Biomedical subjects

L Thunus

Publications and source records attributed to L Thunus.

At least 19 recordsLinked to original sources

PubMed2006

Study of the physicochemical properties in aqueous medium and molecular modeling of tagitinin C/cyclodextrin complexes.

The inclusion complexes of tagitinin C with beta-, 2,6-di-O-methyl-beta- and gamma-cyclodextrin (CyD) was investigated in aqueous medium. The stoichiometric ratios and stability constants (K(f)) which describe the extent of formation of the complexes have been determined by UV spectroscopy and direct current tast polarography (DC(tast)), respectively. For each complex, a 1:1 molar ratio was formed in solution and the trend of stability constants was K(f) (2,6-di-O-methyl-beta-CyD)>K(f) (gamma-CyD)>K(f) (beta-CyD). The effect of molecular encapsulation on the photochemical conversion of tagitinin C was evaluated. No significant protection efficacy was noticed with beta- and gamma-CyD for the complexed drug with the respect to the free one. On the other hand, the photochemical conversion rate was slowed in presence of 2,6-di-O-methyl-beta-CyD. Data from (1)H NMR and ROESY experiments provided a clear evidence of formation of inclusion complexes. The lactone, the ester and the unsaturated ketone parts of tagitinin C inserted into the wide rim of the CyDs torus. These experimental results were confirmed by the molecular modeling using semiempirical Austin Model 1 (AM1) method.

Chemical Phenomena↗

PubMed1999

Application of supercritical carbon dioxide for the preparation of a piroxicam-beta-cyclodextrin inclusion compound.

PURPOSE: Piroxicam is a poorly soluble NSAID, whose solubility is enhanced when included into beta-cyclodextrin. The preparation of a piroxicam-beta-cyclodextrin inclusion compound using supercritical CO2 was investigated. METHODS: The solubility and the stability of piroxicam in supercritical CO2 were determined. Then, the influence of the temperature, the pressure and the time of exposure on the inclusion rate was studied. RESULTS: The solubility of piroxicam varied over a wide range depending on the temperature and pressure (from 0.006 to 1.500 mg/g of CO2). The temperature and the time of exposure had a great influence on the inclusion yield, while pressure did not and a complete inclusion was achieved by keeping a physical mixture of piroxicam and beta-cyclodextrin (1:2.5 mol/mol) for 6 hours at 150 degrees C and 15 MPa of CO2. This complex was characterized by Differential Scanning Calorimetry, differential solubility and Fourier Transform Infrared Spectrometry. CONCLUSIONS: Supercritical carbon dioxide may prove to be a novel useful complexation method of drugs into beta-cyclodextrin.

Calorimetry, Differential Scanning↗

PubMed1995

Anti-inflammatory properties of copper, gold and silver, individually and as mixtures.

It has been previously demonstrated that the mixture of Cu, Au and Ag impaired significantly the clinical and biochemical disorders induced by adjuvant arthritis in the rat. The efficiency of this mixture and of each component was tested on the same animal model. Treated rats were injected daily with either 22.8 micrograms of copper gluconate, 0.2 micrograms of gold thioglucose, 6.8 micrograms of silver proteinate or the blended solution over a period of 29 d. The treatment with the one component solutions was found to have a little or no effect on the plasma levels of fibrinogen, haptoglobin, ceruloplasmin, prostaglandin E2, thromboxane B2, total proteins, Zn, Cu, Mn, Se, Co and Ni, and no significant decrease was observed in the paw oedema resulting from the Freund's adjuvant injection. The treatment with the mixture had a significant preventive effect. Therefore it seems that the administration of low doses of each of the three trace elements have no anti-rheumatic property in the rat. The results indicate an enhanced effect of the metal mixture in the model studied.

Animals↗

PubMed1990

Subfemtomole enzyme immunoassay for human growth hormone using affinity chromatography and enzyme amplified detection.

An immunometric assay is described which allows fast detection of attomole amounts of an antigen. The sensitivity is 100 to 1000 times better than that of classical sandwich immunometric assays. Our system allowed the measurement of human growth hormone in the range of 0.1 amol to 100 fmol in a 4-h time period overall. A chromatography column is sequentially filled with two immunoaffinity resins: SP-M1--E1-Ab1 in the upper half and SP-M2--E2-Ab2 in the lower half, where Ab1 and Ab2 represent complementary antibodies reacting with the antigen to be assayed, E1 and E2 represent enzymes, M1 and M2 represent substances reacting reversibly with E1 and E2, respectively, and SP represents the chromatographic solid phase; the sign - represents covalent linkages and the sign--reversible linkages. The sample solution is passed through the column, resulting in binding of the antigen to the first encountered antibody, yielding the immobilized complex SP-M1--E1-Ab1--Ag. The M1 bound is then destabilized by washing with solution of agonist to M1. The freed complex is immediately trapped by the second antibody in the lower part of the column, resulting in the entity SP-M2--E2-Ab2--Ag--Ab1-E1. After a washing step, and amplified detection allows the measurement of the antigen through the activity of the enzyme E1. The antigen-antibody reactions occur in the presence of a very large excess of antibody. The continuous equilibrium displacement due to the chromatographic procedure enhances the yield of complex formation. These factors explain the extremely low levels (subattomole) capable of being detected with this original technique.

Animals↗

PubMed1990

Anti-inflammatory properties of a preparation containing low doses of copper, gold and silver.

The efficacy of a drug containing three heavy metals together has been tested in adjuvant-induced arthritic rats. Treated rats were injected with 22.8 micrograms copper gluconate, 0.2 microgram gold thioglucose and 6.8 micrograms silver proteinate each day during a period of 29 days. The drug treatment was found to diminish the increases in plasma levels of haptoglobin, ceruloplasmin, PGE2, 6-keto-PGF1 alpha and copper, the decrease in the iron plasma level induced by Freund's adjuvant and the paw swelling. No effect was seen on the plasma levels of TXB2, Zn, Se, Mn and Ni. Therefore the simultaneous administration of low doses of gold, copper and silver had a real anti-rheumatic property in this model. These results should be of interest for the long-term treatment of arthritis.

Animals↗

PubMed1984