A novel photosensitizer, 2-butylamino-2-demethoxy-hypocrellin B (2-BA-2-DMHB) - its photodynamic effects on HeLa cells: efficacy and apoptosis

Involvement of the mitochondria-caspase pathway in HeLa cell death induced by 2-ethanolamino-2-demethoxy-17-ethanolimino-hypocrellin B (EAHB)-mediated photodynamic therapy

In order to elucidate the mechanism of cytotoxicity photoinduced by 2-ethanolamino-2-demethoxy-17-ethanolimino-hypocrellin B (EAHB), a derivative of hypocrellin B (HB), cellular uptake, subcellular localization as well as photodynamic therapy (PDT) efficiency of EAHB, and cell apoptosis photoinduced by EAHB were investigated in HeLa cells by laser confocal fluorescence microscopy, 3-(4,5-Dimethylthiazol-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay, flow cytometry, DNA fragmentation on agarose gel, and Western blot. The results showed EAHB was distributed throughout the cytoplasm of the cell, with no detectable penetration into the nucleus. The proportion of dead cells increased with increases in both the dosage of light and the concentration of EAHB. Its phototoxicity to HeLa cells proceeded via apoptosis. The EAHB-PDT treatment induced a cytochrome c release from the mitochondria into the cytosol followed by the activation of both caspase 3 and caspase 9 in HeLa cells. The results suggested that EAHB-PDT treatment induced apoptosis in HeLa cells, and the cellular apoptosis involved a mitochondria-/caspase-dependent mechanism.

Water-soluble and biocompatible sono/photosensitizer nanoparticles for enhanced cancer therapy

Aims: Most sono/photosensitizers of cancer sonodynamic/photodynamic therapy (SDT/PDT), such as hypocrellin SL052, are water-insoluble, therefore restricting their clinical applications. In this article, we present a water-soluble nanocarrier to load the SDT/PDT sensitizer SL052 with improved pharmacokinetics and therapeutic efficacy. Materials & methods: Nanoclusters of polyvinylpyrrolidones with SL052 formed water-soluble nanoparticles (SL052-NPs) while retaining the chemical structure of SL052. Results: The experimental results show that SL052-NPs improve the drug’s physicochemical properties and significantly enhance the efficacy of SL052 in terms of pharmacokinetics and cancer killing. Water-soluble SL052-NPs can be used to deliver the drug to deep cancer tissues. A potential benefit of SL052-NPs is that polyvinylpyrrolidones can help SL052 evade the reticuloendothelial system, thereby increasing circulation half-life and improving drug biodistribution. Conclusion: SL052-NPs greatly improved the physicochemical properties of SL052 without modifying its chemical structure, allowing for deep-site cancer drug delivery, imaging for diagnosis, and ultrasound or photocontrolled localized cancer therapy.