A microorganism capable of producing substances K97-0239 comprising K97-0239A represented by the following formula [I]: and K97-0239B represented by the following formula [II]: is cultured in a medium and the substances K97-0239 thus accumulated in the medium are collected from the culture medium. The obtained substances have a low toxicity and specifically inhibit the foaming of macrophages. Owing to these characteristics, they are useful in preventing and treating human arteriosclerosis and diseases caused thereby.
