Isolation, structural features, in vitro antioxidant activity and assessment of complexation ability with β-lactoglobulin of a polysaccharide from Borassus flabellifer fruit

This research was intended to investigate the structural feature, antioxidative activity and interaction with β-lactoglobulin (β-lg) of a polysaccharide (P) isolated from Borassus flabellifer fruit thru aqueous extraction, protein elimination and chromatographic techniques. Polysaccharide P (molecular weight: 21,000 g mol(−1)) was constituted of arabinose, galactose, glucose, and rhamnose in a 50:24:20:6 M ratio alongside 9% (w/w) galacturonic acid. It encompassed a petite backbone entailing galacturonopyranosyl and rhamnopyranosyl units substituted with sizable side chains comprising of arabinofuranosyl, galactopyranosyl and esterified coumaric acid (CA) residues. Various series of oligosaccharides including (i) Gal(1,2,4-9)Ac(5-29), (ii) Ara(2-3)Ac(6-8), (iii) Gal(3)Ara(1-3)Ac(13-17), (iv) Gal(4-6)Ara(2)Ac(18-24), (v) Gal(6)Ara(1)Ac(22) and (vi) Gal(1)Ara(2)CA(1)Ac(7) and Gal(1)Ara(3)CA(1)Ac(9) epitomizing polysaccharide structure were generated and characterised. Fraction P exhibited dose-dependent antioxidant activity and possessed a strong β-lactoglobulin binding capability. Accordingly, B. flabellifer fruit offers an antioxidative polysaccharide having novel structure that can associate with β-lg and, hence, useful in formulating novel food possessing adjustable composition.