Armando Silvestre

The wood and bark of four Acacia species growing in Portugal, namely, A. longifolia, A. dealbata, A. melanoxylon, and A. retinodes, were investigated for their sterol content. The lipids fractions of the different wood and bark samples were isolated, and the sterols were identified and quantified by GC-MS. Two delta7 sterols, specifically, spinasterol and dihydrospinasterol, were the main sterols found in considerable amounts, particularly in wood tissues (more than 0.5 g/kg of dry wood in the case of A. melanoxylon and A. retinodes). The corresponding unusual steryl glucosides were also identified in significant amounts in the wood and bark extracts.

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The use of trichloroacetyl isocyanate (TAI) to mark both hydroxyl and carboxyl groups borne by the hydrolysis or methanolysis of suberin fragments (a complex mixture of hydroxy fatty acids), allowed the quantitative assessment of the ratio between carboxyl and hydroxy groups, as well as the ratio between primary and secondary hydroxy groups, to be carried out reliably by 1H nuclear magnetic resonance (NMR) spectroscopy. All the samples thus analyzed displayed an excess of CO2H (or CO2CH3) functions with respect to the OH counterparts, albeit to a variable extent, depending on the procedure adopted to isolate the suberin fragments. The precise knowledge of the molar ratio of these two reactive moieties is fundamental for the correct utilization of suberin monomers in polymerization reactions leading to aliphatic polyesters.

The chemical composition of the epicuticular wax from the fruits of Eucalyptus globulus was studied by GC-MS before and after alkaline hydrolysis. The wax had two main components, ursolic acid and tritriacontan-16,18-dione, together with several other triterpenic acids. After alkaline hydrolysis, a large increase in the amounts of triterpenic acids and fatty acids (particularly in hexadecanoic acid) was observed, suggesting that these components were present predominantly in esterified forms in the fruit wax. Six compounds were isolated from the fruits by preparative chromatography, and were identified as 8-desmethyleucalyptin, sesamin, tritriacontan-16,18-dione, ursolic acid, 3beta-hydroxyurs-11-en-13beta(28)-olide (ursolic acid lactone) and 3beta,11alpha-dihydroxyurs-12-en-28-oic acid, the latter of which was identified for the first time.

To explore proper extractive solvents and to design an optimized separation process it is highly imperative to understand the molecular-based phenomena governing the solutes partitioning. Moreover, the development of new techniques for the biomolecules separation and purification, while maintaining their functional characteristics unchanged, is still ongoing. Therefore, in this work, the partition coefficients of vanillin, a compound with well-known organoleptic

... Andreia F. Sousa, Paula CRO Pinto, Armando JD Silvestre, Carlos Pascoal Neto CICECO and Department of Chemistry, University of Aveiro, 3810-193 Aveiro ... 27. Pelillo, M.; Iafelice, G.; Marconi, E.; Caboni, MF Rap. ... Cordeiro N.; Belgacem MN; Gandini A.; Pascoal Neto C. Ind. ...

... SILVESTRE AJD (1) ; PEREIRA CCL (1) ; NETO C. Pascoal (1) ; EVTUGUIN DV (1) ; CAVALEIROJAS (1) ; ... La liqueur noire de la cuisson de E.globulus a ??t?? extraite de fa??on s??quentielle avec de l'??ther ??thylique ?? des pH de 12, 7 et 2, suivi d'ac??tate d'??thyle ?? un pH de 2. Un ...

This study investigates the effect of pulping time and process parameters on the content of hexenuronic acid (HexA) in Eucalyptus globulus kraft pulps. Under selected standard pulping conditions, the amount of HexA in pulps increases during cooking. This behavior, significantly ...

Acylation of cellulose fibers with fatty acids constitute an interesting way to produce biodegradable plastics,4 as well as to obtain reinforcing materials for composites with common polymeric matrices5 like polyethylene. The cellulose modification reactions can be performed in ...

ABSTRACT The essential oil of Artemisia campestris L. subsp. maritima Arcangelis was studied. The sesquiterpene alcohol cadin-4-en-7-ol, one of the most abundant compounds in the oil, was isolated and exhaustively characterised by NMR techniques.

The structural features of the lignin of bark and core of kenaf has been investigated using nitrobenzene and permanganate oxidation quantitative C-13 NMR and chemical analysis. Significant differences were observed for the relative proportions of G and S units. relative proportions of functional groups, degree of condensation, type and frequency of interunit linkages and for the phenolic acids content of bark and core lignins. These results have implications on the rational utilization of bark and core fractions. and should be considered in the planification of new strategies for the chemical processing of kenaf.

Several samples of MWL and dioxane lignins from different morphological regions and stages of maturity of kenaf were isolated and characterised by different techniques. The results obtained show variations in functional and structural composition of lignins from older and younger parts of kenaf. Thus, the number of phenolic and carboxyl groups is higher in the older parts of the core, decreasing in younger parts. In the bark, the number of methoxyl groups and beta-O-4 linkages without a carbonyl group in the alpha position, increases in younger parts. In bark lignin the contents of CH2 and CH3 in saturated aliphatic chains is higher in younger parts and is strongly dependent of the maturity stage. The sugars composition and the carbonyl group contents of lignin samples depend mainly on the morphological regions. The molecular weight of core lignin is lower than the bark one.

Supercritical fluid extraction (SFE) has been a widely studied green technology to obtain oil and bioactive compounds from grape residues like seed, skin, pomace (marc). In this chapter, research advances regarding the SFE of grape residues are covered, particularly the optimization of operating conditions, modeling, scale-up and preliminary economic evaluation. Carbon dioxide is the most common solvent adopted for extraction, being generally modified with small amounts of cosolvents (e.g. ethanol) in order to enhance the solubility of the target compounds. The operating conditions found lie between 100 and 700 bar, 35ºC and 80ºC, 0 and 40% (v/v) of cosolvent. The existence of patents protecting the use of SFE technology upon grape residues is an acknowledgement of its suitability for food and drink industries, at least from the point of view of bulk extraction. The state-of-art concerning SFE of grape residues fully supports the commercial exploitation of this technological solutio...

Supercritical fluid extraction has been increasingly investigated in food, pharmaceutical, cosmetic and additives fields, since its green character highly suits biorefinery and sustainable challenges. In this context, the valorization of waste and side vegetable products is specifically addressed here, with emphasis on combined and hybrid supercritical extraction technologies. Matrix pretreatments like milling, sonication, enzymatic hydrolysis, and high-pressure carbon dioxide explosion processes are reviewed. The selection of operating conditions and cosolvents, along with their optimization and phenomenological and statistical modeling are also addressed.

The phenolic fraction of cork from Quercus suber L. was obtained following two distinct fractionation schemes, namely methanol/water extraction followed by ethyl ether fractionation and sequential extraction with methanol and water. The extracts were studied in terms of total phenolics content, using Folin-Ciocalteu method, detailed chemical analysis by HPLC–MS, and antioxidant activity. The first method underestimates both total extractives, total phenolics as well as the amounts of identified compounds. The HPLC–MS, revealed that, apart from smaller components, all the extracts displayed the same qualitative composition; 15 phenolic components were identified, with ellagic acid, followed by gallic and protocatechuic acids as the most abundant compounds. Additionally some compounds identified were reported for the first time as cork components, namely salicylic acid, eriodictyol, naringenin, quinic acid and hydroxyphenyllactic acid. The antioxidant activity of the extracts, evaluat...

The lipophilic composition of wild Arbutus unedo L. berries, collected from six locations in Penacova (center of Portugal), as well as some general chemical parameters, namely total soluble solids, pH, titratable acidity, total phenolic content and antioxidant activity was studied in detail to better understand its potential as a source of bioactive compounds. The chemical composition of the lipophilic extracts, focused on the fatty acids, triterpenoids, sterols, long chain aliphatic alcohols and tocopherols, was investigated by gas chromatography-mass spectrometry (GC-MS) analysis of the dichloromethane extracts. The lipophilic extractives of the ripe A. unedo berries ranged from 0.72% to 1.66% (w/w of dry weight), and consisted mainly of triterpenoids, fatty acids and sterols. Minor amounts of long chain aliphatic alcohols and tocopherols were also identified. Forty-one compounds were identified and among these, ursolic acid, lupeol, α-amyrin, linoleic and α-linolenic acids, and β...

ABSTRACT The chemical composition of the lipophilic extracts of three Portuguese elderberries cultivars belonging to the Sambucus nigra L. species (‘Bastardeira’, ‘Sabugueira’ and ‘Sabugueiro’), was studied by gas chromatography–mass spectrometry. The influence of the harvesting season (2012 and 2013), cultivar and the ripening stage was evaluated. Regarding the amount of lipophilic extractives, they ranged from 0.56% to 1.84% of the dry weight. The major chemical families present in these fractions were triterpenoids and fatty acids accounting with 84.9–93.8% and 4.3–11.4% of the total amount of lipophilic components, respectively. The most abundant compounds, identified as elderberries components were ursolic and oleanolic acids, followed by smaller amounts of long chain aliphatic alcohols and sterols. During ripening, a similar profile of the studied chemical families was found for the two sampling seasons and the three cultivars, with an initial growth of their content followed by a systematic decrease until maturity, yet, a higher lipophilic content (p < 0.05) is reported for the 2013 harvest. Regarding mature elderberries, ‘Sabugueira’ and ‘Bastardeira’ showed higher contents of lipophilics, and particularly of triterpenic acids (p < 0.05), for the two sampling years. In-depth study of elderberries, lipophilic extractives can contribute to the valuation of this natural product, being in this study highlighted the profile of these bioactive compounds, as well, the parameters that affect their content. Additionally, since considerable amounts of unripe and overripe elderberries are produced on harvesting, and that our results showed considerable amounts of lipophilics for both ripening stages, this highlights that these wastes can be seen as a promising sources for the preparation of lipophilic extracts enriched in bioactive compounds.

International Journal of Agricultural Research 1 (5): 471-479, 2006 ISSN 1816-4897 © 2006 Academic Journals Inc., USA Composition and ... were also submitted to antibacterial activity tests against three Gram positive bacteria namely Bacillus mbtilis CECT 498, Bacillus cereus ...