Antibacterial and Antifugal Mono- and Di-substituted Symmetrical and Unsymmetrical Triazine-derived Schiff-bases and their Transition Metal Complexes

A new series of antibacterial and antifungal triazine-derived mono- and di-substituted (symmetrical and unsymmetrical) Schiff-bases 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. IR spectra indicated the ligands to act as tridentate towards divalent metal ions via a trazine-N, the azomethine-N and, indole-NH and deprotonated-O of salicylaldehyde. The magnetic moments and electronic spectral data suggest octahedral geometry for the Co(II), Ni(II) and Zn(II)complexes and square-pyramid for Cu(II) complexes. NMR spectral data of the ligands and their diamagnetic zinc(II) complexes well-define their proposed structures/geometries. Elemental analyses data of the ligands and metal complexes agree with their proposed structures/geometries. The synthesized ligands, along with their metal complexes were screened for their antibacterial activity against Escherichia coli, Bacillus subtillis, Shigella flexneri, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The results of these studies show the metal complexes to be more antibacterial/antifungal against two or more species as compared to the uncomplexed Schiff-base ligands.     

Structure and biological properties of first row d-transition metal complexes with N-substituted sulfonamides

Cobalt (II), copper (II), nickel (II) and zinc (II) complexes with 2-hydroxy-1-naphthaldehyde derived N-substituted sulfonamides have been synthesized and the nature of bonding and structure of compounds have been deduced from physical, analytical and spectral (IR, ¹H NMR, ¹³C NMR, Mass and electronic) data. An octahedral geometry has been suggested for the complexes. Complexes along with the ligands were assessed for their antibacterial and antifungal activities on different species of pathogenic bacteria and fungi. The results revealed the ligands to possess moderate to significant antibacterial activity which was, in many cases, enhanced on chelation. Similar results were observed for antifungal activity. Brine shrimp bioassay was also carried out for in vitro cytotoxic properties against Artemia salina.     

Carbonic Anhydrase Inhibitors: Schiff's Bases of Aromatic and Heterocyclic Sulfonamides and their Metal Complexes

Schiff's bases were obtained from aromatic/heterocyclic sulfonamides and amino-sulfonamide derivatives, such as sulfanilamide, homosulfanilamide, 4-aminoethyl-benzenesulfonamide and 5-amino-1,3,4-thiadiazole-2-sulfonamide. Metal complexes of some of these Schiff's bases, incorporating Zn(II), Co(II), Ni(II) and Cu(II) ions, were also prepared and tested as inhibitors of the zinc enzyme carbonic anhydrase (CA), and more specifically the red blood cell isozymes I and II. The Schiff's bases behaved as medium potency CA I and CA II inhibitors, whereas their metal complexes showed a highly enhanced potency, with several low nanomolar CA II inhibitors detected.     

Antibacterial Schiff Bases of Oxalyl-hydrazine/diamide Incorporating Pyrrolyl and Salicylyl Moieties and of Their Zinc(II) Complexes

Schiff bases derived from oxaldiamide/oxalylhydrazine and pyrrol-2-carbaldehyde, or salicylaldehyde respectively, as well as their Zn(II) complexes have been prepared and tested as antibacterial agents. These Schiff bases function as tetradentate ligands, forming octahedral Zn(II) complexes. The ketonic form for the diamide derived Schiff base and the enolic form of the hydrazide derived Schiff base were the preferred tautomers for coordination of the metal ions. The title compounds and their Zn(II) derivatives were evaluated for antibacterial activity against several bacterial strains which easily develop resistance to classical antibiotics, such as Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Some of them showed promising biological activity in inhibiting the growth of such organisms.     

Metal-based sulfonamides: Their preparation,characterization and in-vitro antibacterial,antifungal & cytotoxic properties. X-ray structure of 4-[(2-hydroxybenzylidene) amino] benzenesulfonamide

Synthesis, characterization and biological studies of Schiff base-derived sulfonamides and their Co (II), Cu (II), Ni (II) and Zn (II) complexes have been reported and screened for in-vitro antibacterial activity against six Gram-negative; E. coli, K. pneumoniae, P. aeruginosa, P. mirabilis, S. typhi and S. dysenteriae and four Gram-positive; B. cereus, C. diphtheriae, S. aureus and S. pyogenes bacterial strains and for in-vitro antifungal activity against T. longifusus, C. albicans, A. flavus, M. canis, F. solani, and C. glaberata. All compounds showed moderate to significant antibacterial activity, however, the zinc (II) complexes were found to be more active. Some of the compounds also showed significant antifungal activity against various fungal strains. Only compounds (6) and (10) displayed potent cytotoxic activity with LD₅₀ = 4.644 × 10^{? 4} and 4.106 × 10^{? 4} moles/mL respectively, against Artemia salina. The X-ray structure of 4-[(2-hydroxybenzylidene)amino]benzenesulfonamide is also reported.     

Synthesis of organometallic-based biologically active compounds: In vitro antibacterial,antifungal and cytotoxic properties of some sulfonamide incorporated ferrocences

Sulfonamides incorporated ferrocene (SIF) have been synthesized by the condensation reaction of sulfonamides (sulfanilamide, sulfathiazole or sulfamethaxazole) with 1,1′-diacetylferrocene. The synthesized compounds (SIF¹–SIF⁴) have been characterized by their physical, spectral and analytical properties and have been screened for their in vitro antibacterial properties against pathogenic bacterial strains e.g., Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis Staphylococcus aureus and Salmonella typhi and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata using Agar-well diffusion method. Most of the compounds showed good antibacterial activity whereas, all the compounds exhibited significant antifungal activity. Brine shrimp bioassay was also carried out for in vitro cytotoxic properties against Artemia salina.     

Transcriptional profiling of Zea mays roots reveals roles for jasmonic acid and terpenoids in resistance against Phytophthora cinnamomi

Phytophthora cinnamomi is a soil-borne plant pathogen that has caused widespread damage to vulnerable native ecosystems and agriculture systems across the world and shows no sign of abating. Management of the pathogen in the natural environment is difficult and the options are limited. In order to discover more about how resistant plants are able to defend themselves against this generalist pathogen, a microarray study of plant gene expression following root inoculation with P. cinnamomi was undertaken. Zea mays was used as a resistant model plant, and microarray analysis was conducted using the Affymetrix GeneChip Maize Genome Array on root samples collected at 6- and 24-h post-inoculation. Over 300 genes were differentially expressed in inoculated roots compared with controls across the two time points. Following Gene Ontology enrichment analysis and REVIGO visualisation of the up-regulated genes, many were implicated in plant defence responses to biotic stress. Genes that were up-regulated included those involved in phytoalexin biosynthesis and jasmonic acid/ethylene biosynthesis and other defence-related genes including those encoding glutathione S-transferases and serine-protease inhibitors. Of particular interest was the identification of the two most highly up-regulated genes, terpene synthase11 (Tps11) and kaurene synthase2 (An2), which are both involved in production of terpenoid phytoalexins. This is the first study that has investigated gene expression at a global level in roots in response to P. cinnamomi in a model plant species and provides valuable insights into the mechanisms involved in defence.     

Systemic Down-Regulation of Delta-9 Desaturase Promotes Muscle Oxidative Metabolism and Accelerates Muscle Function Recovery following Nerve Injury

The progressive deterioration of the neuromuscular axis is typically observed in degenerative conditions of the lower motor neurons, such as amyotrophic lateral sclerosis (ALS). Neurodegeneration in this disease is associated with systemic metabolic perturbations, including hypermetabolism and dyslipidemia. Our previous gene profiling studies on ALS muscle revealed down-regulation of delta-9 desaturase, or SCD1, which is the rate-limiting enzyme in the synthesis of monounsaturated fatty acids. Interestingly, knocking out SCD1 gene is known to induce hypermetabolism and stimulate fatty acid beta-oxidation. Here we investigated whether SCD1 deficiency can affect muscle function and its restoration in response to injury. The genetic ablation of SCD1 was not detrimental per se to muscle function. On the contrary, muscles in SCD1 knockout mice shifted toward a more oxidative metabolism, and enhanced the expression of synaptic genes. Repressing SCD1 expression or reducing SCD-dependent enzymatic activity accelerated the recovery of muscle function after inducing sciatic nerve crush. Overall, these findings provide evidence for a new role of SCD1 in modulating the restorative potential of skeletal muscles.     

Prey selection and food habits of three sympatric large carnivores in a tropical lowland forest of the Eastern Himalayan Biodiversity Hotspot

Prey selection and the feeding habits of tiger Panthera tigris, leopard Panthera pardus and Asiatic wild dog Cuon alpinus were investigated from June 2009 to December 2011 in Pakke Tiger Reserve, Arunachal Pradesh. A total of 422 scats were analyzed of which, 109 scats were of tigers, 150 were of leopard and 163 scats were of dholes. Multinomial Likelihood ratio test was used to estimate the prey selectivity of predators and Ivlev index, Pianka index were used to estimate prey preference and overlap respectively. Biomass consumption for three sympatric predators varied from 254.3 kg for dholes to 599.1 kg for tigers. Sambar, barking deer, wild pig were preyed more than their availability by all the predators. Ivlev index shows barking deer and sambar were preferred more than available prey for tiger where as leopard preferred sambar more than available and avoided barking deer. Dhole preferred more than available wild pig and barking deer. There was a high overlap between tiger–leopard (85.3%) and tiger–dhole (77.5%). To the best of our understanding, this study provides the first reliable information on prey selection and food habits of sympatric large carnivores in a protected area of Eastern Himalayan tropical rainforest.     

In Vitro Identification of Gold Nanorods through Hyperspectral Imaging

Due to their unique plasmonic and optical properties, gold nanorods (GNR) have shown tremendous potential for nano-based applications extending into a variety of fields including bioimaging, sensor development, electronics, and cancer therapy. These distinctive, shape-specific properties are strongly dependent upon the GNR aspect ratio, thus producing the ability to be targeted for an application by fine-tuning their physical parameters. It is owing to their characteristic spectral signature, which is vastly different from that of a cellular setting, that GNRs are emerging as an ideal candidate for nano-based imaging applications. However, one challenge that has emerged in the field of bioimaging is the need to account for the observed plasmon coupling effect that arises from GNR agglomeration in a physiological environment. In this study, GNRs with aspect ratios of 2.5 and 6.0 were actively identified in an in vitro setting through a hyperspectral imaging (HSI) analysis; which successfully recognized and separated the light scattering pattern of these particles from that of the surrounding cells. Through inclusion of agglomerated GNR spectral patterns in the HSI spectral library, this imaging technique was able to overcome the complication of plasmon coupling, though to varying degrees. These results demonstrate the tremendous potential of GNRs coupled with HSI analysis to advance the field of nano-based sensing and imaging mechanisms.