Mohammad Abdulkadher Akbarsha

Spermatotoxic effect of aflatoxin B1 in rat: extrusion of outer dense fibres and associated axonemal microtubule doublets of sperm flagellum

Male Wistar rats were treated with aflatoxin B1 (AFB1). Live as well as methanol-fixed cauda epididymal spermatozoa were stained with acridine orange (AO) and ethidium bromide (EB) and observed under a fluorescence microscope. Giemsa-stained smears were observed in a bright field microscope. Unstained smears were observed with phase contrast illumination. The axoneme of more than 10% of the spermatozoa of treated rats had the outer dense fibres (ODFs), in varying numbers, and the associated axonemal microtubule doublets of the flagellum extruded either at midpiece-principal piece junction or connecting piece. This could be perceived in all light microscopic preparations, but AO-EB staining offered an advantage of the assessment of the viability as well. TEM observation of sections of the testis and cauda epididymidis also revealed ODF extrusion, as seen in the transverse sections of sperm flagella missing one or more ODFs and the associated axonemal microtubule doublets. In a few such sections, the extruded elements were seen in the cytoplasm, outside the mitochondrial sheath or peripheral sheath. Marginal to severe mitochondrial pathologies were observed in the spermatozoa and elongated spermatids, suggesting a link between AFB1-induced sperm mitochondrial pathology and extrusion of ODFs. However, the possibility that AFB1 treatment would disrupt the cytoskeletal proteins of the flagellum, resulting in the extrusion of ODFs, cannot be excluded. This sperm abnormality is reported for the first time as produced by a dietary toxin. Dietary aflatoxins, therefore, could also be contributory factors for the deterioration of the reproductive health of men.

Human serum albumin binding and cytotoxicity studies of surfactant–cobalt(III) complex containing 1,10-phenanthroline ligand

The characteristics of the binding reaction of surfactant-cobalt(III) complex, cis-[Co(phen)₂(C₁₄H₂₉NH₂)]Cl₂·3H₂O (phen=1,10-phenanthroline, C₁₄H₂₉NH₂=tetradecylamine) with human serum albumin (HSA) were studied by fluorescence and UV-vis absorption spectroscopy. In addition, the effect of the surfactant-cobalt(III) complex on the conformation of HSA was analysed using synchronous fluorescence spectroscopy. The experimental results showed that surfactant-cobalt(III) complex caused the fluorescence quenching of HSA through a combination of static and dynamic quenching. The number of binding sites (n) and apparent binding constant (K(a)) of surfactant-cobalt(III) complex (above and below the critical micelle concentration (cmc) were determined at various temperatures. According to the thermodynamic parameters, it is likely that hydrophobic interactions are involved in the binding process. The cancer chemotherapeutic potential of surfactant-cobalt(III) complex on ME-180 cervical cancer cell was determined using MTT assay and specific staining techniques. The complex affected the viability of the cells significantly and the cells succumbed through an apoptosis process as seen in the nuclear morphology and cytoplasmic features. In addition, single-cell electrophoresis indicated DNA damage.

Protein binding and biological evaluation of a polymer-anchored cobalt(III) complex containing a 2,2′-bipyridine ligand

The molecular interaction of polymer-anchored cobalt(III) complex, cis-[Co(bpy)2(BPEI)Cl]Cl2·4H2O (bpy = 2,2′-bipyridine, BPEI = branched polyethyleneimine) with two plasma proteins, human serum albumin (HSA) and bovine serum albumin (BSA) using various spectrophotomeric techniques has been investigated. The steady-state and time-resolved fluorescence spectra clearly demonstrated the static quenching mechanism. The calculated thermodynamic parameters revealed that the interaction between the polymer–cobalt(III) complex and HSA/BSA was driven mainly by van der Waals forces and hydrogen bonds. The results observed from three dimensional fluorescence and circular dichorism (CD) spectral studies manifested the conformational changes of HSA/BSA upon addition of the polymer–cobalt(III) complex. Furthermore, the antimicrobial result showed that the polymer–cobalt(III) complex exhibits good antibacterial and antifungal activities against certain human pathogenic microorganisms. In addition, the antiproliferative properties of the polymer–cobalt(III) complex on the HEp-2 human larynx cancer cells were determined using the MTT assay. The mode of cell death induced by the complex following treatment was analyzed adopting specific staining techniques. MTT assay revealed that the viability of the cells thus treated was significantly decreased and the cells succumbed to apoptosis as well as necrosis as reflected in changes in the nuclear morphology and cytoplasmic features by AO & EB and Hoechst staining methods.

Ferrocenyl methylene units and copper(II) phenanthroline complex units anchored on branched poly(ethyleneimine) – DNA binding, antimicrobial and anticancer activity

Polymer conjugates containing copper(II) phenanthroline complex units and ferrocenyl methylene units bound to the same polymer backbone were synthesized and characterized by spectroscopic and analytical techniques. We could observe both the EPR spectrum for the paramagnetic copper(II) units and the proton NMR spectrum due to the diamagnetic ferrocenyl methylene units. Binding interaction of this complex with calf thymus DNA (CT-DNA) has been investigated by absorption, emission, cyclic voltammetry, and circular dichroism studies. The complex displays significant binding properties to the CT-DNA. In fluorimetric studies, the binding mode of the complex with CT-DNA was investigated using ethidium bromide (EB) as a fluorescence probe. The binding of copper(II) complex units to DNA was facilitated by the presence of ferrocenyl methylene units in the same polymer molecule. These polymer conjugates show good anticancer activity against HepG2 cells and antimicrobial studies have shown better activity.

Synthesis, structures, and DNA and protein binding of ruthenium(II)-p-cymene complexes of substituted pyridylimidazo[1,5-a]pyridine: enhanced cytotoxicity of complexes of ligands appended with a carbazole moiety

A series of organometallic Ru(II)-arene complexes of the type [(η6-p-cymene)Ru(L)Cl](BF4) 1–6, where L is 3-phenyl-1-pyridin-2-yl-imidazo[1,5-a]pyridine (L1), dimethyl-[4-(1-pyridin-2-yl-imidazo[1,5-a]pyridin-3-yl)phenyl]-amine (L2), diphenyl-[4-(1-pyridin-2-yl-imidazo[1,5-a]pyridin-3-yl)phenyl]amine (L3), 9-[4-(1-pyridin-2-yl-imidazo-[1,5-a]pyridin-3-yl)-phenyl]-9H-carbazole (L4), 9-ethyl-3-(1-pyridin-2-yl-imidazo-[1,5-a]pyridin-3-yl)-9H-carbazole (L5), and 10-ethyl-3-(1-pyridin-2-yl-imidazo[1,5-a]pyridin-3-yl)-10H-phenothiazine (L6), has been isolated and characterised by elemental analysis, ESI-MS, NMR and cyclic voltammetry. The photophysical properties of the complexes have been studied by electronic absorption and emission spectral techniques. All the ligands exhibit tuneable photoluminescence behaviour with the emission maximum spanning through the visible region (475–670 nm) in dichloromethane while all the complexes are emissive in acetonitrile. The single crystal X-ray structures of 2, 3 and 4 reveal that the complexes have a “piano stool” coordination geometry, comprising one π-bonded arene centroid, two σ-bonded nitrogen atoms from the chelating ligand and one Cl− ion. From DNA induced EthBr emission quenching experiments the apparent DNA binding constants of the complexes (Kapp) have been evaluated, which follows the order, 2 (1.3) 100 μM), exhibit in vitro cytotoxicity against A549 small lung cancer cell lines higher than cisplatin (∼69 μM), as revealed by both MTT (11.8–18.1 μM) and crystal violet staining (12.7–23.5 μM) assays, which is in agreement with their DNA and BSA binding affinity. Also, the complexes 3–6 cause higher cell death mainly through the apoptotic mode, as revealed by the observation of a higher percentage of apoptotic cells in AO/EB (36–43%) and Annexin V-Cy3 (36–45%) stained cancer cells.

Cytotoxic Property of Surfactant–Cobalt(III) Complexes on a Human Breast Cancer Cell Line

The cancer chemotherapeutic potential of surfactant–cobalt(III) complexes, cis‐[Co(bpy)2(C14H29NH2)Cl](ClO4)2 · 3 H2O (1) and cis‐[Co(phen)2(C14H29NH2)Cl](ClO4)2 · 3 H2O (2) (bpy = 2,2′‐bipyridine, phen = 1,10‐phenanthroline) on MCF‐7 breast cancer cell was determined adopting MTT assay and specific staining techniques. The complexes affected the viability of the cells significantly and the cells succumbed to apoptosis as seen in the changes in the nuclear morphology and cytoplasmic features. Since the complex 2 appeared to be more potent, further assays were carried out on the complex 2. Single‐cell electrophoresis indicated DNA damage. The translocation of phosphatidyl serine and loss of mitochondrial potential was revealed by annexin V‐Cy3 staining and JC‐1 staining respectively. Western blot analysis revealed up‐regulation of pro‐apoptotic p53 and down‐regulation of anti‐apoptotic Bcl‐2 protein. Taken together, the surfactant–cobalt(III) complex 2 would be a potential candidate for further investigation for application as a chemotherapeutic for cancers in general and estrogen receptor‐positive breast cancer in particular.

Fluorescent active ruthenium(II) complex units containing bpy or phen or dmp ligands anchored on branched poly(ethylenimine): DNA binding and in vitro biological assessment

Anticancer targeted ruthenium(II) complex units containing bpy(2,2′-bipyridine), phen(1,10-phenanthroline) or 2,9-dmp(2,9-dimethyl 1,10-phenanthroline) anchored on a branched polyethylenimine molecule (RuL-BPEI) were synthesised. These complexes are highly stable, emissive, redox active and show a quasi-reversible response in cyclic voltammetry. Synthesised compounds were characterized by infra-red, UV-visible, NMR, CHN, and AES analysis methods. The interaction of these RuL-BPEI samples with calf thymus DNA was explored using electronic absorption spectroscopy, emission spectroscopy, cyclic voltammetry and circular dichroism techniques. Antimicrobial activities of these polymer metal complexes have been investigated against a range of various bacteria, including clinically resistant microbes. And also anticancer properties have been tested with MCF-7 breast cancer cell lines. All results were positive.