Bafilomycin B1

The bafilomycins are fungal plecomacrolide antibiotics with a 16-membered lactone ring. They inhibit the growth of Gram-positive bacteria and fungi. Bafilomycin B1 is a selective, reversible inhibitor of vacuolar H+-ATPases (V-ATPases), blocking these proton pumps in mammalian, plant, or fungal cells with an IC50 value in the 4-400 nM range. It is at least 1,000-fold less potent at most other types of ATPases. When used at 100 nM, the related macrolide bafilomycin A1 blocks V-ATPase-mediated acidification of lysosomes during autophagy, preventing protein degradation. Remarkably, at only 1 nM, both bafilomycin A1 or B1 dramatically attenuate chloroquine-induced apoptosis of neurons without altering autophagy.