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- Extraction and bioprocessing with supercritical fluidsPublication . Coelho, Jose; Trucillo, Paolo; Nobre, Beatriz; Palavra, António; Campardelli, Roberta; Reverchon, ErnestoSupercritical fluid (SCF) technologies have emerged as a real alternative to various natural product extraction processes and pharmaceutical production to obtain micronized particles, coprecipitates, nanocomposite polymer structures and liposomes, in addition to other increasingly larger applications described in literature. In the present work, a brief literature review of the application of supercritical fluid extraction (SFE) is presented. This is evidenced by several publications and patents, contributions from several countries and the increase of industries around the world dedicated to this technique. Next, we aim to focus the analysis of SFE on a review of the literature applied to microalgae as a substitute primitive feedstock due to its high growth rate, valuable biologically active lipophilic substances, and photosynthetic efficiency without competition with food sources or needs of arable lands. We finally discussing an SCF bioprocess with a very new perspective for liposome production focalized on its potential at industrial scale.
- Novel insights into the biological activity of Croton lechleri twigs extracts and advancements in their sustainable recoveryPublication . Tzintzarov, Alexander; Boyadzhieva, Stanislava S.; Coelho, Jose; Tsvetanova, Flora; Petrova, Maria; Stoev, Georgi; Yankov, Dragomir; Ugrinova, Iva; Stateva, RoumianaSangre de drago, the sap of Croton lechleri Müll. Arg. tree, has been used for centuries in traditional medicine owing to its diverse biological activities. Extracts derived from different parts of the species contain a multitude of phytochemicals with varied applications. Twigs, however, are among the least studied parts of the plant. This study unveils new biological activities of Croton lechleri twig extracts recovered by applying Soxhlet and advanced green techniques. For all extracts, total phenolic content and antioxidant activity were determined. Subsequently, four were selected, and their cytotoxic effects were assessed on both normal (HaCat) and malignant melanoma (A375) skin cell lines using the MTT assay and trypan blue exclusion assay. All showed dose-dependent cytotoxicity, with the Soxhlet ethanol extract demonstrating the highest selectivity towards A375 cells over HaCat cells. The extracts induced apoptosis and necrosis, as confirmed by Annexin V/PI dual-labeling and flow cytometry, highlighting their ability to trigger programmed cell death in cancer cells. The selective inhibition of cell cycle progression in A375 compared to HaCat observed both for Soxhlet ethanol and pressurized ethanol extracts induces cell cycle arrest at multiple points, primarily in the G1 and G2/M phases, and significantly reduces DNA synthesis as evidenced by the decrease in the S-phase population, confirmed by the EdU assay. Consequently, the Soxhlet extract composition was analyzed using LC-MS, which revealed their richness in polyphenolic compounds, particularly flavonoids from the flavonol subclass.
- Mathematical modelling of supercritical CO2 extraction of volatile oils from aromatic plantsPublication . Grosso, C.; Coelho, Jose; Pessoa, F. L. P.; Fareleira, J. M. N. A.; Barroso, J. G.; Urieta, J. S.; Palavra, A. F.; Sovova, H.The modelling of the experimental data of the extraction of the volatile oil from six aromatic plants (coriander, fennel, savoury, winter savoury, cotton lavender and thyme) was performed using five mathematical models, based on differential mass balances. In all cases the extraction was internal diffusion controlled and the internal mass transfer coefficienty (k(s)) have been found to change with pressure, temperature and particle size. For fennel, savoury and cotton lavender, the external mass transfer and the equilibrium phase also influenced the second extraction period, since k(s) changed with the tested flow rates. In general, the axial dispersion coefficient could be neglected for the conditions studied, since Peclet numbers were high. On the other hand, the solute-matrix interaction had to be considered in order to ensure a satisfactory description of the experimental data.
- Effect of harvest year on production, chemical composition and antioxidant activities of essential oil of oregano (Origanum vulgare subsp glandulosum (Desf.) Ietswaart) growing in North AfricaPublication . Mechergui, Mechergui; Jaouadi, Wahbi; Coelho, Jose; Khouja, Mohamed LarbiDried flowers and leaves of Origanum glandulosum (Desf.) Ietswaart collected at different harvesting years were submitted to hydrodistillation. The isolated essential oils were analyzed by GC and GC/MS to study the harvest year effect on oregano chemical composition. Total phenolic contents and antioxidant effectiveness were performed. Nefza essential oils were obtained in yields of 4.6%, 5.8% and 4.3% from plants collected in 2007, 2008 and 2009, respectively. The values of essential oil content of Krib population were close (2-2.7%). There are qualitative and quantitative differences in the chemical composition of essential oils of Krib and Nefza populations from one harvest year to another. p-cymene, -terpinene, thymol and carvacrol are the main compounds of all oils, regardless of the year of harvest. The year that has the highest value in rainfall and which declines in cooler conditions during the flowering period, has been the most important value in essential oil yield. Wide variations were noted in total phenolic content, expressed in gallic acid equivalent which varied in Nefza population, between 8.52–17.67 g GAE/kg dw. The anti-radical activity expressed by IC50 of oregano essential oils was varied from one year to another, from 59.2 mg/L in 2007, to 226.19 mg/L in 2008 for Nefza population. Those of Krib varied from 79.8 to 151.85 mg/L. The controlled culture of oregano is better that using the wild populations if we would like have stable constituents destined to the industries or pharmacological uses. So, we can adjust the controlled parameters of our culture according to our purpose.
- Recovering value from organic waste materials: Supercritical fluid extraction of oil from industrial grape seedsPublication . Coelho, Jose; Filipe, Rui; Robalo, Maria Paula; Stateva, Roumiana P.Supercritical extraction of oil from grape seed samples obtained from a Portuguese industry was carried out at temperatures from (313-333) K, pressures up to 40.0 MPa and different scCO(2) flow rates. The qualitative analysis of the crude oil was carried out by NMR. The fatty acids were analyzed by GC-Fid with reference to the parameters in Annex I to European Commission Regulation. The results show similar content of TAGs and DAGs both in the n-hexane and scCO(2) extraction methods, but the latter have higher PUPA and lower saturated fatty acids content. A dynamic model was used to simulate the extraction curves in gPROMS ModelBuilder. The grape seed oil was represented as either a one or a three component mixture of triacylglycerols, and the deviation between the experimental and calculated extraction yields was in the range (2-9) % for the first, and (4-11) % for the second case.
- Modelling the kinetics of supercritical CO2 extraction of biomassPublication . R. M. Filipe; Coelho, Jose; Robalo, Maria Paula; Cholakov, Georgi; Stateva, R. P.This work addresses the modelling and simulation of the kinetics of CO2 supercritical extraction of oils from biomass. Experimental and simulation results from different matrices and models are presented. gPROMS Model Builder is used to find solutions to three different models applied to study the extraction of three different volatile oils from aromatic plants (coriander, fennel and savoury), and from a bioresidue, industrial grape seeds. The supercritical extraction experiments performed at different temperature, pressure and flow rate conditions provide the data to the modelling studies and for model parameter estimation. The qualitative and quantitative agreement between the experimental and simulated extraction profiles in terms of yields was good for the cases investigated.
- Biological activities and oil properties of Origanum glandulosum Desf: a reviewPublication . Mechergui, Kaouther; Jaouadi, Wahbi; Coelho, Jose; Serra, Maria Celeste; Khouja, Mohamed Larbi ArbiOriganum glandulosum Desf. (Species endemic of North Africa: Tunisia and Algeria) is important medicinally as it has antimicrobial, antifungal, antioxidant, antibacterial, antithrombin, antimutagenic, angiogenic, antiparasetic and antihyperglycaemic activities. Phytochemical investigations of the species of this genus have resulted in the extraction of a number of important bioactive compounds. This emphasizes on the need of extensive study for reporting the additional information on the medicinal importance, the biological activities and properties of oil of other unattended species of Origanum glandulosum. © 2015 Springer-Verlag France.
- Sustainable transformation of two algal species of different genera to high-value chemicals and bioproductsPublication . Tsvetanova, Flora; Boyadzhieva, Stanislava S.; Coelho, Jose; Yankov, Dragomir; Stateva, RoumianaThis study investigates the potential of two algae species from different genera, namely the recently isolated Scenedesmus obliquus BGP and Porphyridium cruentum, from the perspective of their integral sustainable transformation to valuable substances. Conventional Soxhlet and environmentally friendly supercritical fluid extraction were applied to recover oils from the species. The extracts were characterized through analytical techniques, such as GC-Fid and LC-MS/MS, which allowed their qualitative and quantitative differentiation. Thus, P. cruentum oils contained up to 43% C20:4 and C20:5 fatty acids, while those of S. obliquus BGP had only residual amounts. The LC-MS/MS analysis of phenolic compounds in the S. obliquus BGP and P. cruentum extracts showed higher content of 3-OH-4-methoxybenzoic acid and kaempferol 3-O-glycoside in the former and higher amounts of ferulic acid in the latter. Total phenolic content and antioxidant activity of the oils were also determined and compared. The compositional analysis of the oil extracts revealed significant differences and varying potentialities based on their genera and method of extraction. To the best of our knowledge our work is unique in providing such detailed information about the transformation prospects of the two algae species to high-value chemicals and bioproducts.
- On the solubility of three disperse anthraquinone dyes in supercritical carbon dioxide: new experimental data and correlationPublication . Coelho, Jose; Palavra, António F.; Stateva, Roumiana P.Solubility measurements of quinizarin. (1,4-dihydroxyanthraquinone), disperse red 9 (1-(methylamino) anthraquinone), and disperse blue 14 (1,4-bis(methylamino)anthraquinone) in supercritical carbon dioxide (SC CO2) were carried out in a flow type apparatus, at a temperature range from (333.2 to 393.2) K and at pressures from (12.0 to 40.0) MPa. Mole fraction solubility of the three dyes decreases in the order quinizarin (2.9 x 10(-6) to 2.9.10(-4)), red 9 (1.4 x 10(-6) to 3.2 x 10(-4)), and blue 14 (7.8 x 10(-8) to 2.2 x 10(-5)). Four semiempirical density based models were used to correlatethe solubility of the dyes in the SC CO2. From the correlation results, the total heat of reaction, heat of vaporization plus the heat of solvation of the solute, were calculated and compared with the results presented in the literature. The solubilities of the three dyes were correlated also applying the Soave-Redlich-Kwong cubic equation of state (SRK CEoS) with classical mixing rules, and the physical properties required for the modeling were estimated and reported.
- Supercritical carbon dioxide extraction of bioactive compounds from microalgae and volatile oils from aromatic plantsPublication . Palavra, A. M. F.; Coelho, Jose; Barroso, J. G.; Rauter, A. P.; Fareleira, J. M. N. A.; Mainar, A.; Urieta, J. S.; Nobre, B. P.; Gouveia, L.; Mendes, R. L.; Cabral, J. M. S.; Novais, J. M.A discussion of the most interesting results obtained in our laboratories, during the supercritical CO(2) extraction of bioactive compounds from microalgae and volatile oils from aromatic plants, was carried out. Concerning the microalgae, the studies on Botryococcus braunii and Chlorella vulgaris were selected. Hydrocarbons from the first microalgae, which are mainly linear alkadienes (C(23)-C(31)) with an odd number of carbon atoms, were selectively extracted at 313 K increasing the pressure up to 30.0 MPa. These hydrocarbons are easily extracted at this pressure, since they are located outside the cellular walls. The extraction of carotenoids, mainly canthaxanthin and astaxanthin, from C. vulgaris is more difficult. The extraction yield of these components at 313 K and 35.0 MPa increased with the degree of crushing of the microalga, since they are not extracellular. On the other hand, for the extraction of volatile oils from aromatic plants, studies on Mentha pulegium and Satureja montana L were chosen. For the first aromatic plant, the composition of the volatile and essential oils was similar, the main components being the pulegone and menthone. However, this volatile oil contained small amounts of waxes, which content decreased with decreasing particle size of the plant matrix. For S. montana L it was also observed that both oils have a similar composition, the main components being carvacrol and thymol. The main difference is the relative amount of thymoquinone, which content can be 15 times higher in volatile oil. This oxygenated monoterpene has important biological activities. Moreover, experimental studies on anticholinesterase activity of supercritical extracts of S. montana were also carried out. The supercritical nonvolatile fraction, which presented the highest content of the protocatechuic, vanilic, chlorogenic and (+)-catechin acids, is the most promising inhibitor of the enzyme butyrylcholinesterase. In contrast, the Soxhlet acetone extract did not affect the activity of this enzyme at the concentrations tested. (C) 2011 Elsevier B.V. All rights reserved.