A 20(S)-protopanaxadiol derivative PPD12 reverses ABCB1-mediated multidrug resistance with oral bioavailability and low toxicity

Glycyrrhetinic Acid-Modified Silicon Phthalocyanine for Liver Cancer-Targeted Photodynamic Therapy

To supplement shortcomings of existing treatments and enhance the therapeutic effect for liver cancer, a novel photosensitizer is designed using silicon phthalocyanine (SiPC) and a unique targeting moiety, glycyrrhetinic acid (GA). The SiPC is modified with a hydrophilic polymer and finally bound with GA. The solubility, fluorescence, singlet oxygen generation, and UV-vis absorbance are analyzed, and receptor-dependent intracellular influx is estimated in various cell lines. Using flow cytometry and confocal microscopy, intracellular fluorescence was detected in liver cancer because of GA receptor overexpression. To prove in vitro photodynamic therapeutic effects, the sample treated cells are irradiated and viability of liver cancer cells decreases in proportion to laser power. Then, it is confirmed that GA-modified SiPC effectively accumulated in liver cancer of HepG2 tumor-bearing mouse. Additionally, the PDT-combined therapeutic effect of GA-modified SiPC is observed in the tumor model and shown to have a tumor growth inhibition effect (60.36 times higher than the control group) and supported by histological analyses. These results demonstrate that the newly modified SiPC can be applied to liver cancer-specific treatment with high therapeutic efficacy. Consequently, novel SiPC has the potential to alter conventional liver cancer-targeted therapy and chemotherapy in clinical use.

P. Cardoso D, U. Ferreira MJ. Overcoming Multidrug Resistance: Flavonoid and Terpenoid Nitrogen-Containing Derivatives as ABC Transporter Modulators

Multidrug resistance (MDR) in cancer is one of the main limitations for chemotherapy success. Numerous mechanisms are behind the MDR phenomenon wherein the overexpression of the ATP-binding cassette (ABC) transporter proteins P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and multidrug resistance protein 1 (MRP1) is highlighted as a prime factor. Natural product-derived compounds are being addressed as promising ABC transporter modulators to tackle MDR. Flavonoids and terpenoids have been extensively explored in this field as mono or dual modulators of these efflux pumps. Nitrogen-bearing moieties on these scaffolds were proved to influence the modulation of ABC transporters efflux function. This review highlights the potential of semisynthetic nitrogen-containing flavonoid and terpenoid derivatives as candidates for the design of effective MDR reversers. A brief introduction concerning the major role of efflux pumps in multidrug resistance, the potential of natural product-derived compounds in MDR reversal, namely natural flavonoid and terpenoids, and the effect of the introduction of nitrogen-containing groups are provided. The main modifications that have been performed during last few years to generate flavonoid and terpenoid derivatives, bearing nitrogen moieties, such as aliphatic, aromatic and heterocycle amine, amide, and related functional groups, as well as their P-gp, MRP1 and BCRP inhibitory activities are reviewed and discussed.