Monocillin IV (CAS: 75207-14-6)

Monocillin IV is a resorcylic acid lactone (RAL) natural product structurally related to radicicol (monorden) and other Hsp90-inhibitory fungal metabolites. It was isolated from Humicola fuscoatra and later identified from Pochonia chlamydosporia strains. As a member of the radicicol/monorden family, monocillin IV belongs to the RAL class characterized by a resorcinol-containing macrolactone scaffold. Biologically, monocillin IV exhibits antifungal activity against Aspergillus flavus and modest antibacterial activity against plant pathogens such as Xanthomonas campestris. Based on structural homology within the radicicol family, monocillin IV is considered part of the Hsp90-inhibitory resorcylic acid lactone scaffold, although its precise inhibitory potency relative to radicicol varies among analogues. The compound is also associated with biosynthetic gene clusters encoding PKS-derived RAL pathways in Pochonia species.