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Development of an optical fibre Al(III) sensor based on immobilised chrome azurol S

Ahmad M, Narayanaswamy R

Talanta, 1995 Sep;42(9):1337-44.
PMID: 18966361

Chrome azurol S immobilised on XAD-2 has been used in this study as a reagent phase for the development of an optical fibre Al(III) sensor. Using a kinetic approach, this sensor was able to give a linear response in the Al(III) concentration range of 1.3 x 10(-5)-2.0 x 10(-4) M with a limit of detection of 1.0 x 10(-4) M. The optimum responses were obtained at pH 6.0 and when the solution was stirred. The sensor response was found to have a repeatability and reproducibility of 1.6% and 5.8%, respectively. The results obtained for Al(III) determination in aqueous sample were in good agreement with those obtained using graphite furnace-atomic absorption spectrometry.
Molecularly imprinted polymers as optical sensing receptors: correlation between analytical signals and binding isotherms

Ng SM, Narayanaswamy R

Anal Chim Acta, 2011 Oct 10;703(2):226-33.
PMID: 21889638 DOI: 10.1016/j.aca.2011.07.032

Despite the increasing number of usage of molecularly imprinted polymers (MIPs) in optical sensor application, the correlation between the analytical signals and the binding isotherms has yet to be fully understood. This work investigates the relationship between the signals generated from MIPs sensors to its respective binding affinity variables generated using binding isotherm models. Two different systems based on the imprinting of metal ion and organic compound have been selected for the study, which employed reflectance and fluorescence sensing schemes, respectively. Batch binding analysis using the standard binding isotherm models was employed to evaluate the affinity of the binding sites. Evaluation using the discrete bi-Langmuir isotherm model found both the MIPs studied have generally two classes of binding sites that was of low and high affinities, while the continuous Freundlich isotherm model has successfully generated a distribution of affinities within the investigated analytical window. When the MIPs were incorporated as sensing receptors, the changes in the analytical signal due to different analyte concentrations were found to have direct correlation with the binding isotherm variables. Further data analyses based on this observation have generated robust models representing the analytical performance of the optical sensors. The best constructed model describing the sensing trend for each of the sensor has been tested and demonstrated to give accurate prediction of concentration for a series of spiked analytes.
Molecular Docking Analysis of Phytic Acid and 4-hydroxyisoleucine as Cyclooxygenase-2, Microsomal Prostaglandin E Synthase-2, Tyrosinase, Human Neutrophil Elastase, Matrix Metalloproteinase-2 and -9, Xanthine Oxidase, Squalene Synthase, Nitric Oxide Synthase, Human Aldose Reductase, and Lipoxygenase Inhibitors

Narayanaswamy R, Wai LK, Esa NM

Pharmacogn Mag, 2017 Oct;13(Suppl 3):S512-S518.
PMID: 29142407 DOI: 10.4103/pm.pm_195_16

Background: The phytoconstituents phytic acid and 4-hydroxyisoleucine have been reported to posses various biological properties.
Objective: This prompted us to carry out the docking study on these two ligands (phytic acid & 4-hydroxyisoleucine) against eleven targeted enzymes.
Materials and Methods: Phytic acid & 4-hydroxyisoleucine were evaluated on the docking behaviour of cyclooxygenase-2 (COX-2), microsomal prostaglandin E synthase-2 (mPGES-2), tyrosinase, human neutrophil elastase (HNE), matrix metalloproteinase (MMP 2 and 9), xanthine oxidase (XO), squalene synthase (SQS), nitric oxide synthase (NOS), human aldose reductase (HAR) and lipoxygenase (LOX) using Discovery Studio Version 3.1 (except for LOX, where Autodock 4.2 tool was used).
Results: Docking and binding free energy analysis revealed that phytic acid exhibited the maximum binding energy for four target enzymes such as COX-2, mPGES-2, tyrosinase and HNE. Interestingly, we found that 4-hydroxyisoleucine has the potential to dock and bind with all of the eleven targeted enzymes.
Conclusion: This present study has paved a new insight in understanding 4-hydroxyisoleucine as potential inhibitor against COX-2, mPGES-2, tyrosinase, HNE, MMP 2, MMP 9, XO, SQS, NOS, HAR and LOX.
SUMMARY: 4-hydroxyisoleucine has the potential to dock and bind with all 11targeted enzymes such as (cyclooxygenase-2 [COX-2], microsomal prostaglandin E synthase-2 [mPGES-2], tyrosinase, human neutrophil elastase [HNE], matrix metalloproteinase [MMP-2 and -9], xanthine oxidase, squalene synthase, nitric oxide synthase, human aldose reductase, and lipoxygenase)Moreover, docking studies and binding free energy calculations revealed that phytic acid exhibited the maximum binding energy for four target enzymes such as COX-2, mPGES-2, tyrosinase, and HNE; however, for other six target enzymes, it fails to dock. Abbreviations used: COX-2: Cyclooxygenase-2, mPGES-2: Microsomal prostaglandin E synthase-2, HNE: Human neutrophil elastase, MMP-2 and -9: Matrix metalloproteinase-2 and -9, XO: Xanthine oxidase, SQS: Squalene synthase, NOS: Nitric oxide synthase, HAR: Human aldose reductase, LOX: Lipoxygenase, ADME: Absorption, distribution, metabolism, and excretion, TOPKAT: Toxicity Prediction by Computer-assisted Technology.
Fulltext Inhibition of Angiogenesis and Nitric Oxide Synthase (NOS), by Embelin & Vilangin Using in vitro, in vivo & in Silico Studies

Narayanaswamy R, Shymatak M, Chatterjee S, Wai LK, Arumugam G

Adv Pharm Bull, 2014 Dec;4(Suppl 2):543-8.
PMID: 25671187 DOI: 10.5681/apb.2014.080

In recent year's anti-angiogenesis agents have been recognized as effective drugs for the treatment of solid tumors, this prompted us to conduct the present study.
Fulltext Molecular Docking Analysis of Selected Clinacanthus nutans Constituents as Xanthine Oxidase, Nitric Oxide Synthase, Human Neutrophil Elastase, Matrix Metalloproteinase 2, Matrix Metalloproteinase 9 and Squalene Synthase Inhibitors

Narayanaswamy R, Isha A, Wai LK, Ismail IS

Pharmacogn Mag, 2016 Jan;12(Suppl 1):S21-6.
PMID: 27041853 DOI: 10.4103/0973-1296.176111

Clinacanthus nutans (Burm. f.) Lindau has gained popularity among Malaysians as a traditional plant for anti-inflammatory activity.
Fulltext Synthesis and docking studies of 2,4,6-trihydroxy-3-geranylacetophenone analogs as potential lipoxygenase inhibitor

Ng CH, Rullah K, Aluwi MF, Abas F, Lam KW, Ismail IS, et al.

Molecules, 2014;19(8):11645-59.
PMID: 25100256 DOI: 10.3390/molecules190811645

The natural product molecule 2,4,6-trihydroxy-3-geranyl-acetophenone (tHGA) isolated from the medicinal plant Melicope ptelefolia was shown to exhibit potent lipoxygenase (LOX) inhibitory activity. It is known that LOX plays an important role in inflammatory response as it catalyzes the oxidation of unsaturated fatty acids, such as linoleic acid to form hydroperoxides. The search for selective LOX inhibitors may provide new therapeutic approach for inflammatory diseases. Herein, we report the synthesis of tHGA analogs using simple Friedel-Craft acylation and alkylation reactions with the aim of obtaining a better insight into the structure-activity relationships of the compounds. All the synthesized analogs showed potent soybean 15-LOX inhibitory activity in a dose-dependent manner (IC50 = 10.31-27.61 μM) where compound 3e was two-fold more active than tHGA. Molecular docking was then applied to reveal the important binding interactions of compound 3e in soybean 15-LOX binding site. The findings suggest that the presence of longer acyl bearing aliphatic chain (5Cs) and aromatic groups could significantly affect the enzymatic activity.