The cytotoxic activity of fluphenazine (FPZ) in combination with UVA light was evaluated on three human tumor cell lines, HeLa, MSTO-211H and A431. The photobiological effect was determined following irradiation treatment in the presence of/or after the removal of incubated FPZ. Under both conditions, FPZ proved to be very effective in killing tumor cells, with GI₅₀ values in the micromolar range. However, when FPZ was present during irradiation, the photocytotoxicity was at least two times higher than that after its removal suggesting the contribution of the drug both outside and inside the cells. The uptake of FPZ was very fast and, after only 15 minutes of incubation, the compound was accumulated inside lysosomes, as evidenced through fluorescence microscopy. FPZ distribution covered also the nucleus and the cytoplasm without significant plasma membrane association. After irradiation, the membrane of lysosomes in which FPZ was accumulated lost its integrity suggesting that the released lysosomal enzymes played an important role in cell death, and mitochondria were damaged as well, following apoptosis. Indeed, cytofluorimetric studies demonstrated that apoptosis was the main mechanism of cell death. Finally, an extremely high production of ROS was found, indicating a significant photodynamic mechanism involved in the photocytotoxic effect of FPZ. Taken together, our data show that FPZ following UVA irradiation behaves as an effective photoantiproliferative compound inducing apoptosis on various human tumor cells.

Regulation of mitochondrial metabolism is becoming an important target in inhibiting necrosis and apoptosis following secondary spinal cord injury, and physiological compounds that reduce mitochondrial dysfunction are regarded as efficient protective reagents following injury. It has been demonstrated that spermine, a polyamine composed of four primary amines, may be taken up by a mitochondria‑specific uniporter and may preserve mitochondrial bioenergetics, suggesting that it may be important in the pathophysiology of mitochondria. However, the protective mechanism has not yet been definitively clarified. In the present study, isolated spinal cord mitochondria were incubated with spermine to evaluate its physiological functions and Src kinase activities. The results revealed that spermine increased oxidative phosphorylation, attenuated mitochondrial swelling and maintained the membrane potential. An inhibitor of Src kinases, amino‑5-(4‑chlorophenyl)‑7‑(t‑butyl)pyrazolo[3,4‑d]pyrimidine (PP2), markedly reduced the effects of spermine. However, inhibition of tyrosine phosphatases by vanadate led to marginal increases in the effects of spermine. Therefore, the present study hypothesized that tyrosine phosphorylation sites are present in the subunits of respiratory chains and mitochondrial permeability transition pore proteins, which may be modified via phosphorylation and dephosphorylation. Furthermore, spermine may upregulate the phosphorylation of Src kinases, and PP2 and vanadate conversely regulate Src phosphorylation. The results of the present study suggest that spermine is a strategic regulator within mitochondria that may activate Src kinases in the spinal cord, and tyrosine phosphorylation signaling is a primary regulatory pathway of mitochondrial metabolism.

The synthesis of new 6,10-dimethylpyridazino[4,5-h]psoralens, carrying no (4), one (5), or two (6-9) dialkylaminoalkylcarboxamide side chains on the pyridazine ring is reported. All compounds exert a significant photoantiproliferative activity. Moreover, the derivatives characterised by the protonable side chains show a notable cytotoxicity in the dark. The investigation on the mechanism of action demonstrated the capacity to intercalate into DNA base pairs and to inhibit the relaxation activity of topoisomerase II.

In this review we summarize the structure and biological effects of linear and angular psoralens. These compounds exhibit interesting biological effects on the cell cycle, apoptosis and differentiation. These molecules should be considered promising drugs in the therapy of several diseases, including psoriasis, mycosis fungoides and cancer. Also, preclinical data demonstrate a possible use of these molecules for the treatment of beta-thalassemia and other hematological disorders.