Accumulation of porphyrins in Propionibacterium acnes by 5-aminolevulinic acid and its esters.

We have investigated the accumulation of porphyrins in Propionibacterium acnes (P.acnes) by 5-aminolevulinic acid hydrochloride (ALA) and its esters, ALA methyl ester hydrochloride (mALA), ALA octyl ester hydrochloride (oALA), and ALA benzyl ester hydrochloride (bALA). From the fluorescence spectra of porphyrins accumulated in P.acnes, the order of porphyrin accumulation is as follows: ALA≫mALA≈bALA>oALA (≈0). Moreover, the PDT efficacy is reduced in the order of ALA>mALA≈bALA>oALA (≈without additives). These results confirm that ALA is superior to ALA esters in accumulating porphyrins in P.acnes.