Synthesis, structural, spectral and biological evaluation of metals endowed 1,2,4-triazole

Biologically active triazole Schiff base ligand 2,4-dichloro-6-[(1H-1,2,4-triazol-3-ylimino)methyl]phenol (A) has been synthesized by the condensation reaction of an equimolar amount of 1H-1,2,4-triazole-3-amine and 3,5-dichlorosalicylaldehyde and then it coordinated with salts of metals [VO(IV), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] in 2:1 molar ratio to derive a series of transition metal chelates (1)-(6). All the compounds were characterized by various physical, spectral, analytical techniques and elemental analysis. Spectral characterization and magnetic moment data of complexes revealed square pyramidal geometry for vanadium complex and octahedral for remaining (2)-(6) complexes. Quantum chemical calculation has been carried out to explore optimized geometry and electronic structure of the ligand. Density functional theory (DFT) with B3LYP/6-311+g(d,p) method was performed to determine vibrational bands, frontier molecular orbitals (FMOs) and natural bond analysis (NBO) of the ligand. NBO analysis showed that the ligand bears higher molecular stability because of hyper conjugate interactions. Computational study results revealed that there was a close interaction of theoretical and experimental spectroscopic data. Global reactivity descriptors calculated by the energies of FMOs, indicated ligand to be bioactive. The synthesized compounds were studied for antibacterial, antifungal, antioxidant and antiglycation activity and the results revealed that ligand has remarkable activity which considerably increased upon chelation.                     KEY WORDS: Triazole ligand, Transition metal chelates, Antibacterial, Antifungal, Antioxidant, Computational study   Bull. Chem. Soc. Ethiop. 2020, 34(2), 335-351 DOI: https://dx.doi.org/10.4314/bcse.v34i2.11

Control of the stereochemistry of C14 hydroxyl during the total synthesis of withanolide E and physachenolide C

The stereochemical outcome of the epoxidation of Δ_14–15 cholestanes with mCPBA is controlled by the steric bulk of a C17 substituent. When the C17 is in the β configuration, the epoxide is formed in the α face, whereas if the C17 is trigonal (flat) or the substituent is in the α configuration, the epoxide is formed in the β face. The presence of a hydroxyl substituent at C20 does not influence the stereochemical outcome of the epoxidation.

The epoxide configuration in oxidation of C14–C15 alkenes is determined by the configuration of the C17 substituent.

The adverse effects of interferon-free regimens in 149 816 chronic hepatitis C treated Egyptian patients

BACKGROUND

Interferon-free regimens are associated with high sustained virological response; however, associated adverse effects have yet to be fully reported.

AIM

To evaluate the adverse effects associated with the different direct-acting antiviral drug (DAA) regimens in Egyptian patients.

METHODS

This multicenter retrospective study included all adverse effects during and after treatment with DAA regimens of 149 816 chronic hepatitis C treated Egyptian patients. Patients received sofosbuvir (SOF)/ribavirin (RBV) (n = 21 835), SOF/simeprevir (n = 24 215) SOF/daclatasvir (DCV) (n = 58 477), SOF/DCV/RBV (n = 45 188) and paritaprevir/ombitasvir/ritonavir/RBV (n = 101). The duration of treatment varied between 12 and 24 weeks. All changes in the treatment regimens, discontinuation, mortality, and serious side effects were reported.

RESULTS

Adverse effects developed in 2475 (1.7%) (mean age [54 ± 9], male gender [53%]) patients. Serious side effects developed in 68% of these patients, and SOF/RBV was the most common causing regimen (73%, P < 0.001). Anaemia and hyperbilirubinemia were the most common side effects (731/149816, 0.5% and 463/149816, 0.3%, respectively) and SOF/RBV (588/21835, 3% and 353/21835, 1.6%, respectively) showed the highest incidence in the treated patients. Hepatocellular carcinoma and mortality were reported in 0.02% and 0.06% of all treated patients, respectively. Patients with liver cirrhosis showed higher incidence of serious side effects (Log rank P = 0.045) and mortality (Log rank P = 0.025) than patients without liver cirrhosis. Male gender (P = 0.012), lower haemoglobin (P < 0.001), platelets (P < 0.001) and albumin (P = 0.001), higher bilirubin (P = 0.002) and cirrhosis (P < 0.001) were factors associated with serious side effects development.

CONCLUSION

Adverse effects associated with DAAs are few, anaemia being the most common. SOF/RBV regimen showed the highest rate of side effects while SOF/DCV showed the least.

Role of water chemistry and stabilizers on the Vero-cells-based infectivity of Newcastle disease virus live vaccine

Newcastle disease virus (NDV) live vaccines are supplied in lyophilized form and usually administered through conventional routes (drinking water, spray, or eye drop) following reconstitution in a diluent. Virus inactivation due to physico-chemical properties of the diluent at the time of administration may lead to vaccine failure. The present study aimed to evaluate the survival of NDV live vaccine strain immersed in 5 pH-amended water samples (pH 5.00, pH 6.00, pH 7.00, pH 8.00, and pH 9.00) by sequential determination of virus infectivity on Vero cells for 3 hours. Minimum reduction in virus infectivity was recorded in the water with neutral or slightly alkaline pH, while the virus was relatively less stable at extreme pH conditions. Maximum reduction of infectivity was observed in the water with pH 9.00 in which the virus was completely inactivated within 3 hours. Addition of stabilizers (Cevamune^® or skimmed milk) slightly altered the pH and total dissolved solids (TDS) values of the virus-charged water samples. In the stabilizer-added water samples, minimum reduction in infectivity was observed in the water with neutral pH, followed by the ones with a pH of 8.00, 6.00, 5.00, and 9.00. In all types of water samples, T-90 values (time required for 90% reduction in virus infectivity) were highest (485 minutes) at neutral pH (pH 7.00) and lowest (102 to 134 min) at an extreme alkaline condition (pH 9.00). Results of the present study indicate that water with a pH range of 7.00 to 8.00 is suitable for administration of NDV live vaccines. However, the addition of Cevamune^® or skimmed milk may have beneficial effects on preserving the infectivity of the virus, even at extreme pH conditions.

Analyzing various non-surgical treatment modalities for laryngopharyngeal reflux

Objective:To compare the outcomes of various medical treatment modalities for laryngopharyngeal reflux.Study design: Prospective study design.Methods: 150 patients were divided into three groups (A, B, C) based on the mode of intervention used for the control of LPR. Each study group enrolled 50 patients using random tables.• Group A: These patients were put on a twice daily dosage of esomeprazole(20 mg b.d.) and domeperidone(10 mg b.d. ) for four months• Group B: These patients were put on b.d. dosage of esomeprazole(20 mg) and domeperidone(10 mg): and also received counseling for dietary and lifestyle changes. The duration of treatment was for four months.• Group C: These patients received, in addition to above, 10 mg of amitriptyline (tricyclic antidepressant) b.i.d , again for four months.Results: The success achieved in controlling LPR was defined as greater than 50 % improvement in baseline symptoms. The success achieved in Group A was 46 %, in Group B was 54 % and in Group C was 40 %. The relative change in RSI over any given period of time was significantly higher than the relative change in RFS. The relative change in RSI over first month was 30.99%, which is significantly higher than the relative change of RFS (6.39%) over the same period. The mean RSI scores during four months of treatment fell from 20.67 to 8.9 (p < 0.01) in Group A, from 23.3 to 8.6 (p < 0.01) and from 21.3 to 10.8 (p < 0.05) in Group C. The mean RFS during four months fell from 15 to 6.5 (p < 0.05) in Group A, from 16 to 6.4 (p < 0.05) and from 15 to 6.4 (p < 0.05) in Group C.Conclusions:• All the three interventions had a statistically significant impact on the signs and symptoms of LPR.• However, higher success rates were achieved in Group B where patients were put on a b.i.d dosage esomeprazole and domeperidone nad counseled for lifestyle and dietary changes. Paradoxically, success rates achieved in Group C was lower than other groups, possibly because of the anticholinergic effects of amitriptyline causing dry mouth and dry throat.• The symptomatic improvement was seen much earlier than the improvement in laryngoscopic findings. This was evidenced by the fact that relative change in RSI was much higher than the relative change of RFS over a given period of time.• If diagnosed with enough surety and certainty, patients of LPR do not need any antidepressant medications as these medications may not have any role in the treatment of same and may, however, worsen the condition owing to their anticholinergic side effects.  DOI: http://dx.doi.org/10.3329/bjo.v18i1.10413  Bangladesh J Otorhinolaryngol 2012; 18(1): 42-47

Interaction of tissue plasminogen activator inhibitor with cell surface guanidinobenzoatase and urokinase plasminogen activator

This study employs fluorescent inhibitor molecules to detect both cell surface proteases and their receptor sites on colonic carcinoma cells. Present studies are concerned with the interactions of the tumour associated proteases, guanidinobenzoatase (GB) and plasminogen activators (PAs) with PAs inhibitor type 1 (PAI-1). The active enzymes on the cell surfaces in frozen sections of human colonic carcinoma tissue were located by staining with two active site directed fluorescent inhibitors, 9-aminoacridine (9-AA) and Rhodamine labelled PAI-1 (Rh-PAI-1), followed by fluorescence microscopy. Fibrin treated sections, which now lack GB but have receptor proteins for GB, fail to bind 9-AA and Rh-PAI-1. When these fibrin-treated sections were incubated with purified colonic carcinoma GB and u-PA, both enzymes were bound to the tumour cells in these sections and subsequent challenging with fluorescent probes for GB resulted in bright fluorescence under appropriate microscopic conditions. On the other hand when fibrin treated sections were incubated with t-PA, followed by challenging with Rh-PAI-1, no red fluorescence was observed. It is suggested that the GB and u-PA have similar specific binding sites which can recognise and bind to the receptors on tumour cells in fibrin-treated sections, but t-PA has no such binding site and fails to recognise the cell surface receptors for GB. These GB-receptors may have a possible role in the regulation of GB and u-PA activity during tumour cell invasion and metastasis.

Location of tumour cells in colon tissue by Texas red labelled pentosan polysulphate, an inhibitor of a cell surface protease

Pentosan polysulphate (PPS), a highly negatively charged polysaccharide, is a significant inhibitor of an isoenzymic form of a cell surface protease referred to as guanidinobenzoatase GB, associated with colonic carcinoma tissues in frozen sections and free GB in solution, in a concentration-dependent manner. However PPS failed to recognise and bind to the isoenzymic form of GB associated with normal colon epithelial cell surfaces. Texas red labelled PPS (TR-PPS) binds to the tumour cell surfaces of colonic carcinoma and colonic polyps and these cells fluoresce red, whilst the normal colon cell surfaces failed to bind the TR-PPS, and hence lacked red fluorescence. Polysulphonated suramin also selectively recognised and inhibited the colonic carcinoma GB isoenzyme. The kinetic data indicated that this inhibition was not caused by a mere polyanionic effect, since highly sulphated heparin failed to show a significant inhibition of colonic carcinoma GB, however trypan blue did show 50% inhibition. Kinetic studies have also shown that PPS is a non-competitive, reversible inhibitor of colonic carcinoma GB, with an apparent Km 6.8 x 10(-7) M. Gel analysis has shown that PPS binds to another site, distinct from the active centre, and after binding PPS changed the conformation of GB. These studies suggest that TR-PPS is a potent inhibitor of colonic carcinoma GB, and can be used as a novel fluorescent probe for the location of tumour cells in frozen sections of human colon tissues. PSS could also have potential as a vehicle for the transport of cytotoxic compounds to carcinoma cells of the colon.

Dansyl fluoride, a fluorescent inhibitor for the location of tumour cells in human tissues

Dansyl fluoride (Dan-F), an active site directed fluorescent inhibitor of guanidinobenzoatase (GB), has been used for the location of tumour cells in frozen sections of human squamous cell carcinoma and colonic carcinoma tissues. The tumour cell surfaces having active GB bind Dan-F and fluoresce blue. The surrounding normal epithelial lung cell surfaces fail to bind Dan-F and hence lack fluorescence, whilst the normal colon cell surfaces have another isoenzymic form of GB, bind Dan-F and fluoresce blue. Kinetic studies have shown that Dan-F is an irreversible inhibitor of GB, and Dan-GB complexes are not dissociated with SDS and high salt concentration. However hydroxylamine (1 M) can dissociate Dan-GB complexes in the presence of 0.1% SDS, both on membrane-bound and in free solution. These studies suggest that Dan-F is a potent inhibitor of GB, and in very low concentration (3 x 10(-8) M) can be used as a novel fluorescent probe for the location of tumour cells in histological sections of human tissues.

Selectivity of the plasminogen activator inhibitor (PAI-1) for the iso enzyme of guanidinobenzoatase on the surface of colonic carcinoma cells

The interaction of plasminogen activator-inhibitor (PAI-1) with a cell surface protease, guanidinobenzoatase (GB), has been studied in free solution and on the surface of colonic epithelial cells. It has been demonstrated that PAI-1 recognises and inhibits the iso enzymic form of GB associated with colonic carcinoma cells but fails to bind to the iso enzymic form of GB associated with normal donor colonic epithelial cells. This interaction is mediated by a lysyl binding site on the GB: complex formation prevents GB binding to fibrin fibrils which also involves lysyl binding sites.

Differential competitive inhibition of a cell surface protease on normal epithelial cells and carcinoma cells of the colon

The cell surfaces of normal colonic epithelial cells and colonic carcinoma cells both possess a protease referred to as guanidinobenzoatase (GB). Previous studies have shown that these cells possess two distinct isoenzymic forms of GB which could be distinguished by their selective recognition of cytoplasmic protein inhibitors of GB. In the present study we have used competitive inhibitors of GB to demonstrate the differential inhibition of the GB on normal colonic epithelial cells whilst the GB on colonic carcinoma cell surfaces remains active. The enzymic status of GB on these cells has been determined by challenging the treated cells in frozen sections with a second fluorescent inhibitor, followed by fluorescence microscopic analysis.

Retinoic acid inhibition of a tumour protease immobilised on cell surfaces and in free solution

Retinoids are inhibitors of tumour cell proliferation in culture and have been shown to suppress carcinogenesis and decrease the levels of proteases. The present study has demonstrated that retinoic acid is a potential non-competitive inhibitor of a protease (GB) immobilised on the surfaces of tumour cells in thin sections and free GB in solution. The enzymic status of GB on the cell surfaces in sections has been determined by challenging the retinoic acid-treated cells with a second fluorescent inhibitor (9-AA), followed by fluorescence microscopic analysis. The inhibition of cell surface GB by retinoic acid was demonstrated to be reversible. The activity of soluble GB has been measured by the MUGB assay in the presence and absence of retinoic acid. It is suggested that retinoic acid acts on GB by interacting with a binding site, different from the active site, and causes major conformational changes, resulting in enzyme inhibition. It is possible that the modulation of GB activity by retinoic acid may play a role in the control of cell migration and metastasis.

Inhibition of a tumour protease with 3,4-dichloroisocoumarin, pentamidine-isethionate and guanidino derivatives

Guanidinobenzoatase (GB) is a cell surface proteolytic enzyme capable of degrading fibronectin, and is associated with tumour cells and cells capable of migration. The location of active GB in sections has been demonstrated with 9-aminoacridine (9-AA), a competitive inhibitor of GB. 3,4-Dichloroisocoumarin (3,4-DCI) and pentamidine isethionate (PI) are inhibitors of trypsin-like enzymes. It has now been demonstrated that 3,4-DCI, PI, and guanidino derivative compounds are significant inhibitors of GB, on the surfaces of lung squamous cell carcinoma cells in frozen sections and free GB in solution. Dexamethasone acetate (DMA) and medroxy-progesterone (MP) did not show any significant inhibition of GB activity. These molecules lack a reactive chloride or guanidino groups and are thought to react at the nuclear level, rather than directly on this cell surface protease. Kinetic studies have shown that 3,4-DCI, PI and guanidino derivatives are reversible competitive inhibitors of GB, as determined in vitro on the purified enzyme. The inhibition resulting with 3,4-DCI was a time-dependent process. It is suggested that these inhibitors interact with GB by binding to its active site, resulting in the formation of enzyme-inhibiter complexes (GB-I). The GB-I complexes can be dissociated with SDS treatment, resulting in the regain of GB activity.

The interactions of protein inhibitors with tumour proteases studied in solution and immobilised on cell surfaces in frozen sections

The cell surface protease guanidinobenzoatase (GB) has been purified from human colonic and lung carcinoma tissue by an affinity step involving the binding of the enzyme either onto fibrin fibrils or onto agmatine-sepharose. The inhibitor protein (I) was extracted from the cytoplasm of tumour cells and isolated by an affinity step involving the binding of I to GB on the surface of cultured carcinoma cells. The interaction of GB and I in solution was followed by kinetic studies employing the release of the fluorescent 4-methylumbelliferone (MU) from the synthetic substrate 4-methylumbelliferyl-p-guanidinobenzoate (MUGB). The interaction of soluble I with membrane bound GB was followed by using the yellow fluorescent probe 9-aminoacridine (9AA) which binds to active GB but not to GB-I. The results of these studies demonstrated the presence of isoenzymic froms of GB which were recognized specifically by their appropriate isoinhibitor, isolated from the appropriate cell type. This high degree of selectivity suggests a cell specific regulatory role for the inhibitors and the possibility that they might be used for the delivery of cytotoxic molecules to the surface of specific types of tumour cells.

Association and dissociation of a protease and its inhibitor on the surface of lung squamous cell carcinoma cells

Squamous cell carcinoma cells possess a cell surface protease, referred to as guanidinobenzoatase (GB). GB is a plasminogen-activator-like enzyme which can be located by the fluorescent probe 9-amino acridine in frozen sections. Fluorescence microscopy has been used to study the inhibition of this GB, the displacement of inhibitor from GB, the displacement of GB from the cell surface receptor and the preparation of both active GB and inhibitor, obtained from these frozen sections of tumour tissue.

Observations on the conformational changes in the structure of a cell surface protease, followed by its ability to be recognised by competitive and non-competitive inhibitors

Lung tumour cells possess a cell surface protease which can be inhibited by a cytoplasmic protein inhibitor extracted from these cells. The dissociation of this enzyme-inhibitor complex on the surface of tumour cells in sections treated with 10(-4) M sodium dodecyl sulphate has been studied. The dissociation of the inhibitor and regain of enzymic activity was followed by the use of a fluorescent probe which binds to the active centre of the cell surface enzyme in a competitive manner.

Influence of angiotensins (I, II, & III), bradykinin and arachidonic acid on renomedullary PGE production in vitro

Renomedullary tissue from rabbit or rat was incubated with angiotensin I, II, III, arachidonic acid, bradykinin, indomethacin and meclofenamate to study their effect on PGE2 production. Arachidonic acid and bradykinin enhanced PGE2 production significantly. Indomethacin and meclofenamate inhibited PGE2 production by more than 70%. Angiotensin I, II and III did not influence PGE2 production. These results suggest that bradykinin and arachidonic acid stimulate PGE2 production by a direct cellular action whereas the angiotensins do not.