Pigments of Gnomonia erythrostoma. Part I. The structures of erythrostominone, deoxyerythrostominone, and deoxyerythrostominol
Three antibacterial pigments have been isolated from deep cultures of Gnomonia erythrostoma. By a combination of spectroscopic investigation and chemical degradation erythrostominone has been shown to be 2-acetonyl-3,4-dihydro-4,5,10-trihydroxy-8-methoxy-2H-naphtho[2,3-b]pyran-6,9-quinone (1); deoxyerythrostominone is its 4-deoxy-derivative (2), and deoxyerythrostominol is 3,4-dihydro-5,10-dihydroxy-2-(2-hydroxypropyl)-8-methoxy-2H-naphtho[2,3-b]pyran-6,9-quinone (21 ).