SCH 58450, a novel farnesyl protein transferase inhibitor possessing a 6a,12a:7,12-diepoxybenz[a]anthracene ring system

SCH 58450, a novel secondary metabolite possessing the 6a,12a:7,12.diepoxybenz[a]anthracene ring system, has been isolated from a Streptomyces sp. SCH 58450 inhibits farnesyl protein transferase with an IC50 of 29 μM, and shows 25 fold selectivity for farnesyl protein transferase over geranylgeranyl protein transferase-1.