Flaxseed oligosaccharides-derived conjugates for chlorogenic acid delivery with enhanced stability, antioxidant activity, and bioavailability

Flaxseed oligosaccharide-chlorogenic acid (FGOS-CGA) conjugates were synthesized by covalently attaching CGA to the FGOS backbone, facilitating the targeted delivery of CGA. The chemical integrity of the conjugates was meticulously verified through nuclear magnetic resonance spectroscopy, the successful ultraviolet-visible spectroscopy, and scanning electron microscopy, which collectively confirmed the successful conjugation between FGOS and CGA. Compared to free CGA, the resulting FGOS-CGA conjugates exhibited markedly enhanced stability across a range of conditions, including variations in pH, thermal fluctuations, ionic strength, and light exposure. Employing both chemical assays and cellular models, the conjugates demonstrated robust antioxidant activity, with DPPH and ABTS radical scavenging efficiencies of 63.74 ± 1.46% and 58.67 ± 0.50%, respectively, at a concentration of 1 mg/mL-surpassing the performance of free CGA (49.73 ± 1.96% and 23.18 ± 1.60%). Furthermore, FGOS-CGA exhibited superior efficacy in scavenging excessive reactive oxygen species in ethanol-induced HepG2 cells. Notably, after a 6-h incubation with Caco-2 cells, the bioavailability of CGA in the FGOS-CGA conjugate increased by an impressive factor of 7.81. These findings underscore the potential of FGOS as a promising delivery vehicle to enhance the antioxidant properties and bioavailability of CGA.