Sporaviridin

The effects of the glycoside antibiotic sporaviridins (SVDs) on oxidative phosphorylation of rat-liver mitochondria were examined. SVDs released state 4 respiration, dissipated transmembrane electrical potential, and accelerated ATPase activity. These facts demonstrated that SVDs are potent uncouplers of oxidative phosphorylation. During the uncoupling caused by SVDs, large amplitude swelling and oxidation of intramitochondrial NAD(P)H occurred, suggesting that SVDs greatly enhanced nonspecific permeability of the inner mitochondrial membrane. It is suggested that the uncoupling action of SVDs might be caused by dissipation of proton electrochemical potential due to an increase in the permeability of inner mitochondrial membrane.

Six components of sporaviridin (SVD) were successfully isolated by HPLC using methano-1 M ammonium chloride as the mobile phase. Each component possesses expectedly antimicrobial activity. To ensure the structural relationship between the intact SVD and N-acetylated sporaviridins (N-Ac-SVD), they were converted to the corresponding of N-acetates by acetylation in methanol, whose structures had already been determined as glycosides consisting of a 34-membered macrocyclic lactone, viridopentaoses, D-glucose and N-acetylvancosamine.

The planar structure of aculeximycin (1) produced by Streptosporangium albidum has been determined by spectral methods and chemical degradations such as 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU)-methanol reaction, ozonolysis, and periodative oxidation. The antibiotic consists of a 30-membered polyhydroxy lactone ring, an alpha, beta-unsaturated ester group, an intramolecular hemiketal, an oligosaccharide (aculexitriose), a neutral sugar and an amino sugar. The structure of aculeximycin is closely related to those of sporaviridins produced by Streptosporangium viridogriseum. We consider that aculeximycin and sporaviridins belong to a new class of macrolide antibiotics, which is different from the polyol macrolides produced by Streptomyces.