activity of cardiac ryanodine receptor (RyR2) calcium release channels with high affinity and activates skeletal RyR (RyR1) channels with lower affinity. To determine which overall region of the GSTM2-2 molecule supports binding to RyR2, we examined the effects of truncating GSTM2-2 on its ability to alter Ca(2+) release from sarcoplasmic reticulum (SR) vesicles and RyR channel activity. The C-terminal half of GSTM2-2 which lacks the critical GSH binding site supported the inhibition of RyR2, but did not support activation of RyR1. Smaller fragments of GSTM2-2 indicated that the C-terminal helix 6 was crucial for the action of GSTM2-2 on RyR2. Only fragments containing the helix 6 sequence inhibited Ca(2+) release from cardiac SR. Single RyR2 channels were strongly inhibited by constructs containing the helix 6 sequence in combination with adjacent helices (helices 5-8 or 4-6). Fragments containing helices 5-6 or helix 6 sequences alone had less well-defined effects. Chemical cross-linking indicated that C-terminal helices 5-8 bound to RyR2, but not RyR1. Structural analysis with circular dichroism showed that the helical content was greater in the longer helix 6 containing constructs, while the helix 6 sequence alone had minimal helical structure. Therefore the active centre of GSTM2-2 for inhibition of cardiac RyR2 involves the helix 6 sequence and the helical nature of this region is essential for its efficacy. GSTM2-2 helices 5-8 may provide the basis for RyR2-specific compounds for experimental and therapeutic use.

Anthracycline-induced cardiotoxicity has never been investigated in Sri Lanka. Therefore, this study was conducted to determine the prevalence of anthracycline-induced cardiotoxicity in breast cancer patients using echocardiographic findings. A prospective cohort study was performed. All newly diagnosed breast cancer patients who were administered with anthracycline and cyclophosphamide (AC schedule) for the first time were enrolled in the study. In the hospital setting, anthracycline is administered only as a combination therapy, and only this combination was selected to limit the effect of other cardiotoxic chemotherapy agents. Records of echocardiography were obtained: one day before anthracycline chemotherapy (baseline), one day after the first chemotherapy dose, one day after the last chemotherapy dose, and six months after the completion of anthracycline chemotherapy. Following parameters were recorded from the echocardiography results: ejection fraction (EF, %), fractioning shortening (FS, %), posterior wall thickness, left ventricle (PWT, mm), the thickness of interventricular septum (IVS, mm), left ventricular end-diastolic diameter (LVEDD, mm), and left ventricular end-systolic diameter (LVESD, mm). Statistical analysis of the echocardiography results was performed using ANOVA at four stages. A p value <0.05 was considered significant. Subclinical cardiac dysfunction was defined as a fall of EF >10% during the follow-up echocardiography. There was no significant change ( p > 0.05 ) between the baseline echocardiographic parameters and one day after the 1st anthracycline dose. However, significant differences ( p < 0.05 ) were observed between the baseline echocardiographic parameters and one day after the last anthracycline dose and six months after the completion of anthracycline therapy with a gradual and progressive deterioration in functional parameters including EF, FS, PWT, and IVS over time. There were 65 patients out of 196 (33.16%) who developed subclinical cardiac dysfunction six months after the completion of anthracycline chemotherapy. The prevalence of subclinical anthracycline-induced cardiotoxicity was relatively higher in these patients. An equation was also developed based on left ventricular ejection fraction (LVEF) to predict the anthracycline-induced cardiotoxicity of a patient six months after the completion of anthracycline chemotherapy. We believe that this will help in the monitoring of patients who undergo anthracycline therapy for cardiotoxicity. It is recommended to carry out a long-term follow-up to detect early-onset chronic progressive cardiotoxicity in all patients who were treated with anthracycline therapy.

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