New antifungal antibiotics pradimicins FA-1 and FA-2: D-serine analogs of pradimicins A and C.

Pradimicin FA-1 was produced via directed biosynthesis with substitution of D-serine for D-alanine in the 15-position of pradimicin A. This substitution was achieved by the addition of D-serine to the culture medium of Actinomadura hibisca P157-2. Likewise, pradimicin FA-2 was co-produced along with pradimicin FA-1 when the pradimicins A and C producing strain, A. hibisca A2493 was grown in D-serine-supplemented medium. The new pradimicin analogs share a common core structure of 5,6-dihydrobenzo[a]naphthacenequinone substituted by D-serine at C-15, but differ in the disaccharide moiety at C-5. Pradimicin FA-1 has an N-methylamino sugar and D-xylose. Pradimicin FA-2 is the des-N-methyl analog of pradimicin FA-1. The in vitro and in vivo antifungal activity of the analogs was comparable to that of pradimicin A.