Showing papers by "Ranjan K. Singh published in 2018"

Detection and monitoring of in vitro formation of salicylic acid from aspirin using fluorescence spectroscopic technique and DFT calculations.

Abstract: Acetylsalicylic acid commonly termed as aspirin (AS) is a well known antipyretic and anti-inflammatory drug which can also be used to reduce death risks due to heart attack. In addition to this, it also exhibits some adverse effect such as gastrointestinal, tinnitus, Reye's syndrome. The side effects of AS such as gastrointestinal ulcer, tinnitus and Reye's syndrome are caused due to conversion of AS into its active metabolite salicylic acid (SAL). Conversion of AS into SAL has been investigated generally at basic pH. Since the pH of Gastrointestinal tract is on average neutral ranging from 6.5–7.4. Therefore in the present research work, in vitro conversion of AS to SAL was detected at neutral pH in both aqueous medium and human blood serum samples by time series fluorescence measurements and DFT study. The SAL obtained from AS at neutral pH was observed to be stable for ~ 6 and ~ 4 days in aqueous medium and blood serum, respectively. The mechanism of conversion of AS into SAL was investigated using the transition state theory employing density functional theory (DFT). On the basis of DFT calculation the in vitro formation of SAL from AS at neutral pH was found to involve two intermediate transition states.

Effect of Ni addition on PNZT tungsten bronze structure

Abstract: Lead niobate zirconate titanate (PNZT) with general formula 0.5PbNb2O6–0.5Pb(ZrxTi1-x)O3 (where x = 0.15, 0.25, 0.35) and lead nickel niobate zirconate titanate (PNNZT) with general formula Pb(NixNb0.5-xZr0.25Ti0.25)O3 (where x = 0.167, 0.250, 0.333) have been prepared by conventional solid state reaction. The phase formation has been studied by X – ray diffraction analysis. Raman investigations have been carried out in the 200–1000 cm−1 wave number range. The structural changes observed in the X – ray diffraction pattern has been further confirmed by Raman analysis. The major changes in the E(1TO), A1(1TO) and E + B1 phonon modes suggest the structural change from cubic to rhombohedral with increase in Ni concentration in PNNZT. The optical band gap has been calculated from UV – Vis absorption spectra.

A Novel Media Optimized for Production of Pullulan in Flask Type Fermentation System

Abstract: ISSN: 2319-7706 Volume 7 Number 04 (2018) Journal homepage: http://www.ijcmas.com Aureobasidium pullulans, popularly known as black yeast, is one of the most widespread saprophytic fungus associated with wide range of terrestrial and aquatic habitats. The fungus has widely been employed in production of an economically important polysaccharide Pullulan. Pullulan is a linear glucan made mainly of maltotriose repeating units. This gives the polysaccharide structural flexibility and enhances solubility. This polysaccharide is of great economic importance with increase applications in food, pharmaceutical, agriculture, blood plasma substitute and chemical industry. Production of pullulan was observed in a novel media consisting of Sugarcane juice (SCJ) and distilled water. It was found that high amount of pullulan (6.4±0.04g/100ml) was obtained at 37 o C, pH 5 at a concentration of 50% media in 96h. This is a novel study in which pullulan is grown on media consisting of Sugar Cane Juice (SCJ) and distilled water. Further no synthetic minerals are used in the media for the growth of polysaccharide making it very economical. K e y w o r d s Aureobasidium pullulans, Pullulan, Sugarcane juice,

Monitoring the in Vitro Thiazolidine Ring Formation of Antioxidant Drug N-Acetyl-l-cysteine at Basic pH and Detection of Reaction Intermediates: A Raman Spectroscopic and Ab Initio Study

Abstract: The important cyclization reaction of antioxidant drug N-acetyl-l-cysteine (NAC) has been monitored in vitro at basic pH with the help of time series Raman spectroscopy. The thiazoline ring formation of NAC at acidic pH is a well-known reaction and has been studied extensively. However, the formation of a thiazolidine ring from NAC at basic pH has not been investigated precisely till date. The effect of basicity of the medium on the rate of cyclization has been investigated by studying the reaction at five different basic pH values. Raman signatures of cyclization have been observed with the passage of time and are found to appear faster as the basicity of the medium increases. Ab initio calculations have been done to understand the plausible mechanism of the reaction at basic pH. It is observed that formation of a thiazolidine ring from NAC occurs primarily in four steps, which involve proton abstraction from the thiol (SH) group of NAC and subsequent formation of an S–C bond by a nucleophilic attack of the C–S group on the protonated C–O–H group in NAC. Correlation of the theoretically calculated results with experimental Raman spectral analysis has led to a detailed and proper understanding of this important biochemical reaction.

Monitoring the in Vitro Thiazolidine Ring Formation of Antioxidant Drug N-Acetyl-l-cysteine at Basic pH and Detection of Reaction Intermediates: A Raman Spectroscopic and Ab Initio Study.

Abstract: The important cyclization reaction of antioxidant drug N-acetyl-l-cysteine (NAC) has been monitored in vitro at basic pH with the help of time series Raman spectroscopy. The thiazoline ring formati...