Browsing by Author "Dhar P."
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Item Antibacterial Photodynamic Therapy by Zn(II)-Curcumin Complex: Synthesis, Characterization, DFT Calculation, Antibacterial Activity, and Molecular Docking(John Wiley and Sons Inc, 2024) Kushwaha R.; Rai R.; Gawande V.; Singh V.; Yadav A.K.; Koch B.; Dhar P.; Banerjee S.The increase in antibacterial drug resistance is threatening global health conditions. Recently, antibacterial photodynamic therapy (aPDT) has emerged as an effective antibacterial treatment with high cure gain. In this work, three Zn(II) complexes viz., [Zn(en)(acac)Cl] (1), [Zn(bpy)(acac)Cl] (2), [Zn(en)(cur)Cl] (3), where en=ethylenediamine (1 and 3), bpy=2,2�-bipyridine (2), acac=acetylacetonate (1 and 2), cur=curcumin monoanionic (3) were developed as aPDT agents. Complexes 1�3 were synthesized and fully characterized using NMR, HRMS, FTIR, UV-Vis. and fluorescence spectroscopy. The HOMO�LUMO energy gap (Eg), and adiabatic splittings (?S1?T1 and ?S0?T1) obtained from DFT calculation indicated the photosensivity of the complexes. These complexes have not shown any potent antibacterial activity under dark conditions but the antibacterial activity of these complexes was significantly enhanced upon light exposure (MIC value up to 0.025 ?g/mL) due to their light-mediated 1O2 generation abilities. The molecular docking study suggested that complexes 1�3 interact efficiently with DNA gyrase B (PDB ID: 4uro). Importantly, 1�3 did not show any toxicity toward normal HEK-293 cells. Overall, in this work, we have demonstrated the promising potential of Zn(II) complexes as effective antibacterial agents under the influence of visible light. � 2023 Wiley-VCH GmbH.Item Functionalized jute with high-water absorption, low thermal conductivity and efficient radiative cooling for the preservation of perishable green vegetables with reduced cold storage energy requirements(Royal Society of Chemistry, 2024) Bhatt S.B.; Ranjan R.; Dahiya S.; Pal B.N.; Dhar P.Jute bags, traditionally used for storing fruits, vegetables and cereals, lack temperature resilience and catch fire, making the contents inside the bag vulnerable to deterioration. In this study, normal jute fibres (NJFs) were strategically modified via a delignification-cum-phosphorylation route to produce phosphorylated jute fibres (PJFs) using low-cost agro-based chemicals. PJFs exhibit a high water absorption capacity and a lower evaporation rate with prolonged moisture retention capabilities. Interestingly, PJFs also show an ultra-low thermal conductivity of 0.076-0.078 W m?1 K?1, slow rate of burning (0.058 cm s?1), high reflectance to light in the IR region (76%) and high thermal stability. PJF bags used for the storage of perishable vegetables, such as coriander leaves, show an extension in shelf life by ?2 days, along with flame resistance to heat-sensitive vegetables such as chilies on exposure to high temperature. Life cycle assessment (LCA) shows that the production of PJFs generates 49.4% less global warming potential impact as compared to PET production with improved biodegradation within ?21 days. Further, the utilization of PJFs reduced the time for cold storage of coriander leaves to 8 days, which led to reduced energy requirements and lowered environmental impacts by 11% in the terrestrial ecotoxicity and climate change category. The present study provides a strategic, scalable and green route for the production of functionalized jute bags required for the storage of perishable agricultural harvests, reducing global issues associated with food loss and improving human health and the economy. � 2024 The Royal Society of Chemistry.Item Moringa pod derived antioxidant dietary fibre as a quality enhancer in goat meat nuggets(Royal Society of Chemistry, 2024) Das A.; Biswas S.; Nanda P.K.; Chatterjee N.; Pal S.; Dhar P.; Verma A.K.; Bhattacharya D.; Koshy R.; Das A.K.This study evaluated the quality traits and oxidative storage stability of meat nuggets enriched with immature moringa pod powder (MPP) at 1.5% and 3.0% levels in comparison to control samples over a 12 day storage period under refrigerated conditions. MPP is a rich source of protein (18.96%), ash (7.42%), dietary fiber (DF, 43.64%), and a notable concentration of total phenolics (TP, 9.20 mg GAE g?1). The MPP analyzed by GC-MS showed the presence of different phenolic acids, such as cinnamic, benzoic, phthalic, vanillic, p-coumaric, ferulic, and caffeic acids and catechin, with concentrations ranging from 1.031 ppm to 2.949 ppm. Incorporating MPP as a source of DF had a negligible impact (p > 0.05) on the pH levels of both the emulsion and meat nuggets. However, it notably improved the emulsion stability, cooking yield, ash content, DF content, and TP content of the nuggets. Immature MPP at the 3% level significantly (p < 0.05) influenced the lightness and redness of the nuggets. Moreover, the MPP in meat formulations demonstrated a significant (p < 0.05) ability to inhibit lipid oxidation and had no adverse effect on the sensory attributes of meat nuggets. This finding highlights the potential of MPP to enhance oxidative stability during refrigerated storage for up to 12 days. This study suggests that immature moringa pods can serve as a natural functional ingredient by improving the nutritional quality and functionality of meat products while extending their shelf life through their antioxidative properties. � 2024 RSCItem Photodynamic Inactivation of Bacteria Using Nickel(II) Complexes with Catecholate and Phenanthroline Ligands(John Wiley and Sons Inc, 2024) Devraj Prakashchandra R.; Rai R.; Ali Mandal A.; Dhar P.; Banerjee S.; Sarkar T.; Nagendra Babu B.Metal complexes activated by light can combat infections by triggering the photodynamic inactivation of bacteria. Herein, we report six mixed-ligand nickel(II) complexes with the formulation [Ni(NN)2(L)] (1�6), where NN represents an N,N-donor phenanthroline ligand, specifically 1,10-phenanthroline (phen in 1, 2), dipyrido[3,2-d:2�,3�-f]quinoxaline (dpq in 3, 4), and dipyrido[3,2-a:2�,3�-c]phenazine (dppz in 5, 6), while L is an O,O donor bidentate ligand derived from catechol (cat2?, in 1, 3, 5) or esculetin (esc2?, in 2, 4, 6). The paramagnetic d8 octahedral complexes demonstrated good dark and photostability in the solution phase and exhibited significant light absorption in the visible (400�700 nm) region. When exposed to low-energy visible light, these complexes demonstrated significant photodynamic inactivation activity against both Gram-(+) Staphylococcus aureus (S. aureus) and Gram-(?) Escherichia coli (E. coli) bacteria. This resulted in minimum inhibitory concentration (MIC) values ranging from 0.31�9.49 ?M. The activity was caused by the cell-damaging singlet oxygen species produced by the complexes under light exposure. Notably, the complexes showed no bacterial inhibition activity under dark conditions. This study marks the first examples of Ni(II) complexes designed for light-triggered antibacterial activity, illuminating the path for Ni(II)-based non-macrocyclic complexes for antibacterial PDT applications. � 2024 Wiley-VCH GmbH.Item Ratanjot (Alkanna tinctoria L.) Root Extract, Rich in Antioxidants, Exhibits Strong Antimicrobial Activity against Foodborne Pathogens and Is a Potential Food Preservative(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Das A.; Biswas S.; Satyaprakash K.; Bhattacharya D.; Nanda P.K.; Patra G.; Moirangthem S.; Nath S.; Dhar P.; Verma A.K.; Biswas O.; Tardi N.I.; Bhunia A.K.; Das A.K.Natural and sustainable plant-based antioxidants and antimicrobials are highly desirable for improving food quality and safety. The present investigation assessed the antimicrobial and antioxidant properties of active components from Alkanna tinctoria L. (herb) roots, also known as Ratanjot root. Two methods were used to extract active components: microwave-assisted hot water (MAHW) and ethanolic extraction. MAHW extract yielded 6.29%, while the ethanol extract yielded 18.27%, suggesting superior Ratanjot root extract powder (RRP) solubility in ethanol over water. The ethanol extract showed significantly higher antioxidant activity than the MAHW extract. Gas Chromatography�Mass Spectrometry analysis revealed three major phenolic compounds: butanoic acid, 3-hydroxy-3-methyl-; arnebin 7, and diisooctyl pthalate. The color attributes (L*, a*, b*, H�ab, C*ab) for the ethanolic and MAHW extracts revealed significant differences (p < 0.05) in all the above parameters for both types of extracts, except for yellowness (b*) and chroma (C*ab) values. The ethanol extract exhibited antimicrobial activity against 14 foodborne bacteria, with a significantly higher inhibitory effect against Gram-positive bacteria (Listeria monocytogenes and Staphylococcus aureus) than the Gram-negative bacteria (Salmonella enterica serovar Typhimurium and Escherichia coli). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were both 25 mg/mL for the Gram-negative bacteria, while the MIC and MBC concentrations varied for Gram-positive bacteria (0.049�0.098 mg/mL and 0.098�0.195 mg/mL) and the antimicrobial effect was bactericidal. The antimicrobial activities of RRP extract remained stable under broad temperature (37�100 �C) and pH (2�6) conditions, as well as during refrigerated storage for 30 days. Application of RRP at 1% (10 mg/g) and 2.5% (25 mg/g) levels in a cooked chicken meatball model system prevented lipid oxidation and improved sensory attributes and retarded microbial growth during refrigerated (4 �C) storage for 20 days. Furthermore, the RRP extract was non-toxic when tested with sheep erythrocytes and did not inhibit the growth of probiotics, Lacticaseibacillus casei, and Lactiplantibacillus plantarum. In conclusion, the study suggests that RRP possesses excellent antimicrobial and antioxidant activities, thus making it suitable for food preservation. � 2024 by the authors.
