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A natural lactone, whose ring is large, usually of 14–20 atoms; several antibiotics, including erythromycin, are macrolides. They inhibit protein biosynthesis.
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mac·ro·lide 'mak-rə-.līd n any of several antibiotics (as erythromycin) containing a macrocyclic lactone ring that are produced by actinomycetes of the genus Streptomyces and inhibit bacterial protein synthesis
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mac·ro·lide (makґro-līd) 1. a chemical compound characterized by a large lactone ring containing multiple keto and hydroxyl groups. 2. any of a large group of antibacterial antibiotics containing a macrolide ring linked glycosidically to one or more sugars; they are produced by certain species of Streptomyces and inhibit protein synthesis by binding to the 50S subunits of 70S ribosomes. Examples include erythromycin, azithromycin, and clarithromycin.Medical dictionary. 2011.