Transformation of some hydroxy amino acids to other amino acids

It has been observed that -hydroxy--amino acids are transformed into other amino acids, when heated in dilute solutions with phosphorous acid, phosphoric acid or their ammonium salts. It has been shown that as in the case of previously reported glycine-aldehyde reactions, glycine also reacts with acetone to give -hydroxyvaline under prebiologically feasible conditions. It is suggested, therefore, that the formation of -hydroxy--amino acids and their transformation to other amino acids may have been a pathway for the synthesis of amino acids under primitive earth conditions.     

Transformation of some hydroxy amino acids to other amino acids.

It has been observed that beta-hydroxy-alpha-amino acids are transformed into other amino acids, when heated in dilute solutions with phosphorous acid, phosphoric acid or their ammonium salts. It has been shown that as in the case of previously reported glycine-aldehyde reactions, glycine also reacts with acetone to give beta-hydroxyvaline under prebiologically feasible conditions. It is suggested, therefore, that the formation of beta-hydroxy-alpha-amino acids and their transformation to other amino acids may have been a pathway for the synthesis of amino acids under primitive earth conditions.     

Enzymatic synthesis and characterization of aryl iodides of some phenolic acids with enhanced antibacterial properties

Phenolic acids represent a class of drugs with mild antibacterial properties. We have synthesized iodinated gallic and ferulic acids and together with commercially available iodinated forms of salicylic acids studied their cytotoxicity, bacteriostatic and anti-virulence action. Out of these, iodogallic acid had lowest minimal inhibitory concentration (MIC) against Staphylococcus aureus (MIC = 0.4 mM/118.8 μg/ml). Yet, it had strong effect on erythrocyte membrane lipid ordering and on α-hemolysin secretion by the bacteria at lower non-bacteriostatic and non-cytotoxic concentrations (<0.1 mM). Iodogallic acid formed static complexes with α-hemolysin in solutions (logK_b = 4.69 ± 0.07) and inhibited its nano-pore conduction in artificial lipid bilayers (IC50 = 37.9 ± 5.3 μM). These effects of iodogallic acid converged on prevention of hemolysis induced by α-hemolysin (IC50 = 41.5 ± 4.2 μM) and pointed to enhanced and diverse anti-virulence properties of some aryl iodides. The analysis of molecular surface electrostatic charge distribution, molecular hydrophilicity, electronegativity, and dipole moment of studied compounds suggested the importance of the number of hydroxyl groups and their proximity to iodine in anti-virulence activity manifestation. In iodogallic acid, charge redistribution resulted in higher hydrophilicity without concomitant change in overall molecular electronegativity and dipole moment compared to non-iodinated gallic acid. This study shows new directions for the development of antibacterial/antivirulence therapeutics.     

Autoradiographic studies with fatty acids and some other lipids: A review

In this review, we have mainly included studies in which whole-body autoradiography was used. In lipid research, most studies have been done with fatty acids. These studies showed some common characteristics in the pattern of tissue distribution. A major uptake was seen in the brown fat, liver and adrenal cortex but also to some extent in other tissues with a high metabolic activity or high cell turn-over, e.g. the gastric and intestinal mucosa, diaphragm, kidney cortex and bone marrow. Low levels of radioactivity were generally found in the brain, testes, thymus, white fat, skeletal muscles, lungs and spleen. Most fatty acids showed some specific features, e.g the strong uptake of erucic, arachidonic and docosahexaenoic acid in myocardium and of eicosapentaenoic acid in the adrenal cortex. Studies with PGE1 and LTC3 showed that the liver and kidney and to a lesser degree the lungs were the major sites of metabolism. The distribution of free cholesterol and triolein emulsion labelled in the fatty acid moieties did show some similarities with respect to the general pattern found with most fatty acids. Specific for cholesterol was a very strong uptake in the adrenal cortex. There was also a significant uptake in the spleen whereas the uptake in the brown fat was not as marked as for most fatty acids. Specific for triolein was a marked uptake in the spleen and myocardium, in fed animals also in the white adipose tissue. These studies show that whole-body autoradiography can give much valuable information of the uptake and distribution of lipids that would be rather difficult to obtain with conventional methods. Combined with electron-microscopy, autoradiography can be used to study cellular and even subcellular distribution, and thus given further data on the metabolism of lipids in the body.     

The synthesis and bacytracin-catalysed hydrolysis of aryl esters of N-acylamino acids

1. A new method for synthesizing aryl esters of N-acylamino acids is described. The unsymmetrical anhydride resulting from the interaction of an N-acylamino acid and diphenylketen is allowed to react with a phenol. Cleavage of the anhydride by the phenol usually occurs in the desired direction. 2. Bacitracin has been examined as an enzyme model by determining its catalytic activity towards the hydrolysis of aryl esters. In general, it is less effective than imidazole. The variation of the catalytic constant with pH, together with other evidence, suggests that the histidine residue in bacitracin is the effective catalytic centre. 3. The stereoisomers of N-methoxycarbonylalanine p-nitrophenyl ester were hydrolysed at the same rate, but bacitracin was stereoselective towards the stereoisomers of the corresponding phenylalanine derivative.     

The uptake of bacteria and amino acids by Ophryoscolex caudatus, Diploplastron affine and some other rumen Entodiniomorphid protozoa

The rate of uptake of mixed rumen bacteria and free amino acids by washed suspensions of seven species of rumen ciliate protozoa has been followed. By assuming that the behaviour of these protozoa was the same under these conditions as during growth it was shown that Ophryoscolex caudatus could obtain the amino acids for growth by the engulfment of rumen bacteria. However, all the cellulolytic protozoa studied (Diploplastron affine, Diplodinium anacanthum, Diplodinium anisacanthum, Enoploplastron triloricatum, Eremoplastron bovis and Ostracodinium obtusum bilobum) were unable to obtain sufficient amino acids from either source to grow at even 25% of the maximum rate and it is postulated that they might utilize plant protein. O. caudatus grown in vitro did not engulf Klebsiella aerogenes or Escherichia coli but took up other bacteria and a rumen yeast at rates of up to 54000 organisms/protozoon/h from a population density of 10⁹/ml. When grown in vivo it was more selective and engulfed mixed rumen bacteria at only 10% of the rate obtained with protozoa grown in vitro. D. affine grown in vitro did not engulf Bacteroides ruminicola, Esch. coli, Kl. aerogenes or Proteus mirabilis but took up mixed rumen bacteria from a population of 10⁹/ml at a rate of 2200 bacteria/ protozoon/h.     

The fatty acids of some marine teleosts

The lipids of five mesopelagic species of myctophid, two mesopelagic species of stomia-toid, and one epipelagic species of Macrorhamphosidae from the eastern-North Atlantic have been examined by thin-layer chromatography and their fatty acid compositions have been determined by gas-liquid chromatography.     

Synthesis and in vitro antitubercular activity of some 1-[(4-sub)phenyl]-3-(4-{1-[(pyridine-4-carbonyl)hydrazono]ethyl}phenyl)thiourea

Various isonicotinyl hydrazones were prepared by reacting isonicotinyl hydrazide [INH] with 1-(4-acetylphenyl)-3-[(4-sub)phenyl]thiourea and were tested for their antimycobacterial activity in vitro against Mycobacterium tuberculosis H37Rv and INH-resistant M. tuberculosis using the BACTEC 460 radiometric system. Among the synthesized compounds, 1-(4-fluorophenyl)-3-(4-{1-[(pyridine-4-carbonyl)-hydrazono]ethyl}phenyl)thiourea (4d) was found to be the most potent compound with a minimum inhibitory concentration of 0.49 microM against M. tuberculosis H37Rv and INH-resistant M. tuberculosis. When compared to INH, 4d was found to be 3 and 185 times more active against M. tuberculosis H37Rv and INH-resistant M. tuberculosis, respectively, with a selectivity index of >300.     

The nucleic acids of some insect viruses

Purine and pyrimidine bases have been estimated from the desoxyribonucleic acids of eleven insect viruses. Their proportions vary in the different species in a balanced way so that the molar ratios adenine:thymine and guanine:cytosine are constant and close to unity, whereas adenine + thymine:guanine + cytosine ranges from 0.71 to 1.87. This ratio is identical for some biologically dissimilar viruses, and no general parallelism is evident between DNA composition and biological relationship. Two different viruses from one host have distinct DNA's.     

Antituberculous activity of some aryl semicarbazone derivatives

During the course of our work on the synthesis and screening of new drugs for tuberculosis, we have identified N1-(4-acetamido phenyl)-N4-(2-nitro benzylidene) semicarbazone (1b), which inhibited in vitro Mycobacterium tuberculosis H(37)Rv; 100% inhibition at 1.56 microg/mL. This paper is first of its kind in which aryl semicarbazones are reported to possess antimycobacterials potency greater than p-aminosalicylic acid, ethionamide, ethambutol, ciprofloxacin and kanamycin.