Palanivel Rameshthangam

Silver Nanoparticle Embedded α-Chitin Nanocomposite for Enhanced Antimicrobial and Mosquito Larvicidal Activity

Advent of nanotechnology opens up potential avenues for overcoming various challenges that includes control and cure of infectious diseases. The present study is focused on the synthesis of α-chitin nanoparticles (CNP) from the shells of Penaeus monodon Fabricius, silver nanoparticles (AgNP) and α-chitin/silver nanocomposite (CNP/AgNP), and to evaluate their antimicrobial and mosquito larvicidal activities. The antibacterial and antifungal activities are assessed against five different bacterial and fungal strains. Also the mosquito larvicidal potential is studied against Aedes aegypti a potential vector for malaria and dengue fever. The synthesized nanocomposites are characterized using UV–Vis spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, energy-dispersive X-ray spectroscopy, transmission electron microscope and dynamic light scattering analysis. The antibacterial and antifungal assays reveal that the CNP/AgNP has an enhanced antimicrobial effect on inhibition of bacteria (P. vulgaris, K. pneumonia and S. aureus) as well as fungi (C. albicans, T. viridae, A. niger and A. alternate). Mosquito larvicidal assays confirm that CNP/AgNP has shown lowest LC50 and LC90 values than CNP and AgNP against all the instars of A. aegypti. Hence our result suggests that the incorporation of AgNP with CNP could improve the antimicrobial and mosquito larvicidal activity and have the potential to be used as biocompatible antimicrobial and mosquito larvicidal material.

Studies on electrochemical glucose sensing, antimicrobial activity and cytotoxicity of fabricated copper nanoparticle immobilized chitin nanostructure

In this study, copper nanoparticle immobilized chitin nanocomposite (CNP/CuNP) was synthesized and used for the development of non-enzymatic electrochemical sensor. The CNP/CuNP was characterized by X-ray diffraction (XRD), fourier transform infra red (FTIR) spectroscopy and high resolution transmission electron microscopy (HRTEM) analysis. The glucose sensing property of CNP/CuNP was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). As a result of the synergistic effect of CNP and CuNP, the modified electrode displayed effective electro-oxidation of glucose in 0.1M NaOH solution. At 0.45V potential the modified electrode showed response towards glucose in the linear range of 1-1000μM with a lowest detection limit of 0.776μM with better selectivity and stability. In addition, the antimicrobial activity of CNP/CuNP was evaluated against bacterial and fungal strains. CNP/CuNP displayed enhanced antimicrobial activity when compared to CNP and CuNP alone. Similarly, cytotoxicity of CNP/CuNP was tested against Artemia salina, which showed no toxic effect in the tested concentration.

Exploration of potential EGFR inhibitors: a combination of pharmacophore-based virtual screening, atom-based 3D-QSAR and molecular docking analysis

Abstract Epidermal growth factor receptor (EGFR) protein tyrosine kinases are over expressed in several human cancers and considered as a promising target for developing novel anticancer drugs. In this study, the ligand-based pharmacophore mapping and atom-based 3D-QSAR approach was carried out on a series of 40 novel pyrrolo[3, 2-d]pyrimidine derivatives acting as EGFR inhibitors. The best pharmacophore hypothesis AAADRR.295 was selected and an atom-based 3D-QSAR model was generated by applying partial least-squares algorithm. The developed model was validated and used as a 3D query in sequential virtual screening study to filter five chemical databases. The obtained compounds were further filtered according to Lipinski rule of five and fitness score. Subsequently, a multistep molecular docking study was employed on the retrieved hits and finally, 12 compounds were prioritized as potential leads against EGFR, which exhibited high docking scores, correlated binding mode to experimentally proven compounds and constructive drug-like properties. The results of this study provide detailed structural insights and emphasize the important binding features of these compounds, which may assists in the design and development of novel EGFR inhibitors.

Anticancer activity of silver and copper embedded chitin nanocomposites against human breast cancer (MCF-7) cells

Chitin is a natural biopolymer widely used in biomedical and environmental applications due to its distinctive physical, chemical and mechanical properties. Although the anticancer property of chitin nanoforms and chitin derivatives against various cancers were studied earlier, there is no report in the chitin nanostructure incorporated metal nanocomposite. The present study was aimed to investigate the cytotoxicity of chitin incorporated silver and copper nanocomposite against human breast cancer (MCF-7) cells. Cytotoxicity of chitin nanoparticles (CNP), silver nanoparticles (AgNP), copper nanoparticles (CuNP), chitin/silver nanocomposite (CNP/AgNP) and chitin/copper nanocomposite (CNP/CuNP) was evaluated. Among all the above, CNP/AgNP has shown a lower of 31 mg as inhibitory concentration (IC50) value. Our study further showed the increased generation of reactive oxygen species with decreased activity of antioxidant enzymes and damage in the membrane integrity, thus confirms the cellular cytotoxic action of CNP/AgNP. In conclusion, the present study validates that, incorporating chitin nanoparticles with metallic nanostructure could be an effective and promising therapeutic agent against breast cancer.

In Vitro and In Silico Studies of Chitin and Chitosan Based Nanocarriers for Curcumin and Insulin Delivery

The evaluation of drug delivery potential, molecular interactions of the polymeric nanoparticles with the drug molecule and release kinetics encounters more time consumption and also cost. In this study, we have adopted the combination of in vitro and in silico approaches to evaluate the drug delivery property of the polymeric nanoparticles viz. chitin and chitosan. Herein, two different therapeutic agents such as curcumin (a hydrophobic drug) and insulin (a therapeutic protein) were used to study the delivery potential of chitin and chitosan nanoparticles. The drug loaded chitin and chitosan nanoparticles were prepared and characterized using Fourier transform infra red spectroscopy, X-ray diffraction, dynamic light scattering and scanning electron microscopy analysis. In the in vitro drug delivery experiments, chitosan nanoparticles exhibited better encapsulation efficiency, drug loading capacity and prolonged release of the drug molecules than that of the chitin nanoparticles to both curcumin and insulin. Meanwhile the in silico experiments such as molecular docking and molecular dynamics predicted the molecular interactions and binding energy involved between the nanoparticles and the drug molecules. From this study, we suggest that the chitosan nanoparticles could be used as a carrier molecule for both curcumin and insulin.Graphical Abstract

Physicochemical and Microbiological Changes During Drying of Wolf Herring (Chirocentrus dorab) and Coastal Trevally (Carangoides coeruleopinnatus)

ABSTRACT The aim of the present study was to assess the physicochemical and microbiological changes during sun drying of salted wolf herring (Chirocentrus dorab) and coastal trevally (Carangoides coeruleopinnatus). For that purpose, the pH value, moisture, sodium chloride (NaCl) content, total volatile base nitrogen (TVB-N), histamine, cadaverine, putrescine, tryptamine, tyramine, spermine, and spermidine, as well as total aerobic mesophilic count, amine forming bacteria, total coliforms, Staphylococcus spp., and Bacillus spp., were determined. The initial pH value was 6.4 and increased during the salt drying process to 6.9 in both cases. The initial moisture, salt, and TVB-N levels of C. dorab and C. coeruleopinnatus were 64.3 and 60.3%, 2.55 and 2.70%, and 22.8 and 16.2 mg/100 g, respectively. At the end of drying, moisture decreased to 31.3 and 35.6%, respectively; salt increased to 13.71 and 16.04%; and TVB-N increased to 35.9 and 33.13 mg/100 g, respectively. Regarding total aerobic mesophilic count, amine forming bacteria, total coliforms, Staphylococcus spp., and Bacillus spp., a statistically significant (P < 0.05) reduction of the population was observed in both cases. Regarding the biogenic amine forming bacteria, Morganella morganii and Klebsiella pneumoniae were isolated from C. dorab; Bacillus cereus, Staphylococcus xylosus, and Providencia rettgeri were isolated from C. coeruleopinnatus. During sun drying, the amount of histamine, cadaverine, putrescine, and tryptamine was reduced; spermine was detected in C. dorab only during the first day, whereas spermidine was not detected. This reduction may be attributed to the presence of biogenic amine decomposing bacteria. However, further research is necessary in order to verify in situ this capacity and exploit potential applications for fish and fishery products.