Carboxypolystyrene

A traceless solid supported protocol for the synthesis of 2-aminobenzothiazoles is described, employing resin-bound acyl-isothiocyanate and a series of anilines. Cyclization of the resulting N-acyl, N'-phenyl-thioureas generates the 2-aminobenzothiazole scaffold, which can be further elaborated prior to hydrazine-mediated cleavage of the final products from the carboxy-polystyrene resin. A small, focused library of 2-aminobenzothiazoles was prepared.

A solid phase, particle concentration fluorescence immunoassay (PCFIA) was developed for the measurement of prostaglandin (PG) D synthase in the 100,000g supernatant of various regions of the rat central nervous system. In this assay, the enzyme (in the range of 1-25 micrograms protein of brain supernatant or 1-100 ng of the purified enzyme) is attached to submicrometer carboxypolystyrene beads coated with polyclonal anti-rat brain PGD synthase IgG. The total particle-bound enzyme is assayed with fluorescein isothiocyanate (FITC)-conjugated monoclonal anti-PGD synthase IgG after incubation for 1 h. The optimum assay condition was obtained when carboxyl particles coated with ca. 500 micrograms/ml of polyclonal IgG at pH 5.0 and 5 micrograms/ml of FITC-IgG were used. No significant fluorescence was observed when FITC conjugates or carboxyl particles were prepared using IgG from nonimmunized rabbits. Heat treatment of the brain supernatant decreased the specific binding of the enzyme in parallel with the loss of enzyme activity, indicating that the denatured enzyme is not recognized by this assay method. The PGD synthase immunoreactivity was widely distributed in the brain regions and was highest in the paraflocculus. Although slight discrepancy was observed between the concentration by PCFIA and the enzyme activity measured by using [14C]PGH2 in some brain regions, there is a considerable correlation (0.727) between the values by both methods in the same brain regions. The PCFIA now developed showed higher sensitivity (around 10 times), greater reliability, and larger number of samples measurable at once than the radio-TLC assay using [14C]PGH2. This method could provide valuable information concerning the regulatory mechanisms of PGD synthase.

Objectives: A novel and simple method to synthesize antitubercular-protein conjugate by solid phase synthesis was developed employing a carboxypolystyrene resin. The aim was to covalently bind a drug with antitubercular activity, isoniazid, to a biomacromolecule, gelatin, widely used in the pharmaceutical, cosmetic and food industry. Methods: Calorimetric and (1) H NMR analyses were performed to verify the bond formation between the antitubercular drug and gelatin. After absorption isoniazid delivers toxic metabolites and so an oxidation test with tert-butyl hydroperoxide was performed to assess the amount of toxic metabolites released from the prodrug (gelatin linked to isoniazid), compared with isoniazid itself. Key findings: Spectrophotometric analysis revealed that the protein derivative was an excellent isoniazid prodrug since there was a 40% reduction in release of toxic metabolites (isonicotinic acid) by the prodrug. The results clearly showed that antitubercular moieties, covalently linked to a natural polymer, allowed the introduction of peculiar features for specific pharmaceutical applications into the macromolecule. In addition, antitubercular activity of the new polymer was determined by Middlebrook 7H11 medium against Mycobacterium tuberculosis complex. Conclusions: The new isoniazid-gelatin conjugate showed significant antitubercular activity and for this reason should be useful as an efficacious tool in the treatment of tuberculosis.