Carbomycin, also known as magnamycin, is a colorless, optically active crystalline macrolide antibiotic with the molecular formula C42H67N O16. It is derived from the bacterium Streptomyces halstedii and active in inhibiting the growth of Gram-positive bacteria and "certain Mycoplasma strains." Its structure was first proposed by Robert Woodward in 1957 and was subsequently corrected in 1965.