Identification of mannich base as a novel inhibitor of Mycobacterium tuberculosis isocitrate by high-throughput screening.

Mycobacterium tuberculosis (MTB) remains one of the most significant human pathogens since its discovery in 1882. An estimated 1.5 million people died from tubercle bacillus (TB) in 2006, and globally, there were an estimated 9.27 million incident cases of TB in 2007. Glyoxylate bypass pathway occurs in a wide range of pathogens and plays a key role in the pathogenesis of Mycobacterium tuberculosis. Isocitrate lyase (ICL) can catalyses the first step of this pathway, and reversibly cleaves isocitrate into succinate and glyoxylate. So, ICL may represent a good drug target for the treatment of tuberculosis. ICL was cloned, expressed, and purified, and a high-throughput screen (HTS) developed to screen active molecule from a mannich base compounds library for inhibition of ICL. This assay had signal to noise (S/N) of 650.6990 and Z' factor of 0.8141, indicating that the assay was suitable for HTS. Screening of a collection of 124 mannich base compounds resulted in the identification of one mannich base compound, which has a significant inhibitory activity. So, a new family of compound was first reported to inhibit the activity of Mycobacterium tuberculosis ICL. This family of compound might offer new avenue to explore better anti-tuberculosis and fungi drugs.

[Improving the efficacy of synergetically facilitated pertraction of p-aminobenzoic acid by increasing the reextraction rate]. / Marirea eficientei pertractiei facilitate sinergetice a acidului p-aminobenzoic prin cresterea vitezei de reextractie din membrana lichida.

The studies on facilitated pertraction of PABA with Amberlite LA-2 and 1-octanol as phase modifier indicated the increase of the process efficiency and, implicitly, of the transport capacity of the liquid membrane by adding KOH in the stripping phase. Thus, the use of KOH led to the diminution of the kinetic resistance of the reextraction process, with positive effects on the acid final mass flow and permeability factor. Compared to the similar pertraction systems containing NaOH in the stripping phase and in direct correlation with the pertraction parameters (pH-gradient between the feed and stripping phases, carrier and alchohol concentrations inside the liquid membrane), the final mass flow can be accelerated for about 1.9 times, and the permeability through liquid membrane can be enhanced for about 1.5 times in presence of KOH.

[Comparative study on separation of p-aminobenzoic and p-hydroxy-benzoic acids by reactive extraction]. / Studiul comparativ al separarii acizilor p-amino- benzoic si p-hidroxibenzoic prin extractie reactiva.

The comparative study on reactive extraction of p-aminobenzoic and p-hydroxybenzoic acid with Amberlite LA-2 and D2EHPA in two solvents with different polarity (n-heptane and dichloromethane) indicated that the nature of the specific substituents, extractant type and solvent polarity control the extraction mechanism. Although the reactive extraction with Amberlite LA-2 of the two acids occurs by means of rather similar interfacial reactions, the extraction with D2EHPA is based on different mechanisms, due to the participation of the two different substituents of aminic and phenolic type. In all cases, the most efficient extractions have been reached for the combination Amberlite LA-2-dichloromethane.

Cytotoxic metabolites from the wood-decayed fungus Xylaria sp. BCC 9653.

Chemical investigation of the wood-decayed fungus Xylaria sp. BCC 9653 has led to the isolation of a new methyl aminobenzoate (1) together with eleven known compounds. The structures were established by analysis of spectroscopic data. Cytochalasin D (2), one of the known metabolites, exhibited potent cytotoxicity against African green monkey kidney fibroblast (Vero) cells with an IC(50) value of 0.19 microM.

Separation of three water-soluble vitamins by poly(dimethylsiloxane) microchannel electrophoresis with electrochemical detection.

A method for rapid separation and sensitive determination of three water-soluble vitamins, pyridoxine, ascorbic acid (VC), and p-aminobenzoic acid (PABA) has been developed by PDMS microchannel electrophoresis integrated with amperometric detection. After treatment of the microchip with oxygen plasma, the peak shapes of the three analytes were essentially improved. Pyridoxine, VC, and PABA were well separated within only 80 s in a running buffer of 20 mM borate solution (pH 8.5). Good linearity was obtained within the concentration range of 2-200 microM for the three water-soluble vitamins. The detection limits were 1.0 microM for pyridoxine and VC, and 1.5 microM for PABA. The proposed method has been successfully applied to real human urine sample, without solid phase extraction, with recoveries of 80-122% for the three water-soluble vitamins.

Analysis of substances to be used as internal standards in MEKC.

The use of internal standards (ISs) improves the quantitative performance of CE. However, ISs chosen for use in CZE often cannot be used for micellar EKC (MEKC). Therefore 22 substances were investigated as potential ISs in MEKC. These substances were selected based upon a literature search. The substances were investigated using a method similar to the standard operating conditions for MEKC as recommended by S. Terabe. Furthermore, the migration time and the corrected migration time (k(S)) were determined for each substance to establish the migration position relative to other peaks in the electropherograms. A combination of eight substances, selected according to the obtained results (t(m) = 4 up to 12 min), was tested for practical benefit and applicability. The peak area precision was in the range of 0.8 and 1.2% (n = 60), and the peaks were well shaped for all the investigated substances. The selected substances covered a wide migration time window and therefore they can be regarded as suitable for future analysis at any required migration position.

B-535a, b and c, new sphingosine kinase inhibitors, produced by a marine bacterium; taxonomy, fermentation, isolation, physico-chemical properties and structure determination.

In the course of our screening for inhibitors of sphingosine kinase, we found a series of active compounds in a culture broth of a novel marine bacterium, SANK 71896. The structures of the compounds, named B-5354a, b and c, were elucidated by a combination of spectroscopic analyses to be new esters of 4-amino-3-hydroxybenzoic acid with long-chain unsaturated alcohols. B-5354a, b and c inhibit sphingosine kinase activity with IC50 values of 21, 58 and 38 microm, respectively.

[A comparative study on the capacities of different strains of Streptococcus sanguis for P-aminobenzoic acid production].

This study was intended to compare the capacities of different strains of Strep, sanguis for P-Aminobenzoic acid (PABA) production. The synthesis of PABA during the growth of four strains of Strep. sanguis was measured by the reversed-phase high-performance liquid chromatographic method. The results showed that the concentrations of PABA synthesized by S. sanguis 10556, S. sanguis 10557, S. sanguis S34 and S. sanguis H7-4. Were 1.979 +/- 0.081 micrograms/ml, 1.383 +/- 0.193 micrograms/ml, 1.983 +/- 0.052 micrograms/ml and 1.032 +/- 0.229 micrograms/ml, respectively, and in term of PABA concentration, S. sanguis 10556 was significantly different from S. sanguis 10557 and S. sanguis H7-4; S. sanguis S34 was significantly different from S. sanguis 10557 and S. sanguis H7-4. No significant difference was found between S. sanguis 10556 and S. sanguis S34, nor between S. sanguis 10557 and S. sanguis H7-4, either. In conclusion, the method is simple, rapid and accurate. S. sanguis did synthesize PABA, and the difference in ability for PABA formation existed among the four strains of S. sanguis. This study is helpful to researches on the symbiosis between S. sanguis and S. muntans and to determination of their role in the microbial homeostasis of dental plaque.

[Study on the biosynthesis of para-aminobenzoic acid by S. sanguis. I. Establishment of a reversed-phase high-performance liquid chromatography].

In order to study the synthesis of para-aminobenzoic acid (PABA) by S. mutans and the role of PABA in the interaction between S. mutans and S. sanguis, a reversed-phase high-performance liquid chromatography (RP-HPLC) for analysis of PABA was developed. The results showed that the optimal chromatographic parameters were flow rate of 1.5 ml/min, T = 55 +/- 2 degrees C, methanol/phosphate buffer of 10/90(by vol) (pH 2.2 0.1 mol/L), m-hydroxybenzoic acid as an internal standard. The method is simple, rapid accurate and useful.

[Study on the biosynthesis of para-aminobenzoic acid by S. sanguis. II. Qualitative and quantitative analysis].

In this study, the method established in paper 1 was used to analyze PABA synthesized by S. sanguis S34. The results showed: 1. S. sanguis S34 did synthesize PABA and the mean concentration of PABA was 1.236 micrograms/ml. 2. the components had good linear relation and average recovery was 80%. The results of this paper will be helpful to studying influencing factors on PABA synthesis of S. sanguis and the roles of PABA in microbial homeostasis of dental plaque.

[The detection of novocaine and p-aminobenzoic acid in cadaveric material]. / Obnaruzhenie novokaina i p-aminobenzoinoi kisloty v trupnom materiale.

Microcrystalloscopic reactions, TLC and UV spectroscopy methods for novocainum and p-aminobenzoic acid identification in medicolegal examination of the cadaveric material were developed. Sensitivity and specificity of microcrystalloscopic reactions were studied.

An inverse relationship of rat liver folate polyglutamate chain length to nutritional folate sufficiency.

The relative concentrations of folylpolyglutamates of differing chain length in rat liver and the uptake of exogenous [3H]folic acid (20 microCi, 20 microgram) into liver folylpolyglutamates were examined in rats maintained on (a) standard and folate-supplemented standard diets and (b) semi-defined folate-sufficient and folate-deficient diets. Folylpolyglutamates extracted from liver were cleaved to p-aminobenzoylpolyglutamates which were separated by ion-exchange chromatography. The relative concentrations and ultimate radiolabeling of longer-chain folylpolyglutamates (six, seven and eight glutamate residues) were greatest in the livers of folate-deficient rats, whereas the intermediate-chain folylpolyglutamates (three, four and five glutamate residues) were the greatest portion of total liver folates of folate-supplemented rats. Thus, the length of the polyglutamate chain added to liver folates is inversely related to the total concentration of liver folates. These data suggest that folylpolyglutamate biosynthesis in the liver may be controlled by the liver folate concentrations. In folate insufficiency such a control mechanism would serve to enhance the affinity of folates for folate-dependent enzymes and to conserve the liver folate concentration.