| 摘要 |
1355260 Gentamicin antibiotics SCHERICO Ltd 21 June 1971 [22 June 1970] 28962/71 Heading C2A The novel antibiotics gentamicin B, gentamicin B 1 and gentamicin X, and the known antibiotic gentamicin A, having the general Formula (II) wherein R 1 , R 2 , R 3 and R 4 are as follows: and salts and solvates thereof, are produced by subjecting a mixture of the said antibiotics (e.g. the fermentation products of Micromonospora purpurea or Micromonospora echinospora) to chromatography, suitably on silica gel developing with methanol, chloroform and ammonium hydroxide, and recovering the fractions containing each antibiotic. The fermentation products may be initially adsorbed on a cation exchange resin and eluted with ammonium hydroxide, decolorized on charcoal and the solution concentrated in vacuo to provide the starting mixture for the present process. The mixture may be further pretreated, e.g. by adsorption on anion exchange resin, eluting with water to remove gentamicin C, followed by further elution with water to obtain the desired mixture. The mixture is chromatographed on a silica gel column using as developing solvent the lower layer of a mixture of methanol, chloroform and ammonium hydroxide (1 : 1 : 1 v/v), whereby the antibiotics are eluted in the order: gentamicin B 1 , X, B and finally A. The antibiotics may be isolated by lyophilization, and may be recrystallized from ethanol, when they are obtained as the ethanol solvates. When obtained from aqueous solutions, they are in the form of hydrates. Gentamicin A may be obtained as the carbonate salt by exposing the methanolic solution to air, resulting in absorption of CO 2 and precipitation of the said carbonate salt. The antibiotics may be converted to other acid-addition salts by conventional procedures. Gentamicins A, B, B 1 and X have antibiotic activity against Gram-positive and -negative micro-organisms and in addition have antiprotozoal and anthelmintic activity. They may be used individually or together, optionally with a pharmaceutical carrier, in pharmaceutical compositions having corresponding activity. |
