PBA-modified platinum diimine complex

4-phenylbutyric acid (PBA) is a class I and II histone deacetylase inhibitor, which can decrease cell proliferation, enhance cell differentiation, and induce apoptosis and cell cycle arrest in various cancer cells. PBA-modified photoactive platinum diimine complex has been prepared and characterized to augment its photodynamic therapy efficacy. Its ability to generate singlet oxygen, behavior in the presence of esterase, photocytotoxicity, cell cycle distribution, and apoptosis-inducing ability in MCF-7 cells have also been studied. The results suggested that the PBA-modified platinum diimine complex could act as a good singlet oxygen producer, release PBA in the presence of esterase, induce potent photocytotoxicity in tumor cells with a IC₅₀ value of 3.67 ± 0.67 μM, arrest cell cycle at S phase, and induce cell death via apoptosis with the percentage of total apoptotic cells being 34.65 %. The results also revealed that PBA might be able to modulate the mode of cell cycle arrest induced by the photosensitizer in tumor cells.