Structural Properties, Bioactivities, and Applications of Polysaccharides from Okra [Abelmoschus esculentus (L.) Moench]: A Review

Okra [Abelmoschus esculentus (L.) Moench], as a kind of nutritive vegetable, is rich in flavonoids, polyphenols, polysaccharides, amino acids, and other bioactive substances and has various biological activities. As one of main bioactive components, okra polysaccharides (OPs), mainly comprising pectic polysaccharides, have various biological activities. OPs have been extensively investigated in recent years. Many studies characterized structures of OPs obtained by different extraction methods, which were confirmed to be rhamnogalacturonan-I-type polysaccharides in most cases. OPs have a thick and slimy texture, suggesting that they can be a promising source of texture modifiers for complex food matrices. They have various biological activities, such as antioxidant activity, immunomodulatory activity, hypoglycaemic activity, and improving intestinal function. Therefore, OPs may potentially serve as novel immunomodulators or an adjuvant for diabetic nephropathy. Up to now, there is no specific summary on the research progress of OPs. In this paper, the latest research progress on the extraction, purification, characterization, rheological properties, biological activities, and applications of OPs is reviewed, to provide the reference for the processing and comprehensive utilization of OPs in the future.