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A V Delgado

Publications and source records attributed to A V Delgado.

23 records · Page 2Linked to original sources
PubMed1996

Effect of amino acids on the stability properties of nitrofurantoin suspensions. Flocculation and redispersion compared with interaction energy curves.

The influence of the addition of amino acids, lysine, alanine and glutamic acid on the properties of nitrofurantoin suspensions was investigated. Flocculation and redispersability was investigated, taking into account the electrical properties of the nitrofurantoin/solution interface. We conclude that lysine and glutamic acid, but not alanine, would be suitable amino acids for control of the stability of nitrofurantoin suspensions.

Alanine↗
PubMed1995

Effects of different amino acids on the electrical characteristics of pharmaceutical polymers.

The effect of variations in pH and in concentration of five different amino acids (alanine, glycine, lysine, threonine, and glutamic acid) on the electrical properties of the Aquacoat polymer/solution interface was investigated by means of electrophoretic mobility measurements. The results are explained on the basis of determinations of adsorption of the amino acids on the polymer particles. The pH appears to be a determining factor in the way amino acids interact with the negatively charged polymer particles. The net, pH-dependent charge on the amino acid molecules may significantly affect their interaction with Aquacoat; thus, electrostatic effects seem to be most important in the case of lysine and glutamic acid. However, specific effects related to the structure (polarizability, size, charge) of the side group of the amino acid species appear to play an important role in the interaction and adsorption phenomena involved.

Alanine↗
PubMed1992

HIV-1 neutralization and tumor cell proliferation inhibition in vitro by simplified analogues of pyrido[4,3,2-mn]thiazolo[5,4-b]acridine marine alkaloids.

The antiviral/antitumor marine alkaloid dercitin was used as a lead compound to design analogues with anti-HIV and tumor inhibitory activities. Deletion of structural features contributing to cytotoxicity led to analogues with lowered T-lymphocyte toxicity profiles. One compound, 5, induced complete protection against HIV-1 infectivity in vitro at 12.5 micrograms/mL (38 microM) without T-cell toxicity up to 400 micrograms/mL. Compound 4 and 5 also inhibited the binding of HIV-1 to H-9 lymphocytes. These compounds may exert antiviral activity by a unique dual extracellular and intracellular mode of action--both preventing viral attachment to lymphocytes as well as intercalating with viral nucleic acid. Analogues with higher cytotoxicity such as 2 which retain the thiazole ring of the natural product proved effective in completely inhibiting the cell proliferation of breast, colon, and lung tumor cell lines at 1.5 microM concentration compared to a 70 microM dose level of 5-fluorouracil. A means of molecular separation of antiviral activity from cytotoxicity was thus achieved, and putative pharmacophores for antiviral and antitumor actions of the prototype molecule dercitin have been deduced. The 2-thio-9-acridinone derivatives 4 and 5 represent a new structural type exhibiting activity against HIV in vitro, serving as chemical leads in the design of anti-AIDS agents, while thiazolo[5,4-b]acridines such as 2 provide leads in the drug design of new antitumor agents.

Alkaloids↗
PubMed1990

An improved topical formulation for urea.

The solubility of urea in different polar solvents was studied by means of determination of their dielectric constants. The most appropriate solvents turned out to be water and a water/propylene glycol (1:1 in volume) mixture. The best solvents were then used in the study of different semisolid vehicles for topical use (cetylic excipient, Beeler's base and Carbopol gel), which show different physicochemical characteristics. The final formulation contained a 40% (w/w) concentration in urea, since this value is most often used in Dermatology and, at the same time, it is the most problematic from a technological point of view. The stability of the different preparations was investigated by conductimetric and rheological determinations. The results are discussed in terms of both the solubility and stability of the active principles and the organoleptic and rheological characteristics of the final preparations.

Acrylic Resins↗