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Biomedical subjects

A M Bellini

Publications and source records attributed to A M Bellini.

At least 19 recordsLinked to original sources
PubMed1993

Simultaneous determination of propranolol or metoprolol in the presence of butyrophenones in human plasma by gas chromatography with mass spectrometry.

A method has been developed for the simultaneous gas chromatographic determination of propranolol or metoprolol and butyrophenones butyrophenones in human plasma in vitro. The drugs were extracted from plasma by solid-phase extraction. Calibration graphs were linear in the 50-300-ng/mL range. The recovery of the compounds was 80-90%. The sensitivity of the method was adequate for the determination of the drugs at toxic concentrations and at therapeutic levels. It is a simple, rapid, and reproducible method for the simultaneous determination of propranolol or metoprolol and some butyrophenones. The minimum detectable concentration was 50 ng/mL with a flame ionization detector and 10 ng/mL with a mass spectrometer detector.

Butyrophenones↗
PubMed1992

Effect of basic cholane derivatives on intestinal cholic acid metabolism: in vitro and in vivo activity.

A representative series of hydroxy-5 beta-cholanyl-24-amines were tested both in vitro and in vivo with respect to their activity against the intestinal bacteria responsible for bile acid metabolism. For the in vitro studies, radiolabeled [14C]cholic acid was incubated with human stools both in aerobic and anaerobic conditions in the presence of the title compounds at a dose of 10 micrograms/mL, and the biotransformation of cholic acid into radiolabeled deoxycholic acid and other metabolites was followed by TLC-radiochromatography. Of the compounds studied, 3 alpha, 12 alpha-dihydroxy-5 beta-cholan-24-N-methylamine showed the highest activity. This compound was used for the in vivo studies and was shown to inhibit the formation of endogenous secondary bile acids when chronically administered to rats at a dose of 60 micrograms/day for 15 days. The treated rats showed an increased ratio of taurocholic acid (primary bile acid) to taurodeoxycholic acid (secondary bile acid) in bile, a fact further suggesting a potent antibacterial activity of the compound toward bacteria responsible for bile acid metabolism.

Aerobiosis↗
PubMed1992

Basic cholane derivatives. XI: Comparison between acid and basic derivatives.

A series of hydroxycholan-24-amines was synthesized; the carboxyl group of starting unconjugated bile acids was transformed into a basic moiety [-NH2, -NHCH3, -N(CH3)2, or -NHCH2C6H5] at C-24. Solubilities, acidities, partition coefficients, and critical micellar concentrations were measured and compared with those of the corresponding bile acids. Because the steroid nucleus in the amines is the same as that in the bile acids, most of the physical-chemical properties of the two compound classes were similar. The amines were more soluble than the corresponding acids; solubilities depended mainly on the number of steroid hydroxyls and, to a lesser extent, on the side chain. Amines are strong bases in water, whereas unconjugated bile acids can be classified as weak acids. N-Benzylamino derivatives have higher log P (P is partition coefficient) values, as a consequence of the bulky hydrophobic substituent; the log P values were almost the same for the amines and the bile acids and depended on the steroid hydroxyls. Amines can self-aggregate at an acidic pH and form cationic micelles; the critical micellar concentrations of amines were of the same order of magnitude as those of bile acids. The introduction of a basic function in the side chain of the cholane moiety increased the antimicrobial activity toward most gram-positive strains.

Bile Acids and Salts↗
PubMed1992

Simultaneous determination of propranolol or metoprolol in the presence of benzodiazepines in the plasma by gas chromatography.

A method for the simultaneous gas chromatographic determination of propranolol and metoprolol and some benzodiazepines in human plasma is described. After the addition of an internal standard, plasma samples were adjusted to pH 8.5 and extracted by SPE chromatography. The analysis was performed by GC with packed and capillary columns, using a FID detector. The quantitative recovery was reported. The assay response was linear in concentration range 50-300 ng/mL for propranolol-benzodiazepine and 100-350 ng/mL for metoprolol-benzodiazepine mixtures.

Benzodiazepines↗
PubMed1991

Antimicrobial activity of basic cholane derivatives. X. Synthesis of 3 alpha- and 3 beta-amino-5 beta-cholan-24-oic acids.

A simple and convenient route to 3 alpha- and 3 beta-amino-5 beta-cholan-24-oic acids was developed via Leuckart-Wallach amination reduction and subsequent acid hydrolysis. Two epimeric formylamino derivatives were produced (alpha and beta), approximately in a 1:1 ratio, as determined by 13C nuclear magnetic resonance spectroscopy. The two isomers were separated by making use of their different solubilities in ethyl ether. The absolute configuration of the two amino acids was assigned by comparison with authentic reference samples.

Lithocholic Acid↗
PubMed1990

Antimicrobial activity of basic cholane derivatives. Part IX.

Twenty new compounds derived from deoxycholic acid have been synthesized. They contain two basic functions: at C-24 (benzylamino, morpholino, diethanolamino, N,N-diethylethylenediamino, N-methylpiperazino) and at beta-C-3 (amino, methylamino, ethylamino, benzylamino). The compounds showed interesting antimicrobial activity, as expressed in terms of the low M.I.C. values (0.9-31-micrograms/ml) against five Gram(+) and four Gram(-) strains, two fungi and one yeast. The compounds inhibit the production of a fluorescent pigment in Pseudomonas aeruginosa: this result suggests that the ability to cross the bacterium cell membrane is the first step of activity. A discussion in terms of structure-activity relationship is reported.

Anti-Bacterial Agents↗
PubMed1990

Quantitative structure-antimicrobial activity relationship in 5 beta-cholanyl-24-benzylamine derivatives.

Some representative physicochemical properties of benzylamido and amino derivatives of common bile acids have been determined and correlated with their antimicrobial activity against gram-positive bacterial strains. Steroid hydroxyls do not affect the basicity of amino derivatives; they promote solubility in a parallel way to unconjugated bile acids and mainly control hydrophobicity of this class of compounds as measured by log P values. Activity was correlated to hydrophobicity; that is, the nature of the side chain modulated activity, affected basicity, and facilitated changes in partition ability. Benzylamino derivatives proved to be even more active than the corresponding amides when ionization is taken into account. Trihydroxy derivatives possess the lowest log P values and were practically inactive. Decreased activity was also observed in those cases where, due to the orientation of the hydroxy group in the 6 or 7 position, the back beta face of the molecule had a reduced hydrophobic surface area. Antimicrobial activity, in terms of -log MIC (minimal inhibitory concentration), was found to correlate linearly with log P values of uncharged species. This linear relationship is discussed with respect to the structure of the steroid moiety and the ability of these molecules to cross cellular membranes.

Anti-Bacterial Agents↗
PubMed1989

Antimicrobial activity of basic cholane derivatives, VIII.

Two series of new compounds derived from deoxycholic acid have been synthesized: 3,12-dioxo-5 beta-cholan-24-N-substituted amides and their 3 beta-amino and 3 beta-N-alkylamino derivatives. The first series of five compounds 1-5 carries at C-24 the residue of benzylamine, morpholine, diethanolamine, N,N-diethyl-ethylenediamine, and N-methylpiperazine. The second series of twenty compounds 1A-D - 5A-D was prepared by means of reductive amination starting from the compounds of the first series. This reaction proved to be regioselective and stereospecific: it attacks only C-3 of the steroid moiety and introduces the following axial beta-oriented substituents: amino, methylamino, ethylamino, and benzylamino. The compounds of the first series showed moderate scattered antimicrobial activity; while introduction of the 3 beta-amino and 3 beta-N-alkylamino residue greatly increased activity towards Gram (+) strains; even yeast and fungi appear to be sensitive towards this last series of compounds. The results have been discussed with respect to the nature of the substituents both at C-3 and C-24, the highest activity being associated to the hydrophobicity of these residues.

Anti-Bacterial Agents↗
PubMed1984

[Derivatives of lithocholic acid with antibacterial and antifungal activity. IV].

A series of N-substituted amides of litocholic acid and some N-substituted derivatives of 3 alpha-hydroxy-24-amino-5 beta- cholane were prepared and their in vitro antibacterial and antifungal activity determined against a variety of gram-positive and gram-negative strains and two kinds of mycetes . Some of the tested compounds showed an interesting activity against gram-positive strains and mycetes .

Anti-Infective Agents↗
PubMed1979

[Bile acid derivatives with antimicrobial activity].

A series of condensation products of cholic and dehydrocholic acids with (L)-aminoacids was prepared and tested in vitro for antimicrobial activity. The derivatives of cholic acid with basic aminoacids showed significant activity, especially marked when (L)-arginine was the condensed aminoacid.

Amino Acids↗