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Lupane-type triterpenoids from Acacia dealbata bark extracted by different methods
Abstract
The management of invasive species generates large amounts of biomass which end up in low value applications. However, these residues can potentially contain compounds with important bioactive properties. In this study the bark of Acacia dealbata Link (Fabaceae) was extracted by different methods targeting triterpenoids content and bulk product. Batch solid-liquid extraction (SLE-batch), Soxhlet extraction (n-hexane, dichloromethane, ethyl acetate and ethanol) and supercritical fluid extraction (SFE) (CO2 with/without ethanol or ethyl acetate) were performed under different pressure and/or temperature conditions in order to assess total extraction yield (ηTotal), extract concentrations and yields of lupenyl acetate and lupenone. The extracts composition was analysed by gas chromatography coupled to mass spectroscopy. Summarily: (i) the highest values of ηTotal were achieved with ethanol by both Soxhlet and SLE-batch, and by SFE at 300 bar, 80 ⁰C with 5 wt.% ethanol; (ii) the highest concentrations of triterpenoids were obtained with n-hexane by Soxhlet and SLE-batch and, and by SFE at 200 bar, 40 °C with 5 wt.% ethyl acetate; (iii) the maximum individual yields were achieved with ethanol by both Soxhlet and SLE-batch, and by SFE at 200 bar, 40 °C with 5 wt.% ethyl acetate. The solubilities of lupenyl acetate, lupenone, tetracosanoic acid and hexacosan-1-ol in the various solvents were theoretically estimated, providing important insights for the interpretation of the experimental results.
... Several plants produce abundant glycosylated triterpenoids (with a sugar part in their structure), which are called saponins. When this occurs, ethanol is needed as a modifier during the supercritical CO 2 extraction because it increases the molecular weight and polarity, aiding to the extraction of saponins [31]. However, as in the present study the use of modifiers was not necessary, this would indicate that lupeol from lupin hulls is present in its aglycone form. ...
Extraction of lupeol from lupin hulls has been carried out using supercritical CO2 extraction technology under different operating conditions in order to obtain value-added extracts from the raw material of industrial lupin. The operational parameters used include CO2 pressure and flow and sequential depressurization fractionation. The highest lupeol recovery (96.8%) has been obtained using 320 bar and 50 g/min of CO2. For sequential depressurization, the best results were obtained with a CO2 density close to 728 kg/m³ providing up to 92% of lupeol in the extract and an enrichment factor of 1.2. Despite this high enrichment, lupeol recovery decreases to 50% after fractionation. Better extraction recoveries would have been expected and thus further studies are necessary to improve the extraction recovery of extracts with a high lupeol composition.
... The alternative extraction methods are relatively new but have been increasingly applied to lignocellulosic biomass and barks. Triterpenoids such as friedelin, lupenone, and betulin from bark are extractives that have been obtained with SFE methods [141][142][143][144][145][146][147][148][149][150]. ...
Bark-based biorefineries are estimated to become a trending topic in the coming years, particularly with their adsorbent applications and antioxidant production. While the potential benefits of bark-based biorefineries are well-recognized, it is not known how to develop a bark-based biorefinery considering different unit operations and the potential end products. The characterization and screening of different barks for chemical composition is the initial step in biorefinery development, along with the selection of the relevant conversion processes. This state-of-the-art review provides background knowledge on the pyrolysis and extraction studies of bark as the key conversion operations. The results of recent (2010–2022) bark pyrolysis and extraction studies were critically analyzed for process conditions, product properties, and product yields, as well as a discussion of energy-saving possibilities. A biorefinery scheme was proposed based on these data. The current knowledge gaps were identified and future directions were evaluated, which include the production of charcoals, platform chemicals, and extract profiling for specific applications. The results indicate that barks are particularly rich in hydrophilic extractives with potential antioxidant properties and pyrolysis operations, resulting in functional chars that may be used in value-added applications as adsorbent materials. A biorefinery scheme allows for the production of platform chemicals, antioxidant extracts and biochars from barks while contributing to the reduction of waste and environmental pollution.
... The highest efficiency in terms of the whole group of compounds can be achieved in higher pressure and temperature extraction conditions (300 bar and 80 • C, respectively), while higher specificity can be obtained at lower values of these parameters (200 bar and 40 • C) in the extraction of lupane-type triterpenoids from Acacia dealbata bark [144]. In contrast, the settings of 200 bar and 40 • C were sufficient to reach the maximal and individual (specificity) efficiency in the extraction of compounds from Pterodon spp. ...
This review describes the role of silicon (Si) in plants. Methods of silicon determination and speciation are also reported. The mechanisms of Si uptake by plants, silicon fractions in the soil, and the participation of flora and fauna in the Si cycle in terrestrial ecosystems have been overviewed. Plants of Fabaceae (especially Pisum sativum L. and Medicago sativa L.) and Poaceae (particularly Triticum aestivum L.) families with different Si accumulation capabilities were taken into consideration to describe the role of Si in the alleviation of the negative effects of biotic and abiotic stresses. The article focuses on sample preparation, which includes extraction methods and analytical techniques. The methods of isolation and the characterization of the Si-based biologically active compounds from plants have been overviewed. The antimicrobial properties and cytotoxic effects of known bioactive compounds obtained from pea, alfalfa, and wheat were also described.
Supercritical fluid (SCF) extraction has emerged as an effective and efficient method for separating important phytoconstituents. The extraction process is simple and environmentally friendly, generating minimal to no waste. This procedure offers various advantages over traditional extraction techniques. This chapter discusses the procedure, advantages, and different types of phytoconstituents isolated using supercritical fluids, with a preference for natural products.KeywordsSupercriticalExtractionPhytoconstituentsSolventCO2DissolveOilAlkaloidsFlavonoidsTerpenes
Current control methods for invasive alien plants (IAPs) have acceptable short-term outcomes but have proven to be unfeasible or unaffordable in the long-term or for large invaded areas. For these reasons, there is an urgent need to develop sustainable approaches to control or restrict the spread of aggressive IAPs. The use of waste derived from IAP control actions could contribute to motivating the long-term management and preservation of local biodiversity while promoting some economic returns for stakeholders. However, this strategy may raise some concerns that should be carefully addressed before its implementation. In this article, we summarize the most common methods to control IAPs, explaining their viability and limitations. We also compile the potential applications of IAP residues and discuss the risks and opportunities associated with this strategy.
Acacia dealbata Link. is an invasive species with a negative impact on forest production areas. Its removal generates large amounts of residues (biomass) that can be burned for energy production or extracted to obtain high-value compounds, such as triterpenoids of the lupane, ursane and oleanane families, with known bioactive properties. The extraction can be performed with conventional organic solvents or by supercritical fluid extraction (SFE) with CO2 which is a greener alternative. In this work, SFE of A. dealbata Link. leaves was studied in order to identify and optimize the SFE parameters (pressure: 200-300 bar; temperature: 313.15-353.15 K; and addition of ethyl acetate as cosolvent: 0-10 wt.%) that enhance productivity and selectivity towards specific triterpenoids. Even though Soxhlet extraction with dichloromethane provided higher total extraction yield (ηTotal = 3.8 wt.% versus 2.1-3.2 wt.%, for SFE), SFE surpassed Soxhlet results in terms of individual yields and concentrations of squalene, α-tocopherol, α-amyrone, β-amyrone, and lupenone. For these five compounds the SFE yield reached 0.8043 wt.% and the extract concentration reached 35.5 wt.% (15.1 % and 95.1 % higher than with Soxhlet extraction, respectively). Particular emphasis should be given to lupenone, with a maximum yield of 0.4748 wt.% and a concentration of 22.9 wt.% in the SFE extracts obtained at 250 bar, 313.15 K and no cosolvent (ethyl acetate). The optimum conditions of pressure, temperature and ethyl acetate content depended on the response. Productivity, ηTotal, was maximized by increasing all three factors to its maximum conditions. Temperature was one of the most impactful parameters on the individual triterpenoids SFE yields with lower temperatures enhancing the selectivity.
Portugal is a country with a territorial dimension of approximately 90,000 km². However, the forest occupies a prominent position, since it represents about 35% of the total area of the country. Portuguese people always had a very close connection with the forest, which has provided the necessary resources for the development of its communities. The geological substratum of continental Portugal is very old and may therefore have witnessed the evolution of its plants, from the early beginning to the present time, as well as all sort of historical and environmental landmarks such as glacial periods or mass extinctions. Also, from the perspective of human occupation, Portuguese territory was crossed by hunter-gatherer populations who, initially, were constantly moving and looking for sustenance, but at a later stage, chose to settle. This relationship between human populations and the forest is, thus, very old and demonstrates the interdependence between the subsistence of the populations and the resources exploitation. Currently, the main national economic groups are based on forest industries, which depend directly on the exploitation of the three dominant species, Eucalyptus globulus Labill., Pinus pinaster Aiton and Quercus suber L., demonstrating the human role in the development of the forest, motivated by the satisfaction of its needs. This work reviews the historical development of the forest in mainland Portugal, from geological times to the present, including the arrival of exotic species that later acquired invasive behaviors and now occupy significant areas of the national territory.
Acacia dealbata biomass, either from forest exploitation or from the management of invasive species, can be a strategic topic, namely as a source of high-value compounds. In this sense, the present study aimed at the detailed characterization of the lipophilic components of different morphological parts of A. dealbata and the evaluation of their cytotoxicity in cells representative of different mammals’ tissues. The chemical composition of lipophilic extracts from A. dealbata bark, wood and leaves was evaluated using gas chromatography-mass spectrometry (GC–MS). Terpenic compounds (representing 50.2%–68.4% of the total bark and leaves extracts, respectively) and sterols (60.5% of the total wood extract) were the main components of these extracts. Other constituents, such as fatty acids, long-chain aliphatic alcohols, monoglycerides, and aromatic compounds were also detected in the studied extracts. All the extracts showed low or no cytotoxicity in the different cells tested, demonstrating their safety profile and highlighting their potential to be used in nutraceutical or pharmaceutical applications. This study is therefore an important contribution to the valorization of A. dealbata, demonstrating the potential of this species as a source of high value lipophilic compounds.
Floral waste has been considered one of the major concerns, even for those that may have industrial applications, such as dyes or perfumes. In the present study, the possibility of using Acacia dealbata flowers’ extracts and respective fractions as bioactive agents was explored in vitro systems. A. dealbata flowers were extracted with ethanol and the solid residue was further processed with (i) a sequence of organic solvents and (ii) a sequence of greener stages (aqueous, acid and microwave hydrogravity extraction). Total extraction yield and phenolic content were analysed. Ethanolic extracts presented more than 25% phenolic content. Their antiradical activity was evidenced by 85% of the ABTS radical scavenging potency of Trolox. For selected extracts different biological properties, including antibrowning, antilipogenic, anti-inflammatory and cytotoxicity against tumoral cells, were also evaluated. Different extracts were protective against neutrophils oxidative burst and moderately cytotoxic against colon carcinoma HCT-116 and lung adenocarcinoma A549 cells. A multistage extraction process with green solvents was suitable for the production of extracts and fractions from A. dealbata flowers with interesting biological properties. Extracts with higher activities were selected for further assessment as solvents in bioactive hydrogels, observing a positive correlation between gels softening and extracts bioactivity features.
A study was made of the potential use of Acacia dealbata wood extracts as bio-protective agents. Initially, extracts were obtained from Acacia dealbata sapwood, heartwood and bark, and their antioxidant, antimicrobial and anti-quorum sensing activities were determined. Next, the decay resistance of Scots pine wood samples impregnated with these extracts was examined against the brown rot fungus, Coniophora puteana. The impregnation procedure was performed according to the ASTM D (1413) standard test method at two different concentrations, 3% and 5% by weight, using hot water and methanol as extraction solvents. The strongest antioxidant, antimicrobial and anti-quorum sensing activities were those of the bark extract. Hot water extraction led to lower performance than methanol extraction. According to EN 113 testing methods, the highest level of preservative effect against wood-decaying fungi was observed in the case of 5% methanol extract from the bark.
The objective of this study was to evaluate the tannin extraction potential taken from the bark of Acacia dealbata. This tannins were extracted with water at 90°C. An extraction yield of 17.2% solids with a Stiasny number of 82% was obtained from the bark extract of Acacia dealbata. The structure was studied by Fourier transform infrared spectroscopy (FTIR). The thermal behavior of tannins was studied by DSC and a glass- transition temperature (Tg) of 116,77°C was determined. The thermal stability of tannins was studied by TGA. At 196.91°C the decomposition is 3.7% and the maximum of the weight loss rate (DTG) of the degradation was 257.77°C. The curing with formaldehyde showed an exotherm reaction in the range of 100-120°C, which is similar to tannins of other species.
Background: In Europe, Acacia and Eucalyptus, originate large amounts of biomass, due to their need by industries and other biological control, that can be used to extract antimicrobial substances.
Materials and Methods: Foliar aqueous, ethanolic and methanolic extracts of Acacia baileyana (Cootamundra wattle), Acacia dealbata (silver wattle), Acacia melanoxylon (black wattle) and Eucalyptus nicholii (narrow-leaved black peppermint) were assessed for antimicrobial activity against Escherichia coli, Bacillus cereus, Candida albicans and Candida parapsilosis, using the disc diffusion method.
Results: Ethanolic extracts from A. baileyana and A. dealbata showed significant (P< 0.05) antimicrobial activity. Concerning the microbial species tested, differences were found in A. baileyana (P< 0.01) and E. nicholii (P< 0.0001) extracts. These two extracts were effective mostly against B. cereus, followed by C. parapsilosis. According to the antimicrobial activity classification, eucalypt and Cootamundra and silver wattles extracts (both water and ethanol) presented good efficacy against B. cereus, a food poisoning
agent, and moderate efficacy against the remaining microorganisms. E. coli, a Gram negative, exhibited low sensibility to all foliar extracts.
Conclusion: A. baileyana, E. nicholii and A. dealbata foliar biomass could be used to develop alternative substances in microbial control.
Jean-Claude Bradley's Legacy Dataset of Open Melting Points. 28,645 measurements including those found to be incorrect (marked as 'do not use'). csid corresponds to Chemspider ID.
The efficient methods for extracting phenolics from grape seeds have been of great interest to many investigators, due to the special health promoting and disease preventing effects of polyphenols. In this study, extractions were performed by using aqueous ethanol. The effects of single factors such as the concentration of ethanol, the ratio of liquid to solid (L/S), extraction temperature, extraction time, and number of extractions on the extraction efficiency were studied. Total phenol was measured by the Folin-Ciocalteu procedure to monitor the efficiency of the extraction under different experimental conditions. High pressure liquid chromatograph (HPLC) analysis was applied to identify and quantify some specific dimeric and trimeric phenolics in grape seeds. The concentration of ethanol and the extraction temperature showed the most significant impact on the yield of total phenolics. At room temperature, the extract with highest total phenolics was obtained with 50% ethanol. A higher extraction yield was obtained at higher temperature. When ethanol concentration and temperature were kept constant, 1.5 hr extraction time and liquid to solid ratio of 7.5:1 resulted in the best yield. In all cases, the phenolics extracted by first and second stage consisted of 90-97% of the total phenolics of the sum of the three stages. Therefore, two-stage extraction would be more cost efficient than three-stage extraction.
The purpose of this work was to determine the phenolic, flavonoid and alkaloid contents of the ethanol, methanol, acetone and hydroalcoholic crude extracts of Olea europaea, Acacia melanoxylon and Acacia dealbata. The Folin-Ciocalteu's method was used for the determination of total phenols, a colorimetric method with aluminum chloride was used in the determination of flavonoids and Dragendorff's reagent method was used to alkaloids estimation. The methods of DPPH (2,2-diphenyl-1-picrylhidrazil) and β-carotene bleaching test were used to assess the antioxidant activity of extracts. Moreover, the phenolic compounds present in the extracts were analyzed by RP-HPLC.
Eucalyptus bark contains significant amounts of triterpenoids with demonstrated bioactivity, namely triterpenic acids and their acetyl derivatives (ursolic, betulinic, oleanolic, betulonic, 3-acetylursolic, and 3-acetyloleanolic acids). In this work, the supercritical fluid extraction (SFE) of Eucalyptus globulus deciduous bark was carried out with pure and modified carbon dioxide to recover this fraction, and the results were compared with those obtained by Soxhlet extraction with dichloromethane. The effects of pressure (100–200 bar), co-solvent (ethanol) content (0, 5 and 8% wt), and multistep operation were studied in order to evaluate the applicability of SFE for their selective and efficient production. The individual extraction curves of the main families of compounds were measured, and the extracts analyzed by GC-MS. Results pointed out the influence of pressure and the important role played by the co-solvent. Ethanol can be used with advantage, since its effect is more important than increasing pressure by several tens of bar. At 160 bar and 40 °C, the introduction of 8% (wt) of ethanol greatly improves the yield of triterpenoids more than threefold.
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Aim The biophysical impacts of invasive Australian acacias and their effects on ecosystem services are explored and used to develop a framework for improved restoration practices.
Location South Africa, Portugal and Chile.
Methods A conceptual model of ecosystem responses to the increasing severity (density and duration) of invasions was developed from the literature and our knowledge of how these impacts affect options for restoration. Case studies are used to identify similarities and differences between three regions severely affected by invasions of Australian acacias: Acacia dealbata in Chile, Acacia longifolia in Portugal and Acacia saligna in South Africa.
Results Australian acacias have a wide range of impacts on ecosystems that increase with time and disturbance, transform ecosystems and alter and reduce ecosystem service delivery. A shared trait is the accumulation of massive seed banks, which enables them to become dominant after disturbances. Ecosystem trajectories and recovery potential suggest that there are important thresholds in ecosystem state and resilience. When these are crossed, options for restoration are radically altered; in many cases, autogenic (self-driven and self-sustaining) recovery to a pre-invasion condition is inhibited, necessitating active intervention to restore composition and function.
Main conclusions The conceptual model demonstrates the degree, nature and reversibility of ecosystem degradation and identifies key actions needed to restore ecosystems to desired states. Control and restoration operations, particularly active restoration, require substantial short- to medium-term investments, which can reduce losses of biodiversity and ecosystem services, and the costs to society in the long term. Increasing restoration effectiveness will require further research into linkages between impacts and restoration. This research should involve scientists, practitioners and managers engaged in invasive plant control and restoration programmes, together with society as both the investors in, and beneficiaries of, more effective restoration.
The species Himatanthus drasticus is popularly known in Northeast Brazil as "janaguba" and belongs to the family Apocynaceae. The latex collected from its stem bark is used for several purposes including anti-inflammatory properties and presents among its bioactive constituents the pentacyclic triterpene lupeol. The objective of the present work was to study in vivo and in vitro the lupeol acetate (LA) isolated from the plant latex, in several models of inflammation.
Male Swiss mice (25-30 g, 6-24 animals per group) were administered with LA, 30 min before the test initiation. In the evaluation of analgesic activity the formalin test was used. The anti-inflammatory activity was evaluated by the following tests: paw edema induced by carrageenan and dextran, and the carrageenan-induced neutrophil migration into peritoneal cavities. Furthermore, the effect of LA on the myeloperoxidase release (MPO, an inflammation biomarker) from human neutrophils was also determined, as well as its antioxidant potential by the DPPH assay.
In the formalin test, LA (10, 25 and 50 mg/kg, i.p.) inhibited both the 1st (neurogenic, 0-5 min) and mainly the 2nd (inflammatory, 20-25 min) phase. Naloxone completely reversed the LA effect, indicating the participation of the opioid system. LA also significantly inhibited carrageenan- and dextran-induced paw edemas, as well as the neutrophil migration to the peritoneal cavity evaluated by the carrageenan-induced pleurisia. In this model, the effect of a very low dose of LA (0.1 mg/kg) was potentiated by the same dose of pentoxifylline (PTX), a known TNF-alpha inhibitor. LA (25 and 50 μg/ml) was also very effective in inhibiting MPO released from stimulated human neutrophils, and significantly decreased the number of cells expressing iNOS activity in the paw of mice submitted to carrageenan-induced edema, suggesting a drug involvement with the NO system.
The anti-inflammatory effect of LA probably involves the opioid system, as indicated by the complete blockade of the opioid antagonist naloxone. Furthermore, the LA effect was potentiated by PTX (a TNF-alpha inhibitor). LA also decreased the number of iNOS cells, suggesting the participation of pro-inflammatory cytokines and the NO system in the drug action.
• We review current knowledge about the biology of the genus Acacia, and Acacia dealbata Link (silver wattle) in particular, as an invader in Europe, focusing on (i) the biology of the genus Acacia; (ii) biological attributes that are important for the invasiveness of the genus and A. dealbata; (iii) possible hypotheses for the invasion success; and (iv) control methods.
• Several Australian wattles have been recorded as naturalized in Europe. Acacia has attained pest proportions in certain habitats and protected sites (notably coastal dunes, river courses, natural parks and biosphere reserves).
• The spread of Acacia dealbata seems to be assisted by human interference such as soil disturbance and severe fires. The biological attributes favoring invasion by A. dealbata include tolerance of changing soil conditions, the ability to take advantage of environmental disturbance, phenotypic plasticity, vegetative reproduction, fire tolerance and allelopathic potential.
• Different hypotheses explaining invasiveness and transition between invasion steps related to biological attributes as the key factor for A. dealbata invasion are discussed. Effects on the biodiversity of native flora are little understood and studies of suppression of autochthonous species are needed. It is desirable that further studies comparing Acacia at field sites in their native and exotic range should be done.
• Understanding the biology of invasive wattles in Europe is the first step to an effective control method. Studies comparing plant invaders at field sites in their native and invaded areas seem to be most appropriate in order to be able to attack the most vulnerable stages.
This work addresses economic and process aspects of the supercritical fluid extraction (SFE) of Eucalyptus globulus bark at industrial scale. Broken plus intact cells (BIC) model was applied to existing data and new SFE curves were simulated. Then, statistical optimization was performed with Response Surface Methodology (RSM) involving of 5 factors (pressure, temperature, cosolvent content, solvent flow rate and extraction time), and four responses: Total Yield (ηTotal), Productivity, Cost of Manufacturing (COM) and Process Energy. The design and simulation of the industrial process (Aspen Plus® software) was performed including the employment of cosolvent in the system. The best COM scored 28.1 € kgextract⁻¹, where ηTotal was 0.84-0.96 wt.%, Productivity reached 311–362 tonextractyear⁻¹, and Process Energy scored 1.46– 2.10 GJ kgextract⁻¹. These results underline that SFE provides an extended margin for trade-offs, and arguments towards the integration of SFE technology to biorefine the bark of E. globulus in pulp mills.
There are a large number of new structure compounds with good pharmacological activity in the natural plants, can be applied to the treatment of human diseases. Finding active ingredients from the plants is one of the important ways to develop new drugs. Triterpenes are widespread in plants, and lupenone belongs to lupane type triterpenoids. Lupenone is very common natural ingredient distributed in multi-family plants including Asteraceae, Balanophoraceae, Cactaceae, Iridaceae, Musaceae, Urticaceae, Leguminosae, Bombacaceae, etc., but its distribution has no regular. The consumption of lupenone in vegetarian diet is high in human life. Pharmacological screening of lupenone revealed various pharmacological activities including anti-inflammatory, anti-virus, anti-diabetes, anti-cancer, improving Chagas disease without major toxicity. Based on these important pharmacological activities, this review provides detailed account of pre-clinical studies conducted to determine the utility of lupenone as a therapeutic and chemopreventive agent for the treatment of various diseases.
Extracts of Eucalyptus globulus leaves were produced and characterized aiming their enrichment in natural bioactive compounds such as triterpenic acids (TTAs). Soxhlet (methanol, ethanol and dichloromethane) and supercritical (CO2 with/without ethanol) extractions performed under different conditions were assessed by the total extraction yield, TTAs extraction yield, and extracts concentration, and the results were compared to published data for bark and/or leaves of other species. A fast and simple dewaxing pretreatment of the leaves was implemented and its influence on extract production was evaluated. The various extracts, the leaves and the pure TTAs were analyzed by Fourier Transform Infra-Red spectroscopy with Attenuated Total Reflectance (FTIR-ATR) and Gas Chromatography-Mass Spectroscopy (GC-MS), and the data thoroughly discussed by chemometric methods Overall, this work provides guidelines for the production of natural extracts enriched in triterpenic acids.
Supercritical fluid extraction of Eucalyptus globulus leaves was accomplished using carbon dioxide at different pressures (200, 250 and 300 bar) and ethanol contents (0.0, 2.5 and 5.0 wt%), with and without biomass pretreatment (grinding or dewaxing), with the objective to study total (ηTotal) and triterpenic acids (ηTTA) extraction yields. A factorial design of experiments and response surface methodology was performed to assess and optimize the impact of both operating conditions at 40 °C and 12 gCO2 min⁻¹. The best results were obtained for 250 bar and 5.0 wt% ethanol, for which ηTotal = 3.95% and ηTTA = 0.67%. Three kinetic extraction curves were measured and modeled, in order to quantify the influence of both biomass pretreatments, being concluded that grinding favors the total extraction yield while dewaxing enhances the TTAs concentration in the extract. The Broken plus Intact Cells model disclosed kinetic and structural differences between the three biomass samples (natural, ground and dewaxed leaves), being able to explain the distinct trends of the various removal curves.
Utilizing anodic synthesis, a kind of Kolbe reaction, 10 kinds of straight-chain fatty acids, besides those already reported, were synthesized. Electrolytic oxidation of phenylacetic acid and levulic acid respectively gave dibenzyl and 2, 7-octanedione. As an example of electrolytic oxidation, 1-naphthol was prepared from naphthalene. It was found that methanol used as the reaction solvent was also oxidized in this case to formaldehyde.
tThe supercritical fluid extraction (SFE) of Eucalyptus globulus deciduous bark is investigated, under thecontext of biorefinery, aiming at the definition of a pathway for the production of enriched extracts intriterpenic acids (TTAs). Scale-up studies are performed, well supported by modeling and by experimentscarried out at lab, intermediate and pilot scales (0.5, 5.0 and 80.0 L, respectively). By acknowledging thesignificant role played by cosolvent (ethanol) addition on the concentration of TTAs, extraction curvesare measured at 200 bar and 40◦C, using two different ethanol contents, 2.5% and 5.0% (wt). Takinginto account the results achieved by four distinct models, the intraparticle diffusion is confirmed as theprevailing mass transfer resistance in both conditions. Accordingly, the ratio between CO2flow rate andbiomass weight is adopted as scale-up criterion. Despite the geometric differences between the threeunits, the measured extraction yields and TTAs concentration evidence good agreement, which validatesthe established scale-up rule. In the whole, our results legitimate the technical viability of the SFE of E.globulus deciduous bark for future exploitation at larger scales.
Along more than a decade, R&D on supercritical fluid extraction (SFE) of vegetable matrices has been increasingly reported in the literature. Aiming at portraying the current state of this field and its evolution in terms of raw materials, products, modes of operation, optimization, modeling techniques, and closeness to industrial application, a large compilation of almost 600 essays from 2000 to 2013 has been deeply analyzed in order to unveil those indicators and their trends. Furthermore, strengths and weaknesses are identified, and some remarks that may drive upcoming research are provided. Globally, more than 300 species are reported in the literature, with prevalence of the extraction of seeds (28% of works) and leaves (17%). The main families of extracted compounds, cosolvents and operating conditions adopted are critically examined, being possible to conclude that researchers investigate many times working regions far from the optimum due to practical limitations or absence of experimental optimization. Current phenomenological, statistical and semi-empirical approaches are reviewed, along with scale-up studies, and economic analysis. In the whole, the most comprehensive picture over SFE of vegetable matrices is provided in this review, highlighting pertinent aspects and opportunities that may further consolidate the convincing route of this technology for the next years.
Volumetric properties of carbon dioxide, ethyl acetate and their binary mixtures containing 27.7, 42.6, 52.9 and 67.3% by mass CO2 have been determined over a temperature range from 295 to 380K for pure components, and from 295 to 340K for mixtures at pressures up to 32MPa.A new measurement methodology was employed in which a pressure-generator is used to alter the position of a movable piston while continually monitoring its position, thus the internal volume, with a computer-interfaced linear variable differential transformer (LVDT). The real-time recording of the internal volume permits generation of continuous density–pressure data which are correlated by smooth functions and used to determine the isothermal compressibility, the isobaric expansivity, the thermal pressure coefficient, and the excess volumes. The densities were observed to vary in the range from 0.60 to 0.98g/cm3 for carbon dioxide; from 0.80 to 0.92g/cm3 for ethyl acetate, and from 0.75 to 0.98g/cm3 for the mixtures. Depending upon the temperature and pressure, the compressibility values were in the range 0.002–0.04MPa−1 for CO2, and 1.0–2.3×10−3MPa−1 for ethyl acetate. The expansivity values were in the range 3.7–11×10−3K−1 for CO2 and 1.0–1.4×10−3K−1 for ethyl acetate. The thermal pressure coefficients were in the range 0.3–1.9MPa/K for CO2 and 0.55–1.2MPa/K for ethyl acetate. In the mixtures, the isothermal compressibility and isobaric expansivity were found to increase while the thermal pressure coefficients decreased in going from ethyl acetate to carbon dioxide. The mixtures displayed mostly negative excess volumes. The magnitude of the negative excess volume was observed to decrease with pressure at a given temperature, but increase with increasing temperature at a given pressure. The largest (negative) excess volume, approaching −16cm3/mol, was observed at the higher experimental temperature (340K) and the lower pressure (16MPa).
A new yellow pigment isolated from the flowers of Acacia dealbata has been shown to be chalcononaringenin 2′-[O-rhamnosyl-(1→4)-xyloside] by chemical and spectroscopic methods.
Eucalyptus globulus bark contains four significant families of compounds, namely triterpenic (TT) acids (betulinic, betulonic, oleanolic and ursolic acids, and the acetylated forms of the latter two), long chain aliphatic alcohols, fatty acids, and sterols. The first group is the most abundant and possesses demonstrated bioactivity, which raises the importance of this biomass. The supercritical fluid extraction (SFE) of E. globulus bark was carried out in this work with carbon dioxide at 100, 140 and 200 bar, and 40, 50 and 60 degrees C, and the extracts were analyzed by GC-MS. The results are compared with those obtained by Soxhlet with dichloromethane, and the influence of the operating conditions upon the global yield and the individual yields of the triterpenic acids is discussed in detail. The acetylated TT acids imparted a large effect on the extraction yields, as they appeared in large concentrations on the extracts independently of their absolute loadings in the bark. The polarity of the free acids, higher than that of their acetyl derivatives, justifies this behavior. Modeling calculations were also performed for interpreting the SFE results. The experimental observations are in agreement with predictions accomplished for the solubilities and mass transfer fluxes of ursolic acid and 3-acetylursolic acid that were chosen as key IT acids in the process.
The volumetric properties of carbon dioxide + ethanol mixtures have been determined at 323, 348, 373, 398, and 423 K at pressures up to 70 MPa using a variable-volume view cell. Densities for pure components and mixtures containing 90, 80, 70, and 50% by mass carbon dioxide are reported as a function of pressure at each temperature. It is shown that this system undergoes a density crossover at high pressures with each composition, a phenomenon previously reported also for mixtures of carbon dioxide + pentane, carbon dioxide + toluene, and carbon dioxide + acetone. In the composition range investigated, the excess volume of the mixtures becomes more positive with increasing pressure but more negative with increasing temperature.
PvT properties in a single phase were determined for carbon dioxide + ethanol mixtures at four compositions from 313 to 363 K and up to 25 MPa with an uncertainty less than (±0.04 kg·m-3) using a vibrating tube densimeter. The classical calibration method of the vibrating tube densimeter was used with N2 and H2O as the reference fluids.
Aim To examine the different uses and perceptions of introduced Australian acacias (wattles; Acacia subgenus Phyllodineae) by rural households and communities.
Location Eighteen landscape-scale case studies around the world, in Vietnam, India, Réunion, Madagascar, South Africa, Congo, Niger, Ethiopia, Israel, France, Portugal, Brazil, Chile, Dominican Republic and Hawai‘i.
Methods Qualitative comparison of case studies, based on questionnaire sent to network of acacia researchers. Information based on individual knowledge of local experts, published and unpublished sources.
Results We propose a conceptual model to explain current uses and perceptions of introduced acacias. It highlights historically and geographically contingent processes, including economic development, environmental discourses, political context, and local or regional needs. Four main groupings of case studies were united by similar patterns: (1) poor communities benefiting from targeted agroforestry projects; (2) places where residents, generally poor, take advantage of a valuable resource already present in their landscape via plantation and/or invasion; (3) regions of small and mid-scale tree farmers participating in the forestry industry; and (4) a number of high-income communities dealing with the legacies of former or niche use of introduced acacia in a context of increased concern over biodiversity and ecosystem services.
Main conclusions Economic conditions play a key role shaping acacia use. Poorer communities rely strongly on acacias (often in, or escaped from, formal plantations) for household needs and, sometimes, for income. Middle-income regions more typically host private farm investments in acacia woodlots for commercialization. Efforts at control of invasive acacias must take care to not adversely impact poor dependent communities.
A group-contribution method is presented for the prediction of activity coefficients in nonelectrolyte liquid mixtures. The method combines the solution-of-functional-groups concept with a model for activity coefficients based on an extension of the quasi chemical theory of liquid mixtures (UNIQUAC). The resulting UNIFAC model (UNIQUAC Functional-group Activity Coefficients) contains two adjustable parameters per pair of functional groups.
By using group-interaction parameters obtained from data reduction, activity coefficients in a large number of binary and multicomponent mixtures may be predicted, often with good accuracy. This is demonstrated for mixtures containing water, hydrocarbons, alcohols, chlorides, nitriles, ketones, amines, and other organic fluids in the temperature range 275° to 400°K.
Tannins and related polyphenols from leaf, bark and pod samples of Acacia auriculiformis A. cunnex Benth., A. farnesiana Willd., A. leucophloea Willd., A. nilotica Willd., A. caesia W&A., A. ferruginea DC., A. torta Craib., A sundra DC., A. dealbata Link., and A. latronum Willd., have been estimated. Plant samples were collected from natural stands or from biomass plantations. Oven dried samples were extracted with water, 80% methanol, 70% acetone and 50% dimethyl sulfoxide and total phenolic compounds and tannins determined. In leaves the highest extractives were obtained from A. nilotica (40·2%), pods of A. auriculiformis (49·4%) with dimethyl sulfoxide. Total phenolic compounds and tannins of leaf samples were highest in A. nilotica (with acetone) the bark of A. farnesiana and the pods of A. nilotica (with dimethyl sulfoxide). Co-production of tannins, polyphenols, timber, gum and firewood from tree crops of Acacia are discussed.
Typical equations of state fail to accurately represent properties close to the critical point for reasons that are now understood. It is shown that the addition of a specially designed three-term function solves this problem for practical purposes. Although the limiting behavior at the critical point is not correct, the remaining deviations are negligible for more general applications. This method is related to work on H2O by Haar et al. (1980, 1984), and is here tested for CO2 and neopentane, for which equations are presented.
Supercritical extraction and fractionation of natural matter is one of the early and most studied applications in the field of supercritical fluids. In the last 10 years, studies on the extraction of classical compounds like essential and seed oils from various sources: seeds, fruits, leaves, flowers, rhizomes, etc., with or without the addition of a co-solvent have been published. Supercritical extraction of antioxidants, pharmaceuticals, colouring matters, and pesticides has also been studied. The separation of liquid mixtures and the antisolvent extraction are other processes that can perform very interesting separations. Mathematical modelling has also been developed and refined for some of these processes.The objective of this review is to critically analyze traditional and new directions in the research on natural matter separation by supercritical fluids extraction and fractionation.
Phyllanthus emblica L. is an economic plant used in Chinese medicine for the treatment of various diseases. The bark of P. emblica is rich in polyphenols and its extractions have shown strong antioxidative and radical scavenging activity. Response surface methodology (RSM) was used to assess the optimal extraction of polyphenols from P. emblica bark. Various extraction parameters including ethanol concentration, extraction time, temperature, solid-liquid ratio, and extraction times were chosen to identify their effects on polyphenols extraction. Among these parameters, extraction times and solvent concentration were found to have significant effect on polyphenols extraction. RSM was applied to obtain the optimal combination of solvent concentration, extraction time, temperature, and extraction time for maximum rate of extraction. The most suitable condition for the extraction of polyphenols was at ethanol concentration 75%, extraction time 25 min, extraction temperature 45 degrees C, and extraction times 3. At these optimal extraction parameters, the maximum extraction of polyphenols obtained experimentally was found to be very close to its predicted value. The extraction rate of polyphenols was 19.78% at the optimum conditions. The mathematical model developed was found to fit with the experimental data of polyphenols extraction.
Grape byproducts were subjected to an extraction process under various different experimental conditions (namely, solvent type, temperature, solvent-to-solid ratio, time contact, and raw material) in order to study the effect of these conditions on the yield of phenolic compounds and the corresponding antiradical activity of extracts. Although the order of decreasing capacity to extract soluble materials was ethanol > methanol > water, methanol was the most selective for extracting phenolic compounds. Temperature and solvent-to-solid ratio were found to have a critical role in extraction efficiency; values of 50 degrees C (between 25 and 50 degrees C) and 1:1 (between 1:1 and 5:1) maximized the antiradical activity of phenolic extracts. In addition, extracts from grape samples previously subjected to distillation reached higher antiradical values in comparison to those coming directly from pressing; in both cases, seed extracts showed better results than those of stem when ethanol or water was employed, whereas the opposite occurred in the case of methanol. These differences were attributed to the different phenolic compositions of the considered fractions.
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 Δ7 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.
The GC-MS identification of several abundant long-chain aliphatic n-alkyl caffeates, together with other phydroxycinnamic acid esters, in the dichloromethane extracts of the bark of Acacia dealbata and A. melanoxylon, is reported. In addition, the unambiguous differentiation between two delta7-steryl glucosides (namely, spinasteryl glucoside and dihydrospinasteryl glucosides) and the homologous delta5-steryl glucosides was achieved based on the EI-MS fragmentation features of their trimethylsilyl derivatives.
A new method for the estimation of properties of pure organic compounds is presented. Estimation is performed at three levels. The primary level uses contributions from simple groups that allow describing a wide variety of organic compounds while the higher levels involves polyfunctional and structural groups that provide more information about molecular fragments whose description through first-order groups is not possible. The presented method allows estimations of the following properties: normal boiling point, critical temperature, critical pressure, critical volume, standard enthalpy of formation, standard enthalpy of vaporization, standard Gibbs energy, normal melting point and standard enthalpy of fusion. The group contribution tables have been developed from regression using a data set of more than 2000 compounds ranging from C=3 to C=60, including large and complex polycyclic compounds. Compared to the currently used group-contribution methods, the new method makes significant improvements both in accuracy and applicability.
Liquid-liquid and solid-liquid phase equilibria
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