Macrolides are a group of organic compounds that possess a macrolide ring (usually 14-, 15- or 16-membered) as the carbon skeleton. Most of the isolated macrolides are structurally diverse antibiotics such as erythromycin1,2 and are produced by microorganisms such as the soil-dwelling bacterium Streptomyces via polyketide biosynthesis.3 They exhibit various biological activities, including antitumor, antifungal, antiparasitic and immunosuppressant activities. Among the macrolides, bafilomycins4,5 and setamycin6,7 are 16-membered macrolides that are reported to exhibit specific membrane ATPase inhibitory activity.8 In the course of screening for anti-yeast compounds, we isolated a new bafilomycin analog named makinolide (1 in Figure 1a), along with the known macrolide JBIR-100 (2 in Figure 1a)9,10 from newly isolated strain, Streptomyces sp. MK-30. Herein, we describe the isolation and structural determination of makinolide (1).