Krishnan Kannabiran

Antidiabetic and ameliorative potential of Ficus bengalensis bark extract in streptozotocin induced diabetic rats.

The aim of the present study was to evaluate the antidiabetic and ameliorative potential of aqueous extract of Ficus bengalensis bark in streptozotocin induced diabetic rats. The effect of oral administration of aqueous extract of F. bengalensis bark on blood glucose, serum electrolytes, serum glycolytic enzymes, liver microsomal protein, hepatic cytochrome P-450 dependent monooxygenase enzymes and lipid peroxidation in liver and kidney of streptozotocin -induced diabetic rats was studied. Oral administration of Ficus bengalensis to fed, fasted and glucose loaded diabetic rats significantly [F > 0.05 (ANOVA) and P< 0.05 (DMRT)] decreased the blood glucose level at 5 hrs and restored the levels of serum electrolytes, glycolytic enzymes and hepatic cytochrome P-450 dependent enzyme systems and decreased the formation of liver and kidney lipid peroxides at the end of 12 weeks. Further, the aqueous extract of Ficus bengalensis at a dose of 500mg/kg/day exhibits significant antidiabetic and ameliorative activity as evidenced by histological studies in normal and Ficus bengalensis treated streptozotocin induced diabetic rats. On the basis of our findings, it could be used as an antidiabetic and ameliorative agent for better management of diabetes mellitus.

Antifungal activity of Streptomyces sp. VITSTK7 and its synthesized Ag2O/Ag nanoparticles against medically important Aspergillus pathogens

OBJECTIVE The aim of the present study was to assess the anti-Aspergillus activity of culture filtrate of Streptomyces sp. VITSTK7 and biologically synthesized Ag(2)O/Ag nanoparticles using the culture filtrate of VITSTK7. MATERIAL AND METHODS Silver nanoparticles were synthesized by biological reduction of silver nitrate using culture filtrate of Streptomyces sp. VITSTK7. The synthesized nanopaticles were characterized for surface plasma resonance peak, X-ray diffraction patterns, shape and size distribution. Inhibition of mycelial growth was used as an index of anti-Aspergillus activity of synthesized nanoparticles. RESULTS The synthesized nanoparticles were spherical shaped and monodespersive in nature and showed a single surface plasma resonance peak at 420 nm. X-ray diffraction patterns displayed typical peaks of crystalline silver oxide and size distribution histograms indicated production of 20-60-nm-size nanoparticles with average size of 35.2 nm. The synthesized nanoparticles showed anti-Aspergillus activity against Aspergillus niger, Aspergillus flavus and Aspergillus fumigatus with antifungal index in the range of 62-75%. CONCLUSION Thus the bioconversion of Ag(2)O/Ag nanoparticles by Streptomyces sp. VITSTK7 could be employed to control Aspergillus pathogenesis. The results of this study suggest that the green synthesis of Ag(2)O/Ag nanoparticles using marine Streptomyces sp. VITSTK7 yielded 27.9 nm sized particles with potential to act against pathogenic Aspergillus species.

Diversity and exploration of bioactive marine actinomycetes in the Bay of Bengal of the Puducherry coast of India

The present study was designed to investigate the Puducherry coast of the Bay of Bengal, India for the diversity of bioactive actinomycetes. A total of 50 actinomycete strains were isolated from the marine sediments and most of the strains were belongs to Streptomyces. These strains were identified by means of morphological physiological, biochemical and cultural characteristics. The isolates were subjected to shake flask fermentation and the secondary metabolites were extracted with ethyl acetate and screened for cytotoxicity, hemolytic activity and antimicrobial activity against selected bacterial and fungal pathogens. The cytotoxic activity was evaluated using HeLa cell lines by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a tetrazole (MTT) assay, hemolytic activity on mouse erythrocytes and the antifungal activity was evaluated by MTT cytotoxic assay against Aspergillus niger, Aspergillus fumigatus and Candida albicans. The antibacterial activity was studied against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Klebsiella pneumoniae. The cytotoxicity and antimicrobial activity of secondary metabolite was found to be concentration dependent and nearly 24% of isolates showed significant antimicrobial, hemolytic and cytotoxic activity. The results of our study indicate the diversity and bioactive potential of marine actinomycetes isolated in the Puducherry coast.

Leishmanicidal activity of saponins isolated from the leaves of Eclipta prostrata and Gymnema sylvestre

Objective: To evaluate the leishmanicidal activity of saponin, dasyscyphin C of Eclipta prostrata and sapogenin, gymnemagenol from Gymnema sylvestre leaves under in vitro conditions. Materials and Methods: Dasyscyphin C/Gymnemagenol were dissolved in phosphate buffered saline (PBS) and diluted with liquid medium to obtain concentrations ranging from 1000 to 15 μg /ml. The leishmanicidal activity against leishmanial parasites, Leishmania major, Leishmania aethiopica and Leishmania tropica promastigotes was studied by the MTS assay. Result: The Dasyscyphin C isolated from E. prostrata showed good leishmanicidal activity at 1000μg/ml concentration, with the IC50 value of 450μg/ml against L. major promastigote and the percentage of parasitic death was 73; whereas, gymnemagenol of G. sylvestre showed only 52% parasitic death at 1000 μg/ml concentration. The other Leishmania species, L. aethiopica and L. tropica promastigotes, were less sensitive to the saponins of E. prostrata and G. sylvestre. Conclusion: From this study, it can be concluded that the dasyscyphin C of E. prostrata has significant leishmanicidal activity against L. major promastigote.

Biosorption of Cr (VI), Cr (III), Pb (II) and Cd (II) from aqueous solutions by Sargassum wightii and Caulerpa racemosa algal biomass

Heavy metal pollution is one of the most important environmental problems today. Biosorption is an innovative technology that employs biological materials to accumulate heavy metals from waste water through metabolic process or physicochemical pathways of uptake. Even though several physical and chemical methods are available for removal of heavy metals, currently many biological materials such as bacteria, algae, yeasts and fungi have been widely used due to their good performance, low cost and large quantity of availability. The aim of the present study is to explore the biosorption of toxic heavy metals, Cr(VI), Cr(III), Pb(II) and Cd(II) by algal biomass obtained from algae Sargassum wightii (brown) and Caulerpa racemosa (green). Biosorption of algal biomass was found to be biomass concentration- and pH-dependent, while the maximal biosorption was found at pH 5.0 and with the metal concentration of 100 mg L−1. S. wightii showed the maximal metal biosorption at the biomass concentration of 25 g L−1, followed by C. racemosa with the maximal biosorption at 30 g L−1. S. wightii showed 78% biosorption of Cr(VI), Cr(III), Pb(II) and Cd(II) ions. C. racemosa exhibited 85% biosorption of Cd(II) and Cr(VI), and 50% biosorption of Cr(III) and Pb(II). The results of our study suggest that seaweed biomass can be used efficiently for biosorption of heavy metals.

Anticandidal activity of silver nanoparticles synthesized using Streptomyces sp.VITPK1

OBJECTIVES The aim of the present study was to evaluate the anticandidal activity of biologically synthesized silver nanoparticles using the culture filtrate of Streptomyces sp.VITPK1. MATERIALS AND METHODS Silver nanoparticles were synthesized using the culture filtrate of Streptomyces species isolated from brine spring located at Thoubal District, Manipur, India. The isolate was identified by molecular taxonomic characterization and designated as Streptomyces sp.VITPK1. The synthesized silver nanoparticles (AgNPs) were characterized by UV-visible spectra, X-ray diffraction (XRD) patterns, Energy Dispersive Analysis of X-rays (EDAX) and Fourier Transform Infrared (FTIR) analysis. The antifungal activity of the synthesized silver nanoparticles was evaluated against selected Candida species. RESULTS The synthesized AgNPs showed a surface plasmon resonance peak at 425 nm. XRD patterns showed the crystalline peaks at 38.15° (111), 44.35° (200), 64.52° (220) and 77.49° (311) matching with the diffraction facets of silver. The size of the AgNPs was in the range of 20-45 nm. The EDAX analysis revealed the presence of silver as the major metal in the sample. The synthesized AgNPs showed anticandidal activity against Candida albicans, Candida tropicalis and Candida krusei with a maximum zone of inhibition of 20mm against C. albicans. CONCLUSIONS The results of this study suggest that the green synthesis of silver nanoparticles using Streptomyces sp.VITPK1 have the ability to act against pathogenic Candida strains.

Anti-fish nodaviral activity of furan-2-yl acetate extracted from marine Streptomyces spp.

The antiviral activity of furan-2-yl acetate (C6H6O3) extracted from Streptomyces VITSDK1 spp. was studied in cultured Sahul Indian Grouper Eye (SIGE) cells infected with fish nodavirus (FNV). The nodavirus infection in the SIGE cells was confirmed by reverse transcriptase–polymerase chain reaction (RT-PCR) and the antiviral activity of furan-2-yl acetate was assessed by cytopathic effect, as well as reduction in nodaviral titre (TCID50 mL−1, where TCID50 is the 50% tissue culture infective dose) in the cultured SIGE cells under in vitro conditions. Furan-2-yl acetate (20 µg mL−1) effectively inhibited the replication of the FNV-infected SIGE cell lines and the viral titre was reduced from 4.3 to 2.45 log TCID50 mL−1 on treatments. Furan-2-yl acetate (20 µg mL−1)- treated SIGE cell survival was found to be 90%, as determined by methyl thiazol tetrazolium assay. The results of an immunofluorescent assay revealed a strong association between the viral capsid protein inhibition and a decline in viral replication. The results suggest that furan-2-yl acetate suppressed FNV replication in cultured fish cells, providing a potential approach for the control of nodaviral diseases in marine fishes.

Extraction of quinone derivative from Streptomyces sp. VITVSK1 isolated from Cheyyur saltpan, Tamilnadu, India

Extraction of pigments from natural sources is gaining momentum due to many biological applications. The aim of our study was to extract and to identify the pigment produced by Streptomyces species isolated from saltpan soil samples. The pigment-producing isolate was characterized by molecular taxonomy, identified as Streptomyces species, and designated as Streptomyces sp. VITVSK1. The isolate produced green color pigmentation upon solid substrate fermentation using parboiled rice as a media for 7 days at 37°C. The pigment derivative was extracted using methanol as solvent and purified by silica gel column chromatography and preparative thin layer chromatography using chloroform: methanol as solvent system. The purified compound was identified as 2,5-di-tert-butyl-1,4-benzoquinone (DTBBQ) based on similarity index with reference compounds available in the mass spectra library, NIST. Structure of the pure compound was also elucidated by 1H and 13C nuclear magnetic resonance spectra. The compound DTBBQ showed 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity with IC50 value of 0.6 μg/mL. DTBBQ also showed antimicrobial activity with a zone of inhibition of 21 mm against Bacillus cereus. The results of the present study showed that Streptomyces sp. VITVSK1 could be a promising source for the production of biologically active quinone-based pigments.

Biosorption of mercury and lead by aqueous Streptomyces VITSVK9 sp. isolated from marine sediments from the bay of Bengal, India

Toxic heavy metals are increasingly accumulating in the environment worldwide and are considered to be life threatening contaminants. The biosorption of mercury and lead by marine actinomycetes isolated from marine sediment collected from the Bay of Bengal coast of Puducherry, India, was evaluated. The maximum tolerance concentration (MTC) of Streptomyces sp. was determined by a well diffusion method and a broth dilution method. The effects of the initial metal ion concentration, the pH and the biomass dosage on the biosorption of mercury and lead ions were investigated. The MTC of the isolate to metals was 200 mg·L−1 for mercury and 1800 mg·L−1 for lead. At neutral pH, the isolate had a maximum biosorption of metal ions of 200 mg·L−1 and 150 mg·L−1 for mercury and lead respectively. Fourier transform infrared (FTIR) absorption spectra showed the chemical interactions between the functional groups in the biomass such as hydroxyl (−OH), amine (−NH2), carboxyl (−COOH) and the metal ions. The isolate was further characterized by molecular taxonomy and identified as a member of the genus Streptomyces. Based on the phenotypic and phylogenetic analysis, the strain was classified as a new species of the genus Streptomyces and designated as Streptomyces VITSVK9 sp. (HM137310). A blast search of the 16S rDNA sequence of the strain showed the most similarity (95%) with Streptomyces sp. A515 Ydz-FQ (EU384279). Based on the results, it can be concluded that this marine Streptomyces could be used as a biosorbent for the removal of heavy metal ions from aqueous environments.

Studies on interaction of insect repellent compounds with odorant binding receptor proteins by in silico molecular docking approach

The aim of the study was to identify the interactions between insect repellent compounds and target olfactory proteins. Four compounds, camphor (C10H16O), carvacrol (C10H14O), oleic acid (C18H34O2) and firmotox (C22H28O5) were chosen as ligands. Seven olfactory proteins of insects with PDB IDs: 3K1E, 1QWV, 1TUJ, 1OOF, 2ERB, 3R1O and OBP1 were chosen for docking analysis. Patch dock was used and pymol for visualizing the structures. The interactions of these ligands with few odorant binding proteins showed binding energies. The ligand camphor had showed a binding energy of −136 kcal/mol with OBP1 protein. The ligand carvacrol interacted with 1QWV and 1TUJ proteins with a least binding energy of −117.45 kcal/mol and −21.78 kcal/mol respectively. The ligand oleic acid interacted with 1OOF, 2ERB, 3R1O and OBP1 with least binding energies. Ligand firmotox interacted with OBP1 and showed least binding energies. Three ligands (camphor, oleic acid and firmotox) had one, two, three interactions with a single protein OBP1 of Nilaparvatha lugens (Rice pest). From this in silico study we identified the interaction patterns for insect repellent compounds with the target insect odarant proteins. The results of our study revealed that the chosen ligands showed hydrogen bond interactions with the target olfactory receptor proteins.