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Phenolic profile of wild fruits of Rosa canina SL. from Northeast Portugal

Publication . Guimarães, Rafaela; Barros, Lillian; Reis, Filipa S.; Dueñas, Montserrat; Carvalho, Ana Maria; Santos-Buelga, Celestino; Queiroz, Maria João R.P.; Ferreira, Isabel C.F.R.

Plant polyphenols are a wide group of secondary metabolites and are a common component of our diet. Flavonoids represent the most common and widely distributed group of plant phenolics, and can be further broken into classes including flavones, flavonols, flavanones, flavanols, anthocyanins and isoflavonoids. Different classes of bioactive constituents are present in Rosa canina, including phenolic compounds. Rosa canina fruits can be eaten raw as snacks and possess prophylactic and therapeutic activities against a wide range of ailments, including the inflammatory disorders arthritis, rheumatism, gout, colds and gastrointestinal disorders, which might be related with their phenolic composition. This study aimed to characterize the phenolic compounds present in the above mentioned wild fruits. The analysis of phenolic compounds was carried out by reversed-phase HPLC-DAD and the major phenolic compounds were identified by ESI-MS, in order to establish the specific phenolic profile. Rosa canina presented different classes of flavonoids. Flavones, flavonols and dihydroflavonols represented 5.50 mg/100 g dry weight, among which taxifolin, a dihydroflavonol, was prominent (1.18 mg/100 g). Flavan-3-ols (i.e., catechins and proanthocyanidins) were other relevant flavonoids found. (+)-Catechin was the most abundant flavan-3-ol found in the fruits (3.59 mg/100 g), whereas cyanidin 3-O-glucoside was the only anthocyanin detected (0.68 μg/100 g). The studied fruits may have great potential for food industries as a source of colors and flavors, as well as bioactive molecules such as phenolic compounds for dietary supplements or functional foods.

2013Conference object

Open access

Comparative study of the phenolic profile and antioxidant properties of Chamaemelum nobile: infusion, decoction, and hydroalcoholic extract

Publication . Guimarães, Rafaela; Barros, Lillian; Dueñas, Montserrat; Carvalho, Ana Maria; Santos-Buelga, Celestino; Queiroz, Maria João R.P.; Ferreira, Isabel C.F.R.

This stud} aimed to determine the phenolic composition and to evaluate the antioxidant activity o f different preparation' of Roman chamomile: infusion. decoction and methanol: water (80:20) extract. The hydroalcoholic extract revealed the highest antioxidant activity in almost all the performed assays (EC\ , ≤0.62 mg/ml. depending on the assay ). which was in agreement with its highest total content in phenolic compounds. Otherwise. decoctions presented the lowest antioxidant potential (EC50 ≤1.4S mg/mL. depending on the assay). The phenolic profile of the different preparations was identical. varying only in the concentrations found. Phenolic acids (caffooylquinic acids). flavonols (quercetin and kaempferol derivatives) and flavones (apigenin and luteolin derivatives) were found in the three preparations. The most abundant compounds in the infusion and hydroalcoholic ex tract we re 5-0 -caffeoylquinic acid and an apigenin derivative. These. as also the other phenolic compounds, decreased significantly in the decoction .

2012Conference object

Open access

Wild Roman chamomile extracts and phenolic compounds: enzymatic assays and molecular modelling studies with VEGFR-2 tyrosine kinase

Publication . Guimarães, Rafaela; Calhelha, Ricardo C.; Froufe, Hugo J.C.; Abreu, Rui M.V.; Carvalho, Ana Maria; Queiroz, Maria João R.P.; Ferreira, Isabel C.F.R.

Angiogenesis is a process by which new blood vessels are formed from the pre-existing vasculature, and it is a key process that leads to tumour development. Some studies have recognized phenolic compounds as chemopreventive agents; flavonoids, in particular, seem to suppress the growth of tumor cells modifying the cell cycle. Herein, the antiangiogenic activity of Roman chamomile (Chamaemelum nobile L.) extracts (methanolic extract and infusion) and the main phenolic compounds present (apigenin, apigenin-7-O-glucoside, caffeic acid, chlorogenic acid, luteolin, and luteolin-7-O-glucoside) was evaluated through enzymatic assays using the tyrosine kinase intracellular domain of the Vascular Endothelium Growth Factor Receptor-2 (VEGFR-2), which is a transmembrane receptor expressed fundamentally in endothelial cells involved in angiogenesis, and molecular modelling studies. The methanolic extract showed a lower IC50 value (concentration that provided 50% of VEGFR-2 inhibition) than the infusion, 269 and 301 μg mL(-1), respectively. Regarding phenolic compounds, luteolin and apigenin showed the highest capacity to inhibit the phosphorylation of VEGFR-2, leading us to believe that these compounds are involved in the activity revealed by the methanolic extract.

2016Journal article

Open access

Phytochemicals and bioactivity in wild German and Roman chamomiles infusions

Publication . Guimarães, Rafaela; Barros, Lillian; Calhelha, Ricardo C.; Carvalho, Ana Maria; Queiroz, Maria João R.P.; Ferreira, Isabel C.F.R.

Natural matrices represent a rich source of biologically active compounds and are an example of molecular diversity, with recognized potential in drug discovery. In the present work, the infusions of Matricaria recutita L. (German chamomile) and Chamaemelum nobile L. (Roman chamomile) were submitted to an analysis of phenolic compounds and evaluation of bioactivity. Phenolic compounds were characterized by reversed-phase high performance liquid chromatography coupled to diode array detection and mass spectrometry with electron spray ionization (HPLCDAD/ ESI-MS). The bioactivity of the samples was tested in different human tumour cell lines (breast- MCF-7, lung- NCI-H460, colon- HCT -15, cervical- He l a and hepatocellular- HepG2 carcinomas}, and the hepatotoxicity was evaluated using a porcine liver primary cell culture (nontumour cells, PLP2) [1 ,2]. The major compounds found were luteolin 0-acylhexoside in German chamomile, and 5-0-caffeoylquinic acid and an apigenin derivative in Roman chamomile. The highest potential antioxidant activity was showed by German chamomile in all the in vitro assays. Both the infusions showed inhibitory activity of the growth of HCT -15 and He la cell lines, without hepatotoxicity (GI 50>400 μg/ml). Nevertheless, Roman chamomile infusion presented the highest inhibitory activity for all the cell lines (GI50<168 μg/ml ). Overall, infusions of both chamomiles contain important phytochemicals with bioactive properties to be explored in medicinal, food, and cosmetic industries.

2013Conference object

Open access

Inhibition of the VEGFR-2 tyrosine kinase domain by witd Roman chamomile extracts and phenolic compounds

Publication . Guimarães, Rafaela; Calhelha, Ricardo C.; Froufe, Hugo J.C.; Abreu, Rui M.V.; Carvalho, Ana Maria; Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.

Angiogenesis results from new blood vessels growing excessively (e. g. câncer). The Vascular Endothelial Growth Factor (VEGF) is secreted by the tumor cells and plays a crucial role in angiogenesis; low oxygen tension dramatically induces the expression of this major angiogenic factor that when linked to the transmembrane tyrosine kinase receptor VEGFR-2, which is present in endothelial cells, signalizes for the proliferation of these cells towards the tumor. Treatments using small molecules with anti-tyrosine kinase activity (e. g., sorafenib) can block angiogenic signalling, reduce blood tumoral irrigation, and improve chemotherapy distribution [1]. Some studies recognized phenolic compounds as chemopreventive agents, especially flavonoids. Other plant-derived anticancer drugs (e. g. Taxol) proved to be anti-angiogenic. In traditional Chinese medicine, many herbs are used in the treatment of angiogenic diseases such as chronic wounds and rheumatoid arthritis [2]. Furthermore, it has been reported that drinking of green tea could inhibit VEGF-induced angiogenesis in vivo [3]. In the present work, the anti-angiogenic activity of Roman chamomile (Chamaemelum nobile L.) extracts (methanolic extract and infusion) and main phenolic compounds (apigenin, apigenin-7-O-glucoside, caffeic acid, chlorogenic acid, luteolin, luteolin-7-O-glucoside) was evaluated through an enzymatic assay using the VEGFR-2 tyrosine kinase domain. To better understand the inhibition phosphorylation mechanism of the tyrosine kinase receptor by luteolin, apigenin and apigenin-7- 0-glucoside, docking studies were performed. The methanolic extract showed higher phosphorylation inhibition than the infusion (IC50 values of 269 and 301 μg/mL, respectively). Regarding phenolic compounds, luteolin (IC50 2.10 μM) and apigenin (IC50 4.78 μM) were the most potent in inhibiting VEGFR-2 phosphorylation, leading us to believe that these compounds are involved in the anti-angiogenic activity revealed by the methanolic extract.

2015Conference object

Open access