PURPOSE: To provide the subject novel substance hopeful as an agent for preventing or treating arterial sclerosis because of having a cholesterol synthesis- inhibiting activity, a lipid peroxide production-inhibiting activity and a superoxide anion radical-scavenging activity.

CONSTITUTION: A novel pharmacologically active substance chrysosuporin. The appearance; dark brown powder; molecular weight: 502;FAB-MS(m/z)501 08323 (M-H); rational formula: C27H18O10; solubility: soluble in lower alcohols, chloroform, etc. The substance is produced by culturing a chrysosporine- producing bacteria [e.g. novel Chrysosporium panolam M10539 strain (FERN P-12279)] belonging to the genus Chrysosporium preferably at a temperature near to 25°C and at a pH of 6-8, removing bacterial cells from the cultured solution and subsequently isolating and purifying the substance from the remained solution by a known method.