DARU, Journal of Pharmaceutical Sciences
Volume:13 Issue: 3, Autumn 2005

Aldehyde oxidase (EC 1.2.3.1), a cytosolic enzyme containing FAD, molybdenum and iron-sulphur cluster, is a member of non-cytochrome P-450 enzymes called molybdenum hydroxylases which is involved in the metabolism of a wide range of endogenous compounds and many drug substances. Drug metabolism is one of the important characteristics which influences many aspects of a therapeutic agent such as routes of administration, drug interaction and toxicity and therefore, characterisation of the key interactions between enzymes and substrates is very important from drug development point of view. The aim of this study was to generate a three-dimensional model of human aldehyde oxidase (AO) in order to assist us to identify the mode of interaction between enzyme and a set of phethalazine/quinazoline derivatives. Both sequence-based (BLAST) and inverse protein fold recognition methods (THREADER) were used to identify the crystal structure of bovine xanthine dehydrogenase (pdb code of 1FO4) as the suitable template for comparative modelling of human AO. Model structure was generated by aligning and then threading the sequence of human AO onto the template structure, incorporating the associated cofactors, and molecular dynamics simulations and energy minimization using GROMACS program. Different criteria which were measured by the PROCHECK, QPACK, VERIFY-3D were indicative of a proper fold for the predicted structural model of human AO. For example, 97.9 percentages of phi and psi angles were in the favoured and most favoured regions in the ramachandran plot, and all residues in the model are assigned environmentally positive compatibility scores. Further evaluation on the model quality was performed by investigation of AO-mediated oxidation of a set of phthalazine/quinazoline derivatives to develop QSAR model capable of describing the extent of the oxidation. Substrates were aligned by docking onto the active site of the enzyme using GOLD technology and then HASL method were used to generate a 3D-QSAR model. Correlation coefficient (r2) between the test set actual and predicted Km values was 0.65.

On the basis of the structural similarity of 2-hydroxyacetamides (glycolamides) with N-glycolylmuramic acid residues of the cell wall of Mycobacterium tuberculosis several of these compounds were prepared mainly by the reaction of 5-oxo-2,2-dimethyl-1,3-dioxolane 1 (glycolic acid acetonide) with corresponding amines and their antimycobacterial activities were determined by Alamar blue Assay. Of the synthesized compounds disubstituted amides bearing hydrophilic moieties showed moderate activity.

The chemical composition of the essential oil of the aerial parts of Ferulago Bernardii from Iran was analysed by GC and GC/MS. Sixty constituents were found representing 87.9% of the oil. The main constituents of the essential oil were 2,4,5-trimethyl-benzaldehyde (21.2%), α-pinene (17.0%),spathulenol (5.0%), cis-chrysanthenyl acetate (4.4%) and caryophyllene oxide (3.2%). Antimicrobial activity of the essential oil of Ferulago Bernardii by the broth dilution method in comparison with Gentamycin and Fluconazole as standard showed weak activity against Staphylococcus aureus, Bacilus subtilis, Escherichia coli, Candida albicans and Aspergillus niger. The essential oil did not show any activity against Pseudomonas aeruginosa.

Although many pharmacological studies indicate that yohimbine antagonize the antinociceptive effects of α2-adrenoceptor agonists, there are evidences that yohimbine by itself produces antinociceptive effects in the formalin test. However, its site of action on nociceptive processing is not fully understood. In this investigation, a series of experiments were designed to study the antinociceptive effects of intraperitoneal (i.p.), intraplantar (i.pl.) and intrathecal (i.t.) administration of yohimbine in the nociceptive processing.Yohimbine (2 and 4 mg/kg, i.p.) induced antinociception in the early phase (0-5 min) as well as in the late phase (10-60 min) of formalin test. While i.pl. yohimbine (5-100 µg) decreased the response in the early phase, i.t. yohimbine (30 µg) decreased pain behavior in the late phase of formalin test in rats. In conclusion, our findings show that yohimbine induces antinociception in both phases of formalin test and its effects are produced at least in part through actions at the peripheral terminal of primary afferents or at the spinal level.

The goal of this study was to evaluate the effects of ketamine and magnesium on prevention of development of morphine tolerance and dependence in mice. In this study different groups of mice received morphine (50 mg/kg, sc) + (saline 10ml/kg), morphine (50 mg/kg, sc) + ketamine (25,50 or 75mg/kg, ip), morphine (50 mg/kg, sc) + magnesium (10,20 or 40 mg/kg, ip), morphine (50 mg/kg, sc) +ketamine (25 mg/kg, ip) + magnesium (10 mg/kg, ip)] once a day for four days. Tolerance was assessed by administration of morphine (9 mg/kg, ip) and using hot plate test on fifth day. Withdrawal symptoms were assessed by administration of naloxone (4 mg/kg, ip) two hours after co-administration of morphine with either ketamine or magnesium. It was found that pretreatment with ketamine or magnesium decreased the degree of tolerance and dependence. Additionally, co-administration of ketamine and magnesium before morphine administration decreased the tolerance and dependence significantly. From these results it may be concluded that administration of ketamine or magnesium alone or together could prevent the development of tolerance and dependence to the analgesic effects of morphine. These effects may be related to the N-Methyl-DAspartate (NMDA) receptor antagonist behavior of ketamine and the ability of magnesium to block the Ca channel of NMDA receptors.

It has been shown that nitric oxide is a mediator with a major role in pain signaling at the level of dorsal root ganglion neurons of the spinal cord. The main objective of the present study was to elucidate the influence of sex on the effects of nitric oxide on pain mediation in mice. Painful stimuli such as heat induced by light beam focused on tail and hot plate chamber were applied. Animals were injected with either morphine (0.5, 5 and 50 mg/100g body weight) or L-NAME (0.1, 0.5 and 1 mg/100g body weight) intraperitonealy. Changes in tail flick latency and responses to the hot plate chamber were measured in different groups of mice. The tail flick latency was increased significantly in both male and female animals treated with morphine (control male (sec): 2.45 ± 0.16, male which received morphine 50 mg/100g body weight: 13.5 ± 0.6, control female: 3.4 ± 0.3, female which received morphine 50 mg/100g body weight: 13.8 ± 0.6; P<0.001 vs control in both cases). The response time to the hot plate chamber was also increased significantly by morphine pretreatment in both male and female mice. The tail flick latency and the response time to the hot plate chamber were significantly higher in the female mice (eg,the response time to the hot plate chamber (sec) in male: 7.3 ± 0.8, in female: 13.7 ± 1.6, P<0.01 vs female mice). Pretreatment with L-NAME at all concentrations caused a significant non-dose dependent increase in the response time to the hot plate chamber only in the male mice. These results may suggest that pain is mediated through different mediators in male and female mice and probable involves sex hormones. Furthermore, from the effect of L-NAME on pain sensation, it maybe suggested that Larginine-nitric oxide pathway is more important in male in comparison with female in pain signaling.

A simple, sensitive and reproducible HPLC method is presented for determination of mycophenolic acid(MPA) in human plasma. Samples were prepared after precipitation of the plasma protein by addition of acetonitrile and naproxen was used as internal standard (I.S.). Separation was performed by reversedphase HPLC, using a Hamilton PRP-C18 Column, 51% acetonitrile and 49% potassium phosphate buffer (20 mM) at pH 3.0 as mobile phase, flow rate of 1.0 ml/min, and UV detection at 215 nm. MPA and I.S. had retention times of 7.5 and 11.35 min, respectively. The method showed an acceptable linearity in the range of 0.1µg/ml-40µg/ml with r2 of. 9992. The concentration of 0.1µg/ml was determined as quantification limit. Mean absolute recovery was 94.8%. The mean intra- and inter-day reproducibility of method was 4.6 and 11.4% respectively.

In this investigation, the pharmacokinetic variables of continuous infusion and intermittent bolus injection of furosemide and the possible relationship between its pharmacokinetic characteristics and pharmacodynamic profile among intensive care unit (ICU) patients were studied. In this prospective, randomized, clinical trial, twelve patients received IV bolus of 20 mg of the drug during 3 hours period and, the drug dose was doubled, when the urine output was less than 1 ml/kg/h (group 1). The other nine patients received a continuous intravenous furosemide infusion at the rate of 0.1 mg/kg/h (group 2). The amount of furosemide in serum was measured by high performance liquid chromatography (HPLC). Results showed a positive correlation between plasma clearance of furosemide and its diuretic activity (P=0.01). The pharmacokinetic parameters such as Vd (l), CL (ml/min), Ke (min-1) and t½ (min) in continuous infusion patients were not significantly differed from the bolus patients (P-values 0.5, 0.9, 0.9,0.9, respectively). Nevertheless the observed plasma clearance of drug in the continuous infusion group was clinically higher than bolus injection group and as a result the cumulative urine output per hour per mg of furosemide in a continuous infusion was observed to be higher than bolus(P=0.2). Changes in serum sodium and potassium were similar for both groups, but bolus injection patients were associated with higher potassium depletion (P=0.001). Therefore, continuous infusion seems to be better means of diuretic therapy in critically ill patients.