1966 Volume 39 Issue 10 Pages 2242-2249
A cyclic hexapeptide, cyclo-D-phenylalanyl-D-leucyl-L-ornithyl-L-valyl-D-ornithyl-L-prolyl, was once reported to be an antibiotic gramicidin J2, and the synthesis of the compound was described also. However, the natural occurrence of gramicidin J2 was denied recently. For the purpose of comparing its antibacterial activity, if any, with gramicidin S, the synthesis of this compound was carried out. p-Methoxybenzyloxycarbonyl-D-phenylalanyl-D-leucyl-δ-benzyloxycarbonyl-L-ornithyl-L-valyl-δ-benzyloxycarbonyl-D-ornithyl-L-proline p-nitrophenyl ester was prepared, and, after the selective cleavage of p-methoxybenzyloxycarbonyl group, the hexapeptide ester was transformed to the cyclic benzyloxycarbonyl hexapeptide, which was then hydrogenated to afford the desired cyclic hexapeptide as dihydrochloride. The effects of the synthesized cyclic peptide on bacterial growth have been examined. No antibacterial activities were observed in reaction to the microorganisms utilized here.
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