scispace - formally typeset
Search or ask a question
Author

Muhammad Yaqub

Bio: Muhammad Yaqub is an academic researcher from Bahauddin Zakariya University. The author has contributed to research in topics: Ring (chemistry) & Isatin. The author has an hindex of 14, co-authored 67 publications receiving 563 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: The results of these studies show the metal complexes to be more antibacterial and antifungal against one or more bacterial/fungal strains as compared to the uncomplexed compounds.
Abstract: Isonicotinoylhydrazide Schiff's bases formed by the reaction of substituted and unsubstituted furyl-2-carboxaldehyde and thiophene-2-carboxaldehyde with isoniazid and, their Co (II), Cu (II), Ni (II) and Zn (II) complexes have been synthesized, characterized and screened for their in vitro antibacterial activity against Mycobacterium tuberculosis, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae, Bacillus cereus, Corynebacterium diphtheriae, Staphylococcus aureus and Streptococcus pyogenes bacterial strains and for in vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata. The results of these studies show the metal complexes to be more antibacterial and antifungal against one or more bacterial/fungal strains as compared to the uncomplexed compounds. The brine shrimp bioassay indicated Schiff's bases, L3 and L6 and, their Cu (II) and Ni...

104 citations

Journal ArticleDOI
TL;DR: In this article, a series of 19 benzofurane linked N-phenyl semithiocarbazones (3a-3s) were synthesized for enzyme inhibitor activity against Jack bean urease.

58 citations

Journal ArticleDOI
TL;DR: The effects of the nature of aryl groups at N 4 (modified by placement of one or two substituents about the phenyl ring) and the presence of nitro function at position-5 of the isatin scaffold on the urease inhibitory potential of these compounds are described.
Abstract: 4 -substituted 5-nitroisatin-3-thiosemicarbazones 2a-2q has been synthesized and screened for in vitro urease inhibitory activities. Compounds 2a-2d, 2g, 2i, 2j and 2q were found to be potent inhibitors of the enzyme. Of these, 2c exhibited a potent inhibitory activity with IC50 value 16.4 � M and may act as a lead molecule for further studies. Structure-activity relationship studies revealed that electronic effects of the substituents play an important role in the urease inhibitory potential of the synthetic compounds. ery program (15-21), we have recently synthesized a number of N 4 - substituted isatin-3-thiosemicarbazones as urease inhibitors with non toxic nature (22, 23). These findings form a solid basis for further research on such compounds to develop more potent, safe and useful urease inhibitors. Furthermore, structure-activity rela- tionship (SAR) studies revealed that the type and position of the substituents on phenyl ring, substituted at N 4 of the thiosemicarba- zone moiety, play an important role in the urease inhibitory poten- tial of these compounds. To further enhance the activity of new antiurease compounds, the study of the combination of substitution at position-5 of the isatin scaffold with attachment of different aryl groups (having one or two substituents about the phenyl ring) at N 4 of the thiosemicarbazone moiety was considered worth pursuing. The present work therefore deals with the synthesis and evaluation of urease inhibitory potential of a series of seventeen N 4 - arylsubstituted 5-nitroisatin-3-thiosemicarbazones. We describe here the effects of the nature of aryl groups at N 4 (modified by placement of one or two substituents about the phenyl ring) and the presence of nitro function at position-5 of the isatin scaffold on the urease inhibitory potential of these compounds.

41 citations

Journal ArticleDOI
TL;DR: Seven new 5-(un)-substituted isatin-derived bis-Schiff bases/ligands 3a–g and their Cu(II) complexes 5a-g were synthesized and evaluated for their cytotoxic and urease inhibitory activities, and proved to be highly potent enzyme inhibitors and inhibitory activity even better than that of the reference inhibitor.
Abstract: Several isatin-3-thiosemicarbazones (a class of Schiff bases) from our earlier studies have been validated as promising cytotoxic agents and urease inhibitors. Also, a number of isatin-derived imines (Schiff bases) and their Cu(II) complexes have been reported in the literature to exhibit potential cytotoxic activity towards different cells. In view of this, a series of seven new 5-(un)-substituted isatin-derived bis-Schiff bases/ligands 3a–g and their Cu(II) complexes 5a–g were synthesized and evaluated for their cytotoxic and urease inhibitory activities. All the Schiff base ligands 3a–g proved to be active in sulforhodamine B (SRB) bioassay, displaying promising cytotoxic activity against lung carcinoma (H157) cells. Compound 3b was found to be the most potent inhibitor of H157 cells, exhibiting an IC50 value of 2.32 ± 0.11 μM. Similarly, all the metal complexes 5a–g proved to be active in this assay, demonstrating enhanced cytotoxic activity in each case, occurring as a result of coordination of the Schiff base ligands to the metal ion. Compound 5d proved to be the most potent inhibitor of H157 cells, showing cytotoxic activity comparable to that of the standard drug, vincristine (VCN) (IC50 = 1.29 ± 0.06 vs. 1.03 ± 0.04 μM). In the urease inhibition assay, all the synthesized Schiff base ligands except 3f proved to be highly potent enzyme inhibitors, displaying inhibitory activity even better than that of the reference inhibitor, thiourea (IC50 = 0.04 ± 0.004–5.86 ± 0.09 vs. 22.3 ± 1.12 μM), and thus may act as promising lead molecules for further studies. Molecular docking studies were also carried out for bis-Schiff bases 3a–g to elucidate their relationship with the binding pockets of the enzyme.

35 citations

01 Jan 2012
TL;DR: In this paper, the effect of foliar application of Zn, K and salicylic acid (SA) alone or in combination was investigated on fruit yield, excessive fruit drop and juice quality.
Abstract: Fruit yield and quality of citrus, especially KINNOW (Citrus deliciosa x Citrus nobilis) in Pakistan is not competitive with that of other countries which could be attributed mainly to the lack of appropriate nutrient management for citrus orchards. The yield losses in citrus occur mainly due to excessive fruit drop. Experiments to overcome these problems were conducted at four different sites one each in Faisalabad, Toba Tek Singh, Jhang and Sargodha districts of Punjab, Pakistan. The soil and leaf chemical analysis showed severe deficiency of Zn in Kinnow. In the present studies, effect of foliar application of Zn, K and salicylic acid (SA) alone or in combination was investigated on fruit yield, excessive fruit drop and juice quality. The fruit trees were pretreated with a selected NPK level. Zinc (0.25% ZnSO4 solution), K (0.25% K2SO4 solution) and salicylic acid (10 μM) were sprayed at three different stages, i.e. the onset of spring/flush of leaves or flowers, fruit formation and color initiation on fruit. Overall, application of Zn, K and SA or Zn+K+SA was effective in improving the yield and quality parameters of citrus fruit at all sites. Although fruit drop was reduced by the foliar spray of Zn, K, SA or Zn+K but three foliar sprays of 10μM SA + 0.25% each of Zn and K reduced the citrus fruit drop by 30% and also improved the juice quality. Kinnow fruit yield and juice quality can be effectively enhanced with proper nutrient and hormone applications depending on site conditions.

31 citations


Cited by
More filters
Journal ArticleDOI
10 Mar 1970

8,159 citations

Journal ArticleDOI
TL;DR: The results of these studies show the metal(II) complexes to be more antibacterial/antifungal against one or more species as compared to the uncomplexed ligands.
Abstract: A series of antibacterial and antifungal amino acid-derived compounds and their cobalt(II), copper(II), nickel(II), and zinc(II) metal complexes have been synthesized and characterized by their elemental analyses, molar conductances, magnetic moments, and IR, and electronic spectral measurements. Ligands (L1)−(L5) were derived by condensation of β-diketones with glycine, phenylalanine, valine, and histidine and act as bidentate towards metal ions (cobalt, copper, nickel, and zinc) via the azomethine-N and deprotonated-O of the respective amino acid. The stoichiometric reaction between the metal(II) ion and synthesized ligands in molar ratio of M : L (1 : 1) resulted in the formation of the metal complexes of type [M(L)(H2O)4]Cl (where M = Co(II), Cu(II), and Zn(II)) and of M : L (1 : 2) of type [M(L)2(H2O)2] (where M = Co(II), Cu(II), Ni(II), and Zn(II)). The magnetic moment data suggested for the complexes to have an octahedral geometry around the central metal atom. The electronic spectral data also supported the same octahedral geometry of the complexes. Elemental analyses and NMR spectral data of the ligands and their metal(II) complexes agree with their proposed structures. The synthesized ligands, along with their metal(II) complexes, were screened for their in vitro antibacterial activity against four Gram-negative (Escherichia coli, Shigella flexeneri, Pseudomonas aeruginosa, and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and for in vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani, and Candida glaberata. The results of these studies show the metal(II) complexes to be more antibacterial/antifungal against one or more species as compared to the uncomplexed ligands. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties. Five compounds, (3), (7), (10), (11), and (22), displayed potent cytotoxic activity as LD50 = 8.974 × 10−4, 7.022 × 10−4, 8.839 × 10−4, 7.133 × 10−4, and 9.725 × 10−4 M/mL, respectively, against Artemia salina.

196 citations

Journal ArticleDOI
TL;DR: The results suggest that 5-bromosalicylaldehyde amino acid Schiff bases (bs):aa behave as dibasic tridentate ONO ligands and coordinate to Fe(II) in octahedral geometry according to the general formula [Fe(bs:aa)2]·nH2O.

173 citations

Journal ArticleDOI
TL;DR: Antioxidant tests in vitro show the compounds possess significant antioxidant activity against superoxide and hydroxyl radicals, and the scavenging effects of Cu( II) complex are stronger than Zn(II), Ni(II) complexes and some standard antioxidants, such as mannitol and vitamin C.

140 citations

Journal ArticleDOI
TL;DR: The prepared complexes bind to DNA via classical intercalative mode and showed a different DNA activity with the sequence: nhi>nari>nali>nasi>nphali.

131 citations