Carbohydrates from Lamiaceae. VIII. α-Glucan from Scutellaria baicalensis roots

Abstract

The homogeneous polysaccharide S b RP-1cc with MW 110 kDa was isolated during an investigation of watersoluble polysaccharides from Scutellaria baicalensis roots. Its aqueous solution gave a positive reaction with iodine and exhibited high specific rotation ([D] D +188.0°). Chemical, chromatographic, and spectral methods established that S b RP-1s was a slightly branched glucan containing in the main chain D-(1o4)-glucopyranose units, 8.3% of which were branched at the C-6 atom with single D-glucopyranose units. Glucan S b RP-1s was shown to exhibit immunostimulating activity using an azathioprine model of immunosuppression.We have continued our study of the carbohydrate components of plants from the family Lamiaceae [1]. Results from a study of the water-soluble polysaccharides (WSPS) from the aerial part of Scutellaria baicalensis Georgi were reported earlier [2]. Information on the polysaccharides from roots of this species has not been reported. The goal of the present work was to isolate and study the structure and biological activity of the dominant component of the WSPS complex from S. baicalensis roots.WSPS were isolated from S. baicalensis roots using hot water extraction of raw material treated beforehand with EtOH (80%). This produced the fraction of total WSPS S b RP in 2.53% yield of the air-dried raw material mass. Solutions of S b RP gave a positive reaction with iodine and showed high specific rotation ([D] D +190.4°). Hydrolysates of S b RP contained glucose, galacturonic acid, galactose, arabinose, and mannose in a 33.5:3.0:2.4:1.8:1 ratio. Gel chromatography showed the S b RP was heterogeneous, because of which it was fractionated using ion-exchange (DEAE-cellulose) and gel-permeation chromatography (Sephacryl 300-HR, Sephadex G-200). This isolated the homogeneous component S b RP-1s with molecular weight 110 kDa that eluted as a single symmetric peak by chromatography over Sephadex G-200. The studies showed that S b RP-1s contained 97.2% carbohydrates; uronic acids and proteins were not observed. Aqueous solutions of the polymer reacted with iodine solution (O max 615 nm) and gave positive specific rotation ([D] D +188.0°). Chromatography (HPTLC, GC/MS) of the hydrolysate of S b RP-1s detected only glucose. The IR spectrum of the polymer showed bands assigned to absorption by an D-bond (852 cm -1 ) and bands characteristic of D-(1o4)-glucans (914, 1024, 1050, 1154 cm -1 ) [3]. Oxidation of S b RP-1s acetate by chromic anhydride and hydrolysis of the oxidation product established the presence of glucose, which was possible for the D-configuration of the glucose units. Periodate oxidation of the polymer consumed 1.08 mol IO 4 -and released 0.08 mol HCOOH per single anhydro unit. Smith degradation produced glycerin and erythrite in a 1:12.06 ratio, which indicated the presence of (1o4)-and (1o6)-bonds. The completely methylated polysaccharide was hydrolyzed. The decomposition products were analyzed as the aldoacetates by GC/MS. Three types of glucose derivatives were found. These were 1,5-diace...

A comprehensive review on phytochemistry, pharmacology, and flavonoid biosynthesis ofScutellaria baicalensis

“…The main chain is composed of α-(1 → 4)-glucopyranose units, 8.3% of which are substituted with an α-glucopyranose unit at C-6 (Olennikov et al. 2011).…”

“…The polysaccharides from S. baicalensis showed antioxidative and immunostimulating activities (Olennikov et al. 2008a, 2011).…”

Applications, phytochemistry, pharmacological effects, pharmacokinetics, toxicity of Scutellaria baicalensis Georgi. and its probably potential therapeutic effects on COVID-19: a review

“…The polysaccharides of SB are water-soluble, mainly composed of arabinose, galactose, glucose and some differential branched dextran [ 48 – 50 ]. At present, a group of new polysaccharides SP1-1 with molecular weight of 4.56 × 10 5 Da was identified and had anti-inflammatory effect [ 51 ], which is mainly composed of mannose, ribose, glucuronic acid, glucose, xylose and arabinose (the molar ratio were 2.14:3.61:1:2.86:5.98:36.39).…”