Pharmaceutical Sciences
Volume:19 Issue: 4, 2014

A simple, sensitive, selective and precise stability indicating HPLC method is developed and validated for the assay of ambrisentan in pharmaceutical dosage form. Separation of the drug was achieved on Agilent Zorbax C18 column (250 mm × 4.6 mm I.D., 5 μm particle size) under the isocratic mode of elution. The solvent system consisted of 0.1M potassium dihydrogen phosphate buffer (pH was adjusted to 4.4 with orthophosphoric acid) and methanol (30:70 v/v) at a flow rate of 1.0 ml/min. The method was carried out in the absorbance mode at 210 nm. The method was statistically validated according to International Conference on Harmonization guideline. Ambrisentan was subjected to stress degradation studies under acidic, basic, oxidative, thermal and photolytic conditions. The system was found to give compact peak for ambrisentan (Retention time is 3.315 min). The method was linear in the range of 1 - 150 µg/ml. The linear regression data for the calibration plot showed good relationship (r2 = 0.9996). The relative standard deviation and mean recovery values at different concentration levels were within limits. The performance of the method was not changed when small variations in the experimental conditions were made. Degradation products resulting from stress degradation studies did not interfere with the detection of ambrisentan. The proposed stability indicting HPLC method is simple, precise, accurate, robust and selective. This method can be used for quantification of ambrisentan in bulk drug and in pharmaceutical dosage forms.

OCT4 is an important gene involved in stem cell (ESC, ASC and CSC) self-renewal and cell stemness states. The OCT4 gene encodes at least three variants, including OCT4A, B, and B1, each one has different biological activities. OCT4A acts as a silencing factor and downregulates cell differentiation. OCT4B is expressed in stem and somatic cells and does not play a role in cell stemness whereas OCT4B1 is expressed in stem cells, especially cancer stem cells, and has anti-apoptotic properties. The present study was carried out to investigate the relation between these variants and key genes in self-renewal pathways. Cancer cell lines from gastric adenocarcinoma (AGS), bladder tumor (5637), and brain tumor (132N1) were transfected by specific OCT4B1 siRNA using lipofection method and the gene was successfully suppressed in the test group after 48 hours. The expression of OCT4A, OCT4B, SOX2, NANOG and KLF4 genes were evaluated by qRT-PCR after this time. The results demonstrated that expression levels of OCT4A and stemness genes including SOX2, NANOG and KLF4 were decreased following OCT4B1 downregulation, while expression of OCT4B was increased. Our results suggest a direct relation between expression of OCT4B1 and genes that control self-renewal. The data suggests that in the presence of OCT4B1, stemness genes are expressed, while in its absence, these genes will be down-regulated, therefore, strategies that specifically target repression could be considered for future molecular cancer therapies.

Several mechanism including autoxidation of glucose, protein glycation and advanced glycation end products (AGEs) formation may to be involved in hyperglycemia mediated oxidative stress. Herein, in this study, the effects of rutin with high antioxidant activity isolated from Teucrium polium on structural changes of human serum albumin (HSA) were performed. The major compounds of T. polium methanol extract were isolated and their radical scavenging properties were established through various approaches including 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radicals scavenging, and reducing power. The structural changes of HSA with glucose, in the presence of rutin were studied with far-UV CD spectroscopy. Based on our results, rutin, a flavonol glycoside isolated from T. polium exhibited high antioxidant activity compared to the other isolated compounds from T. polium. Rutin inhibited high glucose induced oxidative damages to protein by decreasing protein carbonyl formation (PCO) and preventing thiols group from oxidation. In addition, evaluating the structural changes of HSA by glucose in the presence of rutin showed that rutin may be able to increase the helicity of the protein and prevent helix decrement in the secondary structure of HSA. We found that rutin with high antioxidant activity effectively inhibited the generation of amadori products and exhibited good inhibitory effects on the formations of α-dicarbonyl compounds and AGEs.

In our previous work, we synthesized a novel analogue of losartan (Compound A) with dual calcium (Ca2+) channel blocking andantagonism of angiotensin II (ANG II) type 1 receptor (AT1) activity. In this study, the effects of this compound (compound A) on the blood pressure (BP) and the heart rate (HR) of normotensive rats were investigated and compared to losartan, which was used as a positive control. A novel dihydropyridine compound was synthesized by connecting a dihydropyridine nucleus to an imidazole ring. Three doses of compound A (0.25, 0.5 and 1 mg/kg) and three doses of losartan (1, 2 and 4 mg/kg) were administered intravenously to different groups of normotensive male rats, and their effects on mean arterial BP (MABP) and heart rate (HR) were evaluated. All three doses of compound A reduced the MABP in normotensive anaesthetized rats in a dose-dependent manner. The administration of 1 mg/kg of compound A and 4 mg/kg of losartan (the largest doses) caused a reduction of 67.2 ± 2.2 and 69.3 ± 2.9 mmHg in the MABP, respectively. It can be concluded that like losartan, compound A has hypotensive properties. It can also be concluded that compound A has greater potency than losartan.

Electromagnetic field (EMF) has harmful effects on different tissues specially testis through different mechanisms such as increase free radicals. Therefore, application of antioxidants may reduce these abnormalities. Polygonum aviculare extract (PAe)as an herbal plant has antioxidant activities. Therefore, in the present study, its protective property against EMF was investigated in testis. 6 weeks old male Balb/c mice were divided to control (without EMF exposure), EMF (exposed to 3 mT EMF for 8 weeks), EMF+PAe (received 50 mg/kg PAe and 3mT EMF for 8 weeks) and PAe (received only 50 mg/kg PAe for 8 weeks) groups. After 8 weeks the animals were sacrificed, the testes were dissected out and fixed, and then stained with hematoxylin and eosin (H & E). The sections were subjected to morphometric and histological analysis. Morphological studies showed that germinal epithelium of testes was negatively affected by EMF and the PAe reduced the harmful effects. As expected, EMF waves have destructive effects on testis morphology via producing free radicals that may cause male infertility. The herbal medicines such as polygonum aviculare extract have antioxidant activity and can reduce the harmful effects of EMF.

Honey is being used as an ingredient in more foods, pharmaceuticals and cosmetics than ever before, so honey testing has become essential to maintaining its healthful characteristics and protecting public health. This study was designed to investigate the occurrence of oxytetracycline residue in honey samples. One hundred and forty five honey samples were collected from Ardabil provinces (Northwest region of Iran). ELISA and HPLC were used to qualify and quantify the contamination of the honey samples with oxytetracycline. The ELISA assay showed that out of 145 samples, 34 samples were positive for oxytetracycline residue. ELISA analyses demonstrated that the minimum and maximum level of oxytetracycline residue was 5.32 and 369.1ng/g. HPLC analyses confirmed the ELISA findings although the level of oxytetracycline which detected with HPLC method was remarkably (P<0.05) lower than that of ELISA. Considering the relatively high contamination rates of animal originated food as well as their high rates of consumption, it is likely that consumers experience a high risk of exposure to drug residues, especially through honey bees. Specific causal factors associated with non-adherence of withdrawal requirements of drugs and therefore contaminations of food were mainly knowledge related factors. This underscores the importance of health education of farmers in dealing with the problem of drug residues contaminating animal source food.