Percorrer por autor "Karkanis, Anestis"
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- Alternative sources of n-3 fatty acids from plant originPublication . Petropoulos, Spyridon Α.; Vaz, Josiana A.; Fernandes, Ângela; Karkanis, Anestis; Barros, Lillian; Ferreira, Isabel C.F.R.N-3 fatty acids are considered essential for human health, since they are associated with beneficial effects against many diseases of modern world. The most common dietary sources of n-3 fatty acids are fishes such as salmon and sardines among others, which are also incriminated with high heavy metals content. Flax or linseed is the most widely known plant source of n-3 fatty acids and is the main ingredient of food supplements. The aim of the present study was to evaluate seeds and seed oils of purslane as alternative sources of n-3 fatty acids. For this purpose, purslane seeds, oils from seeds extracted with three methods (screw press methods with or without a cooler), and seed presscakes were evaluated in terms of fatty acids composition and cytotoxicity. For comparison purposes, three commercial linseed oils, one cucurbit oil and one luffa oil were also analyzed in terms of fatty acids composition and cytotoxicity against various human tumor cell lines. The results of the study showed that linseed oils were abundant in α-linolenic acid (65.62%-71-90%), followed by linoleic and oleic acids (12.87%-17.98% and 6.43%-7.09%, respectively), while n6/n3 and PUFA/SFA ratios were lower than 4.0 and higher than 0.45, respectively. In contrast, cucurbit and luffa oils have very low amount of α-linolenic acid, since they contained mostly linoleic, oleic, palmitic and stearic acid, which resulted in very high values of n6/n3 ratios. The main detected fatty acids in purslane seed oils were α-linolenic and linoleic in amounts that depended on the extraction method. Seeds and seed presscakes also contained high amounts of α-linolenic acid and linoleic acids; however, extraction method affected fatty acids composition and values of n6/n3 and PUFA/SFA ratios. Finally, luffa oil showed the highest cytotoxicity against HeLa and NCI-H460 tumor cell lines, followed by cucurbit and one of the tested linseed oils. In conclusion, purslane seeds and seed oils could be considered as alternative n-3 fatty acids, while they have a balanced fatty acids composition and show moderate cytotoxicity against specific tumor cell lines.
- Antioxidant activity and chemical composition of Cichorium spinosum L. in relation to nitrogen ratePublication . Petropoulos, Spyridon Α.; Fernandes, Ângela; Karkanis, Anestis; Ntatsi, Georgia; Barros, Lillian; Ferreira, Isabel C.F.R.In the present study, the effect of nitrogen (N) application rate on phenolic compounds content and antioxidant activity of Cichorium spinosum L. leaves was examined. Seeds were sown in seed trays containing peat and young seedlings were transplanted in 2-L plastic pots containing soil. Four nitrogen rates were applied, namely: a) control (no added N), b) 200 mg L-1 of total N, c) 400 mg L-1 of total N, and d) 600 mg L-1 of total N. Plants were harvested when rosettes reached marketable size. The results showed that the most abundant phenolic compounds of leaves extracts were chlorogenic acid, chicoric acid and kaempferol-3-O-glucuronide, while increasing nitrogen rates resulted in a significant decrease of the main phenolic compounds content. Similarly, the application of 600 mg L-1 of total nitrogen resulted in significant decrease of antioxidant potency of leaf extracts comparing to control, regardless of the performed assay, whereas for all the assays except for DPPH the application of 200 mg L-1 showed the best antioxidant properties. In conclusion, although the application of high nitrogen rates is tempting in order to achieve higher yields, rates higher than 200 mg L-1 are not recommended for C. spinosum cultivation, since a significant decrease of the bioactive compounds is observed that could compromise the quality of the final product.
- Bioactive properties of Sanguisorba minor L. cultivated in central Greece under different fertilization regimesPublication . Finimundy, Tiane C.; Karkanis, Anestis; Fernandes, Ângela; Petropoulos, Spyridon Α.; Calhelha, Ricardo C.; Petrović, Jovana; Soković, Marina; Rosa, Eduardo; Barros, Lillian; Ferreira, Isabel C.F.R.In this study, the chemical characterization and bioactive properties of S. minor cultivated under different fertilization rates (control, half rate and full rate) were evaluated. Twenty-two phenolic compounds were identified, including five phenolic acids, seven flavonoids and ten tannins. Hydrolysable tannins were prevalent, namely Sanguiin H-10, especially in leaves without fertilization (control). Roots of full-rate fertilizer (660 Kg/ha) presented the highest flavonoid content, mainly catechin and its isomers, whereas half-rate fertilizer (330 Kg/ha), presented the highest content of total phenolic compounds, due to the higher amount of ellagitannins (lambertianin C: 84 ± 1 mg/g of dry extract). Antimicrobial activities were also promising, especially against Salmonella typhimurium (MBC = 0.44 mg/mL). Moreover, root samples revealed activity against all tested cell lines regardless of fertilization rate, whereas leaves were effective only against HeLa cell line. In conclusion, S. minor could be a source of natural bioactive compounds, while fertilization could increase phenolic compounds content.
- Chemical composition and bioactive properties of: Sanguisorba minor Scop. under Mediterranean growing conditionsPublication . Karkanis, Anestis; Fernandes, Ângela; Vaz, Josiana A.; Petropoulos, Spyridon Α.; Georgiou, Eleftheria; Ćirić, Ana; Soković, Marina; Oludemi, Taofiq; Barros, Lillian; Ferreira, Isabel C.F.R.Kiwis are an example of fruits with excellent bioactive properties worldwide appreciated and consumed generating tons of waste. Thus, the objective of this work was to compare two varieties of kiwi: Actinidia deliciosa cv. “Hayward” (green) and Actinidia spp. (red) regarding the nutritional value of their pulps, chemical composition and bioactivities of each pulp and peel. The results revealed that pulps have a high water content and low amount of other macronutrients. Both parts of red kiwi presented the highest tocopherols content and red kiwi pulp presented the highest content in ascorbic acid. In general, the peels exhibited the highest antioxidant activity and green kiwi peels showed cytotoxicity and anti-inflammatory activity, which could be related to its higher content in phenolic compounds, especially B-type (epi)catechin dimer. Therefore, kiwi components currently underutilized may be indicated as a source of natural functionalizing ingredients with several benefits for human health.
- Chemical composition and yield of six genotypes of common purslane (Portulaca oleracea L.): an alternative source of omega-3 fatty acids.Publication . Petropoulos, Spyridon Α.; Karkanis, Anestis; Fernandes, Ângela; Barros, Lillian; Ferreira, Isabel C.F.R.; Ntatsi, Georgia; Petrotos, Konstantinos; Lykas, Christos; Khah, EbrahimCommon purslane (Portulaca oleracea L.) is an annual weed rich in omega-3 fatty acids which is consumed for its edible leaves and stems. In the present study six different genotypes of common purslane (A-F) were evaluated for their nutritional value and chemical composition. Nutritional value and chemical composition depended on genotype. Oxalic acid content was the lowest for genotype D, whereas genotypes E and F are more promising for commercial cultivation, since they have low oxalic acid content. Genotype E had a very good antioxidant profile and a balanced composition of omega-3 and omega-6 fatty acids. Regarding yield, genotype A had the highest yield comparing to the other genotypes, whereas commercial varieties (E and F) did not differ from genotypes B and C. This study provides new information regarding common purslane bioactive compounds as affected by genotype and could be further implemented in food industry for products of high quality and increased added value.
- Edible halophytes of the Mediterranean basin: Potential candidates for novel food productsPublication . Petropoulos, Spyridon Α.; Karkanis, Anestis; Martins, Natália; Ferreira, Isabel C.F.R.Background: Recent trends in the food science industry and consumers’ preferences for diversified diets suggest the consumption of wild greens not only as diet complements but also as healthy and functional foods for targeted conditions, rendering its commercial cultivation of major importance in order to avoid irrational gathering and genetic erosion threats. The Mediterranean basin abounds in wild edible species which have been used for food and medicinal purposes by human throughout the centuries. Many of these species can be found near coastal areas and usually grow under saline conditions, while others can adapt in various harsh conditions including high salinity. Scope and approach: The aim of this review focuses on listing and describing the most important halophyte species that traditionally have been gathered by rural communities of the Mediterranean basin, while special interest will be given on their chemical composition and health promoting components. Cases of commercially cultivated halophytes will be also presented to highlight their potential as alternative cash crops, while results from in vitro and in vivo health effects will be presented. Key findings and conclusions: The recent literature has provided useful information regarding the potential of wild halophytes as promising ingredients in functional food products and/or as sources of bioactive compounds. However, further research is needed regarding the chemical characterization of these species under commercial cultivation practices, while further clinical and model trials have to be conducted to assess their long term bioactivity and elucidate potential toxic effects and regulations of safe consumption.
- Estudo da composição química de seis genótipos de Portulaca oleracea L.Publication . Fernandes, Ângela; Petropoulos, Spyridon Α.; Karkanis, Anestis; Barros, Lillian; Ntatsi, Georgia; Petrotos, Konstantinos; Lykas, Christos; Khah, Ebrahim; Ferreira, Isabel C.F.R.Portulaca oleracea L. (vulgarmente designada por beldroega) é uma erva daninha cujas partes aéreas são comestíveis, sendo consumidas cruas, em saladas ou cozidas [1]. Existe uma variação genética significativa entre os genótipos de beldroegas [2], e esta diversidade pode ser utilizada no desenvolvimento de cultivares de alto rendimento com elevado conteúdo em ácidos gordos ómega-3, por exemplo. O objetivo deste trabalho foi analisar a composição química de seis genótipos de beldroega: três ecótipos silvestres provenientes do mar Cáspio da região do Irão (genótipo A, B e C: das cidades de Sari, Gorgan e Aliabad, respetivamente), uma variedade local proveniente da região de “Domokos” na Grécia central (genótipo D) e duas cultivares comerciais beldroega comum de Gemma S.A. (genótipo E) e beldroega verde escura (genótipo F). Os açúcares foram determinados por cromatografia líquida de alta eficiência (HPLC) acoplada a um detetor de índice de refração; os ácidos orgânicos foram analisados por HPLC acoplada a um detetor de fotodíodos e os ácidos gordos por cromatografia gasosa acoplada a um detetor de ionização de chama. Verificou-se que a composição química de beldroegas é dependente do genótipo. O teor em açúcares totais foi mais elevado no genótipo B; o teor em ácido oxálico foi menor no genótipo D e maior no genótipo C. Os ácidos gordos mais abundantes foram o ácido palmítico (C16:0), o ácido oleico (C18:1), o ácido linoleico (C18:2n6) e o ácido alfa-linolénico (C18:3n3), com diferenças significativas nos teores presentes nos diferentes genótipos avaliados. O genótipo D apresentou maior percentagem relativa do ácido alfa-linolénico. O genótipo E revelou possuir uma composição equilibrada de ácidos gordos ómega-3 e ómega-6. As variedades comerciais (genótipos E e F) foram bastante similares aos genótipos B e C. Este estudo fornece novas informações sobre a composição química de beldroegas que podem ser utilizadas na indústria alimentar como produtos de elevada qualidade e valor acrescentado. Assim, estas plantas devem ser valorizadas, nomeadamente como uma fonte de ácidos gordos ómega-3.
- Halophytic herbs of the Mediterranean basin: an alternative approach to healthPublication . Petropoulos, Spyridon Α.; Karkanis, Anestis; Martins, Natália; Ferreira, Isabel C.F.R.Wild native species are usually grown under severe and stressful conditions, while a special category includes halophytic species that are tolerant to high salinity levels. Native halophytes are valuable sources of bioactive molecules whose content is higher in saline than normal conditions, since the adaptation to salinity mechanisms involve apart from changes in physiological functions the biosynthesis of protectant molecules. These compounds include secondary metabolites with several beneficial health effects which have been known since ancient times and used for medicinal purposes. Recent trends in pharmaceutical industry suggest the use of natural compounds as alternative to synthetic ones, with native herbs being strong candidates for this purpose due to their increased and variable content in health promoting compounds. In this review, an introductory section about the importance of native herbs and halophyte species for traditional and modern medicine will be presented. A list of the most important halophytes of the Mediterranean basin will follow, with special focus on their chemical composition and their reported by clinical and ethnopharmacological studies health effects. The review concludes by suggesting future requirements and perspectives for further exploitation of these valuable species within the context of sustainability and climate change.
- Harvesting time affects yield and chemical composition of Cichorium spinosum L.Publication . Petropoulos, Spyridon Α.; Fernandes, Ângela; Karkanis, Anestis; Ntatsi, Georgia; Barros, Lillian; Ferreira, Isabel C.F.R.In the present study, the eff ect of the number of harvests on yield and chemical composition of Cichorium spinosum L. plants was examined. Seeds of were sown in seed trays containing peat and young seedlings were transplanted in 2L pots containing peat and perlite (1:1 v/v). Plants were harvested two or three times during the growing period, while control plants (no prior harvests) were also harvested at the same time. Rosette diameter, number of leaves, SPAD index, and fresh and dry weight were recorded at harvest, while chemical composition of leaves was also assessed (fatty-acids, sugars, organic acids, and tocopherols content). Regardless of the number of harvests, total fresh weight and number of leaves were higher comparing to control plants, whereas dry weight and rosette diameter were higher in control plants. SPAD index was mostly aff ected by harvesting time (growth stage) and decreased during the growing season. Signifi cant diff erences were also observed in chemical composition of the aerial parts of plants in relation to the number of harvests, with control treatment for the third cutting having the higher content in sugars, organic acids, saturated and monounsaturated fatty acids, and 1st cutting showed the best results for tocopherols. In conclusion, successive harvests (two or three harvests) increased total yield of C. spinosum plants, comparing to control plants, whereas they had a negative eff ect on sugar, organic and fatty acids content.
- Nutrient solution composition and growing season affect yield and chemical composition of Cichorium spinosum plantsPublication . Petropoulos, Spyridon Α.; Fernandes, Ângela; Karkanis, Anestis; Antoniadis, Vasileios; Barros, Lillian; Ferreira, Isabel C.F.R.Nitrogen fertilizer form may affect quality and yield of leafy vegetables. In the present study, the effect of ammonium nitrogen rates on yield and chemical composition of Cichorium spinosum L. was examined. Five fertilizer treatments with different amounts of ammonium nitrogen (F1: 14%, F2: 24%, F3: 34%, F4: 43% and F5: 53% NH 4 -0N of total N) were applied. Fertilizer treatments had a significant effect on both plant fresh weight and chemical composition, depending on growing period and harvest stage. For both harvests of the 1st growing period, yield was higher in treatments F4 (43% NH 4 -N) and F5 (53% NH 4 -N), whereas in the 2nd growing period yield was higher for treatments F1, F2 and F3. Moreover, the highest content of total phenolics were recorded in the 2nd growing period. Antioxidant properties were also affected by fertilization treatments and growing periods, with antioxidant potency being higher in the 2nd growing period and for treatments F1 and F2. According to the results of the present study, nitrogen fertilizer form should be considered together with growing period and harvest stage as a useful means towards increasing the quality of the final product without compromising total yield.