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Jayalakshmi N.R.,Bangalore University | Saraswathi K.J.T.,Bangalore University | Vijaya B.,Bangalore University | Prasad D.P.H.S.S.,Lotus Labs. Pvt. Ltd. | Suresh R.,Bangalore University
Journal of Plant Sciences | Year: 2012

Plants of Malva sylvestris L., were studied for morphological variations and anthocyanin production, malvidin and delphinidin with silver nitrate treatment. Effects of exogenous silver nitrate on anthocyanin accumulation have been examined. Foliar spray of 0.1 M silver nitrate for five consecutive days significantly increased the anthocyanin content showing distinct morphological variations with respect to plant height, plant biomass, leaf number and leaf mass. By traditional chilled acidified methanol the total anthocyanins were extracted and estimated by pH differential spectroscopic method. The anthocyanins were purified by C-18 Sep-pak column and further analyzed for different anthocyanins by Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC) methods respectively. The evidence presented in this paper indicates that the enhanced anthocyanin production is related to different levels of oxidative stress induced by silver nitrate to the plant tissues. © 2012 Academic Journals Inc. Source

Shekar R.,Lotus Labs. Pvt. Ltd. | Sinha B.N.,Birla Institute of Technology | Arindam M.,Lotus Clinical Research Academy | Degani M.S.,Institute of Chemical Technology
International Journal of ChemTech Research | Year: 2013

Evaluation of new chemical entities for their drug like properties, early in the discovery phase will help to reduce late stage attrition due to poor stability or unsuitable pharmacokinetic properties. Four newly synthesized triazole compounds viz., 3,3,5-Trimethyl-1-(5-phenyl-4H-1,2,4-triazol-3-yl)cyclohexanol (MSDRT 8), 3,3,5-Trimethyl-1-(5-(pyridin-4-yl)-4H-1,2,4-triazol-3-yl)cyclohexanol (MSDRT 10), Cyclohex-3-enyl(5- (pyridin-4-yl)-4H-1,2,4-triazol-3-yl)methanol (MSDRT 11) and Cyclohex-3-enyl(5-phenyl-4H-1,2,4-triazol-3- yl)methanol (MSDRT 12)), having in vitro antitubercular activity, were screened for chemical stability after acid and alkali hydrolysis. Metabolic stability was also studied after incubating each compound with rat liver microsomes. Based on the results of chemical and metabolic stability, MSDRT 12 was identified as a potential lead compound. A reverse phase high performance liquid chromatographic method with UV/Visible detector was developed for all four compounds and their degradation products were developed and separation were achieved on a Zorbax XDB C18 5 μm column with mobile phase containing a gradient mixture of 0.1 % formic acid and acetonitrile for MSDRT 8, MSDRT 10 and MSDRT 12 and a gradient mixture of 0.1 % formic acid and methanol for MSDRT 11. The method was validated as per International Conference of Harmonisation (ICH) guidelines. Source

Shekar R.,Lotus Labs. Pvt. Ltd. | Sinha B.N.,Birla Institute of Technology | Mukhopadhya A.,Lotus Clinical Research Academy | Degani M.S.,Institute of Chemical Technology
Chromatographia | Year: 2014

Cyclohex-3-enyl(5-phenyl-4H-1,2,4-triazol-3-yl)methanol (MSDRT 12) is a novel triazole-based antitubercular compound with two chiral centres. Evaluation of the enantio-specific antitubercular activity has established that the stereoisomer 3 of MSDRT12 (Isomer 3) was the most potent isomer with a minimum inhibitory concentration of 0.78 μg/mL. The other stereoisomers show negligible or no activity. A sensitive, simple, specific, precise and accurate chiral chromatographic method for the direct analysis of the four stereoisomers of MSDRT 12 and the active Isomer 3 has been developed and validated. The method has also been validated for analysing the stereoisomeric impurities Isomer 1, Isomer 2 and Isomer 4 in the active Isomer 3. The separation of the four stereoisomers of MSDRT 12 was achieved using an immobilized polysaccharide-based column, Chiralpak ID with amylose tris(3-chlorophenylcarbamate) as the chiral selector. The separation was performed using a mixture of n-hexane, isopropyl alcohol, ethanol and diethylamine (60:35:5:0.1 v/v/v/v) at a flow rate of 1 mL/min. The method offers excellent separation of the four stereoisomers with resolution more than 1.5 and tailing factor <1.5. The standard curves were linear over the concentration range 5-500 μg/mL and 0.40-505 μg/mL for MSDRT 12 and Isomer 3, respectively. Excellent linearity in the range 0.4-5 μg/mL was obtained for Isomer 1, Isomer 2 and Isomer 4 and these stereoisomeric impurities could be accurately and precisely quantified at a level of 0.1 % of the active isomer. © 2014 Springer-Verlag. Source

D'Souza H.J.B.,Lotus Labs. Pvt. Ltd. | Pai B.,Lotus Labs. Pvt. Ltd. | Kumar A.,Lotus Labs. Pvt. Ltd. | Shekar R.,Lotus Labs. Pvt. Ltd. | And 2 more authors.
Biomedical Chromatography | Year: 2010

While the practice of using a smaller number of non-zero standards (typically seven to eight) has not been entertained in routine bioanalytical work, it is important to innovate and be pragmatic about minimizing the number of calibration standards to promote cost-eff ective and speedy assessment. In this exercise, two important compounds, omeprazole and clopidogrel carboxylic acid, were considered. Additionally, both analytes off ered a 1000-fold calibration curve range with eight non-zero standards to permit a systematic evaluation. Accordingly various scenarios of post-hoc analysis of the calibration data were formulated which included step-wise reduction of the number of calibration standards from a maximum of n = 8 to a minimum of n = 3. In all the scenarios evaluated in this exercise, a calibration curve was reconstructed and both quality control samples and in vivo pharmacokinetics were calculated in each instance. Based on the data generated in this exercise, a minimum of three non-zero calibration standards were adequate to predict the quality control samples with the predefined accuracy and precision estimates for both omeprazole and clopidogrel carboxylic acid. Additionally, the in vivo pharmacokinetic characterization of the chosen compounds was not hampered by the reduction of calibration standards (from n = 8 to n = 3). Hence, consideration for reducing number of calibration standards in bioanalytical work may provide a viable alternative in several situations such as formulation screening strategies, routine therapeutic drug monitoring and sparse sample analyses. Copyright © 2009 John Wiley & Sons, Ltd. Source

Manjunath S.J.,Lotus Labs. Pvt. Ltd. | Kamath N.,Lotus Labs. Pvt. Ltd. | Shekar A.K.R.,Lotus Labs. Pvt. Ltd. | Srinivas N.R.,Suramus Biopharm | Kristjansson F.,Lotus Labs. Pvt. Ltd.
Biomedical Chromatography | Year: 2010

Sensitivity enhancement via summation of multiple MRM transition pairs is gaining popularity in tandem mass spectrometric assays. Numerous validation experiments describing the assays for two model substrates, clopidogrel and ramiprilat, were performed. The quantitation of clopidogrel was achieved by the summation of transition pairs m/z 322.2 to m/z 212.0 and m/z 322.2 to m/z 184.0, while that of ramiprilat was achieved by the summation of transition pairs m/z 389.2 to m/z 206.1 and m/z 389.2 to m/z156.1. The use of summation approach achieved sensitivities of >2 fold for both compounds as compared with the reported single MRM transition pair assays. The validation experiments addressed some important assay development issues, such as: (a) lack of impact of matrix effect; (b) unequivocal verification of the percentage contribution of each MRM transition pair towards sensitivity; (c) sensitivity enhancement factor achieved by summation approach of MRM transition pairs; and (d) accurate prediction of quality control samples using summation approach vs a single MRM transition pair. In summary, the appropriateness of using two MRM transition pairs for quantitation was demonstrated for both clopidogrel and ramiprilat. Additionally, pharmacokinetic application of the MRM transition pair assays using a summation approach was established for the two compounds. Copyright © 2009 John Wiley & Sons, Ltd. Source

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