Abstract: Substance FA-70D which has the following formula (1), or its salt, a method for its production, a pharmaceutical composition comprising the compound as an active ingredient, a method of treating osteoporosis which comprises administering the compound, use of the compound as a drug, and a microorganism capable of producing Substance FA-70D are disclosed. This compound has specific inhibitory activity against cathepsin series proteases and is of value as a therapeutic drug for various diseases, particularly osteoporosis, with which these enzymes are associated.

Abstract: A substance IT-62-B represented by the following formula (1): ##STR1## a production process thereof, a medicinal composition comprising the compound as an active component, and methods of treating an infectious disease caused by bacteria and a tumor, in which such a substance is administered.The compound according to the invention has good antibacterial activities against gram-positive bacteria and some of gram-negative bacteria, and also possesses excellent antitumor activities against tumors such as human nasopharyngeal carcinoma, and is hence useful as a medicine.

Abstract: The present invention relates to the use of 3-(7-oxo-1-aza-4-oxabicyclo[3.2.0]hept-3-yl)alanine derivatives of formula (I) or a pharmaceutically acceptable salt thereof, as antitumor agents. ##STR1## Wherein R is: hydrogen or COOR.sub.2 wherein R.sub.2 is C.sub.1 -C.sub.3 alkyl group which may be substituted with aryl group.Wherein R.sub.1 is:hydrogen or C.sub.1 -C.sub.3 alkyl group which may be substituted with one or two aryl groups.

Abstract: The present invention relates to the use of 4-oxa-1-azabicyclo [3,2,0] heptan-7-one derivatives of formula (I) or a pharmaceutically acceptable salt thereof, as antitumor agents. ##STR1## Wherein R is --OCOR.sub.1 group wherein R.sub.1 is hydrogen atom, a C.sub.1-9 alkyl group which may be substituted by either one or two substituents selected together from halogen atom, hydroxy, carboxy group or (3RS,5SR)-(4-oxo-1-azabicyclo[3,2,0]heptan-7-one-3-yl) methyloxycarbonyl, a C.sub.2-17 alkenyl group, which may be substituted by carboxy group or (3RS,5SR)-(4-oxa-1-azabicyclo [3,2,0]heptan-7-one-3-yl)methyloxycarbonyl, A C.sub.2-4 alkynyl group, a C.sub.3-6 cycloalkyl group which may be substituted by carboxy group or phenyl group which may have 1, 2 or 3 substituents selected from the group consisting of cyano group, halogen atom, C.sub.1-6 alkoxy group which may be substituted by carboxy group, C.sub.1-6 alkyl group, amino group or hydroxy group.--OR.sub.2 wherein R.sub.