Structural characterization and anti-hypoxia activity of an exopolysaccharide isolated from fermentation broth of Lachnum sp

Valorization of cell wall polysaccharides extracted from Liubao brick tea residues: chemical, structural, and hypoglycemic properties

BACKGROUND

Tea dregs, typically generated during the production of instant tea or tea beverages, have conventionally been regarded as waste material and routinely discarded. Nevertheless, contemporary research endeavors are concentrating on discovering efficient methods for utilizing the potential of this discarded resource.

RESULTS

In this study, we employed a sequential extraction method using chemical chelating agents to extract and isolate four distinct cell wall polysaccharides, designated as CWTPS-1 through CWTPS-4, from the tea dregs of Liubao brick tea. A comprehensive investigation into their physicochemical, structural, and hypoglycemic properties was conducted. The analysis of chemical composition and physicochemical characteristics revealed that all four CWTPSs were characterized as acidic polysaccharides, albeit with varying chemical compositions and physicochemical attributes. Specifically, the xyloglucan fractions, CWTPS-3 and CWTPS-4, were found to be rich in glucose and xylose, displaying a more uniform molecular weight distribution, greater structural stability, and a more irregular surface compared to the others. Moreover, they exhibited a higher diversity of monosaccharide residues. Importantly, our research unveiled that all four CWTPSs exhibited the capacity to modulate key glucose-regulated and antioxidant enzyme activities within HepG2 cells via the IRS-1-PI3K/AKT signaling pathway, thereby ameliorating cellular insulin resistance. Furthermore, our correlation analysis highlighted significant associations between monosaccharide composition and neutral sugar content with the observed hypoglycemic activity of CWTPSs.

CONCLUSION

This study highlights the potential of utilizing tea dregs as a valuable resource, making a significant contribution to the advancement of the tea industry. Furthermore, CWTPS-4 exhibits promising prospects for further development as a functional food ingredient or additive. © 2024 Society of Chemical Industry.

Structure characterization and immunomodulatory activity of a new neutral polysaccharide SMP-0b from Solanum muricatum

In the present study, a novel neutral polysaccharide SMP-0b was extracted and purified from the pulp of Solanum muricatum. Monosaccharide composition analysis revealed that SMP-0b was mainly composed of l-arabinose, d-mannose, d-glucose and d-galactose with the molar ratio of 5.31:2.92:42.23:25.38. The weight-average molecular weight and number-average molecular weight of SMP-0b was calculated to be 13.51 kDa and 9.91 kDa respectively through high performance gel permeation chromatography. The structure of SMP-0b was characterized by methylation and NMR analysis. It showed that the backbone chain of SMP-0b was consisted of →4)-β-d-Galp-(1→, →3,6)-β-d-Manp-(1→ and →6)-α-d-Glcp-(1→, and the side chain was composed of α-l-Araf-(1→ and →4)-α-d-Glcp-(1→. In immunomodulation assays in vitro, SMP-0b exhibited good immunomodulatory activity and could significantly stimulate proliferation and NO production of RAW 264.7 macrophage cells. The results suggested that the neutral polysaccharide from Solanum muricatum might have potential as an immunomodulator or supplement in functional food to enhance immunity.

Anti-fatigue activity of a Lachnum polysaccharide and its carboxymethylated derivative in mice

The present study was designed to evaluate the anti-fatigue activity of an exopolysaccharide LEP-1b and its carboxymethylated derivative CLEP-1b from a Lachnum sp. Carboxymethylation was confirmed through FT-IR and ¹³C NMR spectroscopies, which showed that the (-CH₂COOH) group was attached to an oxygen (O) atom of the hydroxyl group on (C-3) of LEP-1b. Each treatment group LEP-1b and CLEP-1b at doses (50, 100, 200mg/kg, respectively) ameliorated physical fatigue and extended exhaustive swimming time in mice. Results of the fatigue related biochemical markers showed that LEP-1b and CLEP-1b at doses (50, 100, 200mg/kg, respectively) increased the content of hepatic glycogen and decreased the level of serum urea nitrogen and lactic acid. Additionally, LEP-1b and CLEP-1b enhanced the antioxidant enzymes' activities and reduced the lipid peroxidation. Moreover, results revealed that CLEP-1b had higher anti-fatigue activity than LEP-1b at same doses but without statistical significance, especially CLEP-1b (200mg/kg) had strong anti-fatigue effects. Therefore, LEP-1b and CLEP-1b can potentially be exploited as a kind of healthcare compound to combat fatigue and to boost physical strength.

Hypoglycemic and hypolipidemic effects of a polysaccharide from Lachnum YM240 and its derivatives in mice, induced by a high fat diet and low dose STZ

Carboxymethylated and sulfated polysaccharides (CLEP and SLEP) were prepared from an exopolysaccharide previously obtained from Lachnum YM240 (LEP) by chemical modifications. Two doses (50 mg kg-1 and 200 mg kg-1 b. w.) of LEP, CLEP and SLEP were orally administered to normal mice and type 2 diabetic mice (T2DM) that were induced by streptozotocin (STZ) and a high fat diet, respectively. The hypoglycemic effect was evaluated by testing the oral glucose tolerance, fasting blood glucose (FBG) levels, fasting serum insulin (FINS), glycosylated hemoglobin A1c (HbA1c), and the hypolipidemic effect was evaluated by the body, spleen, pancreas, liver and kidney weights, as well as serum triglycerides (TG), cholesterol (TC) and free fatty acids (FFA). After four weeks of administration, LEP, CLEP and SLEP showed a marked FBG fall rate of 11.2%, 44.0% and 42.5% for the high-dose and 7.43%, 38.5% and 33.1% for the low-dose, respectively, as compared to the DC group. Moreover, compared with DC mice, TC concentrations in the high-dose groups of LEP, CLEP and SLEP were significantly decreased by 29.6%, 38.7% (P < 0.05), 33.0% (P < 0.05), and TG concentrations decreased by 18.9%, 43.9% (P < 0.01), 29.0% (P < 0.05), respectively. In addition, LEP and the derivatives significantly upregulated the expression of glucokinase (GK) and adenosine monophosphate-activated protein kinase (AMPK) in the liver, AMPK and glucose transporter 4 (Glut4) in skeletal muscle and peroxysome proliferator-activated receptor (PPAR-γ) in adipose tissue, whereas downregulated the expression of glucose-6-phosphatase (G6P) in the liver; these were examined using ELISA detection kits. These results for FBG and serum lipids indicate that LEP and its derivatives possess significant hypoglycemic and hypolipidemic effects and carboxymethylation improved the hypoglycemic and hypolipidemic effects more effectively than sulfation. Therefore, the carboxymethylated and sulfated modifications were effective ways to enhance the hypoglycemic and hypolipidemic activities of polysaccharides.