A xylan from the fresh leaves of Piper betle: Structural characterization and studies of bioactive properties.

A pure water soluble xylan (PS-I) with an average molecular weight ~1.1 × 105 Da was isolated from the hot water extraction of fresh leaves of Piper betle (paan). The xylan was found to be composed of xylose, galactose and methyl galacturonate in a molar ratio of nearly 3:1:1. The repeating unit was composed of a backbone containing three (1 â†’ 4)-α-D-Xylp residues, one of which was branched at O-2 position with the side chain consisting of (1 â†’ 4)-α-D-GalpA6Me and terminal ß-D-Galp residues. This xylan exhibited macrophage, splenocyte, and thymocyte stimulatory activities. In vitro antioxidant studies demonstrated that the xylan has DPPH radical scavenging potential (EC50 = 148 µg/mL), ABTS radical quenching activity (EC50 = 188 µg/mL) and ferrous ions chelating activity (EC50 = 370 µg/mL). These findings elicit the need for further exploration of the xylan as a natural antioxidant and a potent immunostimulating agent.

A review on antiviral and immunomodulatory polysaccharides from Indian medicinal plants, which may be beneficial to COVID-19 infected patients.

The emergence of the novel coronavirus, SARS-CoV-2 has pushed forward the world to experience the first pandemic of this century. Any specific drug against this RNA virus is yet to be discovered and presently, the COVID-19 infected patients are being treated symptomatically. During the last few decades, a number of polysaccharides with potential biological activities have been invented from Indian medicinal plants. Many polysaccharides, such as sulfated xylomannan, xylan, pectins, fucoidans, glucans, glucoarabinan, and arabinoxylan from Indian medicinal plants, have been shown to exhibit antiviral and immunomodulating activities. Plant polysaccharides exhibit antiviral activities through interference with the viral life cycle and inhibition of attachment of virus to host cell. Intake of certain immune stimulating plant polysaccharides may also protect from the virus to a certain extent. In process of continuous search for most potent drug, Indian plant polysaccharides may emerge as significant biomaterial to combat COVID-19. This review explores a number of polysaccharides from Indian medicinal plants which showed antiviral and immunomodulating activities. It is aimed to provide an overview about the composition, molecular mass, branching configuration and related bioactivities of polysaccharides which is crucial for their classification as possible drug to induce immune response in viral diseases.

Structural studies of immunomodulatory (1 → 3)-, (1 → 4)-α glucan from an edible mushroom Polyporus grammocephalus.

A water soluble polysaccharide (PGPS) with molecular weight ~ 1.4 × 105 Da was isolated by alkali treatment from an edible mushroom Polyporus grammocephalus and purified by gel chromatography using sepharose-6B column. Monosaccharide analysis revealed that PGPS was made up of glucose only. PGPS contained (1 â†’ 3)-α-D-Glcp and (1 â†’ 4)-α-D-Glcp moieties in a molar ratio of nearly 1:2. Through a series of chemical and spectroscopic (1D/2D NMR) investigations, the repeating unit of the glucan was established as: →3)-α-D-Glcp(1 â†’ [4)-α-D-Glcp(1]2→ This α-glucan was observed to stimulate some prime components of immune system, namely, macrophages, splenocytes, and thymocytes.