Microwave-assisted synthesis of antimicrobial dihydropyridines and tetrahydropyrimidin-2-ones: Novel compounds against aspergillosis

Ten 4-aryl-1,4-dihydropyridine and three 4-aryl-1,2,3,4-tetrahydropyrimidin-2-one derivatives have been synthesized and examined for their activity against pathogenic strains of Aspergillus fumigatus and Candida albicans. Although none of the three compounds belonging to pyrimidin-2-one series showed any activity against two pathogens, two of the compounds of the dihydropyridine series, that is, diethyl 4-(4-methoxyphenyl)-2,6-dimethyl-1,4-dihydropyridin-3,5-dicarboxylate and dimethyl 4-(4-methoxyphenyl)-2,6-dimethyl-1,4-dihydropyridin-3,5-dicarboxylate, exhibited significant activity against A. fumigatus in disc diffusion, microbroth dilution and percent spore germination inhibition assays. The most active diethyl dihydropyridine derivative exhibited a MIC value of 2.92 microg/disc in disc diffusion and 15.62 microg/ml in microbroth dilution assays. The MIC(90) value of the most active compound by percent germination inhibition assay was found to be 15.62 microg/ml. The diethyl dicarboxylate derivative of dihydropyridine also exhibited appreciable activity against C. albicans. The in vitro toxicity of the most active diethyl dihydropyridine derivative was evaluated using haemolytic assay, in which the compound was found to be non-toxic to human erythrocytes even at a concentration of 625 microg/ml. The standard drug amphotericin B exhibited 100% lysis of erythrocytes at a concentration almost 16 times less than the safer concentration of the most active dihydropyridine derivative.

Synthesis and antibacterial activity of substituted 1,2,3,4-tetrahydropyrazino [1,2-a] indoles

A series of substituted 1,2,3,4-tetrahydropyrazino [1,2-a] indole derivatives have been synthesized and tested against the Gram positive and Gram negative strains of bacteria namely Staphylococcus aureus (MTCCB 737), Salmonella typhi (MTCCB 733), Pseudomonas aeruginosa (MTCCB 741), Streptomyces thermonitrificans (MTCCB 1824) and Escherichia coli (MTCCB 1652). All synthesized compounds showed mild to moderate activity. However, compounds 4d-f were found to have potent activity against pathogenic bacteria used in the study. Their MIC ranged from 3.75 to 60 microg/disc. In vitro toxicity tests demonstrated that toxicity of 4d-f was not significantly different than that of gentamycin. However, at higher concentration (1000-4000 microg/ml) difference was highly significant.

Investigations on anti-Aspergillus properties of bacterial products

AIMS

To investigate the anti-Aspergillus properties of bacterial products.

METHODS AND RESULTS

In the present study, 12 bacterial strains were screened for antifungal activity against Aspergilli. The culture supernatant and lysates of Pseudomonas aeruginosa, Bacillus cereus, Escherichia coli (BL21, DH5alpha, HB101, XL Blue), Klebsiella pneumoniae, Streptomyces thermonitrificans, Streptococcus pneumoniae, Enterobacter aerogenes, Staphylococcus aureus and Salmonella typhi were examined for antifungal activity in protein concentration ranging from 1000.0 to 7.8 microg ml-1 using microbroth dilution assay. The lysate of Salm. typhi and E. coli BL21 exhibited the maximum activity against Aspergillus fumigatus, Aspergillus flavus and Aspergillus niger. Their in vitro minimum inhibitory concentrations (MICs) were found to be 15.6-31.2 microg ml-1 by microbroth dilution and spore germination inhibition assays. In disc diffusion assay, a concentration of 3.1 microg disc-1 of Salm. typhi lysate showed significant activity against Aspergilli. Escherichia coli BL21 exhibited similar activity at 6.2 microg disc-1. The work on identification of molecule endowed with antimycotic properties is in progress.

CONCLUSION

The products of Salm. typhi and E. coli demonstrated significant activity against Aspergillus species.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first time that E. coli has been reported for anti-Aspergillus activity. It could be an important source of biologically active compounds useful for developing better new antifungal drugs/or probiotics.

Efficacy of 2-(3,4-dimethyl-2,5-dihydro-1h-pyrrole-2-yl)-1-methylethyl pentanoate in a murine model of invasive aspergillosis

2-(3,4-Dimethyl-2,5-dihydro-1H-pyrrole-2-yl)-1-methylethyl pentanoate, an antifungal compound, was found to be nontoxic to RAW cells up to a concentration of 312.5 microg/ml, whereas amphotericin B was lethal to all cells at 37.5 microg/ml. The treatment of Aspergillus fumigatus-infected mice with a dose of 200.0 mg of compound/kg of body weight increased their survival rate by 60%, with a decrease in CFU in organ tissues. The protection afforded by the compound against experimental aspergillosis was found to be dose dependent.

In vitro antifungal activity of 2-(3,4-dimethyl-2,5-dihydro-1H-pyrrol-2-yl)-1-methylethyl pentanoate, a dihydropyrrole derivative

A novel compound 2-(3,4-dimethyl-2,5-dihydro-1H-pyrrol-2-yl)-1-methylethyl pentanoate was isolated from the plant Datura metel L. The in vitro activity of this dihydropyrrole derivative against Aspergillus and Candida species was evaluated by using standard methods approved by the National Committee for Clinical Laboratory Standards. The compound was found to be active against all the species tested, namely Candida albicans, Candida tropicalis, Aspergillus fumigatus, Aspergillus flavus and Aspergillus niger. The MIC at which more than 90% of growth was inhibited (MIC(90)) by the compound ranged from 21.87 to 43.75 microg ml(-1) against various fungal species by microbroth dilution assay. Since the compound 2-(3,4-dimethyl-2,5-dihydro-1H-pyrrol-2-yl)-1-methylethyl pentanoate has antifungal activity it can be explored further to develop new antimycotic drugs.

Association of the PIM3 allele of the alpha-1-antitrypsin gene with chronic obstructive pulmonary disease

OBJECTIVE

The study investigated the association of genetic polymorphism of the alpha1AT gene with COPD.

DESIGN AND METHODS

The mutations and polymorphism of alpha1AT gene were investigated by DNA sequence analysis using polymerase chain reaction.

RESULTS

The frequency of the PIM3 allele in COPD patients was found to be significantly higher than the controls (P < 0.0001). Five SNPs, including a novel SNP (24_25insA), were observed near the junction of exon-intron I. The occurrence of these SNPs didn't show any association with COPD. However, the PIM3 allele of the alpha1AT gene was found to be associated with COPD.

CONCLUSION

The PIM3 allele of the alpha1AT gene is found to have an association with the pathogenesis of COPD in the Indian population.

A fraction from Escherichia coli with anti-Aspergillus properties

The products of various strains of Escherichia coli (BL21, DH5alpha, HB101 and XL Blue) were investigated for antimycotic properties using pathogenic isolates of Aspergillus. Co-culture experiments revealed that E. coli strains exhibited variable activity against Aspergillus fumigatus. The lysates prepared from DH5alpha, HB101 and XL Blue strains of E. coli showed inhibitory activity against A. fumigatus in the protein concentration range of 62.50 to 250.00 microg ml(-1). The highest activity was seen in the lysate of BL21, which inhibited the growth of A. fumigatus and Aspergillus flavus completely at a concentration of 31.25 microg protein ml(-1). The MIC of BL21 lysate against Aspergillus niger was found to be 62.50 microg ml(-1). The in vitro toxicity of BL21 lysate was evaluated using a haemolytic assay. A BL21 lysate protein concentration of 1250.00 microg ml(-1) was found to be nontoxic to human erythrocytes. The standard drug amphotericin B lysed 100 % of erythrocytes at a concentration of 37.50 microg ml(-1). SDS-PAGE showed the presence of at least 15 major proteins in the lysate of BL21. Ion-exchange chromatography resolved the BL21 lysate into five fractions and fraction III was found to be endowed with anti-Aspergillus properties. The MIC of this fraction was found to be 3.90 microg ml(-1). Further work on the purification of the active molecule and its characterization is in progress.

A novel antifungal pyrrole derivative from Datura metel leaves

Phytochemical investigation of the leaves of Datura metel Linn. led to the isolation of a new pyrrole derivative 1 which was characterised as 2beta-(3,4-dimethyl-2,5-dihydro-1H-pyrrol-2-yl)-1'-methylethyl pentanoate on the basis of spectral data analyses and chemical reactions. Compound 1 was endowed with antifungal activity and its MIC was found to be 87.5 microg/ml. Two proteins having molecular weights of 42 and 58 kD of Aspergillus fumigatus are potential targets for compound 1.

Antifungal potential of Indian medicinal plants

Fourteen Indian plants, selected based on their use in respiratory and other disorders in traditional systems of medicine, were analyzed for their potential activity against fungi. The antifungal activity was investigated by disc diffusion, microbroth dilution and percent spore germination inhibition tests against pathogenic Aspergilli. Methanolic extracts of Solanum xanthocarpum and Datura metel inhibited the growth of Aspergillus fumigatus, A. flavus and A. niger and their in vitro MICs were found to be 1.25-2.50 mg/ml by both microbroth dilution and percent spore germination assays. In disc diffusion assay, a concentration of 0.062 mg/disc of methanol extract of D. metel showed significant activity against Aspergilli. S. xanthocarpum exhibited similar activity at 0.125 mg/disc.

Studies on antimycotic properties of Datura metel

The hexane, chloroform, acetone and methanolic fractions of Datura metel L. were investigated for antifungal properties using pathogenic species of Aspergillus. The chloroform fraction was found to be endowed with antifungal activity. The minimum inhibitory concentration (MIC) of chloroform fraction of D. metel L. was 625.0 microg ml(-1) against all the three species of Aspergillus, i.e. A. fumigatus, A. flavus and A. niger, by microbroth dilution and percent spore germination inhibition assays. The MIC by disc diffusion assay was observed to be 12.5 microg disc(-1). The chloroform fraction of D. metel, when investigated for potency, turned to be 9.2 times less active than amphotericin B. However, it was important to note that the cytotoxicity of chloroform fraction in vitro was 117.8 times less than amphotericin B.

Noncoronary transradial angioplasty with coronary equipment: a less invasive technique

As the safety and feasibility of the transradial approach for percutaneous coronary interventions have already been established by many series, we evaluate the safety and feasibility of this approach in noncoronary interventions such as renal, celiac, mesenteric, and subclavian angioplasty procedures. We present here our preliminary experience of noncoronary interventions via the transradial approach using coronary equipment with 100% technical and clinical success. Nine noncoronary interventions were performed in seven patients (five renal, two celiac, one mesenteric and subclavian angioplasty each). The advantage of this approach is that it limits arterial wall damage as well as potential distal embolization by the use of small guiding catheters and 0.014" guidewires. The only limitation of this approach for noncoronary interventions is the guiding catheter length in tall patients and the unavailability of large coronary balloons for subclavian, celiac, and renal interventions. With the miniaturization of equipment and improvements in technique, this approach will also become an excellent alternative for noncoronary interventions.

Purification of alpha feto protein from human cord blood

Alpha Fetoprotein (AFP) is a major serum protein in the developing fetus and is of clinical significance as it is an oncofetal protein being synthesized by fetal organs and malignant tumors. AFP is here used as a diagnostic marker for hepatic carcinomas. In view of structural homology and similarities in physico-chemical properties with serum albumin, the separation and purification of AFP has always been a problem. Immunologically active AFP has been purified from human cord plasma using pseudoaffinity chromatography based on Cibacron blue substituted Sephadex G-100. AFP was quantified using rocket immunoelectrophoresis and double sandwich ELISA. Polyclonal antibodies were raised against purified AFP in mice. The purified antibodies were conjugated with peroxidase for use in double antibody sandwich ELISA. Purification of AFP from human cord plasma by an improved method with 55% recovery is reported.

Analysis of HIV seropositive thalassemic children for antibodies specific to Aspergillus fumigatus by luminescent immunoassay

The applicability of luminescent immunoassay (LIA) in serodiagnosis of fungal infections in multitransfused (MT) thalassemic children seropositive for human immunodeficiency virus (HIV) was investigated. Thirty-one sera samples from HIV infected pediatric patients with thalassemia receiving repeated blood transfusions were analysed for the presence of antibodies specific to Aspergillus fumigatus by LIA. The LIA was standardized using well defined antigens of A. fumigatus. Ten out of 31 (32.2%) of the MT-HIV positive patients were found to have anti-Aspergillus antibodies in their sera by LIA. The ELISA could detect A. fumigatus specific antibodies in 25.8% (8 out of 31) of the patients. Thus, 20% more number of patients turned to be positive for aspergillosis by LIA as compared to ELISA. The difference was found to be statistically significant (p < 0.005). Of the MT-HIV negative patients only 1 out of 33 (3%) showed A. fumigatus specific antibodies by LIA and ELISA both. In age and sex matched control group (n = 25) none of the patients was found to be positive for antibodies to A. fumigatus. LIA was found to have better discriminatory value indicating, thereby, its utility in diagnosis of aspergillosis in compromised patients.

Aspergillus fumigatus specific antibodies in multitransfused children with human immunodeficiency virus (HIV) infection in relation to serum levels of Interleukin-2, gamma Interferon and tumour necrosis factor

Anti-Aspergillus fumigatus antibodies (IgG and IgE class) and serum levels of cytokines (gamma Interferon, Interleukin-2 and tumour necrosis factor-alpha) were studied in multitransfused (MT) children in relation to human immunodeficiency virus (HIV) infection. The specific antibodies to Aspergillus fumigatus were present in 25 per cent of MT children seropositive for HIV as compared to only 2 per cent among HIV-negative MT children (X2 = 14, P < 0.001). Estimation of serum cytokines level in MT children showed that the asymptomatic HIV-infected children had elevated levels of gamma interferon (Y-IFN) and tumor necrosis factor-alpha (TNF-alpha) without any alteration of Interleukin-2 (IL-2) level, compared to HIV-negative group. However, clinically diagnosed cases of AIDS in the HIV-infected group showed elevation of all the three cytokines levels as compared to HIV negative group, as well as asymptomatic HIV infected group. Presence or absence of concomitant A. fumigatus infection did not lead to alteration of Y-IFN and IL-2 level in the HIV infected group, while TNF-alpha levels were markedly raised in the cases with evidences of presence of A. fumigatus specific antibodies irrespective of whether the group belonged to asymptomatic HIV infection or clinically proven cases of AIDS. The significance of these altered cytokines profile with respect to occurence of A. fumigatus infection in HIV-positive MT children has been discussed.

Dimethyl suberimidate as an effective crosslinker for antibody-enzyme conjugation

Dimethyl suberimidate (DMS), a bifunctional reagent was used for the first time to crosslink the alpha-feto protein monoclonal antibodies (AFPMAb) to horse radish peroxidase (HRP). Three batches of conjugates were prepared, purified by Sephadex gel chromatography and evaluated for their immunological reactivity. The Rz values obtained for AFPMAb-HRP conjugate were 0.39 to 1.36. Under optimised conditions the ELISA results showed the optical density of 1.9. The iso-electric focusing for the conjugate revealed different degrees of crosslinking between antibodies and HRP. It was evident that isoperoxidase-C was involved in the crosslinking process. From the dot ELISA, as low as 25 pg of AFP in the test samples could be detected with AFPMab-HRP conjugate. The conjugate prepared by DMS was stable at 0 degrees C for more than 10 months.

Immunogenicity of RNA-protein fraction isolated from axenic Entamoeba histolytica (NIH:200)

The immunogenicity of Entamoeba histolytica RNA (EhRNA) was studied in guinea-pigs. Animals immunized with a single dose of EhRNA and Freund's complete adjuvant (FCA) showed a high level of cell-mediated immune response (CMIR) as assessed by percent leucocyte migration inhibition (74.8 +/- 2.9) after 1 week of immunization. This response faded away gradually and by week 5 after immunization the percent leucocyte migration inhibition was 27.1 +/- 8.27, which is quite close to control values. The immunogenic activity of EhRNA was found to be specific, since yeast RNA failed to elicit immunological responses, and was RNase-sensitive. The CMIR could be maintained at its high level by giving boosters or multiple doses. Anti-EhRNA antibodies (haemagglutinins or precipitins) could not be demonstrated at any stage.

Efficacies of vaccines against canine hookworm disease

Three types of vaccine (1) a sonicated extract of killed larvae, (2) 5-fluorouracil-treated larvae and (3) 40 krad. X-irradiated larvae have been evaluated. Pups aged 3-4 months, weighing 2 +/- 0.5 kg and free of natural hookworm infection were selected for experimental studies. The sonicated extract was given either in a single dose or as 2 doses at weekly intervals, whereas the 5-fluorouracil-treated and X-irradiated larvae were given in a single dose only. After completion of the vaccination schedule, the pups were challenged with filariform larvae and were sacrificed 3 weeks after challenge. Non-vaccinated pups and those vaccinated with a single dose of sonicated extract lost weight and had diarrhoea or dysentery after challenge. Furthermore, in non-vaccinated pups, haemoglobin levels fell and at autopsy the intestinal mucosa was found to be grossly congested and free blood was present in the lumen of the intestine. Such findings were not obtained in pups vaccinated with the other types of vaccines. The percentage of infective larvae which developed to the adult stage in non-vaccinated pups was 82.7 +/- 9.53 compared with 45.1 +/- 12.33, 30.1 +/- 10.05, 20.6 +/- 10.60 and 8.0 +/- 7.46%, respectively in pups vaccinated with a single dose of sonicated extract, double dose of sonicated extract, 5-fluorouracil-treated and 40 krad. X-irradiated larval vaccines. While the irradiated larval vaccine provided maximum protection against clinical ancylostomiasis, 2 doses of the sonicated larval vaccine could also afford almost equal protection to pups.