Purification and characterization of pectins from Abelmoschus esculentus (okra pods) and Citrus limetta (citrus peels) and in silico binding study of pectin and pectic polysaccharides with galectin-1

Abstract

Galectins are a class of animal lectins that bind to β-galactoside residues through a conserved carbohydrate recognition domain of about 130 amino acids. The carbohydrate-binding specificity of mammalian galectins revealed its affinity toward lactose, related beta-galactosides, and any glycoconjugates with a nonreducing galactoside terminus. Recent studies have indicated that galectin-1 upregulation impacts progression of tumor through its pleiotropic roles such as cell transformation and proliferation, angiogenesis, adhesion, and invasiveness and immunosuppression. Several galectin-1 inhibitors such as thiodigalactoside, Anginex GM-CT-01 and GR-MD-02 have been designed for applications in cancer therapy. GM-CT-01 (DAVANAT), a modified polysaccharide, composed of mannose and galactose (galactomannan) and a variant of DAVANAT, GR-MD-02, which is a polysaccharide with a backbone of rhamnogalacturonate and branches that terminate with galactose and arabinose residues are produced from chemically processed and modified industrial-grade apple pectin are also found to be beneficial in therapy toward cancer as well as nonalcoholic steatohepatitis. Various reports have also presented evidence that galectin-1-targeted therapy will play a major role to reduce the distribution of tumor cells, inhibit angiogenesis, and restrict tumor growth, thus seeing the importance of pectins and pectin polysaccharides in cancer therapy, we purified and characterized pectins from okra pods (Abelmoschusesculentus) and citrus peels (Citruslimetta) and studied the residual protein content, total carbohydrate content, characteristic properties using Fourier-transform infrared, galacturonic acid content, equivalent weight, and methoxyl content and methyl esterification of extracted okra and citrus pectins. We further performed insilico binding study of pectin and pectic polysaccharides with Galectin-1.