Synthesis and antisecretory and antiulcer activities of derivatives and analogues of 2-(2-pyridyl)tetrahydrothiophene-2-carbothioamide.

New thioamide derivatives of 2-(2-pyridyl)tetrahydrothiophene-2-carbothioamide (29) and related compounds (in which the tetrahydrothiophene ring was replaced by tetrahydrothiopyran, tetrahydrofuran, 1,3-dithiane, or 1,3-oxathiane and where the pyridine ring was replaced by other nitrogen heterocycles) were synthesized and tested for their antisecretory and antiulcer activities. These thioamides were prepared according to one of the following methods: reaction of an isothiocyanate with the carbanion of the corresponding cyclic precursor (for secondary thioamides); reaction of ammonia or an amine with the dithio ester prepared from the same precursor (for primary, secondary, and tertiary thioamides). These thioamides were evaluated by the Shay method to measure their antisecretory activity and by the stress-induced-ulcer method to test their antiulcer activity.

[Immunostimulating and adjuvant activities of a low molecular weight lipopeptide].

From crude extracts of a Streptomyces strain exhibiting immunopotentiating effects, a tetrapeptide was isolated and its structure established as L Ala leads to D isoGlu leads to L, L Dap comes from Gly. This peptide was devoid of biological activity but its chemical coupling with lauric acid gave a substance endowed with adjuvant and immunostimulating properties. This substance and the corresponding synthetic lauroyltetrapeptide were as active in this respect as the muramyl-dipeptide, thus far considered as the minimal adjuvant-active structure of bacterial cell walls: the presence of a sugar moiety is therefore not a prerequisite for immunopotentiating activities.