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- Ulex europaeus: from noxious weed to source of valuable isoflavones and flavanonesPublication . Spínola, Vítor; Llorent-Martínez, Eulogio J.; Gouveia-Figueira, Sandra; Castilho, Paula C.The screening and quantification of the main phenolic compounds in leaves and flowers of Ulex europaeus (gorse) was carried out by high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI–MSn) after ultrasound-assisted extraction with methanol. About 98% of compounds corresponded to flavonoids, distributed as flavonols, flavones, isoflavones and flavanones. Flavonols were mainly quercetin glucosides; most of the found flavones were apigenin derivatives and the isoflavone group was dominated by glycitin. The flavanone group was composed mainly of liquiritigenin derivatives, substances usually found in liquorice (Glycyrrhiza ssp) and associated with high pharmacological relevance; in Ulex they represent about 25% of total polyphenols content. Phenolic acids and saponins were also detected, as minor components. In vitro antioxidant activity (nitric oxide, superoxide assays, ABTS and DPPH assays) of leaves and flowers, and their inhibitory effects towards digestive enzymes related to carbohydrate metabolism (-glucosidase and -amylase) were also studied.
- Phenolic composition and antioxidant capacity of cultivated artichoke, Madeira cardoon and artichoke‐based dietary supplementsPublication . Gouveia, Sandra C.; Castilho, Paula C.Cynara cardunculus var. scolymus (artichoke) and Cynara cardunculus var. ferocissima (Madeira cardoon) are two Asteraceae plants used in Madeira Archipelago in diet and also for medicinal issues. The present work aimed to compare the phenolic composition and quantify the main compounds of these two plants and two artichoke based dietary supplements (juice and dragées). The methanolic extract of the endemic plant cardoon was basi cally composed of caffeoylquinic acid isomers. The same compounds were observed in artichoke extract, where there was a larger number and variety of other phenolic compounds. Variations in qualitative and quantitative composition of the three artichoke based products were extensive, with only 3 components being common to all 3 products. Mono-O-diglycosilated flavonoids (luteolin, apigenin and quercetin) were found in the artichoke products but not in Madeira cardoon. 1,3-O-dicaffeoylquinic acid (cynarin), usually considered mainly responsi ble for the biological properties of artichoke, was found in high amounts ranging in most samples but was not detected in the analyzed commercial dragées. The antioxidant assays results reflected the highly diversified com position of the artichoke-based products, showing a high radical scavenger and reducing capacities, while the ex tract from Madeira cardoon was a poor antioxidant
- 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.
- Helichrysum monizii Lowe: phenolic composition and antioxidant potentialPublication . Gouveia, Sandra; Castilho, Paula C.Introduction – In Madeira Archipelago there are four endemic Helichyrsum species and three of them are used in the traditional medicine. Helichrysum monizii is a rare endemism with very scarce information available concerning its uses in the local traditional medicine. Objective – The aim of this work was to study for the first time Helichrysum monizii in terms of its antioxidant capacity and the identification of the phenolic compounds to which that activity is due. Methodology – Three different methods of extraction were performed and total phenolic and flavonoid contents of extracts were correlated to radical scavenging and antioxidant capacity by DPPH, ABTS, FRAP and β‐carotene assays. An HPLC‐DAD‐ESI/MSn method was employed for the separation and identification of the phenolic and flavonoid components. Results – The results revealed a high antioxidant potential mainly related to the phenolic profile of the plant. Polar components of methanol extracts of Helichrsyum monizii were detected by a high‐performance liquid chromatography/ electrospray ionisation tandem mass spectrometry (HPLC‐DAD‐ESI/MSn ) method. Thirty‐three compounds were identified and 19 of them were identified as quinic acid derivatives.
- Quantification of artemisinin in Artemisia annua extracts by 1H‐NMRPublication . Castilho, Paula C.; Gouveia, Sandra C.; Rodrigues, Ana I.Artemisinin is a polycyclic sesquiterpene lactone that is highly effective against multidrug-resistant strains of Plasmodium falciparum, the etiological agent of the most severe form of malaria. Determination of artemisinin in the source plant, Artemisia annua, is a challenging problem since the compound is present in very low concentrations, is thermolabile and unstable, and lacks chromophoric or fluorophoric groups. The ain of this study was to develop a simple protocol for the quantification of artemisinin in a plant extract using an (1)H-NMR method. Samples were prepared by extraction of leaf material with acetone, treatment with activated charcoal to remove chlorophylls and removal of solvent. (1)H-NMR spectra were measured on samples dissolved in deuterochloroform with tert-butanol as internal standard. Quantification was carried out using the using the delta 5.864 signal of artemisinin and the delta 1.276 signal of tert-butanol. The method was optimised and fully validated against a reference standard of artemisinin. The results were compared with those obtained from the same samples quantified using an HPLC-refractive index (RI) method. The (1)H-NMR method gave a linear response for artemisinin within the range 9.85-97.99 mm (r(2) = 0.9968). Using the described method, yields of artemisinin in the range 0.77-1.06% were obtained from leaves of the A. annua hybrid CPQBA x POP, and these values were in agreement with those obtained using an HPLC-RI.
- Evaluation of the antimicrobial and antioxidant activities of essential oils, extracts and their main components from oregano from Madeira Island, PortugalPublication . Castilho, Paula C.; Savluchinske-Feio, Sonia; Weinhold, Tatiana S.; Gouveia, Sandra C.Origanum vulgare subsp. virens growing wild in Madeira Island, Portugal was studied within the ongoing investigations on polymorphic Lamiaceae species. The antimicrobial activity of the essential oils and n-hexane extracts of origanum was determined against 10 strains of bacteria and yeasts, found as human pathogenic or food spoilage microorganisms. The essential oils, n-hexane extracts and isolated compounds showed moderately activity, compared to standard antibiotics, inhibiting all tested bacteria except Pseudomonas aeruginosa. The most sensitive microorganism was Mycobacterium smegmatis, reaching MIC ¼ 25 mg mL 1 . The results obtained suggest a potential application of these oils in pre venting the human pathogenic and food spoilage due to microorganism’s growth. The essential oils and n-hexane extracts have greater RSC than polar extracts, probably due to the high contents in thymol, which demonstrated the highest activity in the DPPH assay. All studied origanum samples showed a large content in non-esterified 1-hexacosanol, C26H54O, accumulated mainly in bracts and flowers
- Validation of a HPLC-DAD–ESI/MSn method for caffeoylquinic acids separation, quantification and identification in medicinal Helichrysum species from MacaronesiaPublication . Gouveia, Sandra C.; Castilho, Paula C.The caffeoylquinic acids (CQA) found in Helichrysum species from Madeira Archipelago were identified and quantified. The HPLC-DAD–ESI/MSn method applied was developed and validated showing a good repeatability with recovery values ≥96%. The use of a RP-C18 with a small internal diameter (Ø 3.0 mm) and an acidic mobile phase (acetonitrile and water with 0.1% (v/v) of formic acid) enabled the separation of all compounds within a 30 min analysis. A good resolution between 1,5-O-diCQA and 3,5-O-diCQA isomers, usually hard to separate, was also accomplished. Dicaffeoylquinic acids isomers were the major components among the quantified hydroxycinnamic acids. 1,5-O-diCQA, 3,5-O-diCQA and 5-O-CQA were the compounds found in higher amounts for the different species. The distinct uses of these plants described in the local folk medicine can be related to the phenolic composition.
- Characterization of phenolic compounds and antioxidant activity of ethanolic extracts from flowers of Andryala glandulosa ssp. varia (Lowe ex DC.) R.Fern., an endemic species of Macaronesia regionPublication . Gouveia, Sandra; Gonçalves, João; Castilho, Paula C.Andryala glandulosa spp. varia (Lowe ex DC.) R.Fern. (Asteraceae), is a small shrub that grows in moun tains of Madeira Island, Fuerteventura and Lanzarote from Canary Islands. The flowerheads are used traditionally for the treatment of edemas and in homemade dermo-cosmetic preparations. In this paper the chemical composition of the extracts of this plant, used in folk medicine, and their antioxidant capacity were established; the presence of potentially harmful lactones, so commonly associated with related species used for the same purposes was also evaluated. A reversed-phase high performance liquid chromatography method (RP-HPLC) coupled with diode-array detection (DAD) and electrospray ionization mass spectrometry (ESI/MSn) was used for the characterization of phenolic com pounds in ethanol extracts of flowers from A. glandulosa spp. varia collected in Madeira Island. Total phenolic content (TPC) and total flavonoid content (TFC) were established and three assays (DPPH, ABTS and FRAP) were used to measure the antioxidant capacity of the dichloromethane and ethanol extracts. The dichloromethane extract of A. glandulosa contain long linear chain hydrocarbons and esters. In the alcoholic extracts, a total of 16 compounds were characterized based on their UV, mass spectra and HPLC retention time. Quinic acid and luteolin derivatives were found to be the main compounds. Quantification of caffeoylquinic acids (CQA) detected was performed by HPLC-DAD and 5-O-CQA and 3,5-O-diCQA were the major compounds (with values of 22.40 ± 0.21 and 59.69 ± 1.07 mg/100 g dried plant, respectively). Only the ethanol extract was active, revealing a high radical scavenging capacity and a moderate reducing potential. The potent antioxidant alcoholic extracts are composed mainly of hydroxycinnamic acid derivatives and flavonoids. The presence of sesquiterpene lactones was not detected. Since lactones are very common among related plants, like arnicas, and known to cause dermatitis and other unwanted effects, this can be an explanation for the preference for Andryala over other more easily available alternatives
- 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.