<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A term used to describe a chemical structure of a compound containing a large lactone ring, usually with a 14 or 16-membered ring structure. The prototypical compounds within the macrolide class are the erythromycin-based antibiotics; however, many compounds with this chemical structure are being developed for other diseases.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>