Progressive hemorrhage and myotoxicity induced by echis carinatus venom in murine model: neutralization by inhibitor cocktail of n,n,n `,n `-tetrakis (2-pyridylmethyl) ethane-1,2-diamine and silymarin

Viperbite is often associated with severe local toxicity, including progressive hemorrhage and myotoxicity, persistent even after the administration of anti-snake venom (ASV). In the recent past, investigations have revealed the orchestrated actions of Zn2+ metalloproteases (Zn(2+)MPs), phospholipase A(2)s (PLA(2)s) and hyaluronidases (HYs) in the onset and progression of local toxicity from the bitten site. As a consequence, venom researchers and medical practitioners are in deliberate quest of potent molecules alongside ASV to tackle the brutal local manifestations induced by aforesaid venom toxins. Based on these facts, we have demonstrated the protective efficacy of inhibitor cocktail containing equal ratios of N,N,N', N'-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and silymarin (SLN) against progressive local toxicity induced by Echis carinatus venom (ECV). In our previous study we have shown the inhibitory potentials of TPEN towards Zn(2+)MPs of ECV (IC50: 6.7 mu M). In this study we have evaluated in vitro inhibitory potentials of SLN towards PLA(2)s (IC50: 12.5 mu M) and HYs (IC50: 8 mu M) of ECV in addition to docking studies. Further, we have demonstrated the protection of ECV induced local toxicity with 10 mM inhibitor cocktail following 15, 30 min (for hemorrhage and myotoxicity); 60 min (for hemorrhage alone) of ECV injection in murine model. The histological examination of skin and thigh muscle sections taken out from the site of ECV injection substantiated the overall protection offered by inhibitor cocktail. In conclusion, the protective efficacy of inhibitor cocktail is of high interest and can be administered locally alongside ASV to treat severe local toxicity

Novel thermostable lipase from Bacillus circulans IIIB153: comparison with the mesostable homologue at sequence and structure level

Thermophilic Bacillus circulans IIIB153 isolated from hot springs of North West Himalayas, India, produced an extracellular lipase, which exhibited significant biofilm disruption property on the static biofilm disruption model with a single species of Actinomyces viscosous. The gene encoding the lipase was cloned and overexpressed in Escherichia coli. Recombinant Bacillus circulans lipase (BCL), a monomer with molecular mass of 43 kDa also exhibited significant biofilm disruption activity. The enzyme was optimally active at 60�C, pH 8.5 and retained[70% of its original activity after 1 h incubation at 60�C. 3D structure of BCL developed by homology modeling showed a typical a/b hydrolase fold, a characteristic feature of lipolytic enzymes. Comparison of thermostable BCL with mesostable lipase from Chromobacterium viscosum at the sequence and structure level showed distinct variations in the structural features, with the presence of a high content of proline residues, aromatic amino acids and salt bridges. These features along with the presence of zinc-binding site observed in BCL structure could have a potential role in thermal stability of the enzyme

Quantitative structure–activity relationship (QSAR) of aryl alkenyl amides/imines for bacterial efflux pump inhibitors

A quantitative structureeactivity relationship (QSAR) analysis has been performed on a data set of 42 aryl alkenyl amides/imines as bacterial efflux pump inhibitors. Several types of descriptors including topological, spatial, thermodynamic, information content and E-state indices have been used to derive a quantitative relationship between the efflux pump inhibiting activity and structural properties. Algorithm based on genetic function approximation method of variable selection was used to generate the model. Statistically significant model (with r2 ¼ 0.87) was obtained with the descriptors like radius of gyration and heat of formation besides E-state indices, A log P atom types and solvent accessible charged surface area playing an important role in determining the activity of the compounds against bacterial efflux pump. The model was also tested successfully for external validation criteria. The model is not only able to predict the activity of new compounds but also explained the important regions in the molecules in quantitative manner

Piperine as an inhibitor of Rv1258c, a putative multidrug efflux pump of Mycobacterium tuberculosis

Objectives: To evaluate the role of piperine as an inhibitor of Rv1258c of Mycobacterium tuberculosis. Methods: Rifampicin, in combination with piperine, was tested against M. tuberculosis H37Rv and rifampicinresistant (rifr) M. tuberculosis. A laboratory-generated rifampicin-resistant mutant (rifr) of M. tuberculosis was tested for drug susceptibility and the expression level of the putative efflux protein (Rv1258c) by real-time PCR. The three-dimensional (3D) structure of Rv1258c was also predicted using an in silico approach. Results: In the present study, rifampicin in combination with piperine, a trans-trans isomer of 1-piperoyl-piperidine,reduced the MIC and mutation prevention concentration (MPC) of rifampicin for M. tuberculosis H37Rv, including multidrug-resistant (MDR) M. tuberculosis and clinical isolates. Moreover, piperine effectively enhanced the bactericidal activity of rifampicin in time–kill studies and also significantly extended its post-antibiotic effect (PAE). In the presence of rifampicin, M.tuberculosis rifr showed a 3.6-fold overexpression of Rv1258c.The 3D structure of Rv1258c, using in silico modelling, was analysed to elucidate the binding of piperine to the active site. Conclusions: The results of this study are suggestive of piperine’s involvement in the inhibition of clinically overexpressed mycobacterial putative efflux protein (Rv1258c). Piperine may be useful in augmenting the antimycobacterial activity of rifampicin in a clinical setting