Manzoor Ahmad Gatoo

Physicochemical Properties of Nanomaterials: Implication in Associated Toxic Manifestations

Nanotechnology has emerged as one of the leading fields of the science having tremendous application in diverse disciplines. As nanomaterials are increasingly becoming part of everyday consumer products, it is imperative to assess their impact on living organisms and on the environment. Physicochemical characteristics of nanoparticles and engineered nanomaterials including size, shape, chemical composition, physiochemical stability, crystal structure, surface area, surface energy, and surface roughness generally influence the toxic manifestations of these nanomaterials. This compels the research fraternity to evaluate the role of these properties in determining associated toxicity issues. Reckoning with this fact, in this paper, issues pertaining to the physicochemical properties of nanomaterials as it relates to the toxicity of the nanomaterials are discussed.

Amyloid Form of Ovalbumin Evokes Native Antigen-specific Immune Response in the Host PROSPECTIVE IMMUNO-PROPHYLACTIC POTENTIAL

Background: Amyloids have recently been found to be reversible and dynamic. They release the precursor peptide/protein in a slow and sustained manner. Results: Antibodies produced in response to amyloid immunization could recognize native antigen. Conclusion: OVA amyloids release proteins harboring native antigen epitopes. Significance: The slow and sustained release of native antigen from amyloids makes them potential candidates for inducing a protective antibody response. Amyloids are highly organized protein aggregates that arise from inappropriately folded versions of proteins or polypeptides under both physiological as well as simulated ambiences. Once thought to be irreversible assemblies, amyloids have begun to expose their more dynamic and reversible attributes depending upon the intrinsic properties of the precursor protein/peptide and experimental conditions such as temperature, pressure, structural modifications in proteins, or presence of chemicals in the reaction mixture. It has been repeatedly proposed that amyloids undergo transformation to the bioactive peptide/protein forms under specific conditions. In the present study, amyloids assembled from the model protein ovalbumin (OVA) were found to release the precursor protein in a slow and steady manner over an extended time period. Interestingly, the released OVA from amyloid depot was found to exhibit biophysical characteristics of native protein and reacted with native-OVA specific monoclonal as well as polyclonal antibodies. Moreover, antibodies generated upon immunization of OVA amyloidal aggregates or fibrils were found to recognize the native form of OVA. The study suggests that amyloids may act as depots for the native form of the protein and therefore can be exploited as vaccine candidates, where slow antigen release over extended time periods is a pre-requisite for the development of desired immune response.

In vitro cytotoxcity and interaction of new steroidal oxadiazinanones with calf thymus DNA using molecular docking, gel electrophoresis and spectroscopic techniques

Herein we report synthesis of new steroidal oxadiazinanones from steroidal ketones. After characterization by spectral and analytical data, the interaction studies of compounds (4-6) with DNA were carried out by UV-vis, fluorescence spectroscopy and gel electrophoresis. The compounds bind to DNA preferentially through electrostatic and hydrophobic interactions with Kb; 1.8×10(4) M(-1), 2.2×10(4) M(-1) and 2.6×10(4) M(-1), respectively, indicating the higher binding affinity of compound 6 towards DNA. Gel electrophoresis showed the concentration dependent cleavage activity of compound 6 alone or in presence of Cu (II) causes the nicking of supercoiled pBR322 and it seems to follow the mechanistic pathway involving generation of hydroxyl radicals that are responsible for initiating DNA strand scission. Molecular simulations suggest that compounds binds through minor groove of DNA. MTT assay depicted promising anticancer activity of compound 5 and 6 particularly against HL-60 and MCF-7. The apoptotic degradation of DNA was analyzed by agarose gel electrophoresis and visualized by ethidium bromide staining (comet assay). The results revealed that compound 6 has better prospectus to act as cancer chemotherapeutic candidate which warrants further in vivo anticancer investigations.

DNA Binding, Cleavage Activity, Molecular Docking, Cytotoxicityand Genotoxicity Studies of Newly Synthesized Copper Based MetalComplexes

The design and synthesis of medicinal chemotherapeutic agents of copper with 2-(benzothiazol-2-yl iminomethyl)-phenol, 2-(benzothiazol-2-yliminomethyl)-valine, cyanoaceto (2-mer- captobenzylidene)-hydrazide, 2-(phenacyl bromide)-aminothiophenol, (2-mercaptobenzaldehyde) thio- semicarbazone, N-(phenacyl bromide)-2- yliminobenzothiazole, 2-aminobenzothiazole, benzothiazol-2-yliminomethyl)-phenol and 2-[(2E¹-aminobenzylidene)- amino]-benzenethiol were synthesized. The characterization was done by FTIR, 1H and 13C NMR, MS, TGA and elemental analysis. Interaction of complexes 8 and 9 with CT DNA was done by using UV-vis and fluorescence spectroscopy depicting the hyperchromic behaviour of complexes. The intrinsic binding constants (Kb) for complex 8 and 9 were 2.35 × 103 M-1 and 2.12 × 103 M-1. The cleavage studies of complex 8 and 9 were done with pBR322 plasmid showing the potential cleaving ability of the complexes at very low concentration. The gel electrophoresis pattern also demonstrated that the complex 8 alone or in presence of Cu (II) causes the nicking of supercoiled pBR322 and it seems to follow the mechanistic pathway involving generation of hydroxyl radicals that are responsible for initiating DNA strand scission. The molecular docking studies showed the minor groove binding behaviour of the complexes 8 and 9 with DNA. During the MTT assay against different cancer cell lines like SW480, HepG2, HT29 and HL60, all the complexes showed potential cytotoxic behaviour by giving effective IC50 close to Cisplatin. The bioactivity score and PASS analysis also depicted the drug like nature of the complexes. During the comet assay, apoptotic degradation of DNA in the presence of complex 8 and 9 was analysed by agarose gel electrophoresis and visualized by ethidium bromide staining.

DNA binding, artificial nuclease activity and cytotoxic studies of newly synthesized steroidal pyrimidines

The new steroidal pyrimidine derivatives (4-6) were synthesized by the reaction of steroidal thiosemicarbazones with (2-methyl) diethyl malonate in absolute ethanol. After characterization by spectral and analytical data, the DNA interaction studies of compounds (4-6) were carried out by UV-vis, fluorescence spectroscopy, hydrodynamic measurements, molecular docking and gel electrophoresis. The compounds bind to DNA preferentially through electrostatic and hydrophobic interactions with Kb; 2.31×103M-1, 1.93×103M-1 and 2.05×103M-1, respectively indicating the higher binding affinity of compound 4 towards DNA. Gel electrophoresis demonstrated that compound 4 showed a strong interaction during the concentration dependent cleavage activity with pBR322 DNA. The molecular docking study suggested the intercalation of steroidal pyrimidine moiety in the minor groove of DNA. During in vitro cytotoxicity, compounds (4-6) revealed potential toxicity against the different human cancer cells (MTT assay). During DAPI staining, the nuclear fragmentations on cells occurred after treatment with compounds 4 and 5. Western blotting analysis clearly indicates that compound 4 causes apoptosis in MCF-7 cancer cells. The results revealed that compound 4 has better prospectus to act as a cancer chemotherapeutic candidate, which warrants further in vivo anticancer investigations.

Synthesis of steroidal imidazolidinthiones as potential apoptotic agents: Investigation by theoretical and experimental studies

New steroidal imidazolidinthione derivatives (4-6) were synthesized from steroidal thiosemicarbazones and dichloroethane. The synthesized compounds were characterized using spectral data analysis. Theoretical DFT involving B3LYP/6-31G∗∗ level of theory was employed to gain insights into the molecular structure of the target compounds. MEPS and FMO analysis were carried out. HOMO-LUMO energy gap was determined which helped to evaluate various global descriptors like hardness, chemical potential, electronegativity, nucleophilicity and electrophilicity index, etc. The calculated properties established that the synthesized products are more or less similar in their reactivity behaviour. To explore their biological potential, interaction studies of compounds (4-6) with DNA were carried out using various biophysical techniques. The compounds bind DNA preferentially through electrostatic and hydrophobic interactions with Kb of 3.21 × 103 M-1, 2.79 × 103 M-1 and 2.26 × 103 M-1, respectively indicating the higher binding affinity of compound 4 towards DNA. Gel electrophoresis of compound 4 demonstrated strong interaction during the concentration dependent cleavage activity with pBR322 DNA. It was observed that these steroidal imidazolidinthiones are minor groove binders of DNA which was validated using molecular docking studies. An in vitro cytotoxicity screening using MTT assay revealed that the compounds (4-6) exhibit potential toxicity against different human cancer cells. Highest antiproliferative effect was observed on HeLa cells by compound 4. The results suggested that compounds 4-6 cause apoptotic cell death by cleaving apoptotic protein caspase-3 and suppress anti-apoptotic protein Bcl-2 in HeLa cancer cells.

Structural, optical and antimicrobial studies of 3β-acetoxycholest-5-ene, 3β-acetoxy-6-nitrocholest-5-ene and newly synthesized steroidal pyrazolones

Abstract A convenient synthesis of a new series of nano steroidal pyrazolones is reported. They were characterized by X-ray diffraction, scanning electron microscopy, UV–vis light, Fourier transform-infrared spectroscopy, 1H and 13C nuclear magnetic resonance, mass spectroscopy and analytical data. The X-ray diffraction patterns at room temperature showed that two nano steroids, 7 and 8, are formed in single phase with hexagonal crystal symmetry, while nano steroid 9 is formed with orthorhombic crystal symmetry. Compounds 1–3 are formed with hexagonal, monoclinic and tetragonal crystal symmetry, respectively. Scanning electron microscopy showed that the crystals of nano steroids 7–9 are brick-shaped agglomerates with less sharp edges and a rough surface with a few microcrystals, while the homogeneous crystal of nano steroid 3 has an approximate spherical morphology of nano particles conjoined to the chains. UV–vis absorption analysis showed that the band gap energy of nano steroids 7 and 8 was 3.70 eV and 4.61 eV, while that of 2 and 3 was 4.38 eV and 4.27 eV, respectively. Nano steroids 2, 3 and 7–9 were screened for antimicrobial activity against various strains; nano compound 7 showed potential antimicrobial activity.