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).

Synthesis and cytotoxic activity of some 2-amino-4-aryl-3-cyano-7-(dimethylamino)-4H-chromenes

A series of 2-amino-4-aryl-3-cyano-7- (dimethylamino)-4H-chromenes was synthesized by condensation of 3- (dimethylamino) phenol, an aromatic aldehyde and malonitrile in ethanol containing piperidine. The assignments of the structure of all synthesized compounds were based on spectral data (IR, Mass and(1)H NMR). The cytotoxic activities of the synthesized compounds against six human tumor cell lines were determined by MTT assay. Several compounds showed significant cytotoxic activity.

Unusual treatment of pacemaker pocket infection: a case report

Pocket infection of a cardiac device is usually treated by removing the device and re-implanting it in a new site after complete treatment of the infection. This report illustrates a complicated case of pocket infection in the wake of the implantation of a permanent pacemaker (cardiac resynchronization therapy). The patient was treated conservatively through daily irrigation and dressing, broad-spectrum antibiotics, and debridement without the device being removed; the generator was kept out of the pocket for 5 weeks and then re-implanted in the same location successfully.The method of treatment presented herein can be of value, not least in the elderly population who might experience life-threatening events following the replacement of their cardiac devices.

Effects of novel antituberculosis agents on OmpF channel activity

Nanopore forming proteins spanning the outer membrane mediate in the diffusion of hydrophilic chemicals through the hydrophobic bacterial cell wall. In this study, the effects of two novel anti-TB derivatives, ethyl alpha-[5-(5-nitro-2-thienyl)-1,3,4-thiadiazole-2-ylthio] acetates and propyl alpha-[5-(5-nitro-2-thienyl)-1,3,4-thiadiazole-2-ylthio] acetates, on OmpF channel reconstituted in artificial bilayers were evaluated by voltage clamp technique. Surprisingly, ethyl derivative (MIC > or = 6.75 microg/ml) showed no effects on OmpF channel activity but the propyl derivative (MIC=0.39 microg/ml) reduced the channel conductance considerably and changed the gating pattern of the channel. The findings obtained here at molecular level, might shed light on better understanding of the actual mechanism(s) by which the novel anti-TB agents permeate through the cell wall of the Mycobacterium tuberculosis.

Antigen-specific lymphocyte proliferation assay and virus neutralization test for measurement of measles-specific immunity in 15-19 years old high school students in Tehran, Iran

Limited information is available concerning the role of measles-specific cell mediated immunity as a correlate of long-term protection from measles infection. Although serological responses are determined in epidemiological studies and high antibody titer is a good indicator of protection, the role of Cell-Mediated Immunity (CMI) has to be defined more clearly. In this study, Lymphocyte Proliferation (LP) and Viral Neutralization Test (VNT) were used in order to measure measles-specific cellular and humoral immune responses of 100 high school students in Tehran. From total number of subjects studied, 33 were girls and 67 were boys and all were in good health. Of these, 77 had protective neutralizing measles antibody titers and 23 did not have such titer. The results of LP showed that 89 subjects had protective cellular immune responses and 11 did not. A quantitative relationship between humoral and cellular immune responses was not observed. These findings suggest that measles-specific protective CMI is measurable for longer time in comparison to humoral immunity. These data suggest that LP responses may be better sustained than antibody titers in some children.

Evaluation of anticancer effects of newly synthesized dihydropyridine derivatives in comparison to verapamil and doxorubicin on T47D parental and resistant cell lines in vitro

Failure of current anticancer drugs mandates screening for new compounds of synthetic or biological origin to be used in cancer therapy. Multidrug resistance (MDR) is one of the main obstacles in the chemotherapy of cancer. Efflux of cytotoxic agents mediated by P-glycoprotein (P-gp or MDR1) is believed to be an important mechanism of multidrug resistance. Therefore, we decided to investigate the antiproliferative effects of seven newly synthesized 1,4-dihydropyridine (DHP) derivatives in comparison to verapamil (VP) and doxorubicin (DOX) on human breast cancer T47D cells and its MDR1 overexpressed and moderately resistant cells (RS cells) using MTT cytotoxicity assay. We also examined the effects of these compounds on cytotoxicity of DOX in these two cell types. The cytotoxicity assays using MTT showed that most of the tested new DHP derivatives and VP at 10 microM concentration had varying levels of toxicity on both T47D and RS cells. The toxicity was mostly in the range of 10-25%. However, the cytotoxicity of these DHP derivatives, similar to VP, was significantly less than DOX when comparing IC(50) values. Furthermore, these compounds in general had relatively more cytotoxicity on T47D vs RS cells at 10-microM concentration. Among new DHPs, compounds 7a (3,5-dibenzoyl-4-(2-methylthiazol-4-yl)-1,4-dihydro-2,6-dimethylpyridine) and 7d (3,5-diacetyl-4-[2-(2-chlorophenyl)thiazol-4-yl)]-1,4-dihydro-2,6-dimethylpyridine) showed noticeable potentiation of DOX cytotoxicity (reduction of DOX IC(50)) compared to DOX alone in both cells, particularly in RS cells. This effect was similar to that of VP, a known prototype of MDR1 reversal agent. In other words, compounds 7a and 7d resensitized RS cells to DOX or reversed their resistance. Results indicate that compound 7d exerts highest effect on RS cells. Therefore, these two newly synthesized DHP derivatives, compounds 7a and 7d, are promising as potential new MDR1 reversal agents and should be further studied on other highly resistant cells due to MDR1 overexpression and with further molecular investigation.

The Application of Shannon's Measure of Information for a Complex Chemical System

Information theory and, specifically, Shannon's measure of information is used to compare the interaction parameters (beta) in regular solution theory (RST) and Ingram's model for the mixture of cetyltrimethylammonium bromide (CTAB) and Triton X-100 (TX100). Results show that beta values from regular solution theory are more accurate than those of Ingram's model. Additionally, the procedure applied in this paper for the calculation of uncertainties in the continuous case, prevents difficulties concerning differential entropy.

Extradural spinal cord and intraabdominal ganglioneuroblastoma

We report a rare case of a giant extradural and intraabdominal ganglioneuroblastoma in a young Malay girl who presented to a paediatrician initially at 5 days of life with a palpable abdominal mass. Unfortunately, the parents refused any form of surgical intervention until the child was 3 years old. She subsequently underwent vascular embolisation followed by the removal of this large tumour both via the abdomen and through a laminectomy approach and subsequently refused chemotherapy. The c-myc amplication in this patient was absent and there were no chromosomal aberrations, During the 2 year folow-up the patient remained well, and ambulatory with no tumour recurrence.

Preparation of [61Cu]-2-acetylpyridine thiosemicarbazone complex as a possible PET tracer for malignancies

Due to the interesting anti-proliferative properties of copper-thiosemicarbazone complexes, the production of a (61)Cu-labeled thiosemicarbazone, i.e. 2-acetylpyridine thiosemicarbazone (APTS) was investigated. Copper-61 (T(1/2)=3.33 h) was produced via the (64)Zn(p,alpha)(61)Cu nuclear reaction using a natural zinc target irradiated with 22 MeV protons for 500 microAh. The (61)Cu was separated from the irradiated target material by a two-step method and converted to acetate; this yielded a final activity of 222 GBq (6.0 Ci), with a radiochemical yield of >95%. The (61)Cu-acetate was mixed with 2-acetylpyridine thiosemicarbazone for 30 min at room temperature to yield [(61)Cu]APTS with a radiochemical yield of more than 80%. Colorimetric methods showed that residual chemical impurities in the product were below the accepted limits. Radio thin layer chromatography (RTLC) showed a radiochemical purity of more than 99% after C(18) column chromatography. A specific activity of about 370-740 MBq/mmol (10-20 Ci/mmol) was obtained. The stability of the final product was checked in the absence and presence of human serum at 37 degrees C for up to 3 h. The partition coefficient of the final complex was also determined.

Pre-column derivatization of rofecoxib for determination in serum by HPLC

An HPLC method for determination of rofecoxib in human serum is presented. The method is based on pre-column derivatization of analyte to a phenanthrene derivative of the drug. Rofecoxib and the internal standard were extracted from serum using liquid-liquid extraction. Upon exposure to UV light, the drug was found to undergo a photocyclization reaction, giving a species with high absorbance. Validation of the method has been studied in the concentration range 10-500 ng ml(-1).

Synthesis of [75Se]5-ethoxycarbonyl-4-methyl-1,2,3-selenadiazole

Selenium-75 (t1/2 = 120.4d; 100% EC) was prepared in no-carrier-added form by 22MeV proton-bombardment of natural arsenic(III) oxide powder held in a copper-aluminum drawer target (highest yield, 35 microCi/microAh; maximum current, 6 microA), followed by oxidation to [75Se]selenium(IV) oxide. No-carrier-added [75Se]5-ethoxycarbonyl-4-methyl-1,2,3-selenadiazole was prepared in one step from ethylacetoacetate semicarbazone with [75Se]selenium(IV) oxide in glacial acetic acid at 50 degrees C. Column chromatography of the final solution afforded the desired labeled compound in 30% yield and greater than 98% radiochemical purity.

Application of a simple and sensitive GC-MS method for determination of morphine in the hair of opium abusers

Thirty hair samples were collected from male opioid abusers for whom the presence of morphine in their urine samples was confirmed by thin layer chromatography (TLC). The hair samples were decontaminated by washing with isopropanol, deionized water, and isopropanol, dried at room temperature, and cut into small pieces. Samples of the latter (30 mg ) were digested by incubation in a mixture of methanol-trifluoroacetic acid (9:1) for 18 h at 45 degrees C and sonicated to improve the extraction process. The methanolic phase was evaporated to dryness under a stream of nitrogen at 50 degrees C. The sample was derivatized by addition of N-methyl- N-trimethylsilyltrifluoroacetamide (MSTFA) and 1% trimethyliodosilane (TMIS) at 70 degrees C for 20 min, with sonication. Derivatized samples (1 microL) were injected into a gas chromatograph-mass spectrometer (GC-MS) system fitted with a capillary column; the Finnigan MS was operated in SIM mode. Naltrexone was used as internal standard (IS). The masses of the ions selected for morphine and naltrexone were 429 and 557, respectively. The limit of quantitation was set at 0.03 ng mg(-1) hair. By using the above procedure we detected morphine in all the samples examined, in the concentration range 0.26-10.31 ng mg(-1 )hair.