A novel synthesis of 5,15-trimethylammonium substituted porphyrins and their evaluation as potential antimicrobial photosensitizers

The MacDonald's [2 + 2] condensation of unsubstituted dipyrromethane and 3- or 4-hydroxyalkoxybenzoaldehydes afforded 5,15-meso-hydroxyalkoxyphenylporphyrins. The hydroxyl groups on the side chains were then transformed to tertiary amines via synthesis of the mesylate and substitution with the appropriate amines or aminoalcohols. Methylation of such products afforded a series of cationic porphyrins which have been tested in vitro as photodynamic agents against microorganisms, showing high antimicrobial activity.