(+)-Borneol enhances the protective effect of edaravone against cerebral ischemia/reperfusion injury by targeting OAT3/P-gp transporters for drug delivery into the brain

Abstract

Objectives

Cerebral ischemia-reperfusion (CI/R) injury is a severe neurological condition associated with significant morbidity and mortality. Edaravone-dexborneol is a promising neuroprotective agent for alleviating CI/R injury, which composed of edaravone and (+)-borneol. Several studies have confirmed that combining edaravone with (+)-borneol can exert synergistic effects when compared to using edaravone alone. However, whether the synergistic effect is achieved through the enhanced cerebral delivery of edaravone facilitated by (+)-borneol remains unclear, and the potential binding targets need to be further explored.

Methods

Middle cerebral artery obstruction reperfusion (MCAO/R) rats and an oxygen-glucose deprivation/reoxygenation (OGD/R) treated bEnd.3 cells were used to evaluate the synergistic effects between edaravone and (+)-borneol. The cerebral exposure of edaravone was detected using a rapid HPLC-MS/MS method. Then, we examined whether the mechanism by which (+)-borneol increases the cerebral concentration of edaravone occurs via paracellular or transcellular pathways, and we explored potential binding targets.

Results

The combined administration of edaravone and (+)-borneol significantly attenuating CI/R injury both in vivo and in vitro. What captured our interest was that the co-administration of (+)-borneol increased the exposure of edaravone in cerebral infarction area. We found that the combination of (+)-borneol contributed to the maintenance of BBB integrity. The increased expressions of tight junction proteins indicated that paracellular pathway plays a limited role in the elevated cerebral edaravone concentrations. Furthermore, we found that the co-administration of (+)-borneol up-regulated the expressions of influx transporters (OAT1 and OAT3) and down-regulated the expressions of efflux transporters (P-gp and MRP1). Inhibitor experiments further confirmed that the involvement of P-gp and OAT1/3 in the transcellular transport of edaravone across BBB. Finally, we verified that (+)-borneol could directly bind to P-gp and OAT3, facilitating the entry of edaravone into brain and reducing its efflux.

Conclusion

This study demonstrated for the first time that (+)-borneol could enhance the concentration of edaravone in the infarcted region under conditions of CI/R. The underlying mechanisms may involve the enhancement of trans-BBB delivery of edaravone by (+)-borneol through OAT3/P-gp-mediated transcellular transport.