Over recent decades, many studies have reported that hypocrellin A (HA) can eliminate cancer cells with proper irradiation in several cancer cell lines. However, the precise molecular mechanism underlying its anticancer effect has not been fully defined. HA-mediated cytotoxicity and apoptosis in human lung adenocarcinoma A549 cells were evaluated after photodynamic therapy (PDT). A temporal quantitative proteomics approach by isobaric tag for relative and absolute quantitation (iTRAQ) 2D liquid chromatography with tandem mass spectrometric (LC–MS/MS) was introduced to help clarify molecular cytotoxic mechanisms and identify candidate targets of HA-induced apoptotic cell death. Specific caspase inhibitors were used to further elucidate the molecular pathway underlying apoptosis in PDT-treated A549 cells. Finally, down-stream apoptosis-related protein was evaluated. Apoptosis induced by HA was associated with cell shrinkage, externalization of cell membrane phosphatidylserine, DNA fragmentation, and mitochondrial disruption, which were preceded by increased intracellular reactive oxygen species (ROS) generations. Further studies showed that PDT treatment with 0.08 µmol/L HA resulted in mitochondrial disruption, pronounced release of cytochrome c , and activation of caspase-3, -9, and -7. Together, HA may be a possible therapeutic agent directed toward mitochondria and a promising photodynamic anticancer candidate for further evaluation.

Hypocrellin A (HA), a perihydroxylated polycyclic quinone isolated from the fungus of Shiraia bambusicola, exhibits a wide spectrum of biological activities in pre-clinical studies. However, poor water solubility is a major clinical constraint factor of HA, leading to unpredictable bioavailability. In this study, HA-loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles (PLGA/HA NPs) were prepared by the single-emulsion solvent-evaporation technique. Characterization of PLGA/HA NPs showed that HA was successfully encapsulated on the PLGA. The drug-loading content and encapsulation efficiency (EE) were 7.0% and 57.5%, respectively. The in vitro release profile demonstrated that HA was released more slowly from nanoparticles in pH 1.5 and pH 6.8 than in pH 7.4. Furthermore, the highest solubility of PLGA/HA NPs in aqueous solution was approximately 35.67-fold that of native HA (n-HA). PLGA/HA NPs had more superior stability compared with n-HA in physiological conditions. In this paper, a sample and sensitive LC-MS/MS method was validated for the first time to quantify HA in rat plasma. The pharmacokinetic parameters and bioavailability of HA between PLGA/HA NPs and n-HA were compared after oral administration in rat. The results implied that the relative bioavailability of PLGA/HA NPs was 2.67-fold that of n-HA, and PLGA/HA NPs had a longer half-life. Therefore, these results suggested that PLGAblend nanoparticles improved the solubility, stability and bioavailability of HA, and could become a potential and promising carrier for the oral delivery of HA.

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