Browsing by Subject "phenolic compounds"

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  • Hbika, Asmae; Daoudi, Nour Elhouda; Bouyanzer, Abdelhamid; Bouhrim, Mohamed; Mohti, Hicham; Loukili, El Hassania; Mechchate, Hamza; Al-Salahi, Rashad; Nasr, Fahd A.; Bnouham, Mohamed; Zaid, Abdelhamid (2022)
    Artemisia absinthium L. is one of the plants which has been used in folk medicine for many diseases over many centuries. This study aims to analyze the chemical composition of the Artemisia absinthium ethyl acetate and its aqueous extracts and to evaluate their effect on the pancreatic alpha-amylase enzyme and the intestinal alpha-glucosidase enzyme. In this study, the total contents of phenolic compounds, flavonoids, and condensed tannins in ethyl acetate and the aqueous extracts of Artemisia absinthium leaves were determined by using spectrophotometric techniques, then the antioxidant capacity of these extracts was examined using three methods, namely, the DPPH (2, 2-diphenyl-1picrylhydrazyl) free radical scavenging method, the iron reduction method FRAP, and the beta-carotene bleaching method. The determination of the chemical composition of the extracts was carried out using high-performance liquid chromatography-the photodiode array detector (HPLC-DAD). These extracts were also evaluated for their ability to inhibit the activity of the pancreatic alpha-amylase enzyme, as well as the intestinal alpha-glucosidase enzyme, in vitro and in vivo, thus causing the reduction of blood glucose. The results of this study showed that high polyphenol and flavonoid contents were obtained in ethyl acetate extract with values of 60.34 +/- 0.43 mg GAE/g and 25.842 +/- 0.241 mg QE/g, respectively, compared to the aqueous extract. The results indicated that the aqueous extract had a higher condensed tannin content (3.070 +/- 0.022 mg EC/g) than the ethyl acetate extract (0.987 +/- 0.078 mg EC/g). Ethyl acetate extract showed good DPPH radical scavenging and iron reduction FRAP activity, with an IC50 of 0.167 +/- 0.004 mg/mL and 0.923 +/- 0.0283 mg/mL, respectively. The beta-carotene test indicated that the aqueous and ethyl acetate extracts were able to delay the decoloration of beta-carotene with an inhibition of 48.7% and 48.3%, respectively, which may mean that the extracts have antioxidant activity. HPLC analysis revealed the presence of naringenin and caffeic acid as major products in AQE and EAE, respectively. Indeed, this study showed that the aqueous and ethyl acetate extracts significantly inhibited the pancreatic alpha-amylase and intestinal alpha-glucosidase, in vitro. To confirm this result, the inhibitory effect of these plant extracts on the enzymes has been evaluated in vivo. Oral intake of the aqueous extract significantly attenuated starch- and sucrose-induced hyperglycemia in normal rats, and evidently, in STZ-diabetic rats as well. The ethyl acetate extract had no inhibitory activity against the intestinal alpha-glucosidase enzyme in vivo. The antioxidant and the enzyme inhibitory effects may be related to the presence of naringenin and caffeic acid or their synergistic effect with the other compounds in the extracts.
  • Verni, Michela; Pontonio, Erica; Krona, Annika; Jacob, Sera; Pinto, Daniela; Verardo, Vito; Díaz-de-Cerio, Elixabet; Coda, Rossana; Rizzello, Carlo (2020)
    Brewers' spent grain (BSG) is the major by-product of the brewing industry which remain largely unutilized despite its nutritional quality. In this study, the effects of fermentation on BSG antioxidant potential were analyzed. A biotechnological protocol including the use of xylanase followed by fermentation withLactiplantibacillus plantarum (Lactobacillus plantarum)PU1, PRO17, and H46 was used. Bioprocessed BSG exhibited enhanced antioxidant potential, characterized by high radical scavenging activity, long-term inhibition of linoleic acid oxidation and protective effect toward oxidative stress on human keratinocytes NCTC 2544. Immunolabelling and confocal laser microscopy showed that xylanase caused an extensive cell wall arabinoxylan disruption, contributing to the release of bound phenols molecules, thus available to further conversion through lactic acid bacteria metabolism. To clarify the role of fermentation on the antioxidant BSG potential, phenols were selectively extracted and characterized through HPLC-MS techniques. Novel antioxidant peptides were purified and identified in the most active bioprocessed BSG.
  • Siipola, Sari M.; Kotilainen, Titta; Sipari, Nina; Morales Suarez, Luis Orlando; Lindfors, Anders V.; Robson, T. Matthew; Aphalo, Pedro J. (2015)
    Plants synthesize phenolic compounds in response to certain environmental signals or stresses. One large group of phenolics, flavonoids, is considered particularly responsive to ultraviolet (UV) radiation. However, here we demonstrate that solar blue light stimulates flavonoid biosynthesis in the absence of UV-A and UV-B radiation. We grew pea plants (Pisum sativum cv. Meteor) outdoors, in Finland during the summer, under five types of filters differing in their spectral transmittance. These filters were used to (1) attenuate UV-B; (2) attenuate UV-B and UV-A We studied the relative importance of the UV and blue wavebands of sunlight for the phenolics in leaves of pea (Pisum sativum cv. Meteor) plants grown outdoors. We report a large reduction in epidermal flavonoids and a change in the flavonoid composition in leaf extracts when solar blue light was attenuated. Under the conditions of our experiment, these effects of blue light attenuation were much larger than those caused by attenuation of UV radiation.
  • El Omari, Nasreddine; Akkaoui, Sanae; El Blidi, Omar; Ghchime, Rokia; Bouyahya, Abdelhakim; Kharbach, Mourad; Yagoubi, Maamar; Balahbib, Abdelaali; Chokairi, Omar; Barkiyou, Malika (2020)
    The present study aimed to determine the phenolic compounds of Arislolochia Ion& root extracts and to evaluate their antibacterial activities on multiresistant strains. Phytochemical analysis revealed the presence of flavonoids, tannins, terpenoids, and alkaloids. The HPLC-DAD analysis of A. longa extracts showed the presence of several major bioactive compounds such as ferulic acid, 4-hydroxycinnamic acid, citric acid, and quinic acid. The agar diffusion method was used for the sensitivity test, while minimal inhibitory concentration (MIC) and minimal bactericidal concentration values were determined by microdilution assay. Different tests were carried out on 3 clinical multiresistant strains and 3 reference strains. The diameter of inhibition of Staphylococcus aureus ATCC 25923 induced by the ethyl acetate fraction at 200 mg/mL was 25 +/- 1 mm. Moreover, Escherichia coli ATCC 29522 showed a great sensitivity toward all the concentrations tested. The MICs of the active extracts vary between 12.5 and 100 mg/mL with a bacteriostatic effect on Pseudomonas aemginosa ATCC 27853, Enterococcus faecalis, and S. aureus ATCC 25923.
  • Paaso, Ulla; Keski-Saari, Sarita; Keinänen, Markku; Karvinen, Heini; Silfver, Tarja; Rousi, Matti; Mikola, Juha (2017)
    Abundant secondary metabolites, such as condensed tannins, and their interpopulation genotypic variation can remain through plant leaf senescence and affect litter decomposition. Whether the intrapopulation genotypic variation of a more diverse assortment of secondary metabolites equally persists through leaf senescence and litter decomposition is not well understood. We analyzed concentrations of intracellular phenolics, epicuticular flavonoid aglycones, epicuticular triterpenoids, condensed tannins, and lignin in green leaves, senescent leaves and partly decomposed litter of silver birch, Betula pendula. Broad-sense heritability (H-2) and coefficient of genotypic variation (CVG) were estimated for metabolites in senescent leaves and litter using 19 genotypes selected from a B. pendula population in southern Finland. We found that most of the secondary metabolites remained through senescence and decomposition and that their persistence was related to their chemical properties. Intrapopulation H-2 and CVG for intracellular phenolics, epicuticular flavonoid aglycones and condensed tannins were high and remarkably, increased from senescent leaves to decomposed litter. The rank of genotypes in metabolite concentrations was persistent through litter decomposition. Lignin was an exception, however, with a diminishing genotypic variation during decomposition, and the concentrations of lignin and condensed tannins had a negative genotypic correlation in the senescent leaves. Our results show that secondary metabolites and their intrapopulation genotypic variation can for the most part remain through leaf senescence and early decomposition, which is a prerequisite for initial litter quality to predict variation in litter decomposition rates. Persistent genotypic variation also opens an avenue for selection to impact litter decomposition in B. pendula populations through acting on their green foliage secondary chemistry. The negative genotypic correlations and diminishing heritability of lignin concentrations may, however, counteract this process.
  • Abidizadegan, Maryam; Blomster, Jaanika; Fewer, David; Peltomaa, Elina (2022)
    Simple Summary In recent decades, the demand for natural and sustainable bioproducts has risen markedly. Accordingly, microalgae have received much attention as a promising biological resource with great industrial potential, since the microalgal production of biologically active compounds can be boosted by changing their cultivation conditions. Light is one of the key factors in the photosynthetic process, which directly affects cell division and the production of biochemical compounds. This study investigated the effect of light color and the species-specific capability of cryptophyte algae to produce phycoerythrin, phenolic compounds, and exopolysaccharides. The produced biomolecules were further studied for their antioxidant activity. The results showed that changes in light quality significantly affect the biochemical compositions of cryptophyte algae. Moreover, species-specific responses to changes in light quality were identified. The quantity and quality of derived biomolecules from the studied cryptophytes are remarkable and indicate that cryptophytes could be considered promising candidates for producing natural biochemical products for practical applications in various industry sectors, such as food, pharmacy, and cosmetics. The accumulation and production of biochemical compounds in microalgae are influenced by available light quality and algal species-specific features. In this study, four freshwater cryptophyte strains (Cryptomonas ozolinii, C. pyrenoidifera, C. curvata, and C. sp. (CPCC 336)) and one marine strain (Rhodomonas salina) were cultivated under white (control), blue, and green (experimental conditions) lights. Species-specific responses to light quality were detected, i.e., the color of light significantly affected cryptophyte biomass productivity and biochemical compositions, but the optimal light for the highest chemical composition with high antioxidant capacity was different for each algal strain. Overall, the highest phycoerythrin (PE) content (345 mg g(-1) dry weight; DW) was reached by C. pyrenoidifera under green light. The highest phenolic (PC) contents (74, 69, and 66 mg g(-1) DW) were detected in C. curvata under control conditions, in C. pyrenoidifera under green light, and in C. ozolinii under blue light, respectively. The highest exopolysaccharide (EPS) content (452 mg g(-1) DW) was found in C. curvata under the control light. In terms of antioxidant activity, the biochemical compounds from the studied cryptophytes were highly active, with IC50 -values < 50 mu g mL(-1). Thus, in comparison to well-known commercial microalgal species, cryptophytes could be considered a possible candidate for producing beneficial biochemical compounds.
  • Suihkonen, Terhi (Helsingfors universitet, 2013)
    The literature review dealed with the composition of lingonberry, manufacture of juice powder and the effects of different carriers on properties of juice powder, especially glass transition temperature and stickiness. In addition, physical, functional and nutritional properties and the effect of storage conditions on juice powders were covered. The aim of the experimental work was to investigate the effect of spray- and freeze-drying and carriers on glass transition temperature and water sorption of lingonberry juice as well as the stability of vitamin C and phenolic compounds during drying and storage. The same amounts of maltodextrin (MD), whey protein isolate (WPI) or combination of MD/WPI in equal proportions were added to each sample. All samples were spray- and freeze-dried. After storage of powders at different relative humidities, glass transition temperature, water sorption, content of L-ascorbic acid and content of phenolic compounds were examined. Water sorption was examined by static and dynamic vapour sorption methods. The small particle size of containing WPI was problematic with spray-drying because not all of the powder in the drying air could be separated in the cyclone. Adding water back into the spray-dried samples was most difficult when the samples were stored at low relative humidities (0–11%). The smallest water sorption was observed with both static and dynamic vapour sorption methods in samples which contained only MD. Water contents of freeze-dried samples were lower than those of spray-dried samples. BET sorption isotherm described the water sorption behaviour of the lingonberry juice powders well. Glass transition temperatures of all samples decreased as the relative humidity increased. During storage, the amount of phenolic compounds in samples containing WPI remained the same, whereas the amount of phenolic compounds in samples with MD decreased. Enzymatic spectrophotometric determination was un suitable for determing L-ascorbic acid in lingonberry powder because the sample colour disturbed the measurement. MD and the combination of MD and WPI were suitable carriers in lingonberry juice. The amount of phenolic compounds in lingonberry juice powders were preserved well by whey protein isolate. Therefore, the spray-drying process should be developed in a way that brings about increase in particle size of powder containing WPI.
  • Raitanen, Jan-Erik; Järvenpää, Eila; Korpinen, Risto; Mäkinen, Sari; Hellström, Jarkko; Kilpeläinen, Petri; Liimatainen, Jaana; Ora, Ari; Tupasela, Tuomo; Jyske, Tuula (2020)
    Bark of Norway spruce and Scots pine trees contain large amounts of condensed tannins. Tannins extracted with hot water could be used in different applications as they possess antioxidative and antimicrobial activities. The use of bark tannins as e.g., food preservatives calls for increases in our knowledge of their antioxidative activities when applied in foodstuffs. To assess the ability of bark tannins to prevent lipid oxidation, hot water extracts were evaluated in a liposome model. Isolated tannins were also applied in dry-cured, salty meat snacks either as liquid extracts or in dry-powder form. Consumer acceptance of the snacks was tested by a sensory evaluation panel where outlook, odor, taste, and structure of the snacks were evaluated and compared to a commercial product without tannin ingredients. Our results show that conifer bark tannin-rich extracts have high capacity to prevent lipid oxidation in the liposome model. The efficacies of pine and spruce bark extracts were ten to hundred folds higher, respectively, than those of phenolic berry extracts. The bark extracts did not significantly influence the odor or taste of the meat snacks. The findings indicate that bark extracts may be used as sustainable food ingredients. However, more research is needed to verify their safety.
  • Song, Airu (Helsingin yliopisto, 2020)
    Sorghum and millets are important crops in the world and they are rich of phenolic compounds. Phenolic compounds have good antioxidant ability and they are regarded as the good natural protective screens for oxidative damage. However, the previous studies has only focused on the amount and antioxidant property of phenolic compounds in sorghum and millets and there were limited studies about the effect of sourdough fermentation on the phenolic compounds. Hence, it is necessary to study the fate of phenolic compounds during the sourdough fermentation. The aim of the experimental work was to study the changes of phenolic compounds, namely the soluble and bound phenolics, during lactic acid bacteria fermentation of wholegrain sorghum and millets, and to study the factors contributing to their modifications. Two millet varieties, i.e. finger miller and pearl millet (millet Jaune), and two types of sorghum, i.e. white sorghum and red sorghum were used in this study. Each experiment consisted of two samples, one unfermented and one fermented. The fermented sample was fermented by W. Confusa A16, which was isolated from a sourdough pancake in Burkina Faso and identified in University of Helsinki. During the experiment part, different extraction solvents and methods were used in order to obtain a better extraction of phenolics. Ethanol and methanol were selected as the extraction solvent for soluble phenolics and ultrasonic bath was used to assisst the extraction of insoluble-bound phenolics. And the content of phenolic compounds were determinated by Folin-Ciocalteu assay in coupled with spectrophotometer. The results showed that methanol as the extraction solvent was more efficient in extracting the soluble phenolics than ethanol. And ultrasonic bath could shorten the extraction time of bound phenols from 16h to 2.5h with a good extraction result compared with non-ultrasonic bath. In this study, the content of extracted phenolic compounds varied among different classes and subclasses. Sorghum generally contained higher content of phenolic compounds than millets. And the total phenolic compounds in red sorghum was higher than white sorghum. The changes of total phenolic compounds and insoluble-bound phenolic compounds during sourdough fermentation followed the same trend, both of which decreased after sourdough fermentation. Conversely, soluble phenolic compounds increased during sourdough fermentation both in millet and sorghum samples. Increased enzymatic activities and the increased acidic medium environment during sourdough fermentation might form new interactions between phenolics and other macromolecules or cause the structure changes of phenolics, thus lead to changes of the amount of extractable phenolic compounds. However, the results obtain from this experiment are not completely consistent with literature data, which might be related to the different cultivar of the sorghum and millet raw materials used and the experimental methods adopted .
  • Mälkiä, Kaisu (Helsingin yliopisto, 2017)
    A review of the literature on the role of bilberries in prevention of cardiovascular diseases, including existing knowledge on phenolic compounds in bilberries and their absorption, distribution, metabolism and excretion in humans, was performed. Analysis of phenolic metabolites in plasma and serum was also reviewed. Experimental work was then performed to set up and validate an UPLC-MS/MS method with solid phase extraction (SPE) as a pre-treatment for analysis of phenolic metabolites from bilberries in plasma samples; and to validate the Q-TOF-MS-method and use it with µSPE for analysis of phenolic compounds in plasma from subjects after an 8-week intervention with bilberry powder. It was found that the UPLC-MS/MS method could not be optimised to carry out the sample analyses. A particular challenge was analysis of the chosen internal standard, taxifolin, and determination of gallic acid as one of the phenolic metabolites. Thus, another method using HPLC-Q-TOF-MS was tested and validated. This method proved promising, as the accuracy for determination of compounds ranged from 58.2 to 143.1%, but was mainly around 100%, with LOD 13-4280 nM and LOQ 17-12839 nM. Recovery in the µSPE pre-treatment was poor, only 0.33-5.74%. However, analysis of the samples by different HPLC-Q-TOF-MS methods revealed significant differences between the bilberry intervention group and control group in terms of gallic acid and p-coumaric acid concentrations. Plasma concentrations of both compounds increased during the 8-week intervention.
  • van Dijk, Laura J. A.; Moreira, Xoaquin; Barr, Anna E.; Abdala-Roberts, Luis; Castagneyrol, Bastien; Faticov, Maria; Hardwick, Bess; ten Hoopen, Jan P. J. G.; de la Mata, Raul; Pires, Ricardo Matheus; Roslin, Tomas; Schigel, Dmitry S.; Timmermans, Bart G. H.; Tack, Ayco J. M. (2022)
    The world is rapidly urbanizing, thereby transforming natural landscapes and changing the abundance and distribution of organisms. However, insights into the effects of urbanization on species interactions, and plant-pathogen interactions in particular, are lacking. We investigated the effects of urbanization on powdery mildew infection on Quercus robur at continental and within-city scales. At the continental scale, we compared infection levels between urban and rural areas of different-sized cities in Europe, and investigated whether plant traits, climatic variables and CO2 emissions mediated the effect of urbanization on infection levels. Within one large city (Stockholm, Sweden), we further explored whether local habitat features and spatial connectivity influenced infection levels during multiple years. At the continental scale, infection severity was consistently higher on trees in urban than rural areas, with some indication that temperature mediated this effect. Within Stockholm city, temperature had no effect, while local accumulation of leaf litter negatively affected powdery mildew incidence in one out of three years, and more connected trees had lower infection levels. This study is the first to describe the effects of urbanization on plant-pathogen interactions both within and among cities, and to uncover the potential mechanisms behind the observed patterns at each scale.