Physicochemical, permeability, antioxidant and anti-inflammatory properties of oxyresveratrol ester prodrugs

Abstract

Oxyresveratrol (OXY) is known to exert antioxidant and anti-inflammatory properties but has low oral bioavailability in rats and low permeability in the Caco-2 cell monolayer model. Three ester prodrugs with different acyl chain lengths (oxyresveratrol tetraacetate (OXY-TAc), oxyresveratrol tetrapropionate (OXY-TPr), and oxyresveratrol tetrabutyrate (OXY-TBu) were synthesized to improve the permeability of OXY. Transport of three OXY ester prodrugs across Caco-2 monolayers was higher than that of OXY, and OXY-TAc exhibited the highest permeation. The degradation of OXY-TAc in HCl buffer (pH 1.2), phosphate buffer (pH 6.8 and 7.4), simulated gastric and intestinal fluids, as well as human plasma at 37 °C was followed pseudo-first-order kinetics. Antioxidant and anti-inflammatory effects, as well as mechanisms of action in LPS-stimulated murine macrophage cells (RAW264.7) under oxidative stress and inflammation of bioavailable fraction of OXY-TAc (BF-OXY-TAc), were investigated and compared with the bioavailable fraction of OXY (BF-OXY). All three antioxidant assays (1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC) assays) showed that BF-OXY-TAc exhibited higher antioxidant activities than that of BF-OXY. In the LPS-stimulated RAW264.7 macrophage cells, BF-OXY-TAc attenuated the LPS-induced reactive oxygen species (ROS), nitric oxide (NO), and interleukin-6 (IL-6) levels were 2.5, 2.5, and 1.6-fold higher than that of BF-OXY respectively. Western blot analysis revealed that BF-OXY-TAc decreased inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expressions were 1.2 and 1.4-fold higher than that of BF-OXY, respectively. The results suggest that OXY-TAc can overcome the limitations of OXY in terms of improving permeation, leading to better antioxidant and anti-inflammatory activities of OXY against LPS-stimulated oxidative stress and inflammation in RAW264.7 macrophage cells.