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Rajajinagar, India

Korrapati S.,Bigtec Pvt Ltd | Korrapati S.,Vellore Institute of Technology | Sanjeeva S.K.,Bigtec Pvt Ltd | Vijayalakshmi U.,Vellore Institute of Technology | And 3 more authors.
International Journal of ChemTech Research | Year: 2015

The biophysical parameters like pH of the medium, temperature, refractive index, extinction coefficient of fluorescent compound etc. are responsible for fluorescence quantum yield. Even after maintaining these parameters constant in an assay, peculiarities do occur with respect to quantum yield due to presence of salts and proteins present in the medium. Most of the fluorescent compounds have different quantum yields in presence of Hofmeister series salts and their behaviour has never been studied thoroughly. We performed a systematic study of effects of Hofmeister series salts (urea, sodium chloride, ammonium sulphate, and guanidine isothiocyanate) and BSA (0.1 mg/mL) on fluorescence quantum yield for seven different fluorescent compounds (fluorescein, fluorescein isothiocyanate, DSSA, FITC-attached staurosporine, FITC-attached estrogen, FITC-attached NADH and FITC-attached NADPH). Presence of guanidine isothiocyanate and (NH4)2SO4) has drastically reduced fluorescence quantum yield of all compounds. In general, presence of salts like urea has increased quantum yield, BSA and other salts have minimum effect on quantum yield. Among the dyes studied, the two groups obtained are fluorescein, FITC and E2-FITC in the first; FITC-staurosporine, FITC-NADH and FITC-NADPH in the second, which have similar fluorescence quantum yield behaviour in the studied buffers. DSSA seems to be unique from all the studied buffers due to the presence of two dyes in its structure. © 2015, Sphinx Knowledge House. All rights reserved. Source


Narayanan M.M.,Deakin University | Narayanan M.M.,Bigtec Pvt Ltd | Nair C.B.,Bigtec Pvt Ltd | Sanjeeva S.K.,Bigtec Pvt Ltd | And 4 more authors.
Advances and Applications in Bioinformatics and Chemistry | Year: 2013

Viral neuraminidase inhibitors such as oseltamivir and zanamivir prevent early virus multiplication by blocking sialic acid cleavage on host cells. These drugs are effective for the treatment of a variety of influenza subtypes, including swine flu (H1N1). The binding site for these drugs is well established and they were designed based on computational docking studies. We show here that some common natural products have moderate inhibitory activity for H1N1 neuraminidase under docking studies. Significantly, docking studies using AutoDock for biligand and triligand forms of these compounds (camphor, menthol, and methyl salicylate linked via methylene bridges) indicate that they may bind in combination with high affinity to the H1N1 neuraminidase active site. These results also indicate that chemically linked biligands and triligands of these natural products could provide a new class of drug leads for the prevention and treatment of influenza. This study also highlights the need for a multiligand docking algorithm to understand better the mode of action of natural products, wherein multiple active ingredients are present. © 2013 Narayanan et al. This work is published by Dove Medical Press Ltd. Source


Sanjeeva S.K.,Vellore Institute of Technology | Sanjeeva S.K.,Bigtec Pvt Ltd | Korrapati S.,Bigtec Pvt Ltd | Korrapati S.,Vellore Institute of Technology | And 8 more authors.
Journal of Fluorescence | Year: 2014

Donor -linker -acceptor (DSSA) is a concept in fluorescence chemistry with acceptor being a fluorescent compound (FRET) or quencher. The DSSA probes used to measure thiol levels in vitro and in vivo. The reduction potential of these dyes are in the range of -0.60 V, much lower than the best thiol reductant reported in literature, the DTT (-0.33 V). DSSA disulphide having an unusually low reduction potential compared to the typical thiol reductants is a puzzle. Secondly, DSSA probes have a cyclized rhodamine ring as acceptor which does not have any spectral overlap with fluorescein, but quenches its absorbance and fluorescence. To understand the structural features of DSSA probes, we have synthesized DSSANa and DSSAOr. The calculated reduction potential of these dyes suggest that DSSA probes have an alternate mechanism from the FRET based quenching, namely hydrophobic interaction or dye to dye quenching. The standard reduction potential change with increasing complexity and steric hindrance of the molecule is small, suggesting that ultra- low Eo' has no contribution from the disulphide linker and is based on structural interactions between fluorescein and cyclized rhodamine. Our results help to understand the DSSA probe quenching mechanism and provide ways to design fluorescent probes. © 2014 Springer Science+Business Media New York. Source


Sanjeeva S.K.,Bigtec Pvt Ltd | Sanjeeva S.K.,Vellore Institute of Technology | Pinto M.P.,Bigtec Pvt Ltd | Narayanan M.M.,Bigtec Pvt Ltd | And 10 more authors.
Renewable Energy | Year: 2014

We report distilled technical cashew nut shell liquid (DT-CNSL) as a non-transesterified biofuel and also as an additive to convert triglycerides to biofuel, without the need for the formation of methyl esters. DT-CNSL blends of diesel obey physico-chemical parameters of diesel. DT-CNSL offers stability to blends of straight vegetable oil (SVO) and tallow oil in diesel. Fluorescence studies using charge transfer probes show that the blend of DT-CNSL, triglycerides and diesel is a uniform solution, and fluorescence behavior is similar to that of diesel. The economics for the cultivation of cashew (Anacardium occidentale), its industrial use and rich carbon sink properties indicate that DT-CNSL could complement or replace traditional biodiesel crops like Jatropha and improve income for farmers. © 2014 Elsevier Ltd. Source

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