Daniele Maria-Ferreira

Polysaccharides from prunes: Gastroprotective activity and structural elucidation of bioactive pectins

Prunes are the dried fruits from Prunus domestica. After the purification steps, two homogeneous polysaccharides were characterised, SF-50R and SF-50E and contained Ara:Gal:Rha:GalA in 47.8:31.5:10.7:10.0 and 39.6:50.3:5.1:5.0 molar ratios, respectively. Methylation analysis and (13)C NMR spectroscopy indicated that both fractions are constituted by rhamnogalacturonans with type I arabinogalactans as side chains, differing mainly in the proportions of the rhamnogalacturonan backbone, in the length of the (1→4)-β-galactan chain and in the proportion of the arabinan side chain. Crude water extract (PWH) and fraction SF-50E were evaluated for their gastroprotective properties against ethanol-induced acute gastric lesions in rats. Oral administration of PWH (3 and 10mg/kg) reduced the gastric lesion area by 67±11% and 60±12%, respectively, while fraction SF-50E (10 and 30mg/kg) inhibited the lesion area by 84±12% and 83±12%, respectively. These results indicated that prunes polysaccharides act as gastroprotective agents in rats.

Gastroprotective effect and structure of a rhamnogalacturonan from Acmella oleracea

The plant Acmella oleracea (L.) R.K.Jansen (Asteraceae), locally known as jambu, is widely used in Legal Amazon in local dishes and in folk medicine. A polysaccharide (SC) was isolated from this plant, following aqueous extraction, which contained uronic acid, galactose, arabinose, rhamnose, and glucose in a 15:2:1:1:0.5 molar ratio and had a M(w) 226,000 g/mol. Methylation analysis and NMR spectroscopy indicated that SC is a rhamnogalacturonan composed of a long chain of →4)-6-OMe-α-D-GalpA-(1→, interspersed with some α-L-Rhap residues, partly substituted by side-chains of type II arabinogalactans. SC significantly inhibited ethanol-induced gastric ulcers in rats with an ED₅₀ of 1.5 mg/kg, indicating that SC acts as gastroprotective agent.

Rhamnogalacturonan from Acmella oleracea (L.) R.K. Jansen: Gastroprotective and Ulcer Healing Properties in Rats

A rhamnogalacturonan (RGal) isolated from Acmella oleracea (L.) R.K. Jansen administered by oral route showed gastroprotective activity against acute lesions induced by ethanol. In this study, we investigated the gastric ulcer healing effect of RGal and its mechanisms of action. Intraperitoneal treatment of animals with RGal protected the gastric mucosa against acute lesions induced by ethanol, with participation of gastric mucus. Furthermore, in the chronic ulcer model, oral administration of RGal accelerates the gastric ulcer healing, accompanied by increasing of cellular proliferation and gastric mucus content, reducing inflammatory parameters and oxidative stress. In addition, the repeated 7 days-treatment of animals with RGal did not show alterations of clinical and behavioral symptoms, body and organs weights or plasmatic biochemical parameters. Collectively, these results showed that RGal has an interesting antiulcerogenic activity and could constitute an attractive molecule of interest for the development of new antiulcer agents.

Identification of a dicaffeoylquinic acid isomer from Arctium lappa with a potent anti-ulcer activity

Leaves of Arctium lappa contain several mono- and dicaffeoylquinic acids, as evaluated by liquid chromatography-mass spectrometry. In order to investigate the protection on gastric mucosa against ulcers, rats were treated with fractions from leaf extract prior to ethanol-induced ulcers. The original fraction obtained as ethanol soluble fraction from hot aqueous extract was able to protect de gastric mucosa, and this effect was retained in the ethyl acetate fraction, obtained from liquid/liquid fractionation. The main compound in this fraction was isolated and chemically characterized by nuclear magnetic resonance and mass spectrometry, assisted by isopropylidene derivatization which gave rise a mass increment of 40 units. Therefore, the underivatized compound that had m/z 515.119 [M-H](-) was shifted to m/z 555.151, being confirmed as 1,3-O-dicaffeoylquinic acid, which presented an ED50 of 57 µg kg(-1) on gastric protection, lesser than the therapeutic concentration of omeprazole (40 mg kg(-1)).

Chemical and biological characterization of polysaccharides isolated from Ilex paraguariensis A. St.-Hil.

The potential gastroprotection of polysaccharides (SP) isolated from maté (Ilex paraguariensis) leaves of different growth stages, under different sunlight conditions and of processing methods were evaluated. The SP consist of type I arabinogalactan (AG1) containing a (1→4)-linked β-Galp chain, with substituents of arabinosyl units at O-6. This arabinogalactan seems to be attached to rhamnosyl units from a RG1, via 1→4 linkage. Oral administration of SP1, SP9, SP10, SP11 and SP12 inhibited the gastric lesions induced by ethanol in rats. Altogether, the present data indicate the therapeutic role of maté polysaccharides against gastric lesion and propose its use or of its crude plant extract as a phytotherapic medicine.

Gastroprotective bio-guiding fractionation of hydro-alcoholic extracts from green- and black-teas (Camellia sinensis)

Hydro-alcoholic extracts from leaves of Camellia sinensis (green- and black-tea leaves) were submitted to a fractionation, promoting the compound separation according to their polarity, and analyzed by ultra-high performance liquid chromatography-mass spectrometry. A wide range of compounds could be identified, such as catechins and their gallate (esters) or oxidation derivatives (theaflavins), glycosylated flavonoids and other phenolics, as well as lipids, saponins and alkaloids. Also have been developed, via bio-guided examination, the gastroprotective property of the compounds identified. The samples were assayed using the model of acute gastric lesions induced in rats by ethanol. Hydro-alcoholic extracts of green-tea and black-tea protected the gastric mucosa with ED50=3.6 and 10.2mg/kg, respectively, with participation of gastric mucus and reduced glutathione (GSH). The ethyl acetate fraction from green-tea and aqueous fraction from black-tea were, respectively, 6 and 10 times more effectiveness than the initial extracts. Moreover, the epigallocatechin gallate (EGCG, 0.204mg/kg), a main component of ethyl acetate fraction from green tea, reduced the gastric lesion by 56% and restored the mucus levels, however the rutin (0.0133mg/kg), a flavonoid found in the most active fraction of black-tea, was less significant at the natural concentrations. These results have confirmed that the different compounds present in green- and black-tea hydro-alcoholic extracts and partitioned fractions produce relevant gastroprotection mainly via maintenance of the protective factors, mucus and GSH.

Glucuronoarabinoxylan from coconut palm gum exudate: Chemical structure and gastroprotective effect

A glucuronoarabinoxylan (CNAL) was extracted with 1% aq. KOH (25°C) from Cocos nucifera gum exudate. It had a homogeneous profile on HPSEC-MALLS-RI (Mw 4.6 × 10(4)g/mol) and was composed of Fuc, Ara, Xyl, GlcpA (and 4-O-GlcpA) in a 7:28:62:3 molar ratio. Methylation data showed a branched structure with 39% of non-reducing end units, 3-O-substituted Araf (8%), 3,4-di-O- (15%), 2,4-di-O- (5%) and 2,3,4-tri-O-substituted Xylp units (17%). The anomeric region of CNAL (13)C NMR spectrum contained 9 signals, indicating a complex structure. The main chain of CNAL was characterized by analysis of a Smith-degraded polysaccharide. Its (13)C NMR spectrum showed 5 main signals at δ 101.6, δ 75.5, δ 73.9, δ 72.5, and δ 63.1 that were attributed to C-1, C-4, C-3, C-2 and C-5 of (1→4)-linked β-Xylp-main chain units, respectively. CNAL exhibited gastroprotective effect, by reducing gastric hemorrhagic lesions, when orally administered (1 and 3mg/kg) to rats prior to ethanol administration.

Polysaccharides from Arctium lappa L.: Chemical structure and biological activity

The plant Arctium lappa L. is popularly used to relieve symptoms of inflammatory disorders. A crude polysaccharide fraction (SAA) resulting of aqueous extraction of A. lappa leaves showed a dose dependent anti-edematogenic activity on carrageenan-induced paw edema, which persisted for up to 48h. Sequential fractionation by ultrafiltration at 50kDa and 30kDa cut-off membranes yielded three fractions, namely RF50, RF30, and EF30. All these maintained the anti-edematogenic effect, but RF30 showed a more potent action, inhibiting 57% of the paw edema at a dose of 4.9mg/kg. The polysaccharide RF30 contained galacturonic acid, galactose, arabinose, rhamnose, glucose, and mannose in a 7:4:2:1:2:1 ratio and had a Mw of 91,000g/mol. Methylation analysis and NMR spectroscopy indicated that RF30 is mainly constituted by a type I rhamnogalacturonan branched by side chains of types I and II arabinogalactans, and arabinan.

Gastroprotective effect and chemical characterization of a polysaccharide fraction from leaves of Croton cajucara.

Croton cajucara Benth. is a tree from the Amazon Forest, where it is known as sacaca. Its leaves and barks are used in medicinal preparations to treat different diseases, including gastric ulcers. The crude polysaccharide fraction (CCP), obtained from the hot aqueous extract of C. cajucara leaves, was able to promote gastroprotection on an ethanol induced gastric ulcer model. Therefore, a bioguided fractionation was performed to isolate the active polysaccharide fraction. After freezing-thawing, ultrafiltration and dialyses at 100, 50, and 25kDa cut-off membranes, fraction 25R was obtained. It contained glucose, galactose, rhamnose, arabinose, galacturonic acid and mannose in a 7:5:5:3:1:1 molar ratio approximately, and had a Mw of 42,840g/mol. Methylation analysis and NMR spectroscopy indicated that 25R is a very complex polysaccharide fraction containing type I rhamnogalacturonan, arabinan, type I arabinogalactan, type II arabinogalactan, rhamnan, starch and mannan. It was able to reduce ethanol-induced gastric ulcers in rats, through preservation of mucus and GSH levels.

Phytochemical analysis and anti-inflammatory evaluation of compounds from an aqueous extract of Croton cajucara Benth.

Graphical abstract Figure. No Caption available. HighlightsSeveral different compounds were described for the first time in leaves of Croton cajucara.Liquid/liquid partitioning was able to separate compounds by polarity, enabling their analysis.A thorough investigation by mass spectrometry allowed identification of many unreported compounds.All fractions originating from liquid/liquid partitioning presented anti‐inflammatory activity. Abstract Croton cajucara Benth. is a medicinal plant popularly used in the Brazilian Amazonia, where it is known as sacaca, being consumed as tea, decoction or infusion of the leaves and stem bark. From a decoction of the leaves, a comprehensive phytochemical analysis was developed by liquid chromatography‐mass spectrometry. Many compounds were identified for the first time in C. cajucara, such as O‐glycosides of kaempferol and quercetin, flavonoid‐C‐glycosides, tannins and cinnamic acid derivatives. These compounds were fractionated by polarity and assayed for their anti‐inflammatory activity, using a model of mice edema, induced by an intraplantar injection of carrageenan. All fractions exhibited anti‐inflammatory properties.