Binding site identification of anticancer drug gefitinib to HSA and DNA in the presence of five different probes

This study was carried out to evaluate the binding interaction of gefitinib (GEF) with human serum albumin (HSA) and calf thymus DNA (ct-DNA) using fluorescence, UV–Visible, zeta potential measurements and molecular docking methods in order to understand its pharmacokinetic mechanism. By increasing the temperature, a steady decrease in Stern–Volmer quenching constants was observed for HSA binding properties; this indicates a static type of fluorescence quenching. Negative values were calculated for Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) changes, indicating that the reaction is spontaneous and enthalpy-driven. Probe competitive experimental results showed that GEF contains the same binding site as warfarin and are consistent with modeling results. The zeta potential of the HSA increased with increasing GEF, which represents the presence of electrostatic interactions in the system. DNA binding properties were investigated in the presence of three probes. The experimental results showed that by increasing GEF to DNA-AO (acridine-orange) and DNA-MB (methylene-blue) system, the fluorescence intensity and absorbance spectra had no considerable change. Furthermore, with the addition of GEF to DNA, the zeta potential decreased gradually, indicating that the hydrophobic interaction between the GEF and the bases of DNA is the major factor. Thus, GEF can bind to DNA via a groove binding mode. It was also found that GEF entered into the minor groove in the A–T rich region of DNA fragment and bind via van der-Waals forces and three H-bond with double strands of DNA. This is in good agreement with experimental results.     

Synthesis and urease inhibitory potential of benzophenone sulfonamide hybrid in vitro and in silico

This study deals with the synthesis of benzophenone sulfonamides hybrids (1–31) and screening against urease enzyme in vitro. Studies showed that several synthetic compounds were found to have good urease enzyme inhibitory activity. Compounds 1 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-nitrobenzenesulfonohydrazide), 2 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-3′′-nitrobenzenesulfonohydrazide), 3 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-methoxybenzenesulfonohydrazide), 4 (3′′,5′′-dichloro-2′′-hydroxy-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 6 (2′′,4′′-dichloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 8 (5-(dimethylamino)-N′-((4-hydroxyphenyl)(phenyl)methylene)naphthalene-1-sulfono hydrazide), 10 (2′′-chloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 12 (N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide) have found to be potently active having an IC₅₀ value in the range of 3.90–17.99?µM. These compounds showed superior activity than standard acetohydroxamic acid (IC₅₀?=?29.20?±?1.01?µM). Moreover, in silico studies on most active compounds were also performed to understand the binding interaction of most active compounds with active sites of urease enzyme. Structures of all the synthetic compounds were elucidated by ¹H NMR, ¹³C NMR, EI-MS and FAB-MS spectroscopic techniques.     

Thymoquinone reduces intracytoplasmic oxidative stress and improves epigenetic modification in polycystic ovary syndrome mice oocytes,during in‐vitro maturation

Although in‐vitro maturation (IVM) of oocytes has been presented as an alternative treatment to traditional stimulated in‐vitro fertilization, the culture condition can be improved by natural antioxidants. Thus, we investigated the protective effect of Thymoquinone (TQ) during IVM in the polycystic ovary syndrome (PCOS) mice model. The induction of PCOS was made by dehydroepiandrosterone via subcutaneous injection, in prepubertal female B6D2F1‐mice. After 21 days later, germinal vesicle (GV)‐stage‐oocytes were extracted and incubated in IVM media containing 0, 1.0, 10.0, and 100.0 μM of TQ. To assess fertilization and blastulation rates, after 22–24 hr, the treated oocytes were fertilized in‐vitro with epididymal spermatozoa. Some other oocytes were evaluated for maturation, epigenetic, and oxidative stress markers. Similarly, the mRNA expression of epigenetic enzymes genes (Dnmt1 and Hdac1), three maternally derived genes (Mapk, CyclinB, and Cdk1) and apoptosis‐related genes (Bax and Bcl2) were assessed. Our results showed that the maturation, fertilization, and blastulation rates were significantly higher in the 10.0 μM TQ‐treated group compared with the untreated group and likewise with in‐vivo matured oocytes. The Bax expression was reduced in 10.0 μM TQ matured oocytes, but Bcl2, Dnmt1, Hdac1, Cdk1, and Mapk were upregulated in this group compared to other groups. Furthermore, dimethylation of histone‐3 at lysine‐9 (H3K9m2) and DNA methylation were significantly increased whereas H4K12 acetylation (H4K12ac) was decreased in the 10.0 μM TQ‐treated group in comparison with control and in‐vivo matured oocytes. Therefore, our results are suggesting that 10.0 μM TQ may enhance the developmental competence of PCOS oocytes via the modulation of oxidative stress and epigenetic alterations.     

Performance of AERMOD and CALPUFF models on SO2 and NO2 emissions for future health risk assessment in Tema Metropolis

AERMOD results were compared with the reported CALPUFF results to estimate the concentrations and temporal distributions of SO₂ and NO₂ from Tema Oil Refinery with particlar attention to heavy rainy season (HRS), minor rainy season (MRS), and dry season (DS). Statistical indices, including the fractional bias (FB), geometric mean variance (VG), normalized mean square error (NMSE), index of agreement (IOA), and geometric mean bias (MG), were used to assess the reliability of the models. Overall, AERMOD better predicted ambient SO₂ and NO₂ levels than the reported CALPUFF model. For SO₂, AERMOD showed a good agreement with FB, IOA, and MG while CALPUFF showed a good prediction in NMSE and VG. Also, AERMOD predicted NO₂ well with NMSE, IOA, MG, and VG compared with FB for CALPUFF. The MRS results showed higher hourly maximum concentrations (107.4 µg/m³ for SO₂ and 31.7 µg/m³ for NO₂). Maximum daily concentrations were slightly higher in HRS (37.7 µg/m³ for SO₂ and 9.6 µg/m³ for NO₂) compared to MRS and DS. The performace of the models may provide a better understanding for future epidemiological studies.     

In vitro and in vivo effects of iron on the expression and activity of glucose 6‐phosphate dehydrogenase, 6‐phosphogluconate dehydrogenase,and glutathione reductase in rat spleen

Iron is an indispensable element for vital activities in almost all living organisms. It is also a cofactor for many proteins, enzymes, and other essential complex biochemical processes. Therefore, iron trafficking is firmly regulated by Hepcidin (Hamp), which is regarded as the marker for iron accumulation. The disruption of iron homeostasis leads to oxidative stress that causes various human diseases, but this mechanism is still unclear. The aim of this study is to provide a better in vivo and in vitro understanding of how long‐term iron overload affects the gene expression and activities of some antioxidant enzymes, such as glucose 6‐phosphate dehydrogenase (G6PD), 6‐phosphogluconate dehydrogenase (6PGD), and glutathione reductase (GR) in the spleen. The findings of this study show that iron overload reduces the gene expression of G6pd, 6pgd, and Gr, but its actual effect was on the protein level.     

Plasmodium falciparum uses gC1qR/HABP1/p32 as a receptor to bind to vascular endothelium and for platelet-mediated clumping

The ability of Plasmodium falciparum-infected red blood cells (IRBCs) to bind to vascular endothelium, thus enabling sequestration in vital host organs, is an important pathogenic mechanism in malaria. Adhesion of P. falciparum IRBCs to platelets, which results in the formation of IRBC clumps, is another cytoadherence phenomenon that is associated with severe disease. Here, we have used in vitro cytoadherence assays to demonstrate, to our knowledge for the first time, that P. falciparum IRBCs use the 32-kDa human protein gC1qR/HABP1/p32 as a receptor to bind to human brain microvascular endothelial cells. In addition, we show that P. falciparum IRBCs can also bind to gC1qR/HABP1/p32 on platelets to form clumps. Our study has thus identified a novel host receptor that is used for both adhesion to vascular endothelium and platelet-mediated clumping. Given the association of adhesion to vascular endothelium and platelet-mediated clumping with severe disease, adhesion to gC1qR/HABP1/p32 by P. falciparum IRBCs may play an important role in malaria pathogenesis.     

Concurrent determination of ezetimibe and its phase-I and II metabolites by HPLC with UV detection: quantitative application to various in vitro metabolic stability studies and for qualitative estimation in bile

Simultaneous separation and quantification of ezetimibe (EZM) and its phase-I metabolite i.e., ezetimibe ketone (EZM-K) and phase-II metabolite i.e., ezetimibe glucuronide (EZM-G) in various matrices was accomplished by gradient HPLC with UV detection. The assay procedure involved deproteinization of 500 microL of either incubation or bile sample containing analytes and internal standard (IS, theophylline) with 75 microL acetonitrile containing 25% perchloric acid. An aliquot of 100 microL supernatant was injected onto a C18 column. The chromatographic separation was achieved by gradient elution consisting of 0.05 M formic acid:acetonitrile:methanol:water at a flow rate of 1.0 mL/min. The detection of analyte peaks were achieved by monitoring the eluate using an UV detector set at 250 nm. Nominal retention times of IS, EZM-G, ezetimibe ketone glucuronide (EZM-KG), EZM and EZM-K were 9.39, 24.23, 27.82, 29.04 and 30.56 min, respectively. Average extraction efficiencies of EZM, EZM-G and IS was >75-80% and for EZM-K was >50% from all the matrices tested. Limit of quantitation (LOQ) for EZM, EZM-K and EZM-G was 0.02 microg/mL. Due to the lack of availability of reference standard of EZM-KG, the recovery and LOQ aspects for this metabolite were not assessed. Overall, the method is suitable for simultaneous measurement of EZM, and its phase-I and phase-II metabolite (EZM-G) in in vitro and in vivo studies.     

Two new protease-inhibiting glycosphingolipids from Buddleja crispa

Crispins A (1) and B (2), two new glycosphingolipids, were isolated from the whole plant Buddleja crispa, along with three known compounds: alpha-amyrin, linoleic acid, and stigmasterol. Their structures were elucidated by chemical and spectroscopic techniques. Both 1 and 2 showed significant inhibitory activity against alpha-chymotrypsin in a concentration-dependent manner.     

Isolation and enzyme-inhibition studies of the chemical constituents from Ajuga bracteosa

Bractin A (=(2S,3S,4R,5E)-2-{[(2R)-2-hydroxydodecanoyl]amino}triacont-5-ene-1,3,4-triol; 1) and bractin B (=(2S,3S,4R,5E,8E)-2-{[(2R)-2-hydroxyhexacosanoyl]amino}pentadeca-5,8-diene-3,4,15-triol 1-O-beta-D-glucopyranoside; 2), new sphingolipids, and bractic acid (=(5Z,10Z,15Z)-2-decyl-4,7,8,12,13,17,18-heptahydroxy-20,23-dioxopentacosa-5,10,15-trienoic acid; 3), a long-chain polyhydroxy acid, were isolated from the whole plant Ajuga bracteosa along with four known diterpenoids 4-7. Their structures were deduced by spectral studies including 1D- and 2D-NMR spectroscopy. Compounds 1-3 displayed inhibitory potential against enzyme lipoxygenase, while compounds 4-7 inhibited cholinesterase enzymes in a concentration-dependent manner with IC(50) values in the range 10.0-33.0, 14.0-35.2, and 10.0-19.0 microM for lipoxygenase, acetylcholinesterase, and butyrylcholinesterase, respectively. Lineweaver-Burk, and Dixon plots, and their secondary replots indicated that all compounds exhibit non-competitive type of inhibition with K(i) values in the range of 9.5-35.2, 15.2-36.0, and 11.6-20.5 microM, for lipoxygenase, acetylcholinesterase, and butyrylcholinesterase, respectively.     

Changes in carbohydrate metabolism by triazole growth regulators in cassava (Manihot esculenta Crantz); effects on tuber production and quality

We have evaluated the ability of two triazole growth regulators, viz. triadimefon (TDM) and hexaconazole (HEX), in the enhancement of tuber production and quality in cassava (Manihot esculenta Crantz) through their effects on carbohydrate metabolism. One litre of 20 mg(-1) TDM and 15 mg(-1) HEX solution per plant were used for the treatments and groundwater was given to control plants. Triazole treatments reduced plant height and leaf area, but increased fresh and dry weights. Plants treated with TDM showed an increased net assimilation rate, which is followed by HEX and control plants. Triazole compounds increased the relative growth rate of cassava after 200 DAP, i.e. in the phase of tuber enlargement. Triazole compounds increased the starch and other carbohydrate contents and carbohydrate metabolising enzyme activities. From the results of this study, it can be concluded that these triazoles can significantly enhance the tuber production and quality by affecting the starch metabolism, apart from their fungicidal properties.