On the Role of ROS and Glutathione in the Mode of Action Underlying Nrf2 Activation by the Hydroxyanthraquinone Purpurin

Physiologically based Kinetic Modeling-Facilitated Quantitative In Vitro to In Vivo Extrapolation to Predict the Effects of Aloe-Emodin in Rats and Humans

Aloe-emodin, a natural hydroxyanthraquinone, exerts both adverse and protective effects. This study aimed at investigating these potential effects of aloe-emodin in humans upon the use of food supplements and herbal medicines using a physiologically based kinetic (PBK) modeling-facilitated quantitative in vitro to in vivo extrapolation (QIVIVE) approach. For this, PBK models in rats and humans were established for aloe-emodin including its active metabolite rhein and used to convert in vitro data on hepatotoxicity, nephrotoxicity, reactive oxidative species (ROS) generation, and Nrf2 induction to corresponding in vivo dose-response curves, from which points of departure (PODs) were derived by BMD analysis. The derived PODs were subsequently compared to the estimated daily intakes (EDIs) resulting from the use of food supplements or herbal medicines. It is concluded that the dose levels of aloe-emodin from food supplements or herbal medicines are unlikely to induce toxicity, ROS generation, or Nrf2 activation in liver and kidney.

Self-amplified activatable nanoprodrugs for enhanced chemodynamic/chemo combination therapy

Chemodynamic therapy (CDT) has gained increasing attention by virtue of its high tumor specificity and low side effect. However, the low concentration of hydrogen peroxide (H2O2) in the tumor site suppresses the therapeutic efficacy of CDT. To improve the efficacy, introducing other kind of therapeutic modality is a feasible choice. Herein, we develop a self-amplified activatable nanomedicine (PCPTH NP) for chemodynamic/chemo combination therapy. PCPTH NP is composed of a H2O2-activatable amphiphilic prodrug PEG-PCPT and hemin. Upon addition of H2O2, the oxalate linkers within PCPTH NP are cleaved, which makes the simultaneous release of CPT and hemin. The released CPT can not only kill cancer cells but also upregulate the intracellular reactive oxygen species (ROS) level. The elevated ROS level may accelerate the release of drugs and enhance the CDT efficacy. PCPTH NP shows a H2O2concentration dependent release profile, and can effectively catalyze H2O2into hydroxyl radical (·OH) under acidic condition. Compared with PCPT NP without hemin, PCPTH NP has better anticancer efficacy bothin vitroandin vivowith high biosafety. Thus, our study provides an effective approach to improve the CDT efficacy with high tumor specificity.