Browsing by Author "Cristina Figueiredo, A."
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- Antioxidant and antiproliferative activities of the essential oils from Thymbra capitata and Thymus Species grown in PortugalPublication . Miguel, Maria; Gago, Custódia; Antunes, Maria Dulce; Megias, Cristina; Cortes-Giraldo, Isabel; Vioque, Javier; Sofia Lima, A.; Cristina Figueiredo, A.The antioxidant and antiproliferative activities of the essential oils from Thymbra capitata and Thymus species grown in Portugal were evaluated. Thymbra and Thymus essential oils were grouped into two clusters: Cluster I in which carvacrol, thymol, p-cymene, alpha-terpineol, and gamma-terpinene dominated and Cluster II in which thymol and carvacrol were absent and the main constituent was linalool. The ability for scavenging ABTS(center dot+) and peroxyl free radicals as well as for preventing the growth of THP-1 leukemia cells was better in essential oils with the highest contents of thymol and carvacrol. These results show the importance of these two terpene-phenolic compounds as antioxidants and cytotoxic agents against THP-1 cells.
- Bioproducts from forest biomass II. Bioactive compounds from the steam-distillation by-products of Cupressus lusitanica Mill. and Cistus ladanifer L. wastesPublication . Tavares, Claudia S.; Martins, Alice; G, Miguel; Carvalheiro, Florbela; Duarte, Luis C.; Gameiro, Jose A.; Cristina Figueiredo, A.; Roseiro, Luisa B.Obtaining essential oils and hydrolates from underutilized biomass is an economic and sustainable way for production of these high added-value bioproducts. However, this process still generates large amounts of residues as the by-products obtained during distillation, which can be a concern for the environment, but also adequate substrates for other applications. Considering this fact, the waste distilled by-products remaining after steam distillation of underutilized biomass from Cupressus lusitanica and Cistus ladanifer, were evaluated as a natural source of other high value products with biological activities, namely, phenolic compounds. Thus, the remaining extracted solid residues (ESRs) were characterized and subject to further treatments by ultrasound-assisted extraction (UAE) with ethanol and 70 % acetone, in order to prepare phenolic-rich extracts thereof: ESRs (EtOH) and ESRs(70 % Ace). Together with the distiller condensation waters (DCWs), these extracts were characterized for their phenolic content (total phenols, tannins and flavonoids). Their antioxidant activity was also evaluated by different methodologies. the phenolic profile of DCWs, ESRs(EtOH) and ESRs(70 % Ace) from both waste species was obtained by capillary zone electrophoresis (CZE) and phenolic compounds were tentatively identified. Results obtained for C. lusitanica biomass are here disclosed for the first time. Generally, all samples revealed to be rich in phenolic compounds, being C. ladanifer biomass the one with higher phenolic content. DCWs presented values of 140 mgGAE/g for C. lusitanica and 210 mg GAE/g for C. ladanifer, from which ca. 60 % were tannins. Extracts obtained with 70 % acetone were the ones with the highest results, except for the antioxidant activity by xanthine oxidase and superoxide inhibition, which was higher in DCWs. Catechins were the major compounds found for both species, but gallocatechins and gallic acid were only identified in C. ladanifer. Hydroxycinnamic acid derivatives and salicylic acid were also identified in C. ladanifer, partly justifying the anti-inflammatory effect referred for this species.
- Bioproducts from forest biomass: Essential oils and hydrolates from wastes of Cupressus lusitanica Mill. and Cistus ladanifer L.Publication . Tavares, Claudia S.; Martins, Alice; Faleiro, L; Miguel, Maria; Duarte, Luis C.; Gameiro, Jose A.; Roseiro, Luisa B.; Cristina Figueiredo, A.Unattended forest wastes are, among others, a potential source of wildfires, as well as a growth media for forest pests. As a way of lowering the detrimental effect of these wastes, it is important to convert these under-valued resources into a value-generating market forest wastes use. Essential oils (EOs) and hydrolates (Hs) from Cupressus lusitanica and Cistus ladanifer waste products, resulting from forest landscaping in Portugal, were evaluated for chemical composition and biological activity. Essential oils and Hs were obtained by steam-distillation (SD) and hydrodistillation (HD). Essential oils and Hs volatiles were analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC MS). The antimicrobial activity of EOs was studied by disk agar diffusion method against Escherichia coli, Staphylococcus aureus and Candida albicans. Antioxidant activity of EOs and Hs was evaluated by 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) free radical, superoxide anion radical formation, xanthine oxidase and chelating metal ions assays. Antiinflammatory activity of Hs was assessed by albumin denaturation assay. Monoterpene hydrocarbons and oxygen-containing monoterpenes dominated C. lusitanica EO (SD, 82-86 %, HD, 80-85 %) and Hs volatiles (SD, 93-94 %; HD 64-81 %), respectively. alpha-Pinene (14-36 %), limonene (8-21 %), delta-3-carene (8-19 %) and sabinene (6-18 %) were the main EO constituents. Hydrolates volatiles were dominated by cis-3-hexen-1-ol (0.1-13 %), camphor (1-11 %), umbellulone (t-48 %), p-cymene-8-ol (11-16 %) and terpinen-4-ol (21-31 %). C. ladanifer EOs were dominated by monoterpene hydrocarbons (SD, 48-80 % and HD, 29 %) and Hs by oxygen containing monoterpenes (SD, 38-43 %, HD, 39 %). The EO major constituents were alpha-pinene (13-28 %) and camphene (5-25 %), whereas 2,6,6-trimethyl cyclohexanone (2-12 %) and trans-pinocarveol (5-13 %) dominated the Hs volatiles. This study reports for the first time the chemical composition of the hydrolate volatiles of these two species and their anti-inflammatory properties. Among the studied biological activities, the EOs showed the best antioxidant properties while Hs demonstrated higher anti-inflammatory activity.
- Quality assessment of Portuguese monofloral honeys. Physicochemical parameters as tools in botanical source differentiationPublication . Machado, Alexandra M.; Tomás, Andreia; Russo-Almeida, Paulo; Duarte, Aida; Antunes, Marília; Vilas-Boas, Miguel; Miguel, Maria Graca; Cristina Figueiredo, A.The quality evaluation and physicochemical parameters assessment of Portuguese monofloral honeys were performed. Fifty-one monofloral honeys were collected from several regions from mainland Portugal, and from the Azores islands, producer labelled as carob tree (n = 5), chestnut (n = 2), eucalyptus (n = 5), bell heather (n = 6), incense (n = 4), lavender (n = 8), orange (n = 9), rape (n = 2), raspberry (n = 2), rosemary (n = 1), sunflower (n = 3), and strawberry tree (n = 4). Pollen analysis and microbiological safety were evaluated, and the parameters such as colour index, moisture content, electrical conductivity, hydroxymethylfurfural, pH, free and total acidity, diastase activity, proline, and sugar profile were assessed for physicochemical characterization, in all 51 monofloral honeys. After melissopalynological examination, the honeys were either confirmed as monofloral, or classified as multifloral with predominance of a specific pollen type or multifloral. Microbiological analysis showed that honeys were safe for human consumption. Pairwise comparisons of physicochemical parameters, using only honey types with n >= 3, revealed significant differences between honey types. Despite some homogeneity in sugar profile among honeys, eucalyptus honey was significantly different in glucose, maltose and maltulose content compared to incense, orange and sunflower honeys, and also exhibited a higher isomaltose amount compared to all analyzed honeys. Electrical conductivity, colour index, free and total acidity, and diastase activity showed significant differences between the analyzed honeys, indicating that these parameters may provide an additional tool in monofloral honey identification.