DARU Journal of Pharmaceutical Sciences
Year:2006 | Volume:14 | Issue:1|Papers Count:10

Some ion channels like voltage-operated calcium channels (VOCC) within the plasma membrane of vascular muscle cells from the walls of resistance arteries and arterioles play a central role in the regulation of vascular tone. On the basis of reports about the beneficial attenuating effect of fenugreek (Trigonella foenum-graecum L.; TFG) on the contractile reactivity of aortic rings of diabetic rats, this study was carried out to evaluate the possible involvement of L-type voltage-operated calcium channels in the vascular effect of this medicinal plant. For this purpose, male Wistar rats were made diabetic using streptozotocin (STZ, 60 mg/Kg, i.p). The extract-treated control and diabetic rats received aqueous leaf extract of TFG (200 mg/Kg, i.p.) every other day for two months. At the end of the study, contractile response of isolated aortic rings to KCl and noreadrenaline (NA) was determined in the absence and presence of the calcium channel blocker nifedipine. The results showed that aortic rings from diabetic rats are more responsive to the effect of KCl and NA than those of controls, TFG extract treatment could attenuate the enhanced contractile response of aortic rings of diabetic rats, and nifedipine pretreatment could partially neutralize the beneficial effect of this extract. It is concluded that TFG extract attenuates the enhanced vascular reactivity in chronic diabetic rats and voltage-operated calcium channels are in part responsible for this effect of TFG extract.

The effects of tyrosine kinases on acute and chronic inflammation during diabetes are not fully determined. Therefore, the present study focuses on the effects of genistein, a tyrosine kinase inhibitor, on acute and chronic inflammation in diabetic mice. The mice either received normal saline (control, 0.1 ml, i.p., n=144) or streptozotocin (diabetic, STZ, 200 mg kg-1, i.p., n=144). A week after injection of saline or STZ acute and chronic inflammation was induced by injecting carrageenan and implanting 2 cotton pellets. Before injection carrageenan or 5 day after implantation, 9 mice from each group (control or diabetic) received genistein (10 mg kg-1, i.p.), indomethacin (2 mg kg-1, i.p.) or L-NAME (0.1 mg kg-1, i.p.). Paw edema and the weight of cotton pellets were significantly higher in diabetic mice. Pretreatment with either indomethacin or L-NAME significantly reduced the acute and chronic inflammation in the diabetic group. Genistein reduced chronic inflammation significantly. These results suggest that activation of tyrosine kinases as well as prostaglandins and nitric oxide pathways are involved in the increased chronic inflammatory responses observed in the diabetic animals.

Hydroalcoholic extract of Pycnocycla spinosa Decne. exBoiss. var. spinosa has in vitro spasmolytic action, and at oral dose of 250µg/kg inhibits castor oil induced diarrhoea in mice. In this investigation, effects of P. spinosa var. spinosa extract in comparison with nifedipine on blood pressure and heart rate in animal model was studied. Injection of three bolus doses of P. spinosa var. spinosa extract (100µg/kg, 500µg/kg and 1mg/kg) into the jugular vein, temporary reduced blood pressure and heart rate. However, soon after completion of extract administration blood pressure and heart rate returned to normal. Nifedipine on the other hand caused a sustained reduction in blood pressure and decreased heart rate compared with the control group. From this study it was concluded that P. spinosa var. spinosa extract at antidiarrhoeal dose has no significant effect on blood pressure and heart rate.

A sensitive, accurate and rapid reverse phase HPLC method was developed to quantitate plasma levels of metronidazole in order to conduct a comparative bioavailability studies. The drug and internal standard were added to plasma samples, vortexed and then zinc sulfate solution was added in order to precipitate the plasma proteins. Samples were centrifuged at 3000 rpm for 10 min. The supernatant layer was separated and analyzed on a phenyl (300 × 4.6mm) column, with 5% acetonitrile in 0.1 M KH2PO4 buffer (pH = 4.5) at 324 nm. The standard curve covering 0.15 – 30 µg/ml concentration range, was linear (r2 = 0.9999), relative errors were within 2.48 to 9.15 % and the CV% ranged from 2.999 to 10.796. The method is suitable for bioavailability, pharmacokinetic, and bioequivalent studies in human.The in-vivo study was carried out in 12 healthy volunteers according to a single dose, two-sequence, cross over randomized design. The bioavailability was compared using the total area under the plasma level versus time curve (AUC0-48, AUC0-∞), peak plasma concentration (Cmax) and time to Cmax (Tmax). No statistically significant difference was found between the AUC0-∞ , Cmax and Tmaxx values of the test and reference, Flagyl® (p > 0.05). The 90% CI for the ratio of the AUC0-∞ (0.94-1.07) and Cmax (0.88-1.03) and the logarithmically transformed AUC0-∞ (0.99-1.01) and Cmax (0.94-1.01) values of the generic product over those of Flagyl® was calculated to be within the acceptable limit of 0.80-1.20 and 0.80-1.25, respectively. It was, therefore, concluded that the generic metronidazole was bioequivalent with the innovator formulation.

Applicability of the Jouyban-Acree model for calculation of solvatochromic parameter (ENr ) of binary solvents at various temperatures has been shown by employing 12 experimental data sets collected from the literature. The accuracy of the model was evaluated by calculating average percentage deviation (APD) between calculated and observed values. The obtained overall APD (±S.D.) were 1.2 (± 0.9) and 2.2 (± 1.8) %, respectively for correlative and predictive analyses.

There is an increased risk of neural tube defects and axial skeletal malformations among infants born by mothers who had received Valproic acid...The aim of the present study is, if administration of valproic acid can induce maternal hepatic Metallothionein (MT) synthesis and so secondary decrease of plasma Zn. In the present experimental study, mated rats were divided into four groups of 12 animals each [control, valproic acid (VPA), valproic acid + zinc (VPA+ Zn) and Zinc (Zn) groups]. The VPA group received 300 mg/kg valproic acid; daily. The control group received an equal volume of 0.9% NaCI. The VPA+ Zn group received 300 mg/kg VPA as well as 30 mg/kg zinc sulfate, and the Zn group received 30 mg/kg zinc sulfate, daily. These drugs were administered intraperitoneally from day 6 through day 15 of gestation. Dams were killed on GD 16 or 20. Blood was drawn to determine plasma zinc; furthermore, maternal liver Zn and MT were also determined. The zinc concentration in the plasma of rats treated with valproic acid was significantly lower than those of the other groups on GD 16 (p=0.004), but liver Zn (p=0.016) and MT (p=0.004) were significantly higher than those of the control group. On GD 20 the incidence of skeletal malformations and neural tube defects tended to be higher in VPA group than VPA+ Zn treated group and no anomalies were seen in the control group. The results from the present experiment support hypothesis that one of biochemical lesions causing the teratogenicity of VPA is a drug induced maternal plasma zinc deficiency secondary to Metallothionein induction in liver.

Focal cerebral ischemia (Stroke) is the cessation or severe reduction of blood flow to an area of the brain that through activation of a complex cytotoxic cascade results in neuronal cell death. The present study was designed to examine the effects of post-ischemic treatment with aminoguanidine (AG) on cortical, striatal infarct volume as well as neurological dysfunctions. Rats (n=23) were allocated to sham, saline or AG (300 mg/kg)-treated groups. Ischemia was induced by 90 minutes middle cerebral artery occlusion, followed by 24 hrs reperfusion. Saline or AG was administered intraperitoneal at one hour after induction of ischemia. At the end of 24hrs reperfusion, neurological deficit score was tested and cortical, striatal infarct volumes were determined by Triphenyltetrazolium chloride staining.Administration of AG (300 mg/kg) at one hours after ischemia resulted in a significantly lower cortical (85±25 vs. 210±13 mm3), striatal (35±5 vs. 58±10 mm3) infarct volumes, and neurological deficit score (1.88±0.23 vs. 2.67±0.21). Our findings indicate that aminoguanidine is a potent neuroprotective in rat model of transient focal cerebral ischemia. The future studies are required to clear cerebroprotective mechanism of aminoguanidine and possible use of this agent as a therapeutic target in stroke patients.

In this investigation the reactivation of cholinesterases by pralidoxime in parathion and paraoxon intoxication in plasma and erythrocytes were studied. For this purpose, human plasma and erythrocytes were incubated with various concentrations of parathion (0.1-10 µM) and paraoxon (0.03-0.3 µM) at 37 oC for 10 min. Then, pralidoxime (10-300 µM) was added to the samples and incubated for 10 min before cholinesterases assay.The results showed that effects of parathion and paraoxon were dose dependent. These agents inhibited more than 85% of butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) activity and the inhibitory effect of paraoxon was 10 times more than parathion. BChE activity was significantly higher than the control at 100 µM of pralidoxime and it reduced inhibitory effects of parathion to less than 50% and of paraoxon to 42% of control. When pralidoxime (10 µM) was added to erythrocytes, the inhibitory effects of two organophosphates were reduced to less than 15%. At higher concentrations of pralidoxime (>100 µM), both BChE and AChE activities were inhibited.

Chronic exposure to Lead (Pb) affects neural functions in central nervous system (CNS) particularly the learning and memory. On the other hand, alteration of calcium level in the CNS results in activation of NOS where it is expected to increase nitric oxide level in hippocampus. In this study the role of Lead exposure in NMDA induced NO production in pyramidal hippocampal cells (CA1HP) was investigated. The NO level was determined by measurement of concentration of nitrite and nitrate as NO products using the metHb production at 401 nm. The ACBD (NMDA agonist)-induced NO level was almost reduced to the control level (2.5 nM) in the presence of 10 and 100 nM of Lead acetate. Lead acetate at concentrations which normally results in chronic toxicity did not increase the nitric oxide (NO) production by CA1HP. One reason for this finding could be the interaction of Lead with NMDA receptors due to similarity of Pb2+ to Zn2+ ion. Another reason may be related to direct interaction of Lead with NMDA receptors that inhibit the stimulated NO production.

Radioimmunoscintigraphy (RIS) has found widespread clinical application in tumor diagnosis. The antibody (Ab) PR81 is a new murine anti-MUC1 monoclonal antibody (MAb) against human breast carcinoma. In this study a very simple, rapid and efficient method for labeling of this MAb with 99mTc, particularly suitable for development of a ‘kit’is described. The reduction of Ab was performed with 2-mercaptoethanol (2-ME) at a molar ratio of 2000:1 (2-ME:MAb) and the reduced Ab was labeled with 99mTc via methylene diphosphonate (MDP) as a transchelator. The labeling efficiency which was determined by instant thin layer chromatography (ITLC) was 94.2%±2.3. Radiocolloides measured by cellulose nitrate electrophoresis were 2.5%±1.7. In vitro stability of the labeled product in human serum which was measured by gel filtration chromatography (FPLC) was 70%±5.7 over 24 hr. The integrity of labeled MAb was checked by means of SDS-PAGE and no significant fragmentation was observed. The results of the cell-binding studies showed that both labeled and unlabeled PR81 were able to compete for binding to MCF 7 cells. Biodistribution studies were performed in normal BALB/c mice at 4 and 24 hrs post-injection and no important accumulation was observed in vital organs. These results show that the new radiopharmaceutical may be considered as a promising candidate for imaging of breast cancer.