Hatim S. AlKhatib

Inhibition of glycogen synthase kinase by curcumin: Investigation by simulated molecular docking and subsequent in vitro/in vivo evaluation

Curcumin was investigated as an inhibitor of glycogen synthase kinase-3β (GSK-3β) in an attempt to explain some of its interesting multiple pharmacological effects, such as its anti-diabetic, anti-inflammatory, anti-cancer, anti-malarial and anti-alzheimers properties. The investigation included simulated docking experiments to fit curcumin within the binding pocket of GSK-3β followed by experimental in vitro and in vivo validations. Curcumin was found to optimally fit within the binding pocket of GSK-3β via several attractive interactions with key amino acids. Experimentally, curcumin was found to potently inhibit GSK-3β (IC50 = 66.3 nM). Furthermore, our in vivo experiments illustrated that curcumin significantly increases liver glycogen in fasting Balb/c mice. Our findings strongly suggest that the diverse pharmacological activities of curcumin are at least partially mediated by inhibition of GSK-3β.

Colloidal Stability of Citrate and Mercaptoacetic Acid Capped Gold Nanoparticles upon Lyophilization: Effect of Capping Ligand Attachment and Type of Cryoprotectants

For various applications of gold nanotechnology, long-term nanoparticle stability in solution is a major challenge. Lyophilization (freeze-drying) is a widely used process to convert labile protein and various colloidal systems into powder for improved long-term stability. However, the lyophilization process itself may induce various stresses resulting in nanoparticle aggregation. Despite a plethora of studies evaluating lyophilization of proteins, liposomes, and polymeric nanoparticles, little is known about the stability of gold nanoparticles (GNPs) upon lyophilization. Herein, the effects of lyophilization and freeze-thaw cycles on the stability of two types of GNPs: Citrate-capped GNPs (stabilized via weakly physisorbed citrate ions, Cit-GNPs) and mercaptoacetic acid-capped GNPs (stabilized via strongly chemisorbed mercaptoacetic acid, MAA-GNPs) are investigated. Both types of GNPs have similar core size and effective surface charge as evident from transmission electron microscopy and zeta potential measurements, respectively. Plasmon absorption of GNPs and its dependence on nanoparticle aggregation was employed to follow stability of GNPs in combination with dynamic light scattering analysis. Plasmon peak broadening index (PPBI) is proposed herein for the first time to quantify GNPs aggregation using nonlinear Gaussian fitting of GNPs UV-vis spectra. Our results indicate that Cit-GNPs aggregate irreversibly upon freeze-thaw cycles and lyophilization. In contrast, MAA-GNPs exhibits remarkable stability under the same conditions. Cit-GNPs exhibit no significant aggregation in the presence of cryoprotectants (molecules that are typically used to protect labile ingredients during lyophilization) upon freeze-thaw cycles and lyophilization. The effectiveness of the cyroprotectants evaluated was on the order of trehalose or sucrose > sorbitol > mannitol. The ability of cryoprotectants to prevent GNPs aggregation was dependent on their chemical structure and their ability to interact with the GNPs as assessed with zeta potential analysis.

Evaluation of immunosuppression induced by metronidazole in Balb/c mice and human peripheral blood lymphocytes.

The immunomodulatory effect of metronidazole (MTZ), a nitroimidazole drug used as an antiprotozoal and antibacterial agent, was investigated using Balb/c mice and human peripheral blood lymphocytes. For in vivo studies, mice were divided into six groups, six animals per group, group I received vehicle alone while the other groups (II-VI) received intraperitoneal injections of MTZ (14, 28, 42, 57, and 114 mg/kg) respectively. For in vitro studies different concentrations of MTZ (5, 10, 50, and 200 microg/ml) were used. MTZ showed a significant decrease in the percentage of circulating neutrophils and monocytes and an increase in the percentage of circulating lymphocytes. The relative weights of spleen as well as the relative body weight gain also decreased. Detectable changes were seen in the histology of spleen and thymus. Splenic plaque-forming cells (PFC), hemagglutination (HA) titer to sheep red blood cells (SRBC), spleenocytes and human peripheral blood lymphocytes proliferation (MLR) were markedly suppressed by MTZ treatment as compared to control group. MTZ also induced a significant decrease in delayed-type hypersensitivity (DTH) reaction, phagocytic activity (assessed by phagocytic capacity and phagocytic index) as well as TNF-alpha secretion by peritoneal macrophages. These observations indicate that MTZ significantly induced immunosuppression in mice and in human peripheral blood lymphocytes.

Pancreatic lipase inhibition activity of trilactone terpenes of Ginkgo biloba.

The prevalence of obesity is increasing at an alarming rate, but, unfortunately, only a few drugs are currently available on the market. In the present study, the methanolic extract of Ginkgo biloba L. (Ginkgoaceae) was investigated as an inhibitor of pancreatic lipase (PL) in an attempt to explain its hypolipidaemic activity. In vitro assay of G. biloba leaves extract revealed a substantial PL inhibition activity (IC50 = 16.5 µg/mL). Further investigation was performed by employing theoretical docking simulations and experimental testing to uncover the active constituents responsible for G. biloba anti-lipase activity. Virtually, terpene trilactones, including ginkgolides and bilobalide, were found to fit within the binding pocket of PL via several attractive interactions with key amino acids. Experimentally, ginkgolides A, B, and bilobalide were found to inhibit PL significantly (IC50 = 22.9, 90.0, and 60.1 µg/mL, respectively). Our findings demonstrated that the hypolipidaemic effects of G. biloba extract can be attributed to the inhibition of PL by, at least in part, terpene trilactones. In conclusion, this work can be considered a new step towards the discovery of new natural safe hypolipidaemic PL inhibitors.

Skin‐lightening practice among women living in Jordan: prevalence, determinants, and user’s awareness

Background  The use and misuse of skin‐lightening products among women living in Arab communities have not been documented previously. This study investigates the determinants, the prevalence and users awareness associated with the use and misuse of skin‐lightening products among women living in Jordan.

Sustained-release of buspirone HCl by co spray-drying with aqueous polymeric dispersions

Sustained-release of buspirone HCl (BUH) was attempted by spray drying after dissolving in two commercially available aqueous polymeric dispersions (Eudragit RS 30 D or Kollicoat SR 30 D) at five different drug:polymer ratios (1:1, 1:2, 1:3, 1:6 and 1:9). The produced spray-dried agglomerates were evaluated in terms of their particle size and morphology, production yield, encapsulation efficiency and in-vitro release of BUH. Possible drug-polymer interactions were checked by Differential Scanning Calorimetry (DSC) and FT-IR spectroscopy. Scanning electron microscopy (SEM) was employed for the qualitative characterization of particle size and morphology. Encapsulation efficiency was generally high (around 100%) and independent of the polymeric dispersion type, while production yield was generally low (7.2-31.0%) and significantly lower for the case of Kollicoat SR 30 D (KSR) than for Eudragit RS 30 D (ERS). Scanning electron micrographs showed remarkable changes in size and shape of agglomerates due to the type of aqueous polymeric dispersion and drug:polymer ratio. In-vitro release of BUH from compacted co spray-dried agglomerates was remarkably slower and incomplete for the case of Kollicoat at drug:polymer ratio below 1, presumably due to increased plastic deformation of the developed coating instead of fragmentation in the case of Eudragit coating during compaction.

Olanzapine inhibits glycogen synthase kinase-3β: An investigation by docking simulation and experimental validation

Olanzapine was investigated as an inhibitor of glycogen synthase kinase-3beta (GSK-3beta) in an attempt to evaluate its effect on blood glucose level. The investigation included simulated docking experiments to fit olanzapine within the binding pocket of GSK-3beta followed by in vitro enzyme inhibition assay as well as in vivo subchronic animal treatment. Olanzapine was found to readily fit within the binding pocket of GSK-3beta in a low energy orientation characterized with optimal attractive interactions bridging the tricyclic thienobenzodiazepine nitrogen and sulfur atoms of olanzapine and the residue of VAL-135 of GSK-3beta. In vivo experiments showed a significant decrease in fasting blood glucose level in Balb/c mice at 1.0, 2.0 and 3.0 mg/kg dose levels (P<0.05) and 6 fold increase in liver glycogen level at the 3 mg/kg dose level (P<0.001). Moreover; olanzapine was found to potently inhibit recombinant GSK-3beta in vitro (IC(50) value=91.0 nM). Our findings strongly suggest that olanzapine has significant GSK-3beta inhibition activity that could justify some of its pharmacological effects and glucose metabolic disturbances.

Evaluation of hydrophilic matrix tablets based on Carbopol® 971P and low-viscosity sodium alginate for pH-independent controlled drug release

Background: The aim of this study was to evaluate matrix tablets containing different ratios of Carbopol® 971P (CP) to low-viscosity sodium alginate (SA) and assess their suitability for pH-independent controlled drug release. Methods: Two processing methods (physical mixing, PM and spray-drying, SD) were applied before compaction and the release from corresponding matrices was compared. The release from CP-SA PM matrices was also investigated using three model drugs (paracetamol, salicylic acid, and verapamil HCl) and two dissolution media (0.1 N HCl or phosphate buffer, pH = 6.8), and the release rate, mechanism, and pH-dependence were characterized by fitting of Higuchi and Peppas models, and evaluation of similarity factor. Furthermore, swelling behavior of CP-SA matrix tablets was studied for evaluating its impact on drug release. Results: The processing method (SD or PM) markedly affected the drug release from CP-SA matrices. ANOVA tests showed significant effects of the CP:SA ratio and drug type on the release rate (expressed by the constant, KH, from Higuchi model) and of the dissolution medium on the release mechanism (expressed by the exponent, n, from Peppas model). Similarity factor (f2) indicated that the CP:SA ratios ≥ 25:75 and ≥ 50:50 were suitable for pH-independent release of paracetamol and salicylic acid, respectively, although for verapamil HCl, the matrix with low CP:SA ratio (0:100) showed remarkably reduced pH-dependence of release. Swelling parameters (water uptake and mass loss) were significantly changed with experimental variables (CP:SA ratio, medium, and time) and were in good correlation with drug release. Conclusion: Matrix tablets based on CP and SA form a potentially useful versatile system for pH-independent controlled drug release.

Antioxidant, antihyperuricemic and xanthine oxidase inhibitory activities of Hyoscyamus reticulatus.

Context: Xanthine oxidase (XO) is a key enzyme in the pathophysiological homeostasis of hyperuricemia. It catalyzes the oxidation of hypoxanthine to xanthine and then to uric acid, the reaction involves the formation of free radical intermediates and superoxide byproducts. Objectives: This study was undertaken to investigate the antioxidant, antihyperuricemic, and xanthine oxidase inhibitory potentials of Hyoscyamus reticulatus L. (Solanaceae) extract. Materials and methods: The antioxidant potency was measured using the ABTS•+ scavenging capacity system, which includes Trolox as a standard. The xanthine oxidase inhibitory activity of the extract was quantitated in vitro by measuring the decline in the catalytic rate of xanthine oxidase following incubations with the plant extracts and using xanthine as a substrate. The hypouricemic potential of the extract was evaluated using an in vivo model for hyperuricemia. We tested three different doses of the extract and allopurinol was used as standard antihyperuricemic positive control. Results: H. reticulatus aqueous extract exhibited significant antioxidant scavenging properties (533.26 μmol TE/g dry extract weight) and inhibitory effect on xanthine oxidase activity (IC50 12.8 μg/mL). Furthermore, oral administration of the aqueous extract significantly reduced serum urate levels in oxonate-induced hyperuricemic mice in a dose-dependent manner. Discussion and conclusion: Our results suggest that the aqueous extract of H. reticulatus aerial parts might have great potential as an antioxidant and a hypouricemic agent. Our lab is currently identifying the active compounds in the extract to which the biological activities could be attributed.

Development of a biphasic dissolution test for Deferasirox dispersible tablets and its application in establishing an in vitro–in vivo correlation

In a biphasic dissolution medium, the integration of the in vitro dissolution of a drug in an aqueous phase and its subsequent partitioning into an organic phase is hypothesized to simulate the in vivo drug absorption. Such a methodology is expected to improve the probability of achieving a successful in vitro-in vivo correlation. Dissolution of Dispersible tablets of Deferasirox, a biopharmaceutics classification system type II compound, was studied in a biphasic dissolution medium using a flow-through dissolution apparatus coupled to a paddle apparatus. The experimental parameters associated with dissolution were optimized to discriminate between Deferasirox dispersible tablets of different formulations. The dissolution profiles obtained from this system were subsequently used to construct a level A in vitro-in vivo correlation.