Structural characterization, functional properties and antioxidant activities of polysaccharide extract obtained from okra leaves (Abelmoschus esculentus)

Polysaccharides have been isolated from okra pods (Abelmoschus esculentus), with little focus on the leaves. This study characterized a water-soluble polysaccharide isolated from okra leaves (OLP), and investigated its functional properties, for their potential applications. FT-IR and NMR spectroscopy were used to describe structural characteristics and the influence on functional properties was examined. The result revealed OLP as a low-molecular-weight polysaccharide (26.9 × 103 g/mol−1) consisting of galactose (~54 mol%), galacturonic acid (~29 mol%), rhamnose (~9mol%) and arabinose (~5mol%) as the primary sugars, and rhamnogalacturonan-I as the predominant structural unit. OLP was found to be an extensively-branched, highly acetylated, and unmethylated polysaccharide. OLP exhibited non-Newtonian flow behavior and showed comparable or superior functional properties such as thermal stability and emulsifying capacity, and higher antioxidant capacity than polysaccharide previously obtained from okra pods. This study presents a means of utilizing okra leaves as a new polysaccharide source, with potential applications in food-related industries.