Browsing by Author "Singh, Nikhil Kumar"
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Publication DNA/protein binding and anticancer activity of ruthenium (II) arene complexes based on quinoline dipyrrin(Elsevier B.V., 2023) Singh, Nikhil Kumar; Kumar, Yogesh; Paitandi, Rajendra Prasad; Tiwari, Rajan Kumar; Kumar, Ajay; Pandey, Daya ShankarArene ruthenium complexes [(?6�arene)Ru(L)Cl] (?6�arene = benzene, R1; p-cymene, R2) containing the chelating ligand (2�chloro�3�(di(1H�pyrrol�2�yl)methyl)quinoline) (L) have been synthesized and carefully characterized by various studies (1H and 13C NMR, IR, ESI�MS, UV�vis). The structure of R1 has been verified by X-ray single crystal analyses. Binding of the complexes with calf thymus DNA (CT�DNA) has been investigated by absorption titration, ethidium bromide (EB) displacement and viscosity measurements. Experimental binding constants (5.1 � 104 M?1, R1; 5.7 � 104 M?1, R2) suggested appreciable bonding of the complexes with CT�DNA. Fluorescence, synchronous and 3D fluorescence spectroscopic studies showed that complexes strongly bind with bovine serum albumin. Intercalative interaction of the complexes with DNA has been further supported by DFT studies. Our studies have shown potential anticancer activity of both the complexes R1 and R2 against T cell lymphoma. Among these complexes R2 showed better anticancer activity relative to R1 (IC50, R1, 30 ?M and R2, 20 ?M). � 2022Publication DNA/Protein binding and anticancer activity of Zn(II) complexes based on azo-Schiff base ligands(Elsevier B.V., 2022) Kumar, Yogesh; Singh, Nikhil Kumar; Singh, Vishwa Deepak; Ali, Irshad; Tiwari, Rajan Kumar; Kumar, Ajay; Pandey, Daya ShankarSynthesis of the azo�Schiff base ligands 2-((E)-((4-(diethylamino)phenyl)imino)methyl)-4-((E)-(2-(phenylthio)phenyl)diazenyl)phenol (L1) and-((E)-((4-(diethylamino)phenyl)-imino)methyl)-4-((E)-(2-phenoxyphenyl)diazenyl)phenol (L2) and Zn(II) complexes (C1-C2) containing these ligands have been described. Characterization of the ligands and complexes has been achieved by spectral studies (IR, 1H, 13C, ESI�MS, UV/vis., emission) and structures of C1 and C2 verified by X-ray single crystal analyses. Absorption titration studies on the complexes revealed that these strongly interact with calf thymus DNA (CT-DNA). Calculated equilibrium binding constants (Kb) for C1 and C2 converged to 4.51 � 104 and 3.74 � 104. Protein binding studies of the complexes with BSA have been performed by UV/vis, fluorescence, synchronous and 3D fluorescence spectroscopy. MTT assay toward Hut-78 cell line suggested high cytotoxicity for C1 (IC50: 70 ?M) relative to C2 (IC50: 110 �M). Upon irradiation (UV light; ?, 365 nm) the complexes C1 and C2 exhibited cis�trans photo isomerization and after withdrawal of the light these settled back to more stable trans form. Rate constant (k) for photo isomerization of C1 and C2 has been worked out using electronic absorption data (2.29 � 10?2, C1; 2.12 � 10?2 s?1, C2) and supported by theoretical studies (DFT). � 2022 Elsevier B.V.Publication Effect of nitrogen levels on growth attributes, yield and nutrient uptake of different rice (Oryza sativa l.) varieties under the transplanted condition(Editorial board of Journal of Experimental Biology and Agricultural Sciences, 2021) Maurya, Rakesh; Singh, Manoj Kumar; Singh, Nikhil Kumar; Singh, Manish Kumar; Singh, Anurag KumarRice is very responsive to nitrogen fertilization under transplanted conditions; however N use efficiency and uptake by different varieties may vary. A field study was conducted during the rainy season of 2017 to assess the effect of four nitrogen levels in three rice varieties under the transplanted condition at Agricultural Research Farm, Banaras Hindu University, Varanasi, Uttar Pradesh. The experiment was carried out in a split-plot design (SPD) with three replications. The total number of treatments was twelve involving three rice varieties (V1-BPT-5204, V2-Rajendra Kasturi and V3-HUBR 2-1) in main plots and four nitrogen levels (N1-100, N2-120, N3-140, and N4-160 kg ha-1) in sub-plots. Rice variety BPT-5204 recorded significantly higher growth parameters viz. leaf number hill-1(37.17), SPAD value (chlorophyll content 31.83), the higher number of days taken to 50 percent flowering (103 days), maturity (130.17 days), grain yield (50.73 q ha-1), biological yield (112.90 q ha-1) and harvest index (0.45) as well as NPK uptakes by grain (60.96, 13.01 & 10.95 kg ha-1) and straw (29.72, 7.15 & 101.55 kg ha-1) as compared to other varieties. However, straw yield (62.17 q ha-1) was reported higher under HUBR 2-1 as compared to the rest varieties. Among the nitrogen levels, N4-160 kg N ha-1 was recorded significantly higher above the same parameter as compared to other nitrogen levels. Hence, the application of N @ 160 kg ha-1 along with rice variety BPT-5204 can be recommended for achieving higher rice yield, nutrient uptake, and efficiency in Eastern Uttar Pradesh. � 2021, Editorial board of Journal of Experimental Biology and Agricultural Sciences. All rights reserved.Publication Solid state emissive azo-Schiff base ligands and their Zn(ii) complexes: Acidochromism and photoswitching behaviour(Royal Society of Chemistry, 2021) Kumar, Yogesh; Singh, Vishwa Deepak; Dwivedi, Bhupendra Kumar; Singh, Nikhil Kumar; Pandey, Daya ShankarThe synthesis of Zn(ii) complexes (C1-C2) based on azo-Schiff base ligands 2-((E)-(phenyl-imino)methyl)-4-((E)-(2-(phenylthio)phenyl)diazenyl)phenol (L1) and 4-((E)-(2-(phenyl-thio)phenyl)diazenyl)-2-((E)-(p-tolylimino)methyl)phenol (L2) has been described. These have been thoroughly characterized by spectroscopic studies (IR, 1H, 13C, ESI-MS, electronic absorption, emission) and the structures of C1 and C2 have been determined by X-ray single crystal analyses. The ligands L1 and L2 exhibit reversible acid/base induced "ON-OFF-ON"switching in solution and solid state. Upon exposure to UV light (?, 365 nm) C1 and C2 display cis-trans photoisomerisation and after removal of light they transform to more stable trans-form. Electronic absorption and 1H NMR studies on C1 and C2 revealed rather rapid (1.27 � 10-1 s-1) photoisomerization for C2 relative to C1 (2.7 � 10-2 s-1) which has also been supported by theoretical studies (DFT). The rather fast photoisomerization for C2 compared to C1 may be related to a small energy gap between HOMO and LUMO levels for the respective isomers. � The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.