photosensitizer in the photodynamic diagnosis (PDD) and photodynamic therapy (PDT) of cancer and is synthesized intracellularly from 5-aminolevulinic acid (5-ALA) precursors. Thirteen novel 5-ALA derivatives were designed and synthesized appropriately with tailored hydrophilicity and lipophilicity. The generation of PpIX was detected and their antitumor activity in vitro and in vivo was also investigated