Siderophore activity of chemically synthesized dihydroxybenzoyl derivatives of spermidines and cystamide

Chemically synthesized dihydroxybenzoyl derivatives of spermidine and cystamide containing two-, three- and four-bidentates with the hydroxyl groups in 2,3 or 3,4 position were examined in cross-feeding tests using Gram-negative siderophore indicator strains carrying different iron-related markers, and two Mycobacterium spp. The catecholates were unable to feed tonB mutants of E. coli and S. typhimurium as well as the fepA, fiu, cir mutant of E. coli, pointing to a tonB- and fepA, cir, fiu-dependent transport. Bis(2,3-dihydroxybenzoyl)derivatives promoted Salmonella spp, E. coli, K. pneumoniae and P. aeruginosa strains significantly better than did 3,4-dihydroxybenzoyl derivatives. N4-substituted spermidines acted more effectively than non-substituted derivatives. Bis(2,3-dihydroxybenzoyl) cystamide was superior to the other catecholates tested in growth promotion of Gram-negative bacteria. The two four-bidentates and the tri-bidentate reacted to K. pneumoniae in an inhibitory mode. The position of the hydroxyl groups did not significantly influence the growth promotion of M. smegmatis and M. fortiutum in the cases of substituted spermidines and of cystamides.