|HS-142-1, a novel nonpeptide (polysaccharide) atrial natriuretic peptide (ANP) antagonist which specifically inhibits natriuretic peptide-induced vasorelaxation through the blockade of guanylyl cyclase-linked natriuretic peptide receptors . It was purified from the fermentation broth of Aureobasidium pullulans var. melanigenum . The compound consists of glucose and caproyl subunits. Hexaosyl fragment O-(3-O-caproyl-beta-D-glucopyranosyl)-(1-->6)-[O-(beta-D- glucopyranosyl)-(1-->6)-O-(3-O-caproyl-beta-D-glucopyranosyl)-(1--> 6)]2-D-glucopyranose, is among the major components of the molecule and ithis has been used as the basis for synthesising synthetic analogues of the polysaccharide.