Abstract: An imperfect fungus such as a microorganism belonging to the genus Curvularia in a culture medium containing nutrients utilizable for normal microorganisms and isolating MK7634 substance of a molecular formula: C.sub.8 H.sub.15 N.sub.3 O.sub.4 from the culture by, for example, solvent extraction, ion exchange resin technique or gel filtration chromatography. The MK7634 substance can be used as an active ingredient of drugs. In particular, the MK7634 substance is a novel anthelmintic substance and expected to be used as an active ingredient of anthelmintics.

Abstract: Sesquiterpene derivatives, represented by the following formulae (I) and (II), having progesterone receptor binding inhibitory activity are disclosed. They can be used as therapeutic and prophylactic agents for progesterone-related diseases, for example, as a carcinostatic agent for breast cancer or ovarian cancer, a therapeutic agent for hysteromyoma, endometriosis, meningioma, or myeloma, an abortifacient, an oral contraceptive pill, or a therapeutic or prophylactic agent for osteoporosis or climacteric disturbance. These compounds have no steroid skeleton and, hence, are considered to be advantageously free from side effect inherent in steroid such as found in conventional progesterone receptor binding inhibitors having a steroid skeleton. ##STR1## wherein R.sup.1 represents a hydrogen atom, a halogen atom, C.sub.1 -C.sub.5 alkoxy, or phenylthio; R.sup.2 represents C.sub.1 -C.sub.5 alkoxy or C.sub.2 -C.sub.