Preparation, characterisation, and antioxidant activity of honeysuckle polysaccharide nano-selenium

Using honeysuckle as raw material, honeysuckle polysaccharide (HP) was obtained by water extraction and alcohol precipitation, and polysaccharide nano-selenium (HP-SeNPs) was prepared by HNO3-Na2SeO4 method. The structure of HP, before and after selenisation, was characterised by gas chromatography-mass spectrometry, ultraviolet (UV), Fourier-transform infrared (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD), and the antioxidant activity was studied. The results showed that the content of Se in HP-SeNPs could reach 10.45%. The HP-SeNPs primarily consisted of glucose and mannose, with a molecular weight of 73.8 kDa. The characterisation results revealed that HP-SeNPs exhibited a novel absorption peak at approximately 334 nm in the UV spectrum; distinct absorption peaks were observed at 1079.66 and 619.21 cm-1 in the FT-IR spectrum, while a broad diffraction peak appeared between 19° and 25° in the XRD pattern. SEM further demonstrated that HP-SeNPs formed particle-like surface structures, altering the surface morphology of polysaccharides. These findings collectively indicated the successful preparation of HP-SeNPs. The scavenging ability of HP-SeNPs to DPPH, ·OH, and ABTS free radicals was concentration-dependent, and the highest scavenging rates were 53.85, 62.55, and 49.37%, which were significantly higher than HP. This indicated that selenium modification could outstandingly improve the antioxidant activity of HP.