Browsing by Author "Machado, Alexandra M."
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- Antimicrobial and wound healing effects associated to cytocompatibility and the relationship with phytochemical profile of selected Portuguese monofloral honeysPublication . Machado, Alexandra M.; Marto, Joana; Gonçalves, Lídia Maria; Ribeiro, Helena Margarida; Duarte, Aida; Tomás, Andreia; Falcão, Soraia; Vilas-Boas, Miguel; Miguel, Maria Graça; Figueiredo, Ana CristinaOwing to its applications in both food and pharmaceutical industries honey is regarded as a functional product. This study evaluated 32 Portuguese monofloral honeys and their activity was compared with manuka honey 850 + . The antimicrobial activity was determined against Gram-positive and negative bacteria, and yeast. Antioxidant activity, wound healing ability, and cell viability were studied in the human keratinocyte cell line (HaCaT). Phytochemical profile analysis was performed by UPLC/DAD/ESI-MSn. Chestnut, bell heather, eucalyptus, manuka, and strawberry tree honeys demonstrated higher antioxidant activity and were effective against S. aureus. Incense and orange honeys showed wound healing rates of 89 % and 86 %, respectively. All the honeys had cell viability above 76 %. Bell heather and strawberry tree honeys showed the highest total phenolic content, while incense and orange honeys, showed the lower ones. Phytochemical profile analysis evidenced two main clusters, one dominated by isoprenoids and norisoprenoids, as well as phenolic acids and derivatives, while the other included flavonoids as main compounds. Blending different Portuguese monofloral honeys may be an alternative to faster wound healing, by combining their diverse bioactive components. The gathered knowledge can be further explored in formulations that consider the biological activity capacity and composition of each honey.
- Avaliação de propriedades biológicas em mel dos Açores – atividade antioxidante e antimicrobianaPublication . Machado, Alexandra M.; Miguel, Maria da Graça; Vilas-Boas, Miguel; Faleiro, Maria Leonor; Figueiredo, Ana CristinaO mel e os seus produtos derivados são geralmente consumidos devido às suas características nutricionais e terapêuticas, bem como igualmente empregues em fragrâncias ou cosméticos [1]. Em Portugal, existem nove denominações de origem protegida de mel reconhecidas, entre as quais a do mel dos Açores [2], cujas propriedades biológicas estão pouco estudadas. O objetivo deste trabalho consistiu no estudo de oito méis dos Açores, provenientes das ilhas de São Miguel, Santa Maria, Terceira e Pico, relativamente à quantificação do teor em compostos fenólicos totais e flavonoides, à determinação da atividade antioxidante e anti-inflamatória por métodos espetrofotométricos, bem como o controlo de qualidade microbiológico e a avaliação da atividade antimicrobiana. O teor de fenóis totais variou entre 12 μg e 460 μg equivalentes de ácido gálico (EAG)/g de mel e para os flavonóides entre 0,6 μg e 55 μg equivalentes de quercetina (EQ)/g de mel. A atividade antioxidante determinada pelo método ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) foi relativamente baixa nos oito méis, comparativamente ao padrão utilizado (Trolox), sendo apenas possível determinar o IC50 (concentração de amostra necessária para diminuir ou reduzir a concentração inicial do radical ABTS em 50%) de uma amostra, cujo valor foi 8 mg/mL. Relativamente à capacidade quelante de iões ferro(II), esta foi somente detetada em três amostras de mel, cujas percentagens de inibição variaram entre 5 e 18%. A captação do radical superóxido foi também avaliada. Os valores de IC50 variaram entre 23 e 73 mg/L. A capacidade de inibição da enzima xantina oxidase foi observada em cinco amostras de mel, sendo particularmente elevada numa delas. No que diz respeito ao controlo de qualidade microbiológico dos méis analisados, não foi observada contaminação microbiana. A atividade antimicrobiana dos oito méis foi testada contra Escherichia coli, Staphylococcus aureus, Candida albicans e Pseudomonas aeruginosa, tendo sido verificada ação inibitória dos oito méis para Escherichia coli, de quatro méis em Staphylococcus aureus e de três méis em Pseudomonas aeruginosa. Não foi observada atividade inibitória contra Candida albicans.
- In vitro biological activity and phenolic profile of selected portuguese monofloral honeysPublication . Machado, Alexandra M.; Marto, Joana; Gonçalves, Lídia Maria; Ribeiro, Helena Margarida; Duarte, Aida; Tomás, Andreia; Falcão, Soraia; Vilas-Boas, Miguel; Miguel, Maria Graça; Figueiredo, Ana CristinaPortuguese monofloral honeys from carob tree, chestnut, bell heather, eucalyptus, incense, orange, and strawberry tree, were evaluated in vitro for antimicrobial, antioxidant, wound healing, and cell viability effect, compared to manuka honey 850+. Antimicrobial activity was determined against Gram+-and Gram- bacteria and yeast. Antioxidants, wound healing, and cell viability effects were studied in the Human Keratinocyte (HaCaT) cell line. Chestnut, bell heather, eucalyptus, manuka and strawberry tree honeys were most effective against S. aureus with a minimum inhibitory concentration (MIC) of 12.5%-25.0% (w/v), and greater ability to decrease reactive oxygen species (ROS) production (> 75%), than manuka honey (68%). Incense and orange honeys exhibited high wound healing rates, 89% and 86%, respectively, higher than manuka honey, 53%. Honeys showed cell viability > 76%. Bell heather and strawberry tree honeys exhibited the highest total phenolic content, 38 and 137 mg/100 g honey respectively, being more effective against the microorganisms tested and showing greater antioxidant activity. Opposite, incense, and orange honeys with lower phenolic amounts, 11 and 15 mg/100g honey, respectively, achieved higher wound healing ability. Flavonoid aglycones were the most abundant flavonoids in all honeys. This knowledge can be further explored in formulations that take the best out of each honey type composition and biological activity capacity.
- 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 da Graça; Figueiredo, Ana CristinaThe 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.
- Volatile characterization of different commercial honeys types from the Azores (Portugal)Publication . Machado, Alexandra M.; Miguel, Maria da Graça; Vilas-Boas, Miguel; Figueiredo, Ana CristinaHoney and beekeeping products are usually consumed due to their nutritional and therapeutic properties, being also used in fragrances or cosmetics [1]. The Azores have a specific endemic flora as well as climate and soil conditions that allow the production of a unique honey classified as Protected Designation of Origin (PDO), with multifloral or Pittosporum undulatum Vent. (“incenso”) botanical origin [2]. As part of a research program aiming to evaluate the existence of specific honey volatile markers, this work reports the volatile profile of eight commercial honeys from the Azores (São Miguel, Santa Maria, Terceira and Pico). The volatiles were isolated by hydrodistillation for 1 h and analysed by gas chromatography and gas chromatography-mass spectrometry. The acyclic hydrocarbons n-nonadecane, n-heneicosane, n-tricosane, n-pentacosane, n-heptacosane and n-nonacosane dominated in all samples. Saturated fatty acids were also identified, namely decanoic and hexadecanoic acids. 2-Furfural, benzaldehyde, phenylacetaldehyde, phenylethyl alcohol, limonene and oxygen-containing terpenes, cis- and trans-linalool oxides, linalool, α-terpineol and α-, β- and Y-eudesmol, were detected in lower amounts. Although no previous studies described the volatiles of Pittosporum flowers from the Azores, a comparison with the volatiles isolated from the mainland Pittosporum flowers [3] showed that limonene, linalool, α-terpineol and α-eudesmol were present both in the Azorean honey samples (0.05-0.5%) and in the mainland flowers (0.05-2.2%). Further studies will aim at evaluating both the volatiles of honey from the main botanical origin, and well as the honey‟s biological properties.
- Volatile characterization of honey with dominance of Bupleurum spinosum pollenPublication . Elamine, Youssef; Machado, Alexandra M.; Estevinho, Leticia M.; Lyoussi, Badiâa; Figueiredo, Ana Cristina; Miguel, Maria GraçaMoroccan honey with Bupleurum spinosum (Apiaceae/Umbelliferae) as the main pollen source is locally known as Zantaz honey. In the present work, the volatiles from 18 honeys of this type, were isolated by hydrodistillation and analysed by Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS), for volatiles quantification and identification. The percentage composition of the volatiles and pollen profiling was used to determine the relationship between the different samples by cluster analysis. Two poorly correlated clusters were defined in volatiles analysis. Cluster A, with 17 out of the 18 samples, included four subgroups dominated by straight-chain hydrocarbons and fatty acids in variable proportions. Cluster B included just one sample, with 1-phenyldodec-1-en-3-one as the main component. Mono- and sesquiterpene hydrocarbons, as well as oxygen-containing mono- and sesquiterpenes occurred always <2%. Two moderately correlated clusters were defined after pollen profiling cluster analysis. Pollen Cluster A included 17 samples having in common the presence of B. spinosum and Populus sp. pollen. The one sample from Cluster B was moderately correlated with Cluster A and showed the lowest percentage of B. spinosum pollen. Pollen volatiles analysis would be relevant in assessing the presence of putative pollen volatile marker compounds and the importance of pollen profile on honey volatiles.
- Volatile profile of portuguese monofloral honeys: significance in botanical origin determinationPublication . Machado, Alexandra M.; Antunes, Marília; Miguel, Maria da Graça; Vilas-Boas, Miguel; Figueiredo, Ana CristinaThe volatile profiles of 51 samples from 12 monofloral-labelled Portuguese honey types were assessed. Honeys of bell heather, carob tree, chestnut, eucalyptus, incense, lavender, orange, rape, raspberry, rosemary, sunflower and strawberry tree were collected from several regions from mainland Portugal and from the Azores Islands. When available, the corresponding flower volatiles were comparatively evaluated. Honey volatiles were isolated using two different extraction methods, solid-phase microextraction (SPME) and hydrodistillation (HD), with HD proving to be more effective in the number of volatiles extracted. Agglomerative cluster analysis of honey HD volatiles evidenced two main clusters, one of which had nine sub-clusters. Components grouped by biosynthetic pathway defined alkanes and fatty acids as dominant, namely n-nonadecane, n-heneicosane, n-tricosane and npentacosane and palmitic, linoleic and oleic acids. Oxygen-containing monoterpenes, such as cis- and trans-linalool oxide (furanoid), hotrienol and the apocarotenoid -isophorone, were also present in lower amounts. Aromatic amino acid derivatives were also identified, namely benzene acetaldehyde and 3,4,5-trimethylphenol. Fully grown classification tree analysis allowed the identification of the most relevant volatiles for discriminating the different honey types. Twelve volatile compounds were enough to fully discriminate eleven honey types (92%) according to the botanical origin.