Rhynchophylline-encapsulating core-shell nanoparticles to overcome blood-brain-barrier and inhibit drug efflux for efficient anti-Parkinson therapy

Parkinson's disease (PD), one of common neurodegenerative diseases, afflicts many elderly people lacking of effective treatment strategies. Rhynchophylline (RIN) is an anti-PD natural active compound. However, RIN can hardly cross the blood-brain barrier (BBB) and is easily excreted as a substrate of P-glycoprotein (P-gp), making it difficult to exert anti-PD efficacy in brain. Nanocarrier-based brain targeting strategies provide an attractive platform to address brain distribution problems of drugs. In this work, we designed a brain-targeting core-shell nanoparticle (RIN/TAR-A2-CSN) for the programmed co-delivery of RIN and P-gp inhibitor Tariquidar (TAR). It was composed of Angiopep-2 (A2) modified reduction-responsive PEG shell material and thiamine disulfide system (TDS) grafted polyglutamate core material. After entering the body, first RIN/TAR-A2-CSN crossed the BBB into the brain via A2-receptor-mediated transport. Subsequently, the shell material disintegrated under reducing conditions, and the TDS-grafted core material was reduced to become hydrophilic, thereby leading to the drugs "locked-in" the brain. Finally, the released TAR inhibits P-gp-mediated RIN efflux, increases the retention time of RIN in the brain, and fully exerts the anti-PD effect of RIN. The brain targeting efficiency of RIN/TAR-A2-CSN was improved to 5.8 times that of free RIN. In addition, the therapeutic effect on the MPTP-induced PD mice model was significantly improved. This work develops a novel brain targeting strategy for drugs to overcome BBB and inhibit efflux. RIN/TAR-A2-CSN nanoparticles show the potential to become PD therapeutics.