Characterization of hyaluronic acid extracted from Liparis tessellatus eggs grafted with phenolic acids and nisin

In polymer therapeutics, polymer-based carrier systems conjugated with antioxidants have been synthesized and studied to improve diagnosis and treatment of diseases, such as, in cancer and tumor. The natural bioactive compound hyaluronic acid (HA), which is essential in medical and pharmaceutical fields, is a linear polymer composed of repeating disaccharide units of β-1,3-N-acetyl glucosamine and β-1,4-glucuronic acid. In this study, HA fractions of enzyme-assisted glycosaminoglycans (GAGs) extract from Liparis tessellatus eggs were grafted with gallic acid (GA), caffeic acid (CA), and ferulic acid (FA) via a free radical-mediated method, and with nisin via amide bond formation. The modification has been confirmed through FTIR and 1H NMR spectroscopy and quantified by Folin-Ciocalteu and Bradford assay. FTIR spectra of grafted HA samples exhibited the typical phenolic characteristics within 1450–1650 cm−1, and the formation of amide bond in nisin-grafted HA was shown by absorption peak within 1545–1646 cm−1. 1H NMR spectra showed new peaks of phenyl protons at 6.3–7.7 ppm and new peaks at 0.9–2.9 ppm of amino acids residues protons. These results all confirmed the successful grafting of GA, CA, FA and nisin onto the HA backbone extracted from L. tessellatus eggs.