Papers by Marcello Iacomini
Extraction and characterization of pectins from primary cell walls of edible açaí (Euterpe oleraceae) berries, fruits of a monocotyledon palm
Carbohydrate Polymers, Feb 1, 2017
Açaí berries (Euterpe oleracea) are greatly consumed in Brazil and exported to other countries as... more Açaí berries (Euterpe oleracea) are greatly consumed in Brazil and exported to other countries as a nutritional supplement, due to health benefits attributed to its consumption. However, the complete chemical structure of bioactive polysaccharides was not fully elucidated yet. In this work, we characterize pectic polysaccharides from açaí berries through monosaccharide composition, HPSEC, methylation and (13)C and (1)H/(13)C HSQC-DEPT-NMR analyses. A highly methoxylated homogalacturonan with a DM of 88% and Mw of 22kDa together with small amounts of a mannoglucan were found. Moreover, a type II arabinogalactan (Mw=45kDa) containing a backbone with high portions of 6-O-linked and 3,6-O-linked Galp chains rather than 3-O-linked Galp was also isolated and structurally characterized. The type II arabinogalactan was found as a side chain of a type I rhamnogalacturonan. These findings contribute to correlate the fine chemical structure with the previously reported action of açaí polysaccharides on innate immune response. Moreover, from the taxonomic point of view, the results bring new information about polysaccharide composition of primary cell walls of palms (Arecaceae), that despite being commelinid monocots, have a distinct cell wall composition.
A comparative study of mucilage and pulp polysaccharides from tamarillo fruit (Solanum betaceum Cav.)
Plant Physiology and Biochemistry, Jul 1, 2016
A comparative study of mucilage (locular tissue) and pulp polysaccharides from ripe tamarillo fru... more A comparative study of mucilage (locular tissue) and pulp polysaccharides from ripe tamarillo fruits (Solanum betaceum Cav.) was carried out. After aqueous and alkaline extractions and various purification steps (freeze-thaw and α-amylase - EC 3.2.1.1 treatments, Fehling precipitation and ultrafiltration through 50 kDa cut-off membrane), the obtained fractions from mucilage were analyzed by sugar composition, HPSEC, and NMR spectroscopy analyses. The results showed that the mucilage of tamarillo contains a highly methoxylated homogalacturonans mixed with type I arabinogalactans, a linear (1 → 5)-linked α-L-arabinan, and a linear (1 → 4)-β-D-xylan. A comparison with polysaccharides extracted from the pulp revealed that differences were observed in the yield and in the ratio of extracted polysaccharides. Moreover, structural differences between pulp and mucilage polysaccharides were also observed, such as in the length of side chains of the pectins, and in the degree of branching of the xylans.
A gel-forming β-glucan isolated from the fruit bodies of the edible mushroom Pleurotus florida
Carbohydrate Research, Jul 1, 2008
Glucans of basidiomycetes are considered to be an important class of polysaccharides, as they can... more Glucans of basidiomycetes are considered to be an important class of polysaccharides, as they can act as biological response modifiers. We now isolate a gel-forming, water-soluble beta-glucan, with a molecular mass of 1.2 x 10(6)g/mol (HPSEC), from the fruit bodies of the edible mushroom Pleurotus florida, via alkaline extraction, followed by fractionation by freeze-thawing. Structural assignments were carried out using mono- and bi-dimensional nuclear magnetic resonance spectroscopy, monosaccharide composition, methylation analyses, and a controlled Smith degradation. It was a branched beta-glucan, with a main chain of (1-->3)-linked-Glcp residues, substituted at O-6 by single-unit Glcp side chains, on average to every fourth residue of the backbone.
Carbohydrate Research, Jul 1, 2019
Guavira is a plant that belongs to Myrtaceae family, being widespread in the Brazilian Cerrado. I... more Guavira is a plant that belongs to Myrtaceae family, being widespread in the Brazilian Cerrado. In this study, pectic and hemicellulosic polysaccharides from guavira pomace, an agroindustry residue from pulp production, were structurally characterized using GPC, monosaccharide composition, methylation and NMR experiments. The absolute configurations of monosaccharides and the nature of uronic acids were attributed according to numerous data on the composition of related plant arabinogalactans and hemicelluloses present in the literature. An arabinan was purified, presenting Ara (85.0%), Rha (3.3%), Gal (7.7%) and GalA (4.0%). Mono and bidimensional NMR analyses of this arabinan demonstrated the presence of terminal β-L-Araf units, whose occurrence has been scarcely reported in the literature. Hemicellulosic fraction contained a glucuronoxylan, with α-D-GlcpA/4-O-methyl-α-D-GlcpA group linked to O-2 of a (1 → 4)-β-D-xylan, presenting one uronic acid residue for every six xylose units. These findings about guavira pomace polysaccharides could contribute to develop future nutraceutical and technological uses for this industrial waste.
Gastroprotective effect and chemical characterization of a polysaccharide fraction from leaves of Croton cajucara
International Journal of Biological Macromolecules, Feb 1, 2017
Croton cajucara Benth. is a tree from the Amazon Forest, where it is known as sacaca. Its leaves ... more 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.
Pectins from cashew apple fruit (Anacardium occidentale): Extraction and chemical characterization
Carbohydrate Research, Sep 1, 2019
The cashew tree (Anacardium occidentale) is a tropical evergreen tree largely cultivated in Brazi... more The cashew tree (Anacardium occidentale) is a tropical evergreen tree largely cultivated in Brazil, which produces the cashew apple, a peduncle rich in carbohydrates and considered an industrial waste of the nut production. Until now, there were no data available about the chemical structure of cell wall polysaccharides found in cashew apple. In this work, its pectic polysaccharides have been characterized through monosaccharide composition, HPSEC, methylation and 13C and 1H/13C HSQC-DEPT-NMR analyses. Highly methyl esterified homogalacturonan with a DE of 76% mixed with arabinogalactan were found. This latter was purified and presented a highly branched type II arabinogalactan (AG II) and small amounts of a type I rhamnogalacturonan in which the AG II could be anchored. These findings about the chemical structure of cashew apple pectins could contribute to develop future nutritional, biotechnological and pharmacological uses for this industrial waste from the cashew nut production.
Carbohydrate Polymers, Jun 1, 2019
Chamomile is one of most known species of medicinal plants. It has valuable pharmacological prope... more Chamomile is one of most known species of medicinal plants. It has valuable pharmacological properties that produce positive effects in many therapeutical uses. Some of these properties are attributed to the presence of secondary metabolites but is already known that primary metabolites can also produce positive effects. In this study we elucidate the fine chemical structure of polysaccharides present in the infusion of chamomile flower chapters. After ethanolic precipitation, polysaccharides were obtained from the tea (fraction MRW, 3.2% yield), purified and characterized as an inulin type fructan, a highly methyl esterified and acetylated homogalacturonan (DE = 87% and DA = 19%), and a type II arabinogalactan. From ethanolic supernatant (20.2% yield), fructooligosaccharides (FOS) ranging from GF2 (m/z 543) to GF10 (m/z 1839) were detected. Inulin and FOS are well-established prebiotics, as well as the pectic polysaccharides. Thus, chamomile could be a source of structurally diverse dietary fibers with potential prebiotic, gastrointestinal and immunological functions.
Carbohydrate Polymers, Sep 1, 2017
Polysaccharides were extracted from sweet pepper (Capsicum annum) with hot water and named ANW (9... more Polysaccharides were extracted from sweet pepper (Capsicum annum) with hot water and named ANW (9% yield). Starch was precipitated by freeze-thaw treatment, while pectic polysaccharides (8% yield) remained soluble and consisted of GalA (67.0%), Rha (1.6%), Ara (6.4%), Xyl (0.3%), Gal (6.7%) and Glc (4.4%). A highly methoxylated homogalacturonan (HG, degree of methylesterification of 85% and degree of acetylation of 5%), and type I and type II arabinogalactans (AG-I and AG-II) were observed in NMR analyses. These were fractionated with Fehling's solution to give HG (5.5% yield) and AG fractions (0.6% yield). AG-I and AG-II were further separated by ultrafiltration. AG-II (0.2% yield) consisted of Ara (17.1%), Gal (36.0%), Rha (5.6%) and GalA (12.0%), had a molecular weight of 5.3 × 10 4 g/mol and methylation and 1 H/ 13 C HSQC-DEPT-NMR analyses showed that it was anchored in type I rhamnogalacturonan. This is the first study that reports the presence of AG-I and AG-II in sweet pepper fruits.
Carbohydrate Polymers, 2012
For many years mushrooms have been consumed and appreciated by their nutritional value, and medic... more For many years mushrooms have been consumed and appreciated by their nutritional value, and medicinal properties. The traditional mushroom cultivation takes too long and the macrofungi biotechnology has not been explored in its full potential yet. The goal of this work was to observe if different carbon sources could improve the yield and diversify fungi nutrient composition in submerged culture. Pleurotus pulmonarius mycelia and exopolysacharide productions were evaluated using glucose, galactose, xylose and arabinose. The mycelia yield varied depending on the culture medium, and galactose showed to be the best carbon source to produce EPS. Samples that showed the highest protein contents were grown with xylose (19.44%) and arabinose (26.05%). Furthermore, the biomass cultivated with these carbohydrates and with galactose showed five essential amino acids. All cultured biomass showed low lipid contents (∼1%), being composed mainly of unsaturated fatty acids. All EPS fractions showed as main structures glucans and mannogalactans.
Fems Microbiology Letters, Sep 1, 2004
A structural elucidation of polysaccharides extracted from the aposymbiotically cultured mycobion... more A structural elucidation of polysaccharides extracted from the aposymbiotically cultured mycobiont of the lichen Ramalina peruviana was carried out in order to determine whether the polysaccharides found previously in the symbiotic thalli are produced by the mycobiont or photobiont or both. The mycobiont isolate was cultivated on a solid malt-yeast extract-medium and the freezedried colonies were defatted and the polysaccharides extracted successively with hot water and aq. 2% KOH, each at 100 °C. The alkaline extract was obtained in much higher yield (31.5%) and submitted to a freeze-thawing treatment, giving rise to a precipitate (PK2) of a mixture of (1 ! 3),(1 ! 4)-a-glucan (1.2:1 ratio, nigeran) and a (1 ! 3)-b-glucan (laminaran). The mother liquor was treated with Fehling solution to give a precipitate (galactomannan). This had a (1 ! 6)-linked a-D D-mannopyranosyl main chain, substituted at O-4 and in small proportion at O-2,4 by b-Galp units. All three polysaccharides have previously been found in the symbiotic thalli of R. peruviana, showing that these are produced by the fungus, without the participation of the Trebouxia photobiont. Surprisingly, isolichenan, a cold-water soluble (1 ! 3),(1 ! 4)-a-linked-glucan (3:1 ratio) was not found in the isolated mycobiont, despite being the main polysaccharide found in the thalli.
Plant Physiology and Biochemistry, Sep 1, 2017
The polysaccharide compositions of primary and secondary cell walls of members of the family Arec... more The polysaccharide compositions of primary and secondary cell walls of members of the family Arecaceae in the commelinid clade of monocotyledonous plants have previously been found to be distinguishable from other commelinid families, and to be more similar to those of non-commelinids. However, few studies have been conducted. We aimed to extract and characterize the main cell-wall polysaccharides in the fruit pulp of tucumã (Astrocaryum aculeatum), a member of Arecaceae family. Hemicellulosic polysaccharides extracted by alkali from the fruit pulp were present in greater proportions (6.4% yield) than waterextracted ones (3.0% yield). Thus, the former was analyzed using monosaccharide composition, methylation, molecular weight determination and 13 C-NMR data. The tucumã alkaline extract presented a highly ramified acidic galactoarabinoxylan (53.7%), a linear (1→5)-linked α-L-arabinan (27.8%), a low branched glucuronoxylan (14.1%) and small portions of a xyloglucan (4.4%). The major polysaccharide found in A. aculeatum (acidic galactoarabinoxylan) is similar to those found in other commelinid plants such as grasses and cereals.
Bioactive Carbohydrates and Dietary Fibre, 2017
Depending on their chemical structure, pectic polymers may be fermented by different bacteria in ... more Depending on their chemical structure, pectic polymers may be fermented by different bacteria in the human gut and, therefore, display a different metabolite profile. We aimed to investigate the chemical structure of pectins from peach palm fruits and to evaluate their in vitro fecal fermentation profiles. A fraction (PW-AP) containing a linear highly methyl esterified homogalacturonan (degree of esterification of 70%) with minor portions of xylogalacturonan and type I rhamnogalacturonan was submitted to fermentation by the human gut microbiota. It produced significantly less gas than fructooligosaccharides (FOS) at all evaluated time points, and in 24 h presented a cumulative gas production ~27% lower than FOS. Drops in pH could be observed during fermentation of both FOS and PW-AP. Moreover, the pectin was slower fermented than FOS, though with a similar production of total short chain fatty acids (SCFA) and a lower production of branched chain fatty acids. The amounts of specific SCFA differed from that of FOS, with higher production of acetate (16.2%) and propionate (6.2%) and lower production butyrate (112%). The ratio of total SCFA production to gas production was 4.0 mL/µmol and 5.5 mL/µmol for FOS and PW-AP, respectively, indicating that the latter leads to less gas formation per µmol of produced SCFA. Overall, the understanding of how pectic structures are fermented brings new insights into the fiber utilization by the human gut microbiota and its relation to biological outcomes.
Carbohydrate Polymers, Aug 1, 2013
Cordyceps militaris dried fruiting bodies were extracted with 5% KOH solution. The extract was pu... more Cordyceps militaris dried fruiting bodies were extracted with 5% KOH solution. The extract was purified by freeze-thawing treatment, and dialysis (100 kDa), giving rise to a homogeneous polysaccharide (M w 23,000 Da). Its monosaccharide composition was mannose (56.7%), galactose (34.5%), and glucose (8.8%). The anomeric configurations were determined by their coupling constants. A complex polysaccharide was identified by NMR and methylation analysis. The HSQC spectrum showed signals at ı 107.7/5.06 and 106.1/5.14; 105.9/5.12 relative to -d-Galf, and O-2-substituted -d-Galf units, respectively. The sign at ı 104.4/5.21 corresponded to ␣-d-Galf. Other signals corresponded to ␣-d-Manp O-6-and O-2-substituted (ı 100.2/4.94; 100.5/5.27; 100.6/5.23; 100.7/5.16), and ␣-d-Manp 2,6-di-O-substituted (from ı 99.3 to 99.9). The main linkages, confirmed by methylation analysis, showed the derivatives: 2,3,4-Me 3 -Manp (11.9%) and 3,4,6-Me 3 -Manp (28.6%). The branches were (1 → 6)-linked-␣-d-Manp or (1 → 2)-linked-d-Galf, terminating with -d-Galf, ␣-d-Galf, ␣-d-Galp, or ␣-d-Manp. 42.7% of the partially hydrolyzed product consisted of 3,4,6-Me 3 -Manp, suggesting a (1 → 2)-linked backbone.
Structural characterization of a polysaccharide and a β-glucan isolated from the edible mushroom Flammulina velutipes
Phytochemistry, Oct 1, 2006
Two polysaccharides were isolated from the basidiomycete Flammulina velutipes, via successive hot... more Two polysaccharides were isolated from the basidiomycete Flammulina velutipes, via successive hot extraction with water, 2% and 25% aq. KOH, and then submitted to freeze-drying. The precipitate formed by repeated freeze-thawing from the 2% aq. KOH extraction PK2 was analyzed by determination of its monosaccharide composition, as well as by methylation analyses using GC-MS, mono- ((13)C, (1)H NMR) and bidimensional ((1)H (obs.), (13)C HMQC) spectroscopy, and controlled Smith degradations. It was established to be a branched beta-glucan, with a main chain of (1-->3)-linked-Glcp residues, substituted at O-6 by single-unit beta-Glcp side chains. The precipitate formed by repeated freeze-thawing from the 25% KOH extraction PK25 contained Xyl, Man, and Glc and was heterogeneous by HSPEC and extraction with DMSO gave a soluble xylomannan (XM). It was homogeneous with a molar mass 30.8 x 10(4)g/mol (dn/dc=0.186). Using the above chemical analyses, it was a xylomannan with Man and Xyl in a 3:2 molar ratio. Its main chain consisted of (1-->3)-linked alpha-Manp units, mainly substituted at O-4 by beta-Xylp units or with some beta-Xylp-(1-->3)-beta-Xylp groups.
International Journal of Biological Macromolecules, Feb 1, 2018
Syzygium jambos is an Indo-Malaian found in many tropical countries and it is mainly composed of ... more Syzygium jambos is an Indo-Malaian found in many tropical countries and it is mainly composed of carbohydrates. Fraction PF-WSP and SF-WSP were obtained by aqueous extraction followed by Fehling's treatment. Monosaccharide analysis showed that fraction PF-WSP has a high content of uronic acids (90%) and fraction SF-WSP presented mainly galactose (39.1%) and arabinose (34.2%), as neutral sugars and 9% of galacturonic acid. The presence of type II arabinogalactan in SF-WSP was evidenced by methylation analysis and 13 C/ 1 H HSQC NMR experiments. Immunomodulating properties of SF-WSP was investigated. It decreases THP-1 macrophage viability at the highest concentration tested (200 g/mL). We then tested non-cytotoxic concentrations of SF-WSP on THP-1 cytokine production in the presence and absence of LPS. The results showed that SF-WSP increased TNF-␣, IL-1 and IL-10 secretion in a concentration-dependent manner as well as attenuated the inflammatory response induced by LPS at the highest concentration (100 g/mL). These results contribute to elucidate the effects of fruit pectic polysaccharides on immune cells.
Phytochemical analysis and anti-inflammatory evaluation of compounds from an aqueous extract of Croton cajucara Benth
Journal of Pharmaceutical and Biomedical Analysis, Oct 1, 2017
Croton cajucara Benth. is a medicinal plant popularly used in the Brazilian Amazonia, where it is... more 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.
Journal of food science and nutrition therapy, Jun 2, 2017
Structural characteristics of dietary fi bers are closely related to its biological functions in ... more Structural characteristics of dietary fi bers are closely related to its biological functions in the human body. Previously, soluble dietary fi bers from prunes were extracted and characterized. In this work, structural analysis of insoluble dietary fi bers was conducted using monosaccharide composition, methylation, molecular weight determination and 13 C-NMR data. Prunes' non-cellulosic insoluble fi bers were found to contain, a pectic type I arabinogalactan, a fucogalactoxyloglucan and a heteroxylan. These fi ndings suggest that insoluble dietary fi bers can be composed by some pectic polysaccharides besides cellulose and hemicellulosic polymers. This paper brings important structural features of insoluble dietary fi bers from prunes that may be of biological signifi cance.
Carbohydrate Polymers, 2021
Polysaccharides from P. eryngii mushroom were selectively extracted using low-cost technologies (... more Polysaccharides from P. eryngii mushroom were selectively extracted using low-cost technologies (water at different conditions of temperature and pressure). Mannogalactan was the main polysaccharide in cold-water extracted fraction (CWEF), while a linear (1→6)-β-D-glucan was the main polymer in hot-water extracted fraction (HWEF). Autoclave-extracted fraction (AEF) contained a mixture of at least four different αand β-glucans. The report of linear (1→6)-β-glucan and linear (1→3)-β-glucan is a new finding for P. eryngii fruiting bodies. The immunostimulatory properties of the fractions on THP-1 macrophages were studied. All fractions at 50, 250 and 500 μg/mL were not cytotoxic and produced different stimulus on NO, IL-1β and IL-10 secretion by the cells. Thus, our results showed that it is possible to concentrate different P. eryngii polysaccharides in selected fractions using a simple and low-cost procedure. Since biological effects depends on the polysaccharide structure, this technique allows the obtainment of fractions with distinct immunomodulatory activities.
Naturally methylated mannogalactans from the edible mushrooms Pholiota nameko and Pleurotus eryngii
Journal of Food Composition and Analysis, 2021
Abstract This study reports the presence of mannogalactans in Pholiota nameko and Pleurotus eryng... more Abstract This study reports the presence of mannogalactans in Pholiota nameko and Pleurotus eryngii edible mushrooms, with their purification and detailed structural characterization. Two mannogalactans (R30PN and E30PN) were reported in P. nameko, differing mainly in their Mw (37.9 × 104 g/mol and 2.4 × 104 g/mol). The mannogalactans presented a linear (1→6)-α- d -galactan in the main chain, and single branches at O-2 by β- d -Manp as non-reducing end units. The main chain also contained naturally 3-O-methylated Galp units, in amounts that varied from 15.2–23.7 %. P. nameko mannogalactans were described for the first time. Heteropolysaccharides from mushrooms may display functional activities, like antitumor, anti-inflammatory and immunostimulatory which are related to their chemical structure. Thus, this study is of relevance since it unveils the structural details of two mannogalactans from P. nameko and one from P. eryngii mushrooms. Further studies are encouraged to verify how these structural differences may interfere in their biological activities.
Carbohydrate Polymers, 2020
Passion fruit peel (PFP) is a by-product from the fruit processing industry, accounting for appro... more Passion fruit peel (PFP) is a by-product from the fruit processing industry, accounting for approximately 50 % of the fruit weight. It is well known for its health properties, although few studies evaluated its rheological properties. PFP polysaccharides (PFPP) contain a high methoxyl pectin (HMP), specifically a 70 % methylesterified homogalacturonan. Flow behaviour analysis of PFPP (with or without sucrose) revealed a shearthinning non-Newtonian behaviour. Dynamic oscillatory tests showed a weak gel-like behaviour, even without sucrose addition. Moreover, under simulated pasteurization process PFPP maintained its gel structure. Taken together we demonstrated that PFPP has divergent behaviour from commercial HMP, since it does not require sucrose or low pH to form gel. The present work reinforces the use of PFP as a source of soluble dietary fibres and pectins, providing its alternative application as a rheological modifier in a wide range of products, including those with low sugar.
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Papers by Marcello Iacomini