Borrelidin is a secondary metabolite produced by Streptomyces and other bacteria. It displays potent antiangiogenic activity, preventing tube formation in rat aorta explants (IC50 = 0.8 nM) and inducing apoptosis in endothelial cells. Borrelidin also alters the splicing of VEGF mRNA, producing an antiangiogenic isoform of the growth factor. It has long been known as a powerful inhibitor of both eukaryotic and bacterial threonyl tRNA synthetase. Borrelidin is also an effective anti-malarial drug, as it kills P. falciparum with an IC50 value of 1.8 nM. At higher doses, it inhibits cyclin-dependent kinase in yeast (IC50 = 24 μM), resulting in growth arrest in the G1 phase.
