The present invention relates to a novel, Nonadeca-6-enoic acid-3-(hexadecyloxy-hydroxy-thiophosphoryloxy)-quinoxalin-2-yl ester designated as streptolipin, useful for pancreatic lipase inhibition, isolated from the culture of Streptomyces vayuensis strain N2 having molecular formula (1) and a process for the preparation thereof. ##STR00001##