Monosaccharide Residues Research Articles

New Polyhydroxysteroid Glycosides with Antioxidant Activity from the Far Eastern Sea Star Ceramaster patagonicus

Four new glycosides of polyhydroxysteroids, ceramasterosides A, B, D, and E (1–4), and two previously known compounds, ceramasteroside C1 (5) and attenuatoside B-I (6), were isolated from an extract of a deep-sea sea star species, the orange cookie star Ceramaster patagonicus. The structures of 1–4 were elucidated by the extensive NMR and ESIMS methods. Steroid monoglycosides 1 and 2 had a common 3β,6α,8,15β,16β-pentahydroxysteroid nucleus and a C–29 oxidized stigmastane side chain and differed from each other only in monosaccharide residues. Ceramasteroside A (1) contained 3-O-methyl-4-O-sulfated β-D-xylopyranose, while ceramasteroside B (2) had 3-O-methyl-4-O-sulfated β-D-glucopyranose, recorded from starfish-derived steroid glycosides for the first time. Their biological activity was studied using a model of lipopolysaccharide-induced (LPS) inflammation in a SIM-A9 murine microglial cell line. During the LPS-induced activation of microglial cells, 1, 3, and 5, at a non-toxic concentration of 1 µM, showed the highest efficiency in reducing the production of intracellular NO, while 4 proved to be most efficient in reducing the extracellular nitrite production. All the test compounds reduced the LPS-induced malondialdehyde (MDA) production. The in vitro experiments have demonstrated, for the first time, the antioxidant activity of the compounds under study.

Direct Experimental Characterization of a Sialyl Cation.

Sialic acids are monosaccharide residues involved in several biological processes. Controlling the stereoselectivity of sialylation reactions is challenging and mechanistic studies on the structure of its intermediate, the sialyl cation, are scarce. Here it is shown that a sialyl cation can be generated and isolated from an ionized sialic acid precursor. This short-lived species is structurally characterized for the first time using cryogenic infrared spectroscopy. In combination with quantum chemical calculations, the results reveal that the positive charge at the anomeric carbon of the sialyl cation is stabilized by remote participation of the C5-NHAc group leading to the formation of a bridged structure. In this structure, the β-side is shielded from nucleophilic attack, potentially explaining the α-selectivity of this building block in SN1-type sialylation reactions. Other modes of participation are energetically unfavored and cannot be observed experimentally.

A polysaccharide with a triple helix structure from Agaricus bisporus: Characterization and anti-colon cancer activity

In this study, A polysaccharide WAAP-2 (121 kDa) with a triple-helical structure was isolated and purified from Agaricus bisporus for the first time. The physicochemical properties, structural characteristics and anti-colon cancer activity were preliminarily investigated. The primary structure indicated that WAAP-2 was composed of mannose, glucose and galactose and determined the position of the linkage between monosaccharide residues. The advanced structure revealed that WAAP-2 has a triple helix and tangled chain conformation. In the anti-colon cancer activity investigation, WAAP-2 exerted an apoptosis-inducing effect by causing HT-29 cell cycle arrest in S phase. WAAP-2 promoted HT-29 cell apoptosis by up-regulating the expression of Caspase-3 and Bax proteins while down-regulating the expression of Bcl-2 protein. Besides, WAAP-2 could inhibit the migration and invasion of colorectal cancer cells by inducing E-cadherin expression and inhibiting Vimentin expression to affect epithelial mesenchymal transition. This paper is of importance for the application of WAAP-2, a triple-helical structural polysaccharide from Agaricus bisporus, to low-toxicity anti-colon cancer drugs.

Chemical Resolution of an Epitope Recognized by Blood Group Antibodies Capable of Binding Both A and B Red Blood Cells.

The high specificity of human antibodies to blood group A and B antigens is impressive, especially when considering the structural difference between these antigens (tetrasaccharides) is a NHAc versus a hydroxyl group on the terminal monosaccharide residue. It is well established that in addition to anti-A and anti-B there is a third antibody, anti-A,B capable of recognizing both A and B antigens. To analyze this AB specificity, we synthesized a tetrasaccharide, where the NHAc of the A antigen was replaced with an NH2. This NH2 group was then used to attach the glycan to an affinity resin, creating an AB epitope (ABep) adsorbent where the critical site for recognition by A and B antibodies was not accessible, while the rest of the (conformationally compact) tetrasaccharide remained accessible. Anti-ABep antibodies were then isolated from blood group O donors and found to have expected A,B specificity against immobilized and red cell bound synthetic antigens, including ABep, and were able to agglutinate both A and B red cells. The amount of these anti-ABep (anti-A,B) antibodies found in the blood of group O donors was comparable to levels of anti-A and anti-B found in group B and A individuals. Using STD-NMR the location for the AB epitope on the tetrasaccharide was found.

Sulfated Polyhydroxysteroid Glycosides from the Sea of Okhotsk Starfish Henricia leviuscula spiculifera and Potential Mechanisms for Their Observed Anti-Cancer Activity against Several Types of Human Cancer Cells.

Three new monosulfated polyhydroxysteroid glycosides, spiculiferosides A (1), B (2), and C (3), along with new related unsulfated monoglycoside, spiculiferoside D (4), were isolated from an ethanolic extract of the starfish Henricia leviuscula spiculifera collected in the Sea of Okhotsk. Compounds 1-3 contain two carbohydrate moieties, one of which is attached to C-3 of the steroid tetracyclic core, whereas another is located at C-24 of the side chain of aglycon. Two glycosides (2, 3) are biosides, and one glycoside (1), unlike them, includes three monosaccharide residues. Such type triosides are a rare group of polar steroids of sea stars. In addition, the 5-substituted 3-OSO3-α-L-Araf unit was found in steroid glycosides from starfish for the first time. Cell viability analysis showed that 1-3 (at concentrations up to 100 μM) had negligible cytotoxicity against human embryonic kidney HEK293, melanoma SK-MEL-28, breast cancer MDA-MB-231, and colorectal carcinoma HCT 116 cells. These compounds significantly inhibited proliferation and colony formation in HCT 116 cells at non-toxic concentrations, with compound 3 having the greatest effect. Compound 3 exerted anti-proliferative effects on HCT 116 cells through the induction of dose-dependent cell cycle arrest at the G2/M phase, regulation of expression of cell cycle proteins CDK2, CDK4, cyclin D1, p21, and inhibition of phosphorylation of protein kinases c-Raf, MEK1/2, ERK1/2 of the MAPK/ERK1/2 pathway.

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

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. 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. 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.

Oligosaccharides from black ginseng innovatively prepared by low-temperature steam-heating process ameliorate cognitive impairment in Alzheimer's disease mice via the Keap-1/Nrf2 pathway.

Our objective in this study was to evaluate the effectiveness of oligosaccharides extracted from black ginseng (OSBG), innovatively prepared by a low-temperature steam-heating process, in the improvement of learning and memory impairment in mice, as well as the mechanism(s). Eight carbohydrates involving isomaltose and maltotetraose were detected in black gensing; monosaccharide residues including mannose and rhamnose were also discovered. OSBG-treated mice showed significant amelioration in recognition and spatial memory deficits compared to the scopolamine group. OSBG could decrease acetylcholinesterase activity in a tissue-dependent fashion but not in a dose-dependent manner. Furthermore, in contrast, OSBG administration resulted in significant upregulation superoxide dismutase, glutathione, glutathione peroxidase (GPx), and Kelch-like ECH-associated protein 1, downregulation of malondialdehyde and nuclear factor erythroid 2-related factor 2 in the tissues. Finally, at the genus level, we observed that the OSBG interventions increased the relative abundance of probiotics (e.g., Barnesiella, Staphylococcus, Clostridium_XlVb) and decreased pernicious bacteria such as Eisenbergiella and Intestinimonas, compared to the Alzheimer's disease mouse model group. Herein, our results demonstrate that OSBG restores the composition of the scopolamine-induced intestinal microbiota in mice, providing homeostasis of gut microbiota and providing evidence for microbiota-regulated therapeutic potential. Our results showed for the first time a clear role for OSBG in improving scopolamine-induced memory impairment by inhibiting cholinergic dysfunction in a tissue-dependent manner. Additionally, OSBG administration relieved oxidative stress by activating the Keap-1/Nrf2 pathway and modulating the gut microbiota. Collectively, OSBG may be a promising target for neuroprotective antioxidants for improving memory and cognition in Alzheimer's disease patients. © 2024 Society of Chemical Industry.

Testacosides A–D, glycoglycerolipids produced by Microbacterium testaceum isolated from Tedania brasiliensis

Marine bacteria living in association with marine sponges have proven to be a reliable source of biologically active secondary metabolites. However, no studies have yet reported natural products from Microbacterium testaceum spp. We herein report the isolation of a M. testaceum strain from the sponge Tedania brasiliensis. Molecular networking analysis of bioactive pre-fractionated extracts from culture media of M. testaceum enabled the discovery of testacosides A–D. Analysis of spectroscopic data and chemical derivatizations allowed the identification of testacosides A–D as glycoglycerolipids bearing a 1-[α-glucopyranosyl-(1 → 3)-(α-mannopyranosyl)]-glycerol moiety connected to 12-methyltetradecanoic acid for testacoside A (1), 14-methylpentadecanoic acid for testacoside B (2), and 14-methylhexadecanoic acid for testacosides C (3) and D (4). The absolute configuration of the monosaccharide residues was determined by 1H-NMR analysis of the respective diastereomeric thiazolidine derivatives. This is the first report of natural products isolated from cultures of M. testaceum.Key points• The first report of metabolites produced by Microbacterium testaceum.• 1-[α-Glucopyranosyl-(1 → 3)-(α-mannopyranosyl)]-glycerol lipids isolated and identified.• Microbacterium testaceum strain isolated from the sponge Tedania brasiliensis.Graphical abstract

An arabinose-rich heteropolysaccharide isolated from Belamcanda chinensis (L.) DC treats liver cancer by targeting FAK and activating CD40

An undisclosed polysaccharide, BCP80–2, was isolated from Belamcanda chinensis (L.) DC. Structural investigation revealed that BCP80–2 consists of ten monosaccharide residues including t-α-Araf-(1→, →3,5)-α-Araf-(1→, →5)-α-Araf-(1→, →4)-β-Xylp-(1→, →3)-α-Rhap-(1→, →4)-β-Manp-(1→, t-β-Glcp-(1→, →6)-α-Glcp-(1→, t-β-Galp-(1→, and→3)-α-Galp-(1→. In vivo activity assays showed that BCP80–2 significantly suppressed neoplasmic growth, metastasis, and angiogenesis in zebrafish. Mechanistic studies have shown that BCP80–2 inhibited cell migration of HepG2 cells by suppressing the FAK signaling pathway. Moreover, BCP80–2 also activated immunomodulation and upregulated the secretion of co-stimulatory molecules CD40, CD86, CD80, and MHC-II. In conclusion, BCP80–2 inhibited tumor progression by targeting the FAK signaling pathway and activating CD40-induced adaptive immunity.

Screening and identifying natural products with SARS-CoV-2 infection inhibitory activity from medicinal fungi

The coronavirus disease of 2019 (COVID-19), a global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), can result in severe health complications. In addition to physical preventative measures, pharmaceutical intervention is also crucial. Numerous natural products from medicinal fungi have shown promise as potential antiviral drugs and may serve as a source of effective components with antiviral activity against SARS-CoV-2 and other coronaviruses. In this study, we developed a workflow that integrates viral infection inhibition assays at both cellular and molecular levels, as well as molecular separation and characterization, to screen and identify natural products with antiviral activity. Using this workflow, we screened 167 extracts extracted from 36 medicinal fungi using optimized extraction methods. We assessed the antiviral effects of these extracts by measuring their ability to inhibit SARS-CoV-2 infection and receptor binding domain - human angiotensin-converting enzyme 2 (RBD-hACE2) binding in vitro. Following charge- and size-based characterization of the active compounds through filtration and chromatographic fractionation, mass spectrometry characterization of the fractionated compounds revealed that the active components are polysaccharides and determined their monosaccharide residue composition. Our findings provide new insights into the antiviral potential of natural products and their screening strategies and may contribute to the development of effective antiviral therapeutics against COVID-19 and other diseases.

A polysaccharide from the seed of Gleditsia japonica var. delavayi: Extraction, purification, characterization and functional properties

Gleditsia japonica var. delavayi is widely distributed in Yunnan and Guizhou, China, and the perisperm of its seeds is frequently used as a traditional banquet sweet food with transparent color, smooth-tasting, low-fat, and high-carbohydrate. Herein, a cellulase-assisted extraction method was applied using response surface methodology to optimize the extraction of polysaccharides from the seeds of G. japonica var. delavayi. The highest extraction yield (82.23 ± 0.50%) was obtained under 5% cellulase, 176 mL/g liquid-to-material ratio, and enzymolysis parameters of 55 °C for 90 min at pH 4.5. The purified seed polysaccharide (PS) primarily contained galactomannan (weight average molecular weight, 42.74 kDa), which was linked by the monosaccharide residues 1,6-α-Galp, 1,4,6-α-D-Galp, 1,2,4,6-β-D-Manp, and 1,3,6-α-D-Galp. The PS obtained has a single-crystal structure, is thermodynamically stable, and its molecules aggregate in water. Furthermore, PS possesses high cholate binding capacity and a substantial inhibitory effect on α-glucosidase and α-amylase. Taken together, the findings of this report offer a theoretical foundation for developing and utilizing G. japonica var. delavayi.

Research on the application of Thelephora ganbajun exopolysaccharides in antioxidant, anti-inflammatory and spot-fading cosmetics

Thelephora ganbajun exopolysaccharides (TGEP) with a “coral-like” branched chain structure (main chain diameter ∼ 80 nm) were prepared by liquid fermentation and fractionated by ion-exchange chromatography. The main fraction (TGEP-2) with the highest in vitro antioxidant capacity was composed of Glc, Man, Gal, GalA, GlcA, Ara, Rha, GlcN, Fuc and Rib in a molar ratio of 465.43:420.43:219.14:188.43:37:35.14:31.43:19.43:11.14:1, with a molecular weight of 1.879 × 104 Da. The sequence of monosaccharide residue release revealed that Gal, Glc and Ara residues were more distributed in the side-branch chains and at their ends, whereas Man and GalA residues were more distributed in the main chains. TGEP-2 contained linear residues (mainly →4)-Glcp-(1 → and →4)-Manp-(1→), branch residues (→3,6)-Glcp-(1→, →4,6)-Glcp-(1 → and →3,6)-Galp-(1→) and terminal residues (Galp-(1→, Manp-(1 → and Glcp-(1→). TGEP-2 consisted of α- and β-glycosidically linked pyranosides, with a triple helical conformation and many long branches. Zebrafish oxidative stress and inflammation models found that TGEP-2 had antioxidant and anti-inflammatory activities. The zebrafish skin black spot assay showed that TGEP-2 inhibited melanin formation. Therefore, extracellular polysaccharides of T. ganbajun have strong application potential in anti-oxidant, anti-inflammatory and skin spot-fading functions cosmetics.

The Influence of Polysaccharides on Lipid Metabolism: Insights from Gut Microbiota.

Polysaccharides are complex molecules of more than ten monosaccharide residues interconnected through glycosidic linkages formed via condensation reactions. Polysaccharides are widely distributed in various food resources and have gained considerable attention due to their diverse biological activities. This review presented a critical analysis of the existing research literature on anti-obesity polysaccharides and investigates the complex interplay between their lipid-lowering activity and the gut microbiota, aiming to provide a comprehensive overview of the lipid-lowering properties of polysaccharides and the underlying mechanisms of action. In this review, the study summarized the roles of polysaccharides in improving lipid metabolism via gut microbiota, including the remodeling of the intestinal barrier, reduction of inflammation, inhibition of pathogenic bacteria, reduction of trimethylamine N-oxide (TMAO) production, and regulation of the metabolism of short-chain fatty acids (SCFAs) and bile acids (BAs). These mechanisms collectively contributed to the beneficial effects of polysaccharides on lipid metabolism and overall metabolic health. Furthermore, polysaccharide-based nanocarriers combined with gut microbiota have broad prospects for developing targeted and personalized therapies for hyperlipidemia and obesity.

Preparation and photothermal therapy of gold nanorods modified by Belamcanda chinensis (L.) DC polysaccharide

In recent years, the application of nanoparticles formed by coupling metal nanomaterials of photothermal therapy with polysaccharides as modified carriers in the targeted treatment of liver cancer has attracted extensive attention. In the present work, an undescribed homogeneous polysaccharide BCP50–2 was obtained from Belamcanda chinensis (L.) DC. The structural analysis displayed that BCP50–2 contained galactose and a small amount of arabinose, and was mainly composed of six monosaccharide residues: →3,5)-α-l-Araf-(1→, →4)-β-d-Galp-(1→, →4,6)-β-d-Galp-(1→, →3)-α-l-Galp-(1→, terminal α-l-Araf, and terminal β-d-Galp. To enhance the antitumor activity of BCP50–2, BCP50–2-AuNRs were prepared by coupling BCP50–2 with gold nanorods for the treatment of liver cancer. BCP50–2-AuNRs were rod-shaped with a long diameter of 26.8 nm and had good photothermal conversion effects. Under near-infrared (NIR) light irradiation, BCP50–2-AuNRs possessed photothermal effects and suppressed the growth of HepG2, A549, and MCF-7 cells. In addition, BCP50–2-AuNRs inhibited the development of liver cancer by inducing cell apoptosis, arresting the cell cycle in G2/M phases, and inhibiting cell migration. Moreover, BCP50–2-AuNRs inhibited tumor proliferation, migration, and angiogenesis in zebrafish. In summary, BCP50–2-AuNRs may be potentially useful for cancer treatment.

Composition and mitogenic activity of polysaccharide from Solanum tuberosum L.

Solanum tuberosum polysaccharide (STP) was isolated from the water extract of Solanum tuberosum L. and purified by ion-exchange and gel-filtration chromatography. Its molecular weight was determined by using gel permeation chromatography method and high performance liquid chromatography technique and its monosaccharide composition was analyzed using high performance liquid chromatography and gas chromatography with a flame ionization detector and a capillary column. It was shown that STP was consisted of galactose (Gal) and arabinose (Ara) (37.5 and 23.5%, respectively), along with uronic acids (9.7%), glucose monosaccharide residues (15%) and proteins (no less than 9%). The molecular weight of STP was 70 kDa. The Fourier-transform infrared technique was used for structural analysis of STP. The mitogenic activity of extracted polysaccharide is comparable to that of lipopolysaccharide.

ISOLATION AND STUDY OF POLYSACCHARIDES OF MARGILAN RADISH RAPHANUS SATIVUS

The purpose of this research is to isolate and study the physicochemical characteristics of polysaccharides in the seeds of the Margilan radish of the Brassicaceae family cultivated in the Republic of Uzbekistan.
 For the first time, a water-soluble fraction of polysaccharides was isolated from radish seeds by sowing Margilan successive extraction after the extraction of proteins and polyphenols. Anion exchange chromatography and gel filtration were used to obtain homogeneous polysaccharides. The polysaccharide fraction was separated by ion-exchange chromatography, purified on a Sephadex G-100 column. As a result, two polysaccharides RSP1 and RSP2 were obtained. The monosaccharide composition of the isolated polysaccharides was established. Analysis of monosaccharide residues showed that the composition of the RSP1 polysaccharide is represented by monosaccharides in the following composition: rhamnose - 0.7%, ribose - 4.7%, arabinose - 55.6%, xylose - 1.5%, mannose - 3.7%, glucose - 5.1% and galactose - 28.7%. The composition of the RSP2 polysaccharide is represented by monosaccharides: ribose - 2.8%, arabinose - 9.4%, mannose - 0.9%, glucose - 64.9% and galactose - 18.4%. From the obtained results, it can be seen that the RSP1 polysaccharide consists mainly of arabinose (55.6%) and galactose (28.7%) residues and belongs to the type of arabinogalactans, and the RSP2 polysaccharide mainly consists of glucose residues (64.9%) and galactose (18.4%).

Advanced culture strategy shows varying bioactivities of sulfated polysaccharides of Poria cocos

This study compares the bioactivity of six sulfated polysaccharides derived from glucose- and sucrose-feeding extracted from P. cocos. Anti-inflammatory potentials of these polysaccharides were evaluated by pretreating lipopolysaccharide (LPS)-induced inflammation in RAW264.7 cells. Of the tested polysaccharides, the sulfated polysaccharide derived from sucrose-feeding at the concentration of 40 g/l (referred to as “suc 40”) exhibited the highest anti-inflammatory activity, of 83 %, and 33 % inhibition of IL-6 and TNF-α secretion, respetively. It achieved this by inhibiting the p-38 and c-Jun N-terminal kinase (JNK) MAPK signaling pathways. On the other hand, the sulfated polysaccharide derived from glucose-feeding at a concentration of 20 g/l (referred to as “glc 20”) demonstrated the greatest anti-lung cancer activity. This was achieved by inducing apoptotic-related molecules, such as poly (ADP-ribose) polymerase (PARP) and CHOP. Furthermore, glc 20 had the highest contents of sulfate, fucose, and mannose compared to the other tested polysaccharides. This suggests that the composition of monosaccharide residues are critical factors influencing the anti-inflammatory and anti-cancer activities of these sulfated polysaccharides. Overall, this study highlights the potential of sulfated polysaccharides derived from P. cocos to function as bioactive compounds with anti-inflammatory and anti-cancer properties.

Bifunctionalized Betulinic Acid Conjugates with C-3-Monodesmoside and C-28-Triphenylphosphonium Moieties with Increased Cancer Cell Targetability.

A convenient synthesis is presented for a new class of bioactive bifunctionalized conjugates of lupane-type triterpenoids with triphenylphosphonium (TPP) and glycopyranosyl targeting moieties. The main synthesis steps include glycosylation of haloalkyl esters of the triterpene acid at the C-3 position by the imidate derivatives of glycopyranose followed by the product modification at the C-28 position with triphenylphosphine. The conjugates of betulinic acid (BetA) with TPP and d-glucose, l-rhamnose, or d-mannose moieties were thus synthesized as potential next-generation BetA-derived anticancer compounds. LC-MS/MS analysis in glucose-free physiological solution indicated that the glycosides showed better accumulation in PC-3 prostate cancer cells than both BetA and TPP-BetA conjugate, while the transporting effect of monosaccharide residues increased as follows: d-mannose < l-rhamnose ≈ d-glucose. At saturated concentrations, the glycosides caused a disturbing effect on mitochondria with a more drastic drop in transmembrane potential but weaker overproduction of mitochondrial reactive oxygen species (ROS) compared to TPP-BetA conjugate. Cytotoxicity of the glycosides in culture medium was comparable with or higher than that of the nonglycosylated conjugate, depending on the cancer cell line, whereas the compounds were less active toward primary fibroblasts. Glycosylation tended to increase pro-apoptotic and decrease pro-autophagic activities of the BetA derivatives. Cytotoxicity of the synthesized glycosides was considered in comparison with the summarized data on the natural and modified BetA glycosides. The results obtained are important for the development of bifunctionalized conjugates of triterpenoids with an increased cancer cell targetability.

Djakonoviosides A, A1, A2, B1-B4 - Triterpene Monosulfated Tetra- and Pentaosides from the Sea Cucumber Cucumaria djakonovi: The First Finding of a Hemiketal Fragment in the Aglycones; Activity against Human Breast Cancer Cell Lines.

Seven new monosulfated triterpene glycosides, djakonoviosides A (1), A1 (2), A2 (3), and B1-B4 (4-7), along with three known glycosides found earlier in the other Cucumaria species, namely okhotoside A1-1, cucumarioside A0-1, and frondoside D, have been isolated from the far eastern sea cucumber Cucumaria djakonovi (Cucumariidae, Dendrochirotida). The structures were established on the basis of extensive analysis of 1D and 2D NMR spectra and confirmed by HR-ESI-MS data. The compounds of groups A and B differ from each other in their carbohydrate chains, namely monosulfated tetrasaccharide chains are inherent to group A and pentasaccharide chains with one sulfate group, branched by C-2 Qui2, are characteristic of group B. The aglycones of djakonoviosides A2 (3), B2 (5), and B4 (7) are characterized by a unique structural feature, a 23,16-hemiketal fragment found first in the sea cucumbers' glycosides. The biosynthetic pathway of its formation is discussed. The set of aglycones of C. djakonovi glycosides was species specific because of the presence of new aglycones. At the same time, the finding in C. djakonovi of the known glycosides isolated earlier from the other species of Cucumaria, as well as the set of carbohydrate chains characteristic of the glycosides of all investigated representatives of the genus Cucumaria, demonstrated the significance of these glycosides as chemotaxonomic markers. The membranolytic actions of compounds 1-7 and known glycosides okhotoside A1-1, cucumarioside A0-1, and frondoside D, isolated from C. djakonovi against human cell lines, including erythrocytes and breast cancer cells (MCF-7, T-47D, and triple negative MDA-MB-231), as well as leukemia HL-60 and the embryonic kidney HEK-293 cell line, have been studied. Okhotoside A1-1 was the most active compound from the series because of the presence of a tetrasaccharide linear chain and holostane aglycone with a 7(8)-double bond and 16β-O-acetoxy group, cucumarioside A0-1, having the same aglycone, was slightly less active because of the presence of branching xylose residue at C-2 Qui2. Generally, the activity of the djakonoviosides of group A was higher than that of the djakonoviosides of group B containing the same aglycones, indicating the significance of a linear chain containing four monosaccharide residues for the demonstration of membranolytic action by the glycosides. All the compounds containing hemiketal fragments, djakonovioside A2 (3), B2 (5), and B4 (7), were almost inactive. The most aggressive triple-negative MDA-MB-231 breast cancer cell line was the most sensitive to the glycosides action when compared with the other cancer cells. Okhotoside A1-1 and cucumarioside A0-1 demonstrated promising effects against MDA-MB-231 cells, significantly inhibiting the migration, as well as the formation and growth, of colonies.

Efficient isolation of immunostimulatory polysaccharides from Lentinula edodes by autoclaving-ultrasonication extraction and fractional precipitation

A hyphenated process, autoclaving followed by ultrasonication (AU), was evaluated for efficient extraction of polysaccharides (PS) from Lentinula edodes (Shiitake) mushroom. The PS yield (w/w) was 8.44 % from hot-water extraction (HWE), 11.01 % by autoclaving extraction (AE), and 16.3 % by AUE. The AUE water extract was subject to fractional precipitation in four-steps with increasing ethanol concentration of 40 %, 50 %, 70 % and 80 % (v/v), yielding four PS fractions in descending molecular weight (MW), PS40 > PS50 > PS70 > PS80. All the four PS fractions were composed of four monosaccharide residues, mannose (Man), glucose (Glc) and galactose (Gal) but in different mole ratios. The PS40 fraction with the highest average MW (4.98 × 106) was the most abundant fraction, accounting for 64.4 % of the total PS mass and also had the highest glucose molar ratio (~80 %). PS40 also most significantly enhanced the NO, and ROS generation and phagocytic activity in RAW 264.7 cells. The results proved that AUE followed by fractional ethanol precipitation is an efficient strategy with reduced solvent expenditure for isolation of the major immunostimulatory PS from L. edodes mushroom.