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2022 - 20232
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Author: ARYA P.R ×

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    ThesisItemOpen Access
    EFFICACY OF GREEN SYNTHESISED SILVER-ZINC OXIDE NANOCOMPOSITES AGAINST MULTI-DRUG RESISTANT NON TYPHOIDAL SALMONELLA SPP.
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCS, POOKODE, WAYANAD, KERALA VETERINARY AND ANIMAL SCIENCES UNIVERSITY, 2023-01-13) ARYA P.R; Dr. Jess Vergis
    The indiscriminate use of antibiotics has accelerated the emergence of multi- drug resistant (MDR) bacterial strains. In recent times, nanotechnology offers a novel alternative solution by providing a long-term strategy to combat the emergence of drug resistance. The present study evaluated the antibacterial efficacy of green synthesised silver-zinc oxide nanocomposites (Ag/ZnO NCs) against MDR strains of non- typhoidal Salmonella spp. (NTS). The green synthesis of Ag/ZnO NCs was attempted using the aqueous extract of leaves, stems, and rhizomes of Curcuma longa. Initially, the green synthesised Ag/ZnO NC was subjected to UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential thermogravimetric analysis (DTA), powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The green synthesised Ag/ZnO NCs exhibited absorbance peaks at 340 and 450 nm by UV-Vis spectroscopy, corresponding to Ag and ZnO nanoparticles (NPs), respectively, which was further confirmed by FTIR analysis. The TGA/DTA revealed an initial weight loss of around four per cent from 40oC to 100oC along with a progressive thermal degradation of Ag/ZnO NCs between 200 oC and 450 oC, which in turn corresponded to an exothermic peak at 320 oC. The PXRD analysis of Ag/ZnO NCs confirmed the face-centered cubic structure of AgNPs and hexagonal wurtzite structure with P63 mc symmetry of ZnO NPs. Further, FE-SEM analysis confirmed the agglomerated polycrystalline morphology of Ag/ZnO NCs with a characteristic spherical shape in TEM analysis. This study evaluated in vitro antibacterial efficacy of Ag/ZnO NCs against MDR-NTS strains (S. enterica Typhimurium and S. Enteritidis; n = 3 for each serotype). The minimum inhibitory concentration (MIC; 31.25μg/mL) and minimum bactericidal concentration (MBC62.50 μg/mL) were determined by employing the micro broth dilution technique. Later, Ag/ZnO NCs were assessed for their stability (high-end temperatures, physiological concentration of cationic salts, proteases, and pH); safety (chicken RBCs), and effecton gut beneficial microflora (Lactobacillus acidophilus, L. plantarum, and Paediococcus acidilactis). In general, the Ag/ZnO NCs tested stable at MIC concentration; however, a two-fold rise in the MBC value was detected. Besides, Ag/ZnO NCs tested safe with chicken RBCs; moreover, the beneficial gut microflora was not inhibited. Furthermore, the in vitro time-kill kinetic assay of MDR-NTS strains treated with Ag/ZnO NCs revealed a complete clearance at 240 min, alike meropenem control. In brief, the green synthesised Ag/ZnO NCs were found to exhibit antibacterial activity against the tested MDR-NTS and were tested safe and stable. Overall, the study demonstrated a facile, eco-friendly method for the synthesis of Ag/ZnO NCs, which could be employed as a potential therapeutic alternative candidate.
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    ThesisItemOpen Access
    EFFECT OF TEA POLYPHENOLS ON CALCIUM IN MILK
    (COLLEGE OF DAIRY SCIENCE AND TECHNOLOGY MANNUTHY, THRISSUR, 2022-03-30) ARYA P.R; Athira S
    According to the International Osteoporosis Foundation, 8.9 million people are suffering from osteoporosis worldwide. Milk is a complete food with a good source of calcium. Generally, in India, people hesitate to drink milk as such and they like to have it as a beverage such as tea. So it is very essential to investigate the effect of tea polyphenol on calcium in milk during milk tea preparation. In the present study, milk tea was prepared by adding 2% tea powder in boiled milk and strained after 2 minutes of brewing. The effect of processing parameters such as water: milk ratio, pH, brewing time, the concentration of tea powder, type of milk and amount of sugar on interactive behaviour of tea polyphenols with calcium were also analyzed. The result showed a significant reduction (p-value <0.05) in the calcium and protein content of milk tea beverage (926.24±0.74 ppm and 2.89±0.01 %) compared with the milk (1409.1±0.2 ppm and 3.42±0.009 %). The polyphenol and tannin content was also reduced in milk tea (13.93±0.021 mg GAE/ml and 1.42±0.014 mg TAE/ml) compared with black tea (15.32±0.12 mgGAE/ml and 3.21±0.011 mgTAE/ml). The processing parameters have a positive correlation with interactive behaviour and leads to the reduction in the calcium content of the final brew. The bioavailability of calcium present in the tea beverage was also evaluated by simulated gastrointestinal model. It showed that the bioavailability of calcium gets reduced when milk tea (19.14±04%) was prepared as compared with milk (25.45±0.009%). Hence it is conformed and suggested that consumption of milk is better than milk tea beverage for getting maximum amount of nutrients specially calcium from milk.