Systematic fractionation and immunoenhancement of water-soluble polysaccharides isolated from fruit of Morus alba L

Fructus mori: An Updated Review on Botany, Phytonutrient, Detection, Bioactivity, Quality Marker, and Application

BACKGROUND

Fructus mori (mulberry) is not only a delicious fruit with rich phytonutrients and health functions but also a medicinal plant with many clinical therapeutic values for tonifying kidneys and consolidating essence, making hair black and eyes bright.

METHODS

The related references about F. mori in this review from 1996 to 2022 had been collected from both online and offline databases, including PubMed, Elsevier, SciFinder, Willy, SciHub, Scopus, Web of Science, ScienceDirect, SpringerLink, Google Scholar, Baidu Scholar, ACS publications, and CNKI. The other information was acquired from ancient books and classical works about F. mori.

RESULTS

An updated summary of phytonutrients from F. mori was listed as fellows: flavonoids (1-20) (23.5%), phenolic acids (21-34) 16.5%), alkaloids (35-75) (48.2%), polysaccharides (76- 78) (3.5%), other compounds (79-85) (8.3%). The above chemical components were detected by TLC, UV-Vis, HPLC, GC-MS, and AAS methods for their quality standards. The various bioactivities (hepatoprotective, immunomodulatory, anti-oxidant, hypoglycemic, anti-cancer, and other activities) of mulberry are summarized and discussed in this review, which laid an important basis for analyzing their mechanisms and quality markers. This review summarized its applications for vinegar, wine, yogurt, drink, jelly, and sweetmeat in food fields, and the existing problems and future development directions are also discussed in this review.

CONCLUSIONS

This review made a comprehensive description of F. mori, including botany, phytonutrient, detection, bioactivity, quality marker, and application. It will not only provide some important clues for further studying F. mori, but also provide some valuable suggestions for in-depth research and development of F. mori.

Polysaccharides in fruits: Biological activities, structures, and structure-activity relationships and influencing factors-A review

Fruits are a rich source of polysaccharides, and an increasing number of studies have shown that polysaccharides from fruits have a wide range of biological functions. Here, we thoroughly review recent advances in the study of the bioactivities, structures, and structure-activity relationships of fruit polysaccharides, especially highlighting the structure-activity influencing factors such as extraction methods and chemical modifications. Different extraction methods cause differences in the primary structures of polysaccharides, which in turn lead to different polysaccharide biological activities. Differences in the degree of modification, molecular weight, substitution position, and chain conformation caused by chemical modification can all affect the biological activities of fruit polysaccharides. Furthermore, we summarize the applications of fruit polysaccharides in the fields of pharmacy and medicine, foods, cosmetics, and materials. The challenges and perspectives for fruit polysaccharide research are also discussed.

Extraction, purification, structural modification, activities and application of polysaccharides from different parts of mulberry

The mulberry plant is a member of the Moraceae family and belongs to the Morus genus. Its entire body is a treasure, with mulberries, mulberry leaves, and mulberry branches all suitable for medicinal use. The main active ingredient in mulberries is mulberry polysaccharide. Studies have shown that polysaccharides from different parts of mulberry exhibit antioxidant, antidiabetic, antibacterial, anti-inflammatory, and blood pressure-lowering properties. There are more studies on the biological activities, extraction methods, and structural characterization of polysaccharides from different parts of mulberry. However, the structural characterization of mulberry polysaccharides is mostly confined to the types and proportions of monosaccharides and the molecular weights of polysaccharides, and there are fewer systematic studies on polysaccharides from different parts of mulberry. In order to better understand the bioactive structure of mulberry polysaccharides, this article discusses the recent research progress in the extraction, separation, purification, bioactivity, structural modification, and application of polysaccharides from different parts of mulberry (mulberry leaves, mulberry fruits, and mulberry branches). It also delves into the pharmacological mechanisms of action of mulberry polysaccharides to provide a theoretical basis for further research on mulberry polysaccharides with a view to their deeper application in the fields of feed and nutraceuticals.

An arabinogalactan extracted with alkali from Portulaca oleracea L. used as an immunopotentiator and a vaccine carrier in its conjugate to BSA

A neutral polysaccharide (POPAN) from Portulaca oleracea L. was isolated with alkali and purified to obtain. HPLC analysis suggested POPAN (40.9 kDa) was mainly composed of Ara and Gal with traces of Glc and Man. GC-MS and 1D/2D NMR analysis confirmed POPAN was an arabinogalactan possessing a backbone mainly composing of (1 → 3)-α-l-Araf-linked arabinan and (1 → 4)-β-d-Galp-linked galactan, which was different from structure characterization of typical arabinogalactan reported previously. Importantly, we conjugated POPAN to BSA (POPAN-BSA), and detected the potential and mechanism of POPAN as an adjuvant in POPAN-BSA. The results indicated, in contrast to BSA, POPAN-BSA induced the robust and persistent humoral response in addition to the cellular response with Th2-biased immunity response in mice. Further investigations of mechanism revealed effects of POPAN-BSA were a result of POPAN as the adjuvant to: 1) significantly activate DCs in vitro or in vivo including the upgraded expressions of costimulators, MHCs and cytokines; 2) greatly facilitated the capture of BSA. Overall, present studies demonstrated POPAN can be a potential adjuvant as an immunopotentiator and an antigen delivery vehicle in its conjugate to recombinant protein vaccines.

Application of chromatography in purification and structural analysis of natural polysaccharides: A review

Polysaccharides are widely distributed in natural sources from monocytic microorganisms to higher animals, and are found in a variety of biological activities in recent decades. Natural polysaccharides have the characteristics of large molecular weight, diverse composition, and complex structure, so their purification and structural analysis are difficult issues in research. Chromatography as a powerful separation technique, plays an irreplaceable role in the separation and structural analysis of natural polysaccharides, especially in the purification of polysaccharides, the separation of hydrolysates, and the analysis of monosaccharide composition. The separation mechanisms and application of different chromatographic methods in the studies of polysaccharides were summarized in this review. Moreover, the advantages and drawbacks of various chromatography methods were discussed as well.

Immunological Activity and Gut Microbiota Modulation of Pectin from Kiwano (Cucumis metuliferus) Peels

For developing the recycling of fruit by-products from kiwano, a polysaccharide was extracted from kiwano (Cucumis metuliferus) peels, namely Cucumis metuliferus peels polysaccharide (CMPP), with the aim of investigating the potential beneficial effects. The composition of polysaccharides was analyzed by chemical methods. RAW264.7 macrophages cells and the microbiota dynamics simulator (BFBL gut model) were used for in vitro study. The result showed that CMPP mainly consists of glucuronic acid, arabinose, galactose and rhamnose. By intervening with RAW264.7 cells, CMPP promoted cell proliferation and showed immune-enhancing activity, which significantly (p < 0.05) induced the release of nitric oxide (NO), tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) at a concentration of 50 μg/mL. In addition, CMPP had an impact on the composition of the gut bacteria, increasing the growth of Akkermansia, Bacteroides, Bifidobacterium, Feacalibacterium, and Roseburia. During the intake period, acetic, butyric and propionic acids were all increased, especially (p < 0.05) in the descending colon. Moreover, a decrease in ammonia concentration (10.17 ± 0.50 mM in the ascending colon, 13.21 ± 1.54 mM in the transverse colon and 13.62 ± 0.45 mM in the descending colon, respectively) was observed. In summary, CMPP can be considered as a pectin, showed immunological activity and function of gut microbiota modulation. This study could be the scientific basis of developing kiwano peels as beneficial to human health.

Structural Characterization and In Vitro Fermentation Characteristics of Enzymatically Extracted Black Mulberry Polysaccharides

In this study, we systematically investigated the structural characterization and in vitro fermentation patterns of crude black mulberry fruit polysaccharides (BMPs), either extracted by water (BMP) or by enzymatic treatment. Different enzymatic treatments were pectinase-extracted (PE)-BMP, pectin lyase-extracted (PL)-BMP, cellulase-extracted (CE)-BMP, and compound enzymes-extracted (M)-BMP (pectinase:pectin lyase:cellulase = 1:1:1). Our results show that enzymatic treatment improved the polysaccharide yield and led to a different chemical composition and structure for the polysaccharides. Change dynamics during the in vitro fermentation indicated that BMPs could indeed be degraded and consumed by human fecal microbiota and that different BMPs showed different degrees of fermentability. In addition, BMPs stimulated the growth of Bacteroidetes and Firmicutes, inhibited the growth of Fusobacteria and Proteobacteria (except for CE-BMP), and induced the production of short-chain fatty acids (SCFAs). Furthermore, we found that BMP and PL-BMP exhibited better fermentability and prebiotic potential than the other polysaccharides.

Pharmacological Activities for Morus alba L., Focusing on the Immunostimulatory Property from the Fruit Aqueous Extract

Depending on the extraction method, numerous compounds that have specific pharmacological effects can be obtained from M. alba L. There is a growing scientific interest in health problems related to aging. Efforts to develop safe immune-enhancing pharmaceuticals are increasing. This review aims to summarize and critically discuss the immunity enhancement effects and pharmaceutical efficacy of M. alba L. extracts. The scientific database search was conducted using Google Scholar, Web of Science, and PubMed until May 2021. Additional articles were identified and obtained from references in the retrieved articles. Ethanol or methanol extraction of various parts of M. alba L. identified a large amount of phenols and flavonoids, which are effective for immunosuppression, antioxidants, and cardiovascular diseases, and are antibacterial, and anticancer. Water extraction of M. alba L. enhanced the innate immune response based on immune cell activation. A polysaccharide and an alkaloid related to increased macrophage activity were isolated from M. alba L. fruit extracts. M. alba L. fruit water extracts primarily induced the production of pro-inflammatory substances, in model organisms, via TLR4 in immune cells. Water extracts have been shown to be effective in pathogen defense and tumor suppression by enhancing macrophage activity. Based on our literature review on the bioactivity of M. alba L. fruit extracts, particularly in relation to their immunity enhancement activity, we anticipate that M. alba-derived pharmaceuticals will have excellent potential in future medical research.

Structural elucidation and immunomodulatory evaluation of a polysaccharide from Stevia rebaudiana leaves

Stevia rebaudiana, a sweetener with medicinal functions, has attracted extensive attention due to its application in food and pharmaceutical fields. However, a few studies were performed to explore polysaccharides in this plant. Herein, SRP70-1 was derived from S. rebaudiana. Structural analysis (monosaccharide composition analysis, high-performance liquid chromatography-multi-angle light scattering detection, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectroscopy) revealed that SRP70-1 was composed of mannose, glucose, galactose, and arabinose at the molar ratio of 1.35:1.00:3.23:3.47, with an absolute molecular weight of 7698 Da. SRP70-1 was found to contain → 5)-α-l-Araf-(1→, →2,3,5)-α-l-Araf-(1→, →4)-β-l-Arap-(1→, →4)-β-d-Galp-(1→, →6)-β-d-Galp-(1→, →4)-β-d-Manp-(1→, →6)-β-d-Manp-(1→, and terminal α-l-Araf, β-d-Galp, and β-d-Glcp residues. Cell experiments showed that SRP70-1 could significantly promote phagocytosis and increase the release of nitric oxide and cytokines including IL-1β, IL-6, and TNF-α. Further zebrafish experiments confirmed the immunological enhancement effects of SRP70-1. This study revealed that SRP70-1 may be useful for the development of functional foods.

Recent advances on bioactive polysaccharides from mulberry

Mulberry (Moraceae family), commonly considered as a folk remedy, has a long history of usage in many regions of the world. Polysaccharides regarded as one of the major components in mulberry plants, and they possess antioxidant, antidiabetic, hepatoprotective, prebiotic, immunomodulatory and antitumor properties, among others. In recent decades, mulberry polysaccharides have been widely studied for their multiple health benefits and potential economic value. However, there are few reviews providing updated information on polysaccharides from mulberry. In this review, recent advances in the study of isolation, purification, structural characterization, biological activity and the structure-activity relationship of mulberry polysaccharides are summarized and discussed. Furthermore, a thorough analysis of the current trends and perspectives on mulberry polysaccharides is also proposed. Hopefully, these findings can provide a useful reference value for the development and application of natural polysaccharides in the field of functional food and medicine in the future.

Structure analysis of a non-esterified homogalacturonan isolated from Portulaca oleracea L. and its adjuvant effect in OVA-immunized mice

We isolated and purified a pectin from Portulaca oleracea L. (P. oleracea), and analysed its structure by high-performance size exclusion chromatography (HPSEC), high-performance liquid chromatography (HPLC), gas chromatograph-mass spectrometer (GC-MS), fourier transform infrared spectroscopy (FT-IR), and ¹H, ¹³C nuclear magnetic resonance spectroscopy (NMR). The data indicated that this pectin (designated as POPW-HG) was a linear non-esterified homogalacturonan, which is unique in plants; its molecular weight was around 41.2 kDa. Meanwhile, POPW-HG as an adjuvant was evaluated in the mice immunized with OVA subcutaneously. OVA-specific antibody titres from the sera of immunized mice were tested by ELISA. It showed that POPW-HG significantly enhanced OVA-specific antibody titres (IgG, IgG1, and IgG2b) (p < 0.05) in a dose-dependent manner in the OVA-immunized mice, preliminarily indicating POPW-HG could increase an antibody response, Th1 and Th2 immune response. In addition, the ratio of IgG1/IgG2b suggested POPW-HG induced a Th2-biased response in the OVA-immunized mice. The results demonstrated POPW-HG could be a potential adjuvant candidate in vaccines.

Study on structure characterization of pectin from the steamed ginseng and the inhibition activity of lipid accumulation in oleic acid-induced HepG2 cells

Two acid polysaccharides were obtained from steamed ginseng (GPS-1 and GPS-2) through water extraction, ion-exchange chromatography and gel chromatography. The structural features and ability of the polysaccharides to inhibit lipid accumulation in oleic acid-induced HepG2 cells were studied. GPS-1 consisted of type I arabinogalactans (AG-I), arabinogalactans-II (AG-II) and rhamnogalacturonan I (RG-I) domains. GPS-2 was a pectin-like polysaccharide consisting mainly of the homogalacturonan (HG) domain and a small amount of AG domain. Both GPS-1 and GPS-2 had branches attaching on O-3 of (1 → 6)-GalA or O-4 of (1 → 2)-Rha and terminated by either Ara or Gal. An in vitro experiment revealed that GPS-1 treatment at 50-400 μg/ml could dose-dependently decrease intracellular lipid accumulation and cholesterol (TC) and triglycerides (TG) levels. GPS-1 exerted a more serious hypolipidemic effect than GPS-2 did. Moreover, GPS-1 considerably increased the phosphorylation of AMP-activated protein kinase (AMPK) and affected the expression of AMPK downstream targets, including the inhibition of the protein expression of sterol regulatory element-binding protein 1c (SREBP-1c) and activation of Acetyl-CoA carboxylase (ACC). Results suggest that GPS-1 could inhibit lipid accumulation via the AMPK the signalling pathway.

Trends in the extraction, purification, characterisation and biological activities of polysaccharides from tropical and sub-tropical fruits - A comprehensive review

Tropical and sub-tropical fruits are tremendous sources of polysaccharides (PSs), which are of great interest in the human welfare system as natural medicines, food and cosmetics. This review paper aims to highlight the recent trends in extraction (conventional and non-conventional), purification and analytic techniques of fruit polysaccharides (FPSs). The chemical structure and biological activities, such as immunomodulatory, anti-cancer, anti-oxidant, anti-inflammatory, anti-viral, anti-coagulant and anti-diabetic effects, of PSs extracted from 53 various fruits were compared and discussed. With this wide coverage, a total of 172 scientific articles were reviewed and discussed. This comprehensive survey from previous studies suggests that the FPSs are non-toxic and highly biocompatible. In addition, this review highlights that FPSs might be excellent functional foods as well as effective therapeutic drugs. Finally, the future research advances of FPSs are also described. The content of this review will promote human wellness-based food product development in the future.

Sulfated polysaccharides from Rhodiola sachalinensis reduce d-gal-induced oxidative stress in NIH 3T3 cells

In this study, three sulfated polysaccharides (S-RSP_1-2, S-RSP_1-4 and S-RSP_1-8) from Rhodiola sachalinensis were produced by chlorosulfonic acid-pyridine method. d-gal was used to develop an oxidative stress model in the mouse embryonic fibroblast cell line NIH 3T3. Effects of the three sulfated polysaccharides on d-gal-induced oxidative stress were investigated. The results showed that S-RSP_1-4 improved the viability of the d-gal-induced oxidative stress in NIH 3T3 cells. The sulfated polysaccharides were found to have a better protective effect against d-gal-induced oxidative stress as compared to the native polysaccharide. Scanning electronmicroscopy also showed a significant change in the surface morphology of sulfated polysaccharides. In addition, the sulfated polysaccharides had noticeable DPPH radical-scavenging activity. In summary, our results demonstrated that d-gal was able to induce oxidative stress in NIH 3T3 cells, and sulfated group might play an important role in resistance to d-gal-induced oxidative damage.