Chemical structures, extraction methods and health benefits of okra-derived polysaccharides (ODPs): emphasis on their antioxidant, antihyperlipidemic and antidiabetic actions

Abstract

Okra-derived polysaccharides (ODPs) are among the most predominant and prominent complex compounds in okra ( Abelmoschus esculentus L. Moench) and have caused increasing interest in the area of functional foods due to their wide applications. Although the literature on their pharmacological properties is still scanty, ODPs show structural diversity and related therapeutic actions, including alleviation of diabetes and related disorders including impaired lipid accumulation and cellular oxidation. In support of their therapeutic potential, these complex compounds confer low toxicity and relatively good bioavailability profiles. The extraction methods for these complex carbohydrates have a significant influence on their extraction yields, monosaccharide compositions, structural characteristics and pharmacological properties. In line with this, rhamnogalacturonan I, II and homogalacturonan were reported to be the most common types. The monomers constituting these complex polysaccharides from okra, including arabinose ; galactose ; galacturonic acid; glucose; glucuronic acid ; mannose and rhamnose, were extracted by different techniques such as ultrasound-assisted, microwave-assisted, pressurized water and hot-water extractions. The present review comprehensively highlights the documented preclinical ( in vitro and in vivo ) studies on the ameliorative roles of ODPs against diabetes, oxidative stress and hyperlipidemia . However, clinical trials of ODPs against several disorders, including diabetes are yet to be documented. Therefore, these compounds are recommended for clinical investigations and more preclinical studies to further unveil their effectiveness and health-promoting functions against diabetes and related impairments such as cellular oxidation and defective lipid accumulations. Also, this will further establish these complex polysaccharides from okra as functional function agents with therapeutic properties. • Okra-derived polysaccharides (ODPs) are predominant and prominent biologically active compounds in okra. • Rhamnogalacturonan 1, II and homogalactoronan are the most common types of ODPs. • ODPs display antihyperlipidemic action through inhibition of FAS and SREBP1c, and CPT1A activation. • ODPs possesses antidiabetic and antioxidant activities via P13K/AKT/ GSK-3β casde, Nrf2 translocation and enhanced Nrf2-modulated HO-1 and SOD2.