Photo-killing mechanism of 2-demethoxy-2,3-ethylenediamino hypocrellin B (EDAHB) to HeLa cells

2-Demethoxy-2,3-ethylenediamino hypocrellin B (EDAHB) is a diamino-substituted hypocrellin B (HB) with high absorption of red light and high quantum yield of both singlet oxygen (1O2) and superoxide anions (O2-). Here we reported the cellular uptake, subcellular location, and cytotoxicity of EDAHB, as well as EDAHB-mediated photodynamic therapy (PDT) efficiency, and cell apoptosis. Results showed that EDAHB accumulated in HeLa cells rapidly up to 1 h, with a subsequent decrease in the rate of uptake. EDAHB distributed with well-defined spots throughout the cytoplasm of the cells. EDAHB showed a much higher photopotentiation factor than HB. The phototoxicity of EDAHB to HeLa cells occurred via a mitochondria/caspase apoptosis pathway. This study showed EDAHB to be a promising candidate of photosensitizer for anti-tumor PDT.

► EDAHB showed a much higher photopotentiation factor than HB to HeLa cells.
► The photocytotoxicity of EDAHB to HeLa cells acts via apoptosis.
► EDAHB-PDT causes loss of mitochondrial membrane potential.
► Cytochrome c is released from mitochondria followed by the activation of caspase-9 and caspase-3.