Synthesis of Schiff bases derived from 2-hydroxy-1- naphth- aldehyde and their tin(II) complexes for antimicribial and antioxidant activities

Neelofar, N.; Ali, Nauman; Khan, Ajmal; Amir, Somi; Khan, Nadia; Bilal, Muhammad

doi:10.4314/bcse.v31i3.8

Cited by 29 publications

(13 citation statements)

References 30 publications

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“…The azomethine and phenoxy carbon signals resonated at δ = (157.72–151.97) and δ = (156.29–116.28) ppm, respectively ( Supplementary file Figures S17, S19 and S21 ). The presence of azomethine proton and a carbon signals were in concord with the reports from various literature confirming the successful synthesis of Schiff bases 1 – 9 [ 39 , 40 ].…”

Section: Discussionsupporting

confidence: 86%

Investigation into the Thermal Response and Pharmacological Activity of Substituted Schiff Bases on α-Amylase and α-Glucosidase

Okoli¹,

Modise²

2018

Antioxidants

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The emphasis of previous studies has targeted the development of insulin mimic with little attention given to the development of metabolic enzyme inhibitors. Our focus is to synthesise nine o-hydroxy and p-nitro-azomethine analogues, investigate their digestive enzyme inhibitory capacity, as well as the antioxidant and antimicrobial activities. The substituted Schiff bases were analysed using thermal gravimetric analyser (TGA), X-ray diffractometer (XRD), nuclear magnetic resonance spectroscopy (NMR), elemental analyser, and Fourier-transform infrared spectroscopy (FT-IR). Determination of synthetic yield revealed that the o-hydroxy analogues produced the highest yield of ≥77.1% compared to p-nitro and unsubstituted analogues. Spectra study showed the presence of azomethine stretching vibration at 1698–1613 cm−1, proton signals at δ 8.46–9.81, and carbon signals at δ 145.95–159.53 ppm. Investigation into the thermal property indicated an elevated melting point for the o-hydroxy analogue, compared to the p-nitro derivative which showed high stability to heat. There are similarities in crystalline structure with few unique patterns suggesting different substituent group. The antioxidant activities of the substituted analogues registered low half maximal inhibitory concentration (IC50), with exception to the ferric reducing power; indicating that the Schiff bases are weak siderophores. All nine Schiff bases were bacteriostatic or fungistatic at the screened concentrations; however, the nitro-substituted analogues have an enhanced activity with Minimum Inhibitory Concentration (MIC) values of 0.03–2.54 µM. Both o-hydroxy and p-nitro-substitution does not improve the antifungal activity of the compounds against A. niger. The o-hydroxyl and p-nitro Schiff base derivatives showed enhanced activity towards the inhibition of α-amylase and α-glucosidase by hydroxylation and glycosylation, respectively. Although, hydroxy derivatives of sulphonic acid derived Schiff base slightly decreased the activities on α-glucosidase and α-amylase. Our findings suggest that p-nitro substitution enhances the in vitro nonenzymatic activity while the o-hydroxy derivatives are good hydrolase inhibitors. Therefore, substituent modification can be used as an enhancement technique in designing novel pharmacophore.

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Section: Discussionsupporting

confidence: 86%

Investigation into the Thermal Response and Pharmacological Activity of Substituted Schiff Bases on α-Amylase and α-Glucosidase

Okoli¹,

Modise²

2018

Antioxidants

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“…Stronger antioxidants can reduce absorbance rapidly. The IC 50 value, defined as the concentration of the sample causing the DPPH concentration to be reduced by 50%, is calculated from the linear regression of the concentration graphs of the compounds tested against the mean percentage of antioxidant activity [123,124]. The lower the IC 50 value, the higher the antioxidant activity of the tested samples.…”

Section: Antioxidant Activity Resultsmentioning

confidence: 99%

Pt(II) complex of Schiff base derived from L-phenylalanine and furfuraldehyde in the presence of 8-hydroxyquinoline: Structural analysis, composition of complex and biological activity

Altun¹,

Koçer²

2020

Comptes Rendus. Chimie

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In the present study, we synthesized a Schiff base (L 1) derived from L-phenylalanine with furfuraldehyde and its Pt(II) complex ([Pt(L 1)(L 2)]: [Pt(N-(furfuralidene)phenylalanine)(8hydroxyquinoline)]) in the presence of 8-hydroxyquinoline (L 2). The chemical structures of the synthesized Schiff base and Pt(II) complex were characterized using ESI-MS, UV-Visible, FT-IR, 1 H NMR, 13 C NMR, and powder-XRD spectroscopy. The surface morphologies and elemental composition were determined by SEM and EDX. Thermal analysis was performed with TG-DTA. Mole ratio of Meyer and Job methods were used for the composition of complexes. According to these methods, the ratio [Pt 2+ ] : [L 1 + L 2 ] was found to be 1 : 1. In addition, the antimicrobial activities of L 1 and the complex showed that the compounds have significant antibacterial and antifungal properties. They also show important cytotoxic effects against the growth of mouse embryo fibroblasts (MEF) and human prostate adenocarcinoma (Du145) cancer cells. L 1 , L 2 , and the Pt(II) complex also displayed effective antioxidant activity.

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“…Which is in the usual range of reported Schiff base complexes. 39 The 1 H-NMR spectrum of ligand E exhibited a singlet peak at δ 2.5 ppm is assigned to (-CH 2 -Br) group attached to azomethine group when the other peaks which appeared around δ 7.47-8.13 ppm is attributed to fourteen aromatic rings.…”

Section: Nmr Spectral Analysismentioning

confidence: 96%

Novel Nickel (II), Copper (II) and Cobalt (II) Complexes of Schiff Bases A, D and E: Preparation, Identification, Analytical and Electrochemical Survey

2018

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A novel set of Cobalt(II), Copper(II) and Nickel(II) complexes of ligands, (E)-2-(((2,5-difluorophenyl)imino) methyl)phenol (A), (E)-2,4-dibromo-1-((2-hydroxybenzylidene) amino)anthracene-9,10-dione (D) & (Z)-1-((1-([1,1'-biphenyl]-4-yl)-2-bromoethylidene) amino)-2,4-dibromo anthracene-9,10-dione (E) were synthesized and characterized. Their structures were investigated on the basis of CHN, conductance measurements and spectral studies (H1-NMR & C13-NMR,FT-infrared and Electronic spectroscopies), cyclic voltammetry. It has observed from spectral and analytical studies that metal complexes have the composition of (ML2.X2) and one mole of ligand behaves as bidentate chelating agents around the corresponding metal ion. From solubility test, we obtained that metal complexes of ligands A, D and E had no ionic properties and dissolve partially in polar and slightly in nonpolar solvents. These results confirmed the behavior of metal complexes as weak electrolyte from their low value of molar conductivity. Conductance data and solubility test of the complexes enhanced them to be (1:2 M:L ratio). All data confirmed an octahedral geometry of these complexes and their structures as {[M (A, D or E)2(CH3COO)2], when M= Co or Ni} and {[Cu (A, D or E)2 Cl2]}. Cyclic voltammetry measurements were accomplished of Cobalt(II), Copper(II) and Nickel(II) complexes using Pt wire as counter electrode and Ag/AgNO3 as reference electrode and (Bu4N+PF6+) as supporting electrolyte. The result exhibit the irreversible process showing single one electron transfer process of Cobalt(II) and Nickel(II) complexes and unique quasi-reversible redox couple is attributed to Cu(II) complexes.

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Synthesis of Schiff bases derived from 2-hydroxy-1- naphth- aldehyde and their tin(II) complexes for antimicribial and antioxidant activities

Cited by 29 publications

References 30 publications

Investigation into the Thermal Response and Pharmacological Activity of Substituted Schiff Bases on α-Amylase and α-Glucosidase

Investigation into the Thermal Response and Pharmacological Activity of Substituted Schiff Bases on α-Amylase and α-Glucosidase

Pt(II) complex of Schiff base derived from L-phenylalanine and furfuraldehyde in the presence of 8-hydroxyquinoline: Structural analysis, composition of complex and biological activity

Novel Nickel (II), Copper (II) and Cobalt (II) Complexes of Schiff Bases A, D and E: Preparation, Identification, Analytical and Electrochemical Survey

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