Browsing by Author "Tanu Srivastava"

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Green synthesis, characterization and in vitro biological studies of quercetin complexes with Zn (II) acetate and N^N Moiety
(Research Journal of Pharmacy and Technology, 2021) Tanu Srivastava; S.K. Mishra; O.P. Tiwari; Kavindra Nath Tiwari; Pradeep Kumar; Jitendra Kumar; Amit Kumar Singh; Angaraj Singh; Ashutosh Dwivedi
Green synthesis of two coordination complexes of zinc acetate with N^N moiety on quercetin, which is a flavonoid is carried out. The complexes were obtained in high yields (> 97%) by grinding methods without the involvement of any solvent. Neither catalyst nor any additives were needed to perform the reactions. It was characterized by FT-IR, UV-Vis, NMR, HRMS, and elemental analysis. Antioxidant activity was done through the DPPH method which was compared with ascorbic acid and ligand (Quercetin). The study reveals that Complex 1 (IC50 163.093µg/ml) has significant free radical scavenging activity as compared to complex 2 (IC50 258.683µg/ml). Biological activity was performed against microbes (E. coli and S. aureus). MIC value of complex 1 (15.50µg/ml E. coli, 7.18µg/ml S. aureus) was found more significant as compared to complex 2 (22.51µg/ml E. coli, 18.62µg/ml S. aureus) and quercetin. © RJPT All right reserved.
Synthesis, characterization, antimicrobial and cytotoxicity evaluation of quaternary cadmium (II)-quercetin complexes with 1,10-phenanthroline or 2,2’-bipyridine ligands
(Taylor and Francis Ltd., 2020) Tanu Srivastava; Sunil Kumar Mishra; Om Prakash Tiwari; Avinash Kumar; Kavindra Nath Tiwari; Pradeep Kumar; Jyoti Dixit; Jitendra Kumar; Amit Kumar Singh; Pooja Verma; Rajesh Saini; Angaraj Singh; Ashutosh Kumar Dwivedi
This study reports the synthesis and antibacterial evaluation of two novel complexes, [Cd (Q) (Bpy) (CH3COO)2, complex 1] and [Cd (Q) (Phen) (CH3COO)2, complex 2], based on quercetin ligand. The method of synthesis was by reacting natural flavonoid quercetin (Q) with a good chelator (Bpy = 2,2’-bipyridine, Phen= 1,10-phenanthroline and Q = quercetin) and metal ions. The produced metal complexes were studied in the solid state by Fourier-transform infrared (FTIR) spectroscopy and in solution by UV-Vis absorption. Further analysis included high resolution mass spectrometry (HRMS) for confirmation. To understand the nature and coordination of quercetin and its metal complexes, density functional theory (DFT) calculation was performed. The scavenging (DPPH radical), antibacterial, MTT, enzymatic and non-enzymatic antioxidant activity assay, cytotoxicity assay (fluorescence study) were done and quercetin was used for comparison. Both complex 1 and complex 2 induced loss of cell viability via impairment of metabolic activity, leakage of intracellular proteins, and increased oxidative stress. The free-radical scavenging activity of complex 2 (IC50 340.175 µg/mL) was statistically significantly more potent than that of complex 1. The MIC values of complex 2 (7.80 µg/mL Escherichia coli, 15.62 µg/mL Staphylococcus aureus) were higher as compared to complex 1 and quercetin in both test microorganisms. There was inhibition of cell proliferation in Escherichia coli treated with 2 µg/mL of complex 2, whereas Staphylococcus aureus did not show inhibition at this concentration. The cytotoxicity screening on MG 63 cell line showed that the compounds were safe up to 500 mg/L. © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.