Ethyl Acetate → N-[(7-Hydroxy-2,11-dimethoxy-3,12,16-trimethyl-1,4,10,13-tetraoxo-1,5,6,7,9,10,13,14,14a,15-decahydro-4H-6,15-epiminoisoquinolino[3,2-b][3]benzazocin-9-yl)methyl]-2-oxopropanamide

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Reaction Steps

After completion of the cultivation, the cultured broth is filtered to separate mycelia from the filtrate. The filtrate is adjusted to pH 8.0 with 10 N sodium hydroxide. The filtrate may be previously concentrated to 1/2-1/3 volume for better extraction efficiency with a solvent. In the solvent extraction as noted above, basic, water-soluble antibiotics, for example, streptothricin simultaneously produced by the strain No. 314 are left in the filtrate, while saframycin complex and the like are extracted into the solvent phase. The solvent phase is concentrated to dryness under reduced pressure, the concentrate is dissolved in a small amount of ethyl acetate, the solution is shaken with aqueous sodium carbonate and separated, whereupon acidic substances are transferred into an aqueous phase. The solvent phase is extracted with 1 N hydrochloric acid, adjusted to pH 8-9 with aqueous ammonia and extracted with chloroform. This step is repeated several times and the solvent phase is concentrated to dryness under reduced pressure to give a reddish brown, crude basic component containing saframycin complex. The crude basic component is dissolved in a small amount of ethyl acetate, the solution is washed several times with a small amount of water and shaken with 1 N hydrochloric acid, whereupon the antibiotic substances are transferred into an aqueous layer. The aqueous layer is adjusted to pH 8.0 carefully and extracted with dichloromethane. The dichloromethane layer is separated, dried over anhydrous sodium sulfate and the solvent is distilled off to obtain dark red solid, which contains all of saframycins A, B, C, D, E and S. The solid is chromatographed over silica gel column, which is then developed successively with a mixture of benzene and ethyl acetate (10:1), (4:1) and (2:1). Saframycin S is eluted with an eluent of the mixture (2:1) and further purified by preparative thin layer chromatography. Saframycin S is obtained as a dark yellow powder. Saframycin S was subjected to thin layer chromatography over silica gel, which was developed successively with benzene:acetone (1:1), benzene:ethyl acetate (1:3) and chloroform:ethyl acetate (1:1) and gave yellow spots at the position of Rf values of 0.45, 0.25 and 0.16, respectively. Identification and quantitative determination of saframycin S was conducted by measuring the position and area of the yellow spots on scanning profile with 270 nm.

Provenance & Evidence