Ansamitocins, a new group of ansamycin antibiotics with potent antitumor activity, were first reported in the journal Nature in 1977 by researchers from Takeda Chemical Industries. Anisomitocin P3 is the 3-O-methylpropanoyl derivative of maytansinol produced by bacteria rather than maytansinoid-producing plants. Ansamitocin P3 inhibits the growth of several eukaryotic microorganisms but has no activity against prokaryotic microorganisms. The acyl moieties at the C-3 position of ansamitocins are essential for their antifungal activities. Ansamitocin P3 targets cell division protein FtsZ, the analogue of β-tubulin in bacteria.