CYTOTOXICITY AND ANTIMICROBIAL ACTIVITY OF MONO-, DI- AND TRINUCLEAR RUTHENIUM(II) POLYPYRIDINE COMPLEXES

Objectives: To evaluate the in vitro cytotoxicity, antibacterial and antifungal activity of the synthesized mono-, di- and trinuclear ruthenium(II) polypyridine complexes.Methods: A series of synthesized ruthenium(II) complexes, R1, R2 and R3, are screened for in vitro antiproliferative activity against HepG2 cancer cell line using 96-well plate method. An assay of antimicrobial activity was performed by disc diffusion method. In addition an assay of an antifungal was performed by broth micro-dilution method.Results: The cytotoxicity of complexes revealed IC50 values of 14.52 (R3), 19.53 (R2) and 22.32 μM (R1) against HepG2 cell line in a dose dependent manner. All the complexes inhibited moderately the growth of Gram positive bacteria (G+) such as Staphylococcus aureus (MRSA), Eubacterium lentum, and Bacillus subtillis, quite meagerly the growth of the Gram negative bacterium (G─), Enterobacter aerogenes, but did not inhibit at all the growth of Erwinia amylovora (MTCC 2760) and showed a slight antifungal activity.Conclusion: From this study, we could suggest that the systematic increase in number of imidazole moiety along with expanding cloud of conjugated Ï€-electron system of ruthenium(II) polypyridine complexes is responsible for the antiproliferative activity which increases in the order, R1 < R2 < R3 against HepG2 cancer cells. Consecutively, the complexes show good antimicrobial activity against Gram positive bacteria, but show poor or no effect against Gram negative bacteria and exhibit a little antifungal activity.Â

Antimicrobial activity of some actinomycetes from Western Ghats of Tamil Nadu, India

Introduction: Microbial diseases are increasing year by year and they are becoming a big threat to public health. There are more than 200 known diseases transmitted by bacteria, fungi, viruses, prions, rickettsia and other microbes to humans. The emergence of drug resistance to chemical drugs is the biggest threat in controlling human pathogens. Hence novel antimicrobial agents from actinomycetes are timely needed for the control of several human pathogens.Aim: The aim was to find some actinomycetes with antimicrobial metabolites.Methods: Soil samples were collected from Nilgiris district in Western Ghats of Tamil Nadu, India. Actinomycetes were isolated using serial dilution and plating techniques on actinomycetes isolation agar. Streptomycin and ketoconazole (25 lg/disc) were used as reference controls. The active strains were identified by 16S rRNA and phylogenetic tree was constructed; the sequences were submitted in the GenBank.Results: Totally 106 actinomycete strains were isolated and cross streaked against various human microbial pathogens. Only 44 (41.50%) exhibited good antimicrobial activity against different pathogenic microbes. Five isolates (FMS-20, TGH-30, TGH-31, TGH-31-1 and IS-4) were chosen for secondary screening using filtrate. Among them FMS-20 filtrate showed good inhibition on the 16th day against all tested microbial pathogens. Further the intracellular methanol extract of FMS- 20 showed maximum zone of inhibition against A. brasiliensis (22 mm) at 5 mg/disc. Similarly the extracellular ethyl acetate extract of FMS-20 showed maximum zone of inhibition against B. subtilis (25 mm).Conclusions: The present work revealed that, among 106 actinomycetes screened, Streptomyces rimosus (FMS-20) (Accession No-KT827106) showed promising antimicrobial activity against all the tested human microbial pathogens.Keywords: Streptomyces rimosus; Antimicrobial activity; Disc diffusion; Zone of inhibitio

Computational analysis of sequential and structural variations in stromelysins as an insight towards matrix metalloproteinase research

Matrix metalloproteinases are zinc-dependent protein and peptide hydrolases. They are broadly involved in metabolic regulation through both extensive protein degradation and selective peptide-bond hydrolysis. Stromelysins belong to this group of proteinases and involved in various physiological and pathological functioning of the cell. This study aims at assessing the sequential and structural aspects of stromelysins based on in silico approaches. Deduced stromelysin sequences were predicted to possess regulatory domain, protease domain, and proline-rich hinge regions. Sequential analysis revealed MMP-3 and 10 are more similar than MMP-11 regarding stability and aminoacid distribution. Secondary structure prediction showed that beta-sheets dominated other secondary structural elements (alpha helices, coils, and turns) in stromelysins. Validation of predicted models with different approaches confirms the accuracy and best quality of models. The binding mode of zinc atom provides information regarding their interaction with stromelysins. The predicted models showed little variation in binding mode with their natural inhibitor, TIMP-1. The predicted models will be used in an extensive range of studies for functional analysis and improvement activity of stromelysins. Keywords: Matrix metalloproteinases, Zinc-binding motif, Structure prediction, Ramachandran plot, Stromelysin, Superfamil

Isolation and molecular characterization of actinomycetes with antimicrobial and mosquito larvicidal properties

The present study aimed to isolate actinomycetes from soil samples collected from Western Ghats regions, Tamil Nadu, India. Totally 400 actinomycetes isolates were isolated, of which 161 (40.2%) showed antimicrobial activity in preliminary screening. Secondary screening yielded 27 active isolates; twelve of them showed good antimicrobial and larvicidal activities. Five isolates namely S12-4, S12-17, S12-8, DPS-14 and FMS-20 presented 98%, 93%, 87%, 82%, and 80% larvicidal activity against Cx. quinquefasciatus; very low larvicidal activity was observed against Ae. aegypti. S12-4 showed 100% larval mortality against An. stephensi. RAPD results showed highest similarity between DPS-122 and KFS-24 (0.89246). The polymorphic index observed in the primers ranged from 0.286 (OPA-09) to 0.07 (OPC-18). The results suggest that Western Ghats regions may be a good natural source for isolation of actinobacteria and thereby for discovering novel molecules with antimicrobial and mosquito larvicidal properties