Purification,preliminary structural characterization and in vitro antioxidant activity of polysaccharides from Acanthus ilicifolius

Crude Acanthus ilicifolius (A. ilicifolius) polysaccharides (CAIP) were obtained by hot water extraction and deproteinated. Two major polysaccharide fractions, the neutral A. ilicifolius polysaccharide (NAIP) and the acid A. ilicifolius polysaccharide B (AAIP-B), were isolated from CAIP by chromatography using DEAE-Sepharose Fast Flow and Sepharose CL-6B. The molecular weights (M_w) of NAIP and AAIP-B, determined by high performance gel-filtration chromatography (HPGFC), were 11,775 and 23,161 Da, respectively. AAIP-B contained 51.23% uronic acid, characteristic of a pectin-type hetero-polysaccharide. Analysis of the neutral monosaccharide composition indicated that NAIP contained high proportions of arabinose, galactose and glucose. However, AAIP-B was mainly composed of rhamnose, arabinose and galactose. Their structure properties were confirmed by FT-IR.     

Structural characterisation of polysaccharides from Tricholoma matsutake and their antioxidant and antitumour activities

In this study, polysaccharides from Tricholoma matsutake (TM-P) were purified using a DEAE-Sepharose fast flow column and three polysaccharide fractions (TM-P1, TM-P2 and TM-P3) were obtained. The chemical composition and structural characteristics of TM-P2 were quite different from those of TM-P1 and TM-P3. TM-P2 consisted of glucose, galactose and mannose with a molar ratio of 5.9:1.1:1.0. The glycosidic linkages were mainly composed of 1,6- and 1-linked glucose. Furthermore, TM-P2 showed the strongest in vitro antioxidant and antitumour activities. The oxygen radical absorbance capacity (ORAC) of TM-P2 was 2100.44 μmol Trolox/g. The antiproliferative activities of TM-P2 (4.0 mg/ml) on the growth of HepG2 and A549 cells were 67.98% and 59.04%, respectively.     

Characterisation of antioxidant and antiproliferative acidic polysaccharides from Chinese wolfberry fruits

Wolfberry fruit polysaccharides (WFPs) were isolated by hot-water extraction and ethanol precipitation. With HPLC analysis, WFPs were for the first time identified as acidic polysaccharides with galacturonic acid being the main component monosaccharide (24.9%), followed by galactose (21.3%), arabinose (18.5%), and glucose (15.9%), accounting for up to 80.6% of the molar percentage. WFPs exhibited a high antioxidant activity and a dose-dependent antiproliferative effect, with IC₅₀ values of 134.9, 70.1 and 138.4 μg/mL against A549, MCF-7 and LoVo cancer cells after 48 h of incubation as estimated by MTT assay, respectively. Flow cytometry analysis showed that WFPs exerted a stimulatory effect on apoptosis of MCF-7 cells, and induced the cell-cycle arrest at the G0/G1 phase, with the observation of intracellular ROS production and DNA damage. The present study demonstrated that these polysaccharides might have the potential to provide significant natural defence against human cancer.     

Chemical composition and anti-inflammatory activity of a pectic polysaccharide isolated from sweet pepper using a simulated gastric medium

A pectic polysaccharide named capsicuman (CA) was isolated from fresh sweet pepper by extraction with a saline solution containing hydrochloric acid (pH 1.5) and pepsin at 37 °C for 4 h. Capsicuman was shown to consist of d-galacturonic acid (GalA, 74.0%), rhamnose (Rha, 1.6%), arabinose (Ara, 2.6%) and galactose (Gal, 2.4%) residues. This polysaccharide was digestible with 1,4-alpha-d-galacturonase to yield d-GalA, thus confirming capsicuman as a pectic polysaccharide. Partial acid hydrolysis of capsicuman revealed galacturonan to be the core of the macromolecule. Purified capsicuman (CA-2) was obtained from CA by ion-exchange chromatography on DEAE-cellulose. Nuclear magnetic resonance (NMR) spectra indicated that the backbone of capsicuman contained 1,4-alpha-d-galacturonan partially substituted with methyl and O-acetyl ester groups. After oral administration to mice, capsicuman CA, CA-2 and the galacturonanic fragment of CA (CA-H) were found to decrease tumour necrosis factor-alpha TNF-alpha release and to increase production of interleukin-10 (IL-10) in lipopolysaccharide (LPS)-stimulated whole blood. This pectin was also shown to improve the survival of mice that were subjected to a lethal dose of LPS.     

Arabinan and arabinan-rich pectic polysaccharides from quinoa (Chenopodium quinoa) seeds: Structure and gastroprotective activity

After removal of starch, cell wall polysaccharides of seeds of quinoa were studied. They were extracted successively with water and with aq. 10% KOH. The extracted polysaccharides were fractionated and purified by freeze–thaw treatment and by sequential ultrafiltration through membranes. The purified fractions (PQW, K2-30EM, K1-10RM and K1-30RM) were analyzed by sugar composition, HPSEC, methylation and ¹³C NMR spectroscopy analysis. The results showed that PQW consisted of a linear arabinan with (1 → 5)-linked α-l-arabinofuranosyl units. Fractions K2-30EM, K1-10RM and K1-30RM were related to rhamnogalacturonan type I with a branched arabinan and galactan side-chains. This arabinan has (1 → 5)-linked α-l-arabinofuranosyl units substituted exclusively in O-3. The main differences between these fractions were their molecular mass and content of Rha and GalA, which probably arise from an increase in their rhamnogalacturonan backbone. A pool of these polysaccharides (arabinan and arabinan-rich pectic polysaccharides) showed gastroprotective activity on ethanol-induced acute gastric lesions in rats.     

Characterisation of polysaccharides from green tea of Huangshan Maofeng with antioxidant and hepatoprotective effects

This study was to examine the hepatoprotective effects of polysaccharides from green tea of Huangshan Maofeng (HMTP) against CCl₄-induced oxidative damage in mice. HMTP is an acidic heteropolysaccharide with galactose (35.0%, mol.%), arabinose (28.9%) and galacturonic acid (11.3%) being the main monosaccharide components. HMTP (400 and 800 mg/kg·bw) administered orally daily for 14 days before CCl₄ administration significantly reduced the impact of CCl₄ toxicity on the serum markers of liver damage, alanine aminotransferase, aspartate aminotransferase, total-cholesterol and triglycerides. This method of HMTP administration also markedly restrained hepatic lipid peroxidation formation of malondialdehyde and 15-F_2t isoprostanes, and elevated the antioxidant levels of hepatic glutathione and superoxide dismutase. These results together with liver histopathology indicated that HMTP exhibited hepatoprotection against CCl₄-induced injury, which was found to be comparable to that of biphenyldicarboxylate. The hepatoprotective effects of HMTP may be due to both the inhibition of lipid peroxidation and the increase of antioxidant activity.     

Characterisation of the antioxidant activity of flavonoids

Inhibition of the superoxide anion (O₂⁻) generation catalysed by xanthine oxidase using certain flavonoids was examined to determine their antioxidant effects. All of the flavonoids and their glycosides, except for kaempferol-3-glucoside, considerably and markedly inhibited O₂⁻ generation. Flavonoids also inhibited uric acid formation, whereas their glycosides did not. The flavonoids and their glycosides with scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl radical had more than one conjugated en-diol group and exhibited more potent inhibition of the O₂⁻ generation than the uric acid formation catalysed by xanthine oxidase. The results show that the inhibition of O₂⁻ generation with flavonoids without any conjugated en-diol group was due to competitive inhibition of uric acid formation, while the inhibition with flavonoids having more than one conjugated en-diol group was due to the reduced form of the enzyme.     

Chemical composition and antioxidant activity of the essential oil of Clinopodium vulgare L.

This study was designed to examine the chemical composition and in vitro antioxidant activity of the essential oil of Clinopodium vulgare. GC–MS analysis of the oil resulted in the identification of 40 compounds, representing 99.4% of the oil; thymol (38.9%), γ-terpinene (29.6%) and p-cymene (9.1%) were the main components. The samples were subjected to a screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene-linoleic acid assays. In the first case, IC₅₀ value of the C. vulgare essential oil was determined as 63.0 ± 2.71 μg/ml. IC₅₀ value of thymol and γ-terpinene, the major compounds of the oil, was determined as 161 ± 1.3 μg/ml and 122 ± 2.5 μg/ml, respectively, whereas p-cymene did not show antioxidant activity. In β-carotene-linoleic acid system, C. vulgare essential oil exhibited 52.3 ± 1.19% inhibition against linoleic acid oxidation. In both systems, antioxidant capacities of BHT, curcumine and ascorbic acid were also determined in parallel experiments.     

Studies on the antioxidant potential of flavones of Allium vineale isolated from its water-soluble fraction

The aim of this work was to examine the chemical constituents and antioxidant potential of water-soluble fractions from the commonly consumed vegetable, Allium vineale. The water-soluble fraction, containing phenolic compounds, was extracted with ethyl acetate to obtain flavonoids which were separated and purified by repeated column chromatography over Sephadex LH-20, RP C18 and silica gel. The isolated compounds were identified according to their physicochemical properties and spectral data (UV, HPLC–TOF/MS, ¹H NMR, ¹³C NMR and 2D NMR). Three flavonoids were isolated and identified as chrysoeriol-7-O-[2″-O-E-feruloyl]-β-d-glucoside (1), chrysoeriol (2), and isorhamnetin-3-β-d-glucoside (3). Antioxidant studies of the aqueous extract and three isolated compounds, 1, 2, 3, were undertaken and they were found to have significant antioxidant activity. Antioxidant activities were evaluated for total antioxidant activity by the ferric thiocyanate method, ferric ion (Fe³⁺) reducing antioxidant power assay (FRAP), ferrous ion (Fe²⁺) metal chelating activity, and DPPH free radical-scavenging activity. The water-soluble ethyl acetate and methanol extraction methods were also compared using HPLC–TOF/MS.     

Enhanced antioxidant activity of Monascuspilosus fermented products by addition of ginger to the medium

The fermented products of Monascus sp. are known for their antihypercholesterolaemic effects, however, their antioxidant activities are different from those of many plant-derived foods. To evaluate the effect of ginger addition into the medium on the antioxidant activity of Monascuspilosus fermented products, we cultured uninoculated PDB medium (PDB), inoculated PDB medium (MP), uninoculated ginger-containing medium (PDBG), and inoculated ginger-containing medium (MPG). The broth and mycelia were collected, freeze-dried, and extracted to evaluate their free radical scavenging activities, inhibition of peroxidation, phenolic content, inhibition of DNA damage, cellular antioxidant activity, and expression of the antioxidant enzymes. The results showed that MPG had significantly higher antioxidant activity than PDB, MP, and PDBG at all fermentation time points. Moreover, the fermentation process significantly increased the antioxidant activities of MPG. After the inherent level of antioxidant capacity was increased, the modified M. pilosus fermented product demonstrated a higher anti-atherosclerotic value than the unmodified product.     

Solvent-free microwave extraction of essential oil from Dryopteris fragrans and evaluation of antioxidant activity

Solvent-free microwave extraction (SFME) of the essential oil from Dryopteris fragrans and its antioxidant activity were investigated. A central composite design combined with response surface methodology was applied to study the influences of extraction time, irradiation power and humidity (proportion of water pretreatment). A maximal extraction yield of 0.33% was achieved under optimal conditions of extraction time 34 min, irradiation power 520 W and humidity 51%. Sixteen compounds, representing 89.65% of the oil, were identified, of which the major ones, (1R,4S,11R)-4,6,6,11-tetramethyltricyclo[5.4.0.0(4,8)]undecan-1-ol (30.49%), 1R,4S,7S,11R-2,2,4,8-tetramethyltricyclo[5.3.1.0(4,11)]undec-8-ene (22.91%) and, 1,4,4a,5,6,7,8,8a-octahydro-2,5,5,8a-tetramethyl-1-naphthalenemethanol (15.11%), accounted for 68.51% of the oil. The antioxidant activity of the essential oil was assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH), β-carotene/linoleic acid, and reducing power assay, the IC₅₀ values were 0.19, 0.09 and 0.18 mg/mL, respectively. All these results suggest that SFME represents an excellent alternative protocol for production of essential oils from plant materials.     

Flavonols, betacyanins content and antioxidant activity of cactus Opuntia macrorhiza fruits

Flavonols, betacyanins content and antioxidant activity of red-purple cactus Opuntia macrorhiza fruits, a promising cactus pear species, were evaluated in comparison to the well known cactus pear fruits of Opuntia ficus-indica. Flavonol profile was evaluated by HPLC-DAD prior to and after enzymatic hydrolysis (glycosides vs. aglycons). In addition betacyanins, responsible for the purple to red color of cactus pear fruits were also estimated and compared to Beta vulgaris ssp. (roots) and red O. ficus-indica fruits. In all cases, cactus fruit pulps showed no flavonols at all. While different derivatives of isorhamnetin glycosides were found in O. ficus-indica fruit's peel, isorhamnetin-3-O-rutinoside was the only compound in O. macrorhiza fruit. Correspondingly, antioxidant activity assays showed a high antioxidant activity of both, O. macrorhiza fruit's peel and pulp. With regard to betacyanins, O. macrorhiza fruit's peel and pulp provide a deep red-purple color, whose average impact is higher compared to red beet (B. vulgaris spp.) and about 8-fold higher than red fruits from O. ficus-indica. Supporting these results, estimation of color attributes (L*, a*, b*, C and H°) showed also a high color impact of both O. macrorhiza fruit's peel and pulp.     

Identification and characterisation of anthocyanins in the antioxidant activity-containing fraction of Liriope platyphylla fruits

The objective of this study was to investigate antioxidant activities and anthocyanin profiles in the fruits of Liriope platyphylla, where these are considered functional substances in Korea. The acidic methanol extract of this species exhibited potent antioxidant activities, showing 83.9% DPPH scavenging activity and 92.5% ABTS scavenging activity at a concentration of 0.5 mg/ml. Moreover, anthocyanins were identified by reversed-phase C₁₈ column chromatography, NMR spectroscopy, and HPLC-DAD-ESI/MS analysis. Seven anthocyanins were characterised, including delphinidin-3-O-glucoside (1), delphinidin-3-O-rutinoside (2), cyanidin-3-O-glucoside (3), petunidin-3-O-glucoside (4), petunidin-3-O-rutinoside (5), malvidin-3-O-glucoside (6), and malvidin-3-O-rutinoside (7). Among these, petunidin-3-O-rutinoside (5) (7302.2 μg/g) and malvidin-3-O-rutinoside (7) (5776.1 μg/g) were the predominant anthocyanins, whereas the least prevalent anthocyanin was found to be cyanidin-3-O-glucoside (3) (64.9 μg/g). Therefore, our results suggest that strong antioxidant activities of the acidic methanol extract of L. platyphylla fruits are correlated with high anthocyanin contents, particularly the petunidin-3-O-rutinoside (5) and malvidin-3-O-rutinoside (7).     

Purification,composition analysis and antioxidant activity of a polysaccharide from the fruiting bodies of Ganoderma atrum

A water-soluble protein-bound polysaccharide was extracted from the fruiting bodies of Ganoderma atrum and isolated by gel-filtration chromatography. Its primary structural features and molecular weight were characterized by infrared spectrometry, gas chromatography, size exclusion chromatography, amino acid analyzer and high-performance liquid chromatography (HPLC). The data obtained indicated that the glycoprotein contains 10.1% of protein and 17 general amino acids and it is rich in glutamic acid, asparagic acid, alanine, glycine, threonine, and serine. It was mainly composed of mannose, galactose and glucose in a molar ratio of 1:1.28:4.91, with an average molecular weight of about 1013 kDa. The existence of an O-glycosidic linkage in PSG-1 (polysaccharide1) was demonstrated by a β-elimination reaction. The antioxidant activity of the purified polysaccharides was evaluated in vitro by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay, self-oxidation of 1,2,3-phentriol assay. Those various antioxidant activities were compared to standard antioxidants vitamin C and BHT. It was found that the scavenging effects of the purified polysaccharides increased with measuring concentration. The results indicated that the purified polysaccharides showed strong DPPH free radical and superoxide anion radical scavenging activities. This study suggested that the purified polysaccharides could potentially be used as natural antioxidants.