Antiamyloidogenic Effects of Ellagic Acid on Human Serum Albumin Fibril Formation Induced by Potassium Sorbate and Glucose.

Oxidative stress has the main role in protein conformational changes and consequent direct involvement in different kind of diseases. Potassium sorbate as a widespread industrial preservative and glucose are two important oxidants that can be involved in oxidative stress. In this study the effect of ellagic acid as a phenolic antioxidant on amyloid fibril formation of human serum albumin upon incubation of potassium sorbate and glucose was studied using thioflavin T assay, surface tension, atomic force microscopy, Amadori product, and carbonyl content assays. The thioflavin T assay and atomic force microscopy micrographs demonstrated the antiamyloidogenic effect of ellagic acid on the human serum albumin fibril formation. This antioxidant also had the repair effect on surface tension of the modified human serum albumin (amyloid intermediates), which was destructed, caused by potassium sorbate and glucose. This mechanism takes place because of potent carbonyl stress suppression effect of ellagic acid, which was strengthening by potassium sorbate in the presence and absence of glucose.

Relationship of seminal reactive nitrogen and oxygen species and total antioxidant capacity with sperm DNA fragmentation in infertile couples with normal and abnormal sperm parameters.

The objective of this study was to investigate the association between the amount of superoxide anion, peroxynitrite as oxidative stress (OS) markers and total antioxidant capacity (TAC) with sperm DNA fragmentation in infertile men with abnormal semen parameters. Semen samples were obtained from 102 infertile couples and divided into groups with normal and abnormal semen parameters according to the World Health Organization (WHO). Peroxynitrite and superoxide anions were detected using spectrofluorometric assays combined with 2,7 dicholorofluorescein (DCF)-DA and 4-chloro-7-nitrobenzo-2-oxa -1, 3-diazole (NBD-CL). Colorimetric assay was used for evaluation of TAC, while DNA fragmentation was studied by using sperm chromatin dispersion test. Superoxide anion, peroxynitrite and DNA fragmentation were significantly higher in infertile couples with abnormal semen parameters as compared to infertile couples with normal semen (P < 0.01). TAC was significantly lower in infertile men with abnormal semen parameters (P < 0.01). There was also a significant positive correlation between OS markers with sperm DNA fragmentation (r = 0.59, P < 0.01 and r = 0.67, P < 0.01, respectively). We have found that imbalance between superoxide anion and peroxynitrite with antioxidant capacity in infertile men with abnormal sperm parameters is associated with higher sperm DNA fragmentation.

Energetic domains and conformational analysis of human serum albumin upon co-incubation with sodium benzoate and glucose.

Sodium benzoate (SB), a powerful inhibitor of microbial growth, is one of the most commonly used food preservative. Here, we determined the effects of SB on human serum albumin (HSA) structure in the presence or absence of glucose after 35 days of incubation under physiological conditions. The biochemical, biophysical, and molecular approaches including free amine content assay (TNBSA assay), fluorescence, and circular dichroism spectroscopy (CD), differential scanning calorimetry (DSC), and molecular docking and LIGPLOT studies were utilized for structural studies. The TNBSA results indicated that SB has the ability to bind Lys residues in HSA through covalent bonds. The docking and LIGPLOT studies also determined another specific site via hydrophobic interactions. The CD results showed more structural helicity for HSA incubated with SB, while HSA incubated with glucose had the least, and HSA incubated with glucose + SB had medium helicity. Fluorescence spectrophotometry results demonstrated partial unfolding of HSA incubated with SB in the presence or absence of glucose, while maximum partial unfolding was observed in HSA incubated with glucose. These results were confirmed by DSC and its deconvoluted thermograms. The DSC results also showed significant changes in HSA energetic structural domains due to HSA incubation with SB in the presence or absence of glucose. Together, our studies showed the formation of three different intermediates and indicate that biomolecular investigation are effective in providing new insight into safety determinations especially in health-related conditions including diabetes.

A comparative study of two novel nanosized radiolabeled analogues of methionine for SPECT tumor imaging.

It has been reported that most tumor cells show an increased uptake of variety of amino acids specially methionine when compared with normal cells and amino acid transport is generally increased in malignant transformation. Based on the evidences, two novel nanosized analogues of methionine (Anionic Linear Globular Dendrimer G(2), a biodigredabale anionic linear globular-Methionin, and DTPA-Methionine(1) conjugates) were synthesized and labeled with (99m)Tc and used in tumor imaging/ therapy in vitro and in vivo. The results showed marked tumor SPECT molecular imaging liabilities for both compounds but with a better performance by administration of (99m)Tc-Dendrimer G(2)-Methionin. The results also showed a good anticancer activity for 99mTc-DTPA-Methionine. Based on the present study (99m)Tc-Dendrimer G(2)-Methionin or 99mTc-DTPA-(Methionine)(1) have potentials to be used in tumor molecular imaging as well as cancer therapy in future.

Kinetic and conformational studies of adenosine deaminase upon interaction with oxazepam and lorazepam.

Oxazepam and lorazepam inhibit the adenosine deaminase (ADA) differently. In the case of lorazepam temperature increment causes an increase in the inhibition potency whereas higher temperature reduces the inhibitory effect of oxazepam; which proposes the overall profounder structural changes in the case of lorazepam relative to those caused by oxazepam.

Synthesis and cloxacillin antimicrobial enhancement of 2-methylsulfonylimidazolyl-1,4-dihydropyridine derivatives.

BACKGROUND AND THE PURPOSE OF THE STUDY: Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) has been a major problem worldwide in chemotherapy of infection disease. This study was designed to assess the enhancing effects of a new group of dihydropyridine-3,5dicarboxamides, in combination with cloxacillin with distinctly different mechanisms of action against MRSAs. MATERIAL AND METHODS: Dihydropyridine-3,5-dicarboxamides with 2-methylsulfonylimidazole at 4 position 6a-k were synthesized by the reaction of corresponding aldehyde 5 with different N-aryl acetoacetamides 3 in the presence of ammonium hydroxide. Agar disc diffusion method was used to determine the antibacterial and potentiating activity of different synthetic compounds in the presence and absence of cloxacillin to evaluate their activity as modulators of multidrugresistant (MDR). RESULTS AND MAJOR CONCLUSION: The antibacterial effect of cloxacillin was enhanced by compounds 6g and 6h against cloxacillin-resistant strains (MRSA(1) and MRSA(2)). The potentiation was found 1 2 to be statistically significant (p<0.01). Compound 6g at concentration of 1000 µg/disc, caused a 329 percent potentiation of the activity of cloxacillin against MRSA(1).

Thermal dissociation and conformational lock of superoxide dismutase.

The kinetics of thermal dissociation of superoxide dismutase (SOD) was studied in 0.05 M Tris-HCl buffer at pH 7.4 containing 10(-4) M EDTA. The number of conformational locks and contact areas and amino acid residues of dimers of SOD were obtained by kinetic analysis and biochemical calculation. The cleavage bonds between dimers of SOD during thermal dissociation and type of interactions between specific amino acid residues were also simulated. Two identical contact areas between two subunits were identified. Cleavage of these contact areas resulted in dissociation of the subunits, with destruction of the active centers, and thus, lost of activity. It is suggested that the contact areas interact with active centers by conformational changes involving secondary structural elements.

Enhancement of indomethacin-induced gastric damage by mouth breathing in rabbits.

Previous studies have reported that mouth breathing is associated with respiratory acidosis. Regarding to the reports that renal elimination of weak acids such as indomethacin is pH dependent, this study was carried out to evaluate the role of mouth breathing on plasma level of indomethacin and indomethacin-induced gastric damage in rabbits. Mouth breathing was induced by surgical ligation of nostrils under general anesthesia. One day after the operation, arterial blood samples were collected for acid-base balance analysis and indomethacin was administered intraperitoneally in a single dose of 40mg/kg. The animals were killed 4h after indomethacin administration and blood samples were collected for spectrofluorometric determination of indomethacin in plasma. The results showed that indomethacin induces more severe gastric damage in nose obstructed rabbits compared with sham and unoperated (UNOP) animals. Acid-base analysis revealed a respiratory acidosis in nose obstructed rabbits and indomethacin level of plasma was significantly higher in nose obstructed animals in comparison with control rabbits. The study shows that mouth breathing can increase the potentiation of indomethacin-induced gastric mucosal damage that may be due to higher level of indomethacin in plasma of nose obstructed animals.

Antimicrobial activity of crude methanolic extract of Satureja khuzistanica.

The methanolic extract of the aerial parts of Satureja khuzistanica was investigated for its antimicrobial activity. The maximum antibacterial and antifungal activities were observed against Staphylococcus aureus and Candida albicans.

Inhibition study of adenosine deaminase by caffeine using spectroscopy and isothermal titration calorimetry.

Kinetic and thermodynamic studies were made on the effect of caffeine on the activity of adenosine deaminase in 50 mM sodium phosphate buffer, pH 7.5, using UV spectrophotometry and isothermal titration calorimetry (ITC). An uncompetitive inhibition was observed for caffeine. A graphical fitting method was used for determination of binding constant and enthalpy of inhibitor binding by using isothermal titration microcalorimetry data. The dissociation-binding constant is equal to 350 microM by the microcalorimetry method, which agrees well with the value of 342 microM for the inhibition constant that was obtained from the spectroscopy method. Positive dependence of caffeine binding on temperature indicates a hydrophobic interaction.

Studies on mechanism of 8-methoxypsoralen-DNA interaction in the dark.

The interaction of 8-methoxypsoralen (8-MOP) with calf thymus DNA was studied in darkness at 25 degrees C and pH 7.4. The enthalpy curve for 8-MOP-DNA interaction was obtained by isothermal titration calorimetry and showed a two-step process for the interaction. According to the spectrophotometric data, it was suggested that some compaction may occur in the DNA structure at higher [8-MOP](t)/[DNA] ratio. Using the fluorescence quenching data, the Scatchard analysis was performed for 8-MOP-DNA interaction at the extended ranges of drug concentration. The results indicated that the first set of binding sites was occupied by 1 mol of drug bound per near eight base pairs of DNA. Also 8-MOP caused the quenching of the fluorescence emission of DNA-ethidium bromide complex. The Scatchard analysis of these data indicated the non-competitive manner for quenching. A non-displacement based quenching mechanism has been suggested for this behavior. The circular dichroism spectra also confirmed the non-intercalative binding of 8-MOP at higher concentrations accompanied by some conformational changes in DNA structure. It has been suggested that at low drug load, 8-MOP binds to DNA as an intercalator, which is an endothermic process, whereas at higher ratios of [8-MOP](t)/[DNA], it binds to the outside of DNA, probably in the minor groove and causes some compaction in DNA, which is the exothermic process.

Anti-inflammatory and analgesic activity of Biebersteinia multifida DC. root extract.

The root of Biebersteinia multifida DC (Geraniaceae), a native plant of Iran, has been used topically for the treatment of musculoskeletal disorders as a folk medicine. The anti-inflammatory and analgesic effects of the root extract were studied using carrageenan induced edema and formalin tests. A similar activity was seen between Biebersteinia multifida root extract (10 mg/kg; i.p.) and indomethacin (4 mg/kg; i.p.) in carrageenan test. The results of formalin test showed the analgesic activity of the root extract (50 mg/kg; i.p.) was comparable with morphine (10 mg/kg; i.p.) at the first phase of formalin test. Furthermore, the probable ulcerogenic activity of the root extract was also studied. The extract did not show any ulcerogenic effect at anti-inflammatory doses (10 mg/kg; p.o.).

Naloxone is protective against indomethacin-induced gastric damage in cholestatic rats.

We compared indomethacin-induced gastric damage in three groups of rats-bile duct-ligated, sham-operated, and unoperated-and evaluated the role of the opioid system by blocking the effects of endogenous opioids with naloxone. Indomethacin was administered orally in a dose-dependent manner at 10, 30, and 45 mg/ kg. Naloxone was administered intraperitoneally in several doses of 0.5 and 1 mg/kg, starting 30 min before indomethacin (10mg/kg) administration and continued every 30 min. The animals were killed 4h after indomethacin administration. Indomethacin induced more severe gastric damage in bile duct-ligated rats than in sham and unoperated animals, and administration of naloxone (1 mg/kg) every 30 min inhibited the potentiation of indomethacin-induced gastric damage in bile duct-ligated rats, but not in the control groups (sham-operated and unoperated rats). Plasma indomethacin level was also measured, by fluorometry, but showed no significant difference between the groups. Endogenous opioids have been reported to accumulate in plasma of cholestatic animals, and, considering the results of this study, we suggest the opioid system plays an important pathophysiologic role in the pathogenesis of peptic ulcers in cholestatic subjects.

Synthesis and pharmacological activity of thebaine-derived mu-opioid receptor agonists.

Thebaine-derived mu-opioid agonists were synthesized through the reaction of thebaine with N-aryl maleimide and tested for opioid activity. Morphine was used as reference compound. Our results show that an attachment of aryl succinimide group to thebaine produced series of compounds with mu-opioid agonist activity. The most active compound in smooth muscle preparation was compound 6 with an IC50 ratio of delta/mu = 248.69 and was as potent as morphine with ED50 value 26.65 mg kg-1 i.p. in hot-plate test and showed good antinociceptive activity.

Determination of dosage requirements of warfarin in Iranian patients using HPLC technique.

In this study the warfarin level in the plasma of 60 patients receiving different dosage regimens of warfarin were determined by HPLC. The corresponding prothrombin times (PT) were also measured. The steady state plasma level of warfarin in 10 healthy volunteers was 900.7+/-158.21 ng/ml. A mean dose of 3.79+/-1.02 mg of warfarin corresponded to a therapeutic level of 1193.81+/-300.35 ng/ml with a mean PT of 20.13+/-0.69 s. The results of this study suggest that Iranian subjects are more sensitive to warfarin than North American and European subjects, but have responses very similar to those of Asians. Dietary, ethnic and geographical factors as well as differences in drug dispensition may be the cause of the observed dosage variability of warfarin.

Rapid method for the determination of piroxicam in rat plasma using high-performance liquid chromatography.

A previously published method was used for the determination of piroxicam in plasma samples obtained from rat. The sample preparation involved liquid extraction, centrifugation and evaporation. Separation of piroxicam from internal standard occurred on a reversed-phase C18 column with a mobile phase consisting of methanol-phosphate buffer pH 2 (45:55). The detection limit of the assay was 0.02-20 micrograms/ml. The assay linearity was good (typically r = 0.9992). The method was applied for determination of piroxicam in rats after administration of an oral dose of 2 mg/kg piroxicam.