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Extraction of aloesin from aloe vera rind using alternative green solvents: Process optimization and biological activity assessment
Publication . Añibarro-Ortega, Mikel; Pinela, José; Ćirić, Ana; Lopes, Elsa; Molina, Adriana K.; Calhelha, Ricardo C.; Soković, Marina; Ferreira, Olga; Ferreira, Isabel C.F.R.; Barros, Lillian
Aloesin is an aromatic chromone with increasing applications in the cosmetic and health food industries. To optimize its extraction from the Aloe vera leaf rind, the independent variables time (10–210 min), temperature (25–95â—¦C) and organic solvent composition (0–100%, w/w) were combined in a central composite design coupled with response surface methodology. The solvents consisted of binary mixtures of water with ethanol, propylene glycol, or glycerol. The aloesin levels quantified in each extract were used as response for optimization. The theoretical models were fitted to the experimental data, statistically validated, and used to obtain the optimal extraction conditions. Then, a dose–response analysis of the solid/liquid ratio (S/L) was performed under the optimal conditions determined for each alcohol–water system and revealed that a linear improvement in extraction efficiency can be achieved by increasing the S/L ratio by up to 40 g/L. This analysis also allowed to experimentally validate the predictive models. Furthermore, the aloesin-rich extracts revealed antioxidant activity through thiobarbituric acid reactive substances (TBARS) formation inhibition, antimicrobial effects against bacterial and fungal strains, and no toxicity for PLP2 cells. Overall, this study provided optimal extraction conditions for the recovery of aloesin from Aloe vera rind through an eco-friendly extraction process and highlighted its bioactive potential.
Extensive characterization of choline chloride and its solid–liquid equilibrium with water
Publication . Ferreira, Ana I.M.C. Lobo; Vilas-Boas, Sérgio M.; Silva, Rodrigo M.A.; Martins, Mónia A.R.; Abranches, Dinis O.; Paz, Filipe A. Almeida; Ferreira, Olga; Pinho, Simão; Santos, Luís M.N.B.F.; Coutinho, João A.P.; Soares-Santos, Paula C.
The importance of choline chloride (ChCl) is recognized due to its widespread use in the formulation of
deep eutectic solvents. The controlled addition of water in deep eutectic solvents has been proposed to
overcome some of the major drawbacks of these solvents, namely their high hygroscopicities and
viscosities. Recently, aqueous solutions of ChCl at specific mole ratios have been presented as a novel,
low viscous deep eutectic solvent. Nevertheless, these proposals are suggested without any information
about the solid–liquid phase diagram of this system or the deviations from the thermodynamic ideality
of its precursors. This work contributes significantly to this matter as the phase behavior of pure ChCl
and (ChCl + H2 O) binary mixtures was investigated by calorimetric and analytical techniques. The
thermal behavior and stability of ChCl were studied by polarized light optical microscopy and differential
scanning calorimetry, confirming the existence of a solid–solid transition at 352.2 0.6 K. Additionally,
heat capacity measurements of pure ChCl (covering both ChCl solid phases) and aqueous solutions of
ChCl (xChCl o 0.4) were performed using a heat-flow differential scanning microcalorimeter or a high-
precision heat capacity drop calorimeter, allowing the estimation of a heat capacity change of (ChCl) E
39.3 10 J K 1 mol 1
, between the hypothetical liquid and the observed crystalline phase at 298.15 K.
The solid–liquid phase diagram of the ChCl + water mixture was investigated in the whole concentration
range by differential scanning calorimetry and the analytical shake-flask method. The phase diagram
obtained for the mixture shows an eutectic temperature of 204 K, at a mole fraction of choline chloride
close to xChCl = 0.2, and a shift of the solid–solid transition of ChCl–water mixtures of 10 K below the
value observed for pure choline chloride, suggesting the appearance of a new crystalline structure of
ChCl in the presence of water, as confirmed by X-ray diffraction. The liquid phase presents significant
negative deviations to ideality for water while COSMO-RS predicts a near ideal behaviour for ChCl.
Aspectos químicos y nutricionales del filete de Aloe vera
Publication . Pinela, José; Añibarro-Ortega, Mikel; Barros, Lillian; Silva, Soraia P.; Coelho, Elisabete; Coimbra, Manuel A.; Ferreira, Isabel C.F.R.
El Aloe vera (Aloe barbadensis Mill.) es una planta suculenta de la familia Asphodelaceae actualmente naturalizada en muchos países tropicales y subtropicales. En la medicina tradicional, se ha utilizado ampliamente durante siglos para tratar trastornos de la piel y otras enfermedades, así como por su efecto purgante [1]. Hoy en día, esta especie se usa como ingrediente para alimentos funcionales, cosméticos y medicamentos [2]. Las hojas son la parte más utilizada de la planta, en la que se pueden identificar dos fracciones principales, la corteza externa y el parénquima interno conocido como pulpa o filete. Aunque hay varios estudios sobre el Aloe vera [1,2], muchos de ellos tienen descripciones confusas, principalmente sobre el interior de la hoja, debido a los diferentes términos que se han usado indistintamente. En este sentido, en este trabajo se realizó una caracterización del valor nutricional y composición química del parénquima interno de la hoja (filete), que es la parte comestible de la planta.
El filete de las hojas de Aloe vera fue separado de la cáscara y se determinó el contenido en humedad. Después, la muestra se liofilizó y se pulverizó y se determinó el contenido en proteína, grasa, cenizas, hidratos de carbono disponibles y fibra alimentaria. También se determinó la composición en ácidos orgánicos, ácidos grasos, tocoferoles, azúcares libres y polisacáridos de alto peso molecular utilizando diferentes técnicas cromatográficas. El perfil en compuestos fenólicos se caracterizó en un extracto hidroetanólico mediante HPLC-DAD-ESI/MSn.
Se verificó que el filete corresponde aproximadamente al 58% de la masa de la hoja de Aloe vera y que su mayor constituyente es el agua (98%). En base seca, la fibra alimentaria resultó ser el macronutriente predominante (50.1%), constituida principalmente por manano (posiblemente acemanano), seguida por los hidratos de carbono disponibles (37.4%). Apenas 1% en grasa, 2.6% en proteína y 9% en cenizas, hacen que el filete sea un alimento de bajo poder calórico (4,5 kcal/100 g fw y 270 kcal/100 g dw). También se detectaron cantidades interesantes de α-tocoferol (5 mg/100 g dw) y ácido málico (5 g/100 g dw). Respecto al perfil fenólico, se detectaron de forma predominante cromonas (5.5 mg/g extracto) y antronas (5.3 mg/g extracto), incluyendo aloesina y aloínas A y B, respectivamente.
El filete fresco de Aloe vera es un alimento bajo en calorías debido a su alto contenido en agua y bajo contenido en grasa. Además, se destaca por su contenido en tocoferoles, ácido málico y cromonas [3]. Todo esto hace que el filete de Aloe vera sea un ingrediente interesante para ser explorado tanto por la industria alimentaria como por la industria cosmética.
Valorization of Juglans regia leaves as cosmeceutical ingredients: bioactivity evaluation and final formulation development
Publication . Besrour, Nermine; Oludemi, Taofiq; Mandim, Filipa; Pereira, Carla; Dias, Maria Inês; Soković, Marina; Stojković, Dejan; Ferreira, Olga; Ferreira, Isabel C.F.R.; Barros, Lillian
The cosmetic industry is constantly searching for bioactive ingredients, namely, those
obtained from natural sources with environmentally friendly connotations and less toxic effects.
A previous study of our research group optimized the extraction of phenolic compounds from
Juglans regia by heat-assisted extraction. Due to its richness in different phenolic compounds, the
present work aimed to develop a formulation containing J. regia leaf extract. The extract’s antioxidant,
anti-tyrosinase, antimicrobial, anti-inflammatory, wound healing, cytotoxicity, and photostability
properties were evaluated. The extract was then incorporated into an O/W base cream, followed by
characterization of the final formulation in terms of its antioxidant properties, phenolic composition,
and stability over time and at different storage conditions. The most abundant compounds in the
hydroethanolic extract were 3-O-caffeoylquinic acid (18.30 0.04 mg/g), quercetin-O-pentoside
(9.64 0.06 mg/g), and quercetin 3-O-glucoside (6.70 0.19 mg/g). Besides those, the extract
presented antioxidant, anti-inflammatory, wound closure, and antibacterial effects against several
skin pathogens. In addition, HaCaT cell viability was maintained up to 98% at 400 g/mL.Within
Proteus vulgaris-infected HaCaT cells, the extract also presented an over 40% bacterial mortality rate
at its nontoxic concentration (200 g/mL). After incorporating the extract, the obtained formulation
presented a good physicochemical profile over time and at different storage conditions while also
maintaining its antioxidant effect; as such, it can be considered stable for topical application. Future
work to evaluate its performance in terms of skin permeation and detailed toxicological studies
with a focus on regulatory requirements, involving skin irritation, eye irritation, genotoxicity, photoirritation,
and dermal absorption, should be conducted, as the prepared formulation demonstrated
relevant properties that deserve to be further explored.
Phytochemical composition and in vitro antioxidant and antimicrobial properties of Aloe vera leaf tissue extracts
Publication . Añibarro-Ortega, Mikel; Pinela, José; Ćirić, Ana; Caleja, Cristina; Ferreira, Olga; Soković, Marina; Barros, Lillian; Ferreira, Isabel C.F.R.
Over the last decades, Aloe vera has been subject of several scientific studies that aimed to characterize compositional and biological properties.1,2 Despite this, a lack of information on the exact part of the plant analysed or even the species involved is common in many of these works. There are confusing descriptions, mostly about the inner part of the leaf, due to the different terms that have been used interchangeably, such as fillet, pulp, mucilage, gel, and parenchyma, among others.3 However, these terms do not refer to the same part of the leaf. Therefore, this study was performed to evaluate and compare chemical and bioactive features of Aloe vera leaf fillet, mucilage and rind. Freshly cut Aloe vera samples of certified organic production were provided by an agricultural company located in Elvas, Portugal. The green rind was separated from the inner fillet and the transparent slippery exudate consisting mainly of gel was collected from the mucilage layer of the outer leaf pulp adjacent to the rind. After lyophilisation, the powdered samples underwent a solid-liquid extraction with an hydroethanolic mixture to obtain the extracts. These were analysed by HPLC-DAD-ESI/MS to characterize their phenolic profile, and in vitro screened for antioxidant (by the capacity to inhibit the oxidative haemolysis (OxHLIA), the formation of thiobarbituric acid reactive substances (TBARS), and the β-carotene bleaching) and antimicrobial (against skin-associated pathogenic bacteria and fungi) activities.4
Up to seventeen phenolic compounds were identified in the Aloe vera leaf extracts and classified into four groups: phenolic acids, flavonoids, chromones, and anthrones. The chromones aloesin and 2'-p-methoxycoumaroylaloresin and the anthrones aloin A and B, 10-hydroxyaloin A and B, and malonyl aloin A and B were detected in the three leaf extracts. The mucilage contained the highest level (131±3 mg/g extract) of phenolic compounds, mostly anthrones (62.1%) and chromones (34.6%), followed by two luteolin glucosides (3.3%). The rind was ranked second, with 105±3 mg/g extract of phenolic compounds, of which 44.9% anthrones and 43.8% chromones; it also contained luteolin and apigenin glucosides and p-coumaroylquinic acid. However, the chromone levels found in the rind did not differ statistically from those of the mucilage. Although the phenolic profiles of fillet and mucilage were similar, a significantly lower concentration (11.2 ± 0.2 mg/g extract) of these secondary metabolites was found in fillet. In addition, this leaf part had an equal ratio of anthrones and chromones. The mucilage and rind extracts revealed interesting antioxidant properties. On the other hand, fillet and rind extracts showed a powerful antifungal activity against Aspergillus flavus, A. niger, Penicillium funiculosum, and Candida albicans, higher than that of the positive control ketoconazole. This study showed that the three studied extracts of Aloe vera leaf have a different content of phenolic compounds and a high antifungal activity. Since the rind of this plant is often discarded as a biowaste, in future studies we intend to evaluate the potential of green solvents with a different number of hydroxyl groups to extract phenolic compounds from this matrix.
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Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
9471 - RIDTI
Funding Award Number
PTDC/EQU-EPQ/30463/2017