Purification, characterization and immunoregulatory activity of a polysaccharide isolated from Hibiscus sabdariffa L

Isolation, structure characterization and in vitro immune-enhancing activity of a glucan from the peels of stem lettuce (Lactuca sativa)

BACKGROUND

Stem lettuce is a medicinal and edible plant. The peels, accounting for 300-400 g kg-1 raw stem lettuce and containing polysaccharides 200 g kg-1 , are discarded as industrial waste, causing environment pollution and resource waste.

RESULTS

A polysaccharide named PPSL10-2 was obtained from the peels of stem lettuce after hot water extraction, and gradation with cascade ultrafiltration and purification using DEAE-Sepharose cellulose. The purity and molecular weight of PPSL10-2 is 96.10% and 2.2 × 104  Da respectively, as detected by high-performance gel permeation chromatography. PPSL10-2 was found to be an α-(1→4)-d-glucan that branched at O-6 with a terminal 1-linked α-d-Glcp as side chain, and devoid of helix conformation, which was characterized by monosaccharide composition analysis, Fourier-transform infrared spectroscopy, Congo red test, scanning electron microscopy, methylation analysis and NMR spectroscopy. Furthermore, PPSL10-2 exhibited potent immune-enhancing effect by improving proliferation and phagocytosis, promoting the secretion of nitric oxide and cytokines, as well as the expression of related genes in RAW264.7 macrophages.

CONCLUSION

The findings of the present study suggest that peels as an agricultural by-product of stem lettuce are good sources of polysaccharides, which could be developed as immunopotentiator for improving human health. © 2023 Society of Chemical Industry.

Characterization of Novel Exopolysaccharides from Enterococcus hirae WEHI01 and Its Immunomodulatory Activity

Exopolysaccharide (EPS) from probiotic Enterococcus hirae WEHI01 was isolated and purified by anion exchange chromatography and gel chromatography, the results of which show that the EPS consists of four fractions, namely I01-1, I01-2, I01-3, and I01-4. As the main purification components, I01-2 and I01-4 were preliminarily characterized for their structure and their immunomodulatory activity was explored. The molecular weight of I01-2 was 2.28 × 104 Da, which consists mainly of galactose, and a few other sugars including glucose, arabinose, mannose, xylose, fucose, and rhamnose, while the I01-4 was composed of galactose only and has a molecular weight of 2.59 × 104 Da. Furthermore, the results of an evaluation of immunomodulatory activity revealed that I01-2 and I01-4 could improve the viability of macrophage cells, improve phagocytosis, boost NO generation, and encourage the release of cytokines including TNF-α and IL-6 in RAW 264.7 macrophages. These results imply that I01-2 and I01-4 could improve macrophage-mediated immune responses and might be useful in the production of functional food and medications.

Antidiabetic potential of the isolated fractions from the plants of Rosaceae family in streptozotocin-induced diabetic rats

Background and purpose:

Diabetes is a group of multifactorial disorders characterized by chronic-elevated blood glucose levels (hyperglycemia). Natural remedies are used as alternative medications to treat diabetes. Here, we tested the protective effect of the plant extracts of the Rosaceae family on improving insulin secretion and repairing the pancreatic beta cells in diabetic rats.

Experimental approach:

The oligosaccharide fraction was isolated from the Rosaceae family of herbs. LC-MS/MS was applied to characterize the isolated fractions. The male Wistar rats were randomly divided into six groups, 10 each, including the control group with no intervention, diabetic rats without treatment, diabetic rats that received the extract of Malus domestica (apple), Cydonia oblonga (quince), Prunus persica (nectarine), and Prunus persica (peach), separately. Rats were monitored for the weight, fasting plasma glucose, and insulin levels. The effect of extracts in streptozotocin (STZ)-induced diabetic rats on the pancreatic islets was evaluated by morphometric analysis.

Findings/Results:

LC-MS/MS results indicated a similar mass spectrum of isolated fractions from nectarine and peach with Rosa canina. Oral administration of nectarine and peach extracts to STZ-induced diabetic rats showed restoration of blood glucose levels to normal levels with a concomitant increase in insulin levels. Morphometric analysis of pancreatic sections revealed the increase in number, diameter, volume, and area of the pancreatic islets in the diabetic rats treated with extracts compared to the untreated diabetic rats.

Conclusion and implications:

Nectarine and peach extracts’ anti-diabetic properties improved insulin secretion and pancreatic beta-cell function and subsequently led to restoring pancreatic islet mass in STZ-induced diabetic rats.

Immunomodulatory and Mechanistic Considerations of Hibiscus sabdariffa (HS) in Dysfunctional Immune Responses: A Systematic Review

Hibiscus sabdariffa calyx (HS) water decoction extract is a commonly consumed beverage with various pharmacological properties. This systematic review examines the possible effect of HS intake on immune mediators. The Scopus and PUBMED databases were searched for all human and animal studies that investigated the effect of HS administration on immune related biomarkers. For each of the immune biomarkers, the mean, standard deviation and number of subjects were extracted for both the HS treated and untreated group. These values were used in the computation of standardized mean difference (SMD). Statistical analysis and forest plot were done with R statistical software (version 3.6.1). Twenty seven (27) studies met the eligibility criteria. Twenty two (22) of the studies were used for the meta-analysis which included a total of 1211 subjects. The meta-analysis showed that HS administration significantly lowered the levels of TNF-α (n=10; pooled SMD: -1.55; 95% CI: -2.43, -0.67; P < 0.01), IL-6 (n=11; pooled SMD:-1.09; 95% CI: -1.77, -0.40; P < 0.01), IL-1β (n=7; pooled SMD:-0.62; 95% CI: -1.25, 0.00; P = 0.05), Edema formation (n=4; pooled SMD: -2.29; 95% CI: -4.47, -0.11; P = 0.04), Monocyte Chemoattractant Protein -1 (n=4; pooled SMD: -1.17; 95% CI: -1.78, -0.57; P < 0.01) and Angiotensin converting enzyme cascade (n=6; pooled SMD: -0.91; 95% CI: -1.57, -0.25; P < 0.01). The levels of IL-10 (n=4; pooled SMD: -0.38; 95% CI: -1.67, 0.91; P = 0.56), Interleukin 8 (n=2; pooled SMD:-0.12; 95% CI: -0.76, 0.51; P = 0.71), iNOS (n=2; pooled SMD:-0.69; 95% CI: -1.60, 0.23 P = 0.14) and C- Reactive Protein (n=4; pooled SMD: 0.05; 95% CI: -0.26, 0.36; P = 0.75), were not significantly changed by HS administration. Some of the results had high statistical heterogeneity. HS may be promising in the management of disorders involving hyperactive immune system or chronic inflammation.

Structural characterization and biological activities of a novel polysaccharide containing N-acetylglucosamine from Ganoderma sinense

A novel homogeneous heteropolysaccharide (GSPB70-S) with a molecular weight of 2.87 kDa was isolated from Ganoderma sinense. Structural analysis showed that GSPB70-S was composed of glucose, glucosamine, mannose, and galactose with a molar ratio of 12.90:3.70:2.26:1.00. The repeating structure units of GSPB70-S were characterized by the combined application of chemical methods and nuclear magnetic resonance. GSPB70-S contains a backbone of →3)-β-D-Glcp-(1 → 4)-α-D-GlcpNAc-(1 → 4)-α-D-Manp-(1 → 3)-β-D-Glcp-(1→, with branches of β-D-Glcp-(1→, α-D-GlcpNAc-(1 → and →4)-α-D-Galp-(1→. Scanning electron microscope (SEM) showed that GSPB70-S presented a long strip shape with different thicknesses, and there were many lamellar substances on the surface. Biological research showed that GSPB70-S inhibited the activity of α-glucosidase in vitro, increased the viability of RAW 264.7 macrophages, and promoted the release of NO. In addition, GSPB70-S showed good abilities to scavenge free radicals.

Characterization, antioxidant, and anticancer activities of a neutral polysaccharide from Duchesnea indica (Andr.) Focke

A neutral polysaccharide (DIP-1) from Duchesnea indica (Andr.) Focke was obtained by hot water extraction, ethanol precipitation and chromatographic separation (DEAE-52 cellulose anion-exchange column and Sephadex G-100 gel column). The physicochemical properties of DIP-1 were elucidated by gel permeation chromatography, monosaccharide composition, Fourier transform infrared spectrometry, UV-visible spectrophotometry, scanning electron microscope and Congo red test. The results indicated that DIP-1 was consisted of mannose, glucosamine, glucose, galactose and arabinose in a ratio of 1.00:0.42:18.36:14.17:0.81, and its molecular weight was 218.3 kDa. Meanwhile, DIP-1 presented a straight hexahedron structure, but no triple-helical conformation. In antioxidant activity tests, DIP-1 exhibited powerful scavenging activities on hydroxyl, DPPH, ABTS radicals and reducing power in a dose-dependent manner. Especially, DIP-1 demonstrated high inhibitory activities against SKOV-3 and Hep-G2 cells in vitro, with IC₅₀ values of 1.42 and 1.23 mg/ml, respectively. PRACTICAL APPLICATIONS: D. indica has been used for a long time as a Chinese medicine for therapy of many diseases, including cancer, inflammation, leprosy, fever, bleeding and so on. At present, polysaccharides have attracted comprehensive attention because of a large range of pharmacological and biological properties, including antitumor, antidiabetic, antioxidant and immunomodulatory activity. In the present study, we purified and characterized a neutral polysaccharide from D. indica for the first time. Moreover, the neutral polysaccharide exhibits significant antioxidant and antitumor activities. Therefore, the present study laid a foundation for the high-value application of D. indica polysaccharides in functional food and pharmaceutical industries.

Therapeutic effects of polysaccharides from Anoectochilus roxburghii on type II collagen-induced arthritis in rats

Anoectochilus roxburghii, a famous Chinese herbal medicine, has been commonly used for the treatment of liver disease, diabetes, and rheumatoid arthritis. Our study aimed to investigate the anti-rheumatoid arthritis effects of A. roxburghii polysaccharides (ARP), using the rat's model of type II collagen-induced arthritis (CIA). ARP was prepared by alcohol sedimentation and structurally characterized based on combined chemical, chromatographic and spectroscopic methods. High Performance Size Exclusion Chromatography-Multiangle Laser Light Scattering-Refrative Index (HPSEC-MALLS-RI) analysis revealed that ARP includes two peaks, and the weight-average molecular weight (Mw) of the principal one was estimated as 5.90 kDa with a relative content of 98.2%. Pharmacological results exhibited that ARP significantly decreased the arthritis index and ameliorated the inflammatory cell infiltration and the synovial tissue destruction in CIA rats. Additionally, ARP possessed significant NO production inhibitory effects and antioxidant activity. Further anti-inflammatory mechanism investigations indicated that ARP significantly inhibited the activation of nuclear factor κB (NF-κB) pathway by suppressing the phosphorylation of IκB and p65, which subsequently down-regulated the mRNA expressions of IL-1β and IL-6 in LPS-stimulated RAW 264.7 cells. These findings suggested that ARP has great potential in the development of functional foods and dietary supplements for the treatment of rheumatoid arthritis.

Purification, characterization and immunomodulatory activity of polysaccharides from stem lettuce

Stem lettuce has a long history of cultivation in China and possesses high nutritional and medicinal value. In our previous studies, extraction optimization, characterization, and bioactivities of stem lettuce polysaccharides (SLP) were investigated. In this study, SLP were further separated into two purified polysaccharides, SLP-1 and SLP-2, by anion exchange chromatography followed by size exclusion chromatography. SLP-1, with a molecular weight of 90 KDa, was mainly composed of galacturonic acid, galactose and arabinose in a molar ratio of 17.6:41.7:33.9. SLP-2, with a molecular weight of 44 KDa, was mainly composed of mannose, galacturonic acid, galactose and arabinose in a molar ratio of 11.5:69.5:9.3:8.2. In addition, both purified polysaccharides contain sulphate radicals, have triple helical structures and can promote macrophage proliferation without cytotoxicity. SLP-2 was better able to stimulate phagocytic and nitric oxide production than SLP-1. The results suggest that polysaccharides from stem lettuce could be explored as immunomodulatory agents in the field of pharmaceuticals and functional foods.

Characterization and immunological activity of polysaccharides from Ixeris polycephala

A water-soluble polysaccharide, named KMCP, was isolated and purified from edible plant Ixeris polycephala by using DEAE-52 cellulose chromatography. Its structure was determined by chemical analysis, methylation analysis, and NMR analysis, coupled with characterization by scanning electron spectroscopy (SEM). The resulting data indicated that KMCP was an arabinogalactan, with an average molecular weight of 1.95×10⁶Da, which was mainly composed of arabinose and galactose in a relative molar ratio of 28.1% and 70.3%, respectively. The structure of KMPC was characterized as 72.5% of (1→4)-β-Galp residues interspersed with 27.5% of (1→4,6)-β-Galp residues in the main chain, and the branches were composed of (1→5)-α-Araf moieties or α-Araf (1→5) α-Araf (1→disaccharide moieties attached at O-6 of the (1→4,6)-β-Galp residues. KMCP was revealed to be capable of exhibiting macrophage-mediated innate immune responses via enhancing phagocytosis of macrophages and increasing production of NO, activating NF-κB signaling pathway and promoting the mice spleen cells proliferation in a dose-dependent manner within the test concentrations (10.0-200.0μg/mL). These results suggested that KMCP could potentially be an effective and safe immunomodulator valuable to be utilized in pharmacological fields or in the development of functional foods.

Purification, characterization and immunomodulatory activity of water extractable polysaccharides from the swollen culms of Zizania latifolia

The swollen culms of Zizania latifolia is a popular vegetable and traditional herbal medicine mainly consumed in some Asian countries. In our previous study, water extractable polysaccharide (ZLPs-W) and alkali extractable polysaccharide (ZLPs-A) was sequentially prepared from the swollen culms of Zizania latifolia. In vitro cell assay revealed that ZLPs-W without cytotoxicity had higher immunomodulatory activity than ZLPs-A. Therefore, in this study, ZLPs-W was further separated to three purified polysaccharides of ZLPs-W1, ZLPs-W2, and ZLPs-W3 by anion exchange chromatography and size exclusive chromatography in sequence. They were found to be homogeneous polysaccharides in β-type glycosidic linkage. ZLPs-W1 and ZLPs-W2 without triple helix conformation mainly contained Glc in molar percentage of 96.47% and 85.1%, respectively. ZLPs-W3 with triple helix conformation mainly consisted of Man, Rha, GalA, Glc, Gal and Ara in the molar ratio of 10.23:14.14:37.44:17.14:16.54:4.51. In addition, all the three purified polysaccharides could effectively enhanced the proliferation, phagocytosis, and nitric oxide production of murine macrophage RAW 264.7, suggesting that they possessed a potent immunostimulatory activity and could be developed as immunomodulator in medicine or functional food areas.