Browsing by Author "Castilho, Paula C."
Now showing 1 - 10 of 51
Results Per Page
Sort Options
- An attractive, sensitive and high-throughput strategy based on microextraction by packed sorbent followed by UHPLC-PDA analysis for quantification of hydroxybenzoic and hydroxycinnamic acids in winesPublication . Gonçalves, João; Silva, Catarina L.; Castilho, Paula C.; Câmara, José S.An attractive, fast, low-consumption and very promising high-throughput strategy based on microextraction by packed sorbent (MEPS), and reversed phase ultra-high pressure liquid chromatography (UHPLC), was developed and validated for the determination and quantification of hydroxybenzoic (gallic acid, protocatechuic acid, gentisic acid, vanillic acid, syringic acid), and hydroxycinnamic acids (p-coumaric acid, m-coumaric acid, o-coumaric acid, ferrulic acid and cinnamic acid) in wines. Important factors affecting the performance of MEPS such as the type of sorbent material (C2, C8, C18, SIL and C8/SCX), number of extraction cycles (extract–discard), sample volume and elution volume were tested and optimized. The optimal MEPS extraction conditions were obtained using C8 phase as sorbent and 50 μL of the sample in five extraction cycles. The analytes were separated on a new Trifunctional High Strength Silica analytical column (HSS T3; 100% silica particle), specially designed for polar compounds, using a binary mobile phase composed of aqueous 0.1% formic acid (eluent A) and methanol (eluent B) in the gradient elution mode (10 min of total analysis). This new stationary phase, proved to be an excellent alternative to conventional C18 columns for the determination of benzoic and cinnamic acids derivatives in wines. The analytical method was fully validated in terms of linearity, limits of detection (LOD), limits of quantification (LOQ), extraction yield, accuracy and inter/intra-day precision, using a synthetic wine spiked with hydroxybenzoic and hydroxycinnamic acids, and demonstrated good linearity with r2‐values > 0.998 within the established concentration range (0.2–40 μg mL− 1). Under the optimized conditions, LOD of 0.01–0.2 μg mL− 1, LOQ of 0.03–0.7 μg mL− 1, and precision, expressed as the relative standard deviation (RSD %), within 0.3–6% were observed. The proposed method was also applied to the analysis of hydroxybenzoic and hydroxycinnamic acids in red and white wines and recoveries of 80–100% and 77–99%, respectively, were obtained. The new approach offers an attractive alternative for analysis of phenolic acids from wine samples, providing a number of advantages including decreased sample preparation, faster sample throughput and easy to perform as compared to traditional methodologies. Moreover it could potentially be extended to other extraction media.
- An improved and fast UHPLC-PDA methodology for determination of L-ascorbic and dehydroascorbic acids in fruits and vegetables. Evaluation of degradation rate during storagePublication . Spínola, Vítor; Mendes, Berta; Câmara, José S.; Castilho, Paula C.This study provides a versatile validated method to determine the total vitamin C content, as the sum of the contents of L-ascorbic acid (L-AA) and dehydroascorbic acid (DHAA), in several fruits and vegetables and its degradability with storage time. Seven horticultural crops from two different origins were analyzed using an ultra-high-performance liquid chromatographic-photodiode array (UHPLC-PDA) system, equipped with a new trifunctional high strength silica (100% silica particle) analytical column (100 mm × 2.1 mm, 1.7 μm particle size) using 0.1% (v/v) formic acid as mobile phase, in isocratic mode. This new stationary phase, specially designed for polar compounds, overcomes the problems normally encountered in HPLC and is suitable for the analysis of large batches of samples without L-AA degradation. In addition, it proves to be an excellent alternative to conventional C18 columns for the determination of L-AA in fruits and vegetables. The method was fully validated in terms of linearity, detection (LOD) and quantification (LOQ) limits, accuracy, and inter/intra-day precision. Validation experiments revealed very good recovery rate of 96.6 ± 4.4% for L-AA and 103.1 ± 4.8 % for total vitamin C, good linearity with r(2)-values >0.999 within the established concentration range, excellent repeatability (0.5%), and reproducibility (1.6%) values. The LOD of the method was 22 ng/mL whereas the LOQ was 67 ng/mL. It was possible to demonstrate that L-AA and DHAA concentrations in the different horticulture products varied oppositely with time of storage not always affecting the total amount of vitamin C during shelf-life. Locally produced fruits have higher concentrations of vitamin C, compared with imported ones, but vegetables showed the opposite trend. Moreover, this UHPLC-PDA methodology proves to be an improved, simple, and fast approach for determining the total content of vitamin C in various food commodities, with high sensitivity, selectivity, and resolving power within 3 min of run analysis.
- Analysis of phenolic compounds from different morphological parts of Helichrysum devium by liquid chromatography with on-line UV and electrospray ionization mass spectrometric detectionPublication . Gouveia, Sandra C.; Castilho, Paula C.A simple and rapid method has been used for the screening and identification of the main phenolic compounds from Helichrysum devium using high-performance liquid chromatography with on-line UV and electrospray ionization mass spectrometric detection (LC-DAD/ESI-MS(n)). The total aerial parts and different morphological parts of the plant, namely leaves, flowers and stems, were analyzed separately. A total of 34 compounds present in the methanolic extract from Helichrysum devium were identified or tentatively characterized based on their UV and mass spectra and retention times. Three of these compounds were positively identified by comparison with reference standards. The phenolic compounds included derivatives of quinic acid, O-glycosylated flavonoids, a caffeic acid derivative and a protocatechuic acid derivative. The characteristic loss of 206 Da from malonylcaffeoyl quinic acid was used to confirm the malonyl linkage to the caffeoyl group. This contribution presents one of the first reports on the analysis of phenolic compounds from Helichrysum devium using LC-DAD/ESI-MS(n) and highlights the prominence of quinic acid derivatives as the main group of phenolic compounds present in these extracts. We also provide evidence that the methanolic extract from the flowers was significantly more complex when compared to that of other morphological parts.
- Analysis of phenolic compounds in leaves from endemic trees from Madeira Island. A contribution to the chemotaxonomy of Laurisilva forest speciesPublication . Llorent-Martínez, Eulogio J.; Gouveia, Sandra; Castilho, Paula C.Phenolic compounds present high antioxidant activity and, therefore, health promoting effects, serving as a type of preventive medicine. Hence, research on the chemical composition of plants with potential antioxidant value is of high interest. Forest cleaning, thinning, and pruning are beneficial activities that help maintaining healthy forests. In addition, they can provide vegetal material as source of valuable bioactive compounds that can have health promoting effects. In this work, the phenolic composition of several trees native to Madeira Archipelago (Portugal) was studied. Specifically, the leaves from Olea europaea ssp. cerasiformis, Ilex per ado ssp. perado, Clethra arborea, and Heberdenia excelsa have been analyzed. The screening of the main phenolic compounds from their methanolic extracts has been carried out using high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI-MSn). This is the first report on the phenolic composition of these Madeira native species, and more than 100 compounds have been detected and identified or tentatively characterized.
- Analysis of the environmental impact of botanical pesticides in soilPublication . Pereira, Verónica; Castilho, Paula C.; Pereira, Jorge A. M.; Augusto Machado Pereira, JorgePlant-based pesticides are considered viable complements of conventional synthetic pesticides in agriculture. Their environmentally benign nature and potential to mitigate ecological impacts render them advantageous options for sustainable farming practices. However, the long-term effects of botanical pesticides on soil ecosystems remain unclear. This review aims to examine current evidence concerning the persistence of botanical pesticides in soil environments and their potential effects. Specifically, it addresses their biodegradation pathways in soil as well as their impact on soil enzymes and biology. The methodologies available to perform these studies are also briefly discussed, particularly focusing on how they can be tailored to improve the analysis of the impacts and challenges posed by the use of botanical pesticides in ecosystems.
- Antioxidant capacity, cytotoxicity and antimycobacterial activity of Madeira Archipelago endemic helichrysum dietary and medicinal plantsPublication . Gouveia-Figueira, Sandra C.; Gouveia, Carla A.; Carvalho, Maria J.; Rodrigues, Ana I.; Nording, Malin L.; Castilho, Paula C.The potential bioactivity of dietary and medicinal endemic Helichrysum plants from Madeira Archipelago was explored, for the first time, in order to supply new information for the general consumer. In vitro antioxidant properties were investigated using DPPH, ABTS(•+), FRAP and β-Carotene assays, and the total phenolic content (TPC) and total flavonoid content (TFC) were also determined. Although the results generally showed a large variation among the three analyzed plants, the methanolic extracts showed the highest antioxidant capacity. Exception is made for H. devium n-hexane extract that showed good radical scavenger capacity associated to compounds with good reducing properties. In the Artemia salina toxicity assay and antimycobaterial activity, H. devium was the most potent plant with the lowest LD50 at 216.7 ± 10.4 and MIC ≤ 50 μg·mL(-1). Chemometric evaluation (Principal Component Analysis-PCA) showed close interdependence between the ABTS, TPC and TFC methods and allowed to group H. devium samples.
- Antioxidant polyphenols of Madeira sorrel (Rumex maderensis): How do they survive to in vitro simulated gastrointestinal digestion?Publication . Spínola, Vítor; Llorent-Martínez, Eulogio J.; Castilho, Paula C.In this work, we report the phytochemical profile and antioxidant activity of different morphological parts of Rumex maderensis Lowe (Polygonaceae), a wild leafy-vegetable growing in Madeira Island (Portugal). Methanol extracts from leaves, flowers, and stems were submitted to high-performance liquid chromatography with mass spectrometry detection to obtain the phytochemical profile, which allowed the identification of 86 polyphenols (about 70% C- and O-flavonoids) and 9 non-phenolic compounds. In vitro antioxidant activities were measured against ABTS, DPPH, nitric oxide and superoxide free radicals. Then, the samples were subjected to an in vitro digestion, observing a decrease of about 50% in both the content of phenolics and the antioxidant activity. However, relevant antioxidant capacity was still observed after the simulated digestion. Therefore, this study supports the consumption of R. maderensis as an interesting foodstuff and a dietary source of antioxidant phytochemicals that survive the gastrointestinal digestion process.
- Antioxidant potential of Artemisia argentea L'Hér alcoholic extract and its relation with the phenolic compositionPublication . Gouveia, Sandra; Castilho, Paula C.Artemisia argentea, known as losna or Madeira wormwood is used as aperitif drink with tonic effects. A reversed-phase high-performance liquid chromatography method (RP-HPLC) coupled with diode-array detection (DAD) and electrospray ionization mass spectrometry (ESI/MS) was used for the separation/ characterization of phenolic compounds in A. argentea. A wide variety of components was found, mainly flavonoids (O- and C-glycosylated) and hydroxycinnamic acids derivatives. Five saponins, an uncommon type of compound in Artemisia species, were reported. Quantification of caffeoylquinic acids (CQA) was performed and 5-O-CQA and 3,5-O-diCQA were the major compounds (ca. 300 mg/100 g dried plant). Total phenolic content (TPC) and total flavonoid content (TFC) were established and four assays were used to measure the antioxidant capacity of the plant, revealing a high radical scavenging capacity and a weak reducing potential. Unlike other Artemisia subspecies, A. argentea is totally free of harmful components such as thujene, thujone or artemisia ketone.
- Artemisia annua L.: Essential oil and acetone extract composition and antioxidant capacityPublication . Gouveia, Sandra C.; Castilho, Paula C.Aerial parts of Artemisia annua growth in three different locations of Madeira Archipelago were studied. The essential oil composition was established by GC-MS and the main components were mono- and sesquiterpenes; artemisia ketone was not detected. The presence of phenolic compounds in the acetone extracts was investigated by HPLC-DAD-ESI/MSn and a diversified phenolic profile of 40 hydrocinnamic acid derivatives and glycosylated flavonoids was found. A few compounds were reported for the first time in Artemisia annua. The antioxidant capacity of essential oils and extracts were measured by three different in vitro assays. For the essential oils, a very good antioxidant response was found and the extracts also showed a good antioxidant capacity, in particular as antiradical scavengers.
- Assessing the In Vitro Inhibitory Effects on Key Enzymes Linked to Type-2 Diabetes and Obesity and Protein Glycation by Phenolic Compounds of Lauraceae Plant Species Endemic to the Laurisilva ForestPublication . Spínola, Vítor; Castilho, Paula C.Methanolic leaf extracts of four Lauraceae species endemic to Laurisilva forest (Apollonias barbujana, Laurus novocanariensis, Ocotea foetens and Persea indica) were investigated for the first time for their potential to inhibit key enzymes linked to type-2 diabetes (α-amylase, α-glucosidase, aldose reductase) and obesity (pancreatic lipase), and protein glycation. Lauraceae extracts revealed significant inhibitory activities in all assays, altough with different ability between species. In general, P. indica showed the most promissing results. In the protein glycation assay, all analysed extracts displayed a stronger effect than a reference compound: aminoguanidine (AMG). The in vitro anti diabetic, anti-obesity and anti-glycation activities of analysed extracts showed correlation with their flavonols and flavan-3-ols (in particular, proanthocyanins) contents. These Lauraceae species have the capacity to assist in adjuvant therapy of type-2 diabetes and associated complications, through modulation of the activity of key metabolic enzymes and prevention of advanced glycation end-products (AGEs) formation.