Thiolutin is a dithiolopyrrolone antibiotic synthesized by Streptomyces. Thiolutin displays broad spectrum antibacterial activity as well as some antifungal and anti-angiogenic activities. Thiolutin inhibits bacterial and yeast RNA polymerase, preventing RNA synthesis or transcription. Thiolutin also inhibits mRNA degradation. In vitro, this compound modulates HSP27 interactions to decrease actin stress fiber and F-actin levels and to increase cortical actin levels, resulting in inhibition of endothelial cell adhesion. Additionally, thiolutin decreases levels of paxillin and prevents endothelial cell adhesion in other in vitro models, inhibiting angiogenesis in S-180 tumor cells.