ANTIBACTERIAL ACTIVITY OF ACYL POLYAMINES ISOLATED FROM Cinachyrella kuekenthali (Demospongiae, Tetillidae) AND THEIR EFFECT ON THE MORPHOLOGY OF Bacillus subtilis AND Escherichia coli.

A mixture of long-chain acyl polyamines (baptized as cinachyramides) was isolated from the marine sponge Cinachyrella kuekenthali, with a yield of 4.24% from the crude extract. The mixture of cinachyramides exhibited an antibacterial activity that was more pronounced against Gram positive bacteria with half lethal concentration (LC50) values of 2.58, 5.91, 16.40 and 56.40 mu g/mL against B. subtilis, M. luteus, E. faecalis and E. coli, respectively. The cinachyramides caused morphological changes in B. subtillis and E. coli. The scanning electron microscopy (SEM) analysis suggests formation of protuberances and permeabilization of membranes, which might generate bacterial lysis with loss of cytoplasmic components and reduction in bacterial size. The antibacterial action can be associated to the electrical charges on the cinachyramides being more sensitive the Gram positive bacteria. The antibacterial power of the mixture of cinachyramides is similar to that of the penicillin G sodium salt. The organic fraction from the hydrolyzate of the mixture of cinachyramides was found to consist of an acyl residue derived from: decanoic, tridecanoic, pentadecanoic, hexadecanoic, octadecanoic or 9-Z-octadecenoic while the polyaminic part was composed of up to 12 repeated units of N-methylated propylamine.