HPLC DEIERMINATION OF CATECEINS IN GRAPE SEEDS OF PLAVAC MALI CULTIVAR

Sa saznanjem važnosti katehina i mogućnosti njihove primjene u farmakologiji, te važnosti polifenola u kemotaksonomiji biljaka istraživali smo sadržaj katehina (flavan 3-ol monomera) u sjemenkama grožđa autohtone sorte plavac mali. Metodom rada obavljena je uspješna separacija katehina ekstrahiranih iz sjemenki grožđa. Sorta plavac mali sadrži visoke koncentracije flavan 3-ol monomera. Tijekom dozrijevanja grožđa sadržaj (+) katehina i (-) epikatehina se mijenja. Najveće se promjene zbivaju u vremenu šarka.Using HPLC technique on reversed-phase, the amounts of (+) - catechin and (-) epicatechin in grape seeds of autochthonous Dalmatian cultivar plavac mali, were analyzed during the growth season. To prevent interference between phenolic compounds, because many of them have similar UV absorption spectra, we fractionated acidic and neutral phenolic compounds on Sep Pak C 18 cartridges. Catechins were separated using HPLC with gradient solvent system at 280 mm. The grape seeds were analyzed during various stages of ripening. The results show the highest concentrations of catechins in the verison. The level decrease quickl troughout maturation. The major flavan- 3-ol monomer was (+) - catechin

The Antioxidant Power and Level of Lipid Peroxidation Products in the Sera of Apparently Healthy Adult Males

The aim of this study was to determine the antioxidant potential of the serum and the level of lipid oxidation products in the sera of apparently healthy adult males. The »antioxidant power« of the serum, defined as the ability to reduce ferric ions by antioxidants from the serum (FRAP), was taken as the indicator of total antioxidation potential. The formation of lipid oxidation products was evaluated as thiobarbituric reactive species serum test (TBARS). The ferrous oxidation in xylenol orange version 2 (FOX2) assay coupled with triphenylphosphine was used for measurement of total sera hydroperoxides (ROOHs). The following biochemical variables were determined in the sera: aspartat aminotranspherase (AST), alanine aminotranspherase (ALT), g-glutamyl transpherase (GGT), bilirubin, glucose, creatinine, cholesterol, triglycerides and hemoglobin. Blood sera from apparently healthy subjects (166 adult males) were analyzed. Median age of study participants was 36 years (range 25–50 years). The X±SD sera FRAP level of the 166 apparently healthy adult males was 1047±131 mmol/L (779–1410 range). The X±SD level of sera TBARS was 1.2±0.3 mmol/L of the sera (0.5–2.2 range). Compared with the level of TBARS in the sera, the level of FOX2-ROOH was significantly higher. The X±SD level of lipid hydroperoxides in the fresh sera, determined as FOX2, was 3.9±1.5 mmol/L of the sera (1.9–6.9 range). Observation of correlation between FRAP and determined biochemical variables in the sera have confirmed a statistically significant linear correlation between sera FRAP and bilirubin, hemoglobine, glucose, ALT and triglycerides (p<0.05). The results of sera FRAP, TBARS and FOX2 levels can help in estimating the antioxidant status of humans. Significant correlation between the antioxidant power of blood serum and particular biochemical parameters indicates the complexity of defence mechanisms and various molecules involved in increasing the reduction power of the serum

The Antioxidant Power and Level of Lipid Peroxidation Products in the Sera of Apparently Healthy Adult Males

The aim of this study was to determine the antioxidant potential of the serum and the level of lipid oxidation products in the sera of apparently healthy adult males. The »antioxidant power« of the serum, defined as the ability to reduce ferric ions by antioxidants from the serum (FRAP), was taken as the indicator of total antioxidation potential. The formation of lipid oxidation products was evaluated as thiobarbituric reactive species serum test (TBARS). The ferrous oxidation in xylenol orange version 2 (FOX2) assay coupled with triphenylphosphine was used for measurement of total sera hydroperoxides (ROOHs). The following biochemical variables were determined in the sera: aspartat aminotranspherase (AST), alanine aminotranspherase (ALT), g-glutamyl transpherase (GGT), bilirubin, glucose, creatinine, cholesterol, triglycerides and hemoglobin. Blood sera from apparently healthy subjects (166 adult males) were analyzed. Median age of study participants was 36 years (range 25–50 years). The X±SD sera FRAP level of the 166 apparently healthy adult males was 1047±131 mmol/L (779–1410 range). The X±SD level of sera TBARS was 1.2±0.3 mmol/L of the sera (0.5–2.2 range). Compared with the level of TBARS in the sera, the level of FOX2-ROOH was significantly higher. The X±SD level of lipid hydroperoxides in the fresh sera, determined as FOX2, was 3.9±1.5 mmol/L of the sera (1.9–6.9 range). Observation of correlation between FRAP and determined biochemical variables in the sera have confirmed a statistically significant linear correlation between sera FRAP and bilirubin, hemoglobine, glucose, ALT and triglycerides (p<0.05). The results of sera FRAP, TBARS and FOX2 levels can help in estimating the antioxidant status of humans. Significant correlation between the antioxidant power of blood serum and particular biochemical parameters indicates the complexity of defence mechanisms and various molecules involved in increasing the reduction power of the serum

Insight in the phenolic composition and antioxidative properties of Vitis vinifera leaves extracts

In the present investigation, leaf ethanolic extracts of Vitis vinifera were assayed for their polyphenolic composition and antioxidative properties. The leaves were collected during lush vegetation period (May leaves) and after the harvest (September leaves). Air dried plant material was homogenized and the polyphenolic constituents were extracted using conventional solvent extraction procedure. Total phenolics, flavonoids, non-flavonoids, catechins and flavanols were determined using spectrophotometric methods. Both extracts were very rich in phenolic compounds. The concentration of total phenols in September leaves extract was about 30 % higher compared to May leaves extract, due to the increase of flavonoid (catechin) fraction. Non-flavonoid compound content was almost equal in both extracts. The amount of flavanols, determined with p-dimethylaminocinnamaldehyde method, was taken as indicator of flavan-3-ol monomers, while high catechin content determined by vanillin method, indicated the presence of polymeric fraction. The total catechin content in September leaves extract was more than 3 folds higher in comparison to May leaves extract. Principal phenolic compounds were separated by high pressure liquid chromatography on reverse phase. Antioxidant properties, determined as: 2,2-diphenyl-1-picrylhydrazyl radical and 2,2\u27-azinobis-(3-ethylbenzthiazoline-6-sulfonate) radical cation scavenging ability, ferric reducing/antioxidant power, Fe2+ chelating activity, and using β-carotene bleaching assay, were total phenol concentration dependent. September leaves extract had better free radical scavenging capacity, higher reducing power, and was more efficient in protecting the oxidation of emulsified linoleic acid, in comparison with May leaves extract which showed better chelating ability. The presence of active phenolic compounds: phenolic acids (3-hydroxybenzoic acid, caffeic acid, gallic acid, vanillin acid), flavonoids ((+)-catechin, (-)-epicatechin, apigenin, myricetin, quercetin, quercetin-4\u27-glucoside, rutin), and stilbenes (trans-resveratrol and resveratrol derivatives) was confirmed in both extracts. According to the results achieved, vine leaf extracts can be considered rich natural source of polyphenols with significant antioxidant properties

Effect of the extraction solvent on the oleuropein content and antioxidant properties of olive leaf (cv. Oblica, Lastovka and Levantinka) extracts

In the last few decades numerous studies have proved that an olive leaf is a rich source of bioactive phenolic compounds, mainly oleuropein and its derivatives. The aim of this study was to investigate the influence of the extraction solvent on the phenolic and oleuropein content in the leaf extracts of Dalmatian autochthonic olive cultivars: Oblica, Lastovka and Levantinka. The antioxidant activity of leaf extracts was determined using FRAP method and by metal chelating activity evaluation. The recovery obtained using methanol and ethanol (50:50, v/v) was higher than by use of water solvents. The highest share of total phenols and oleuropein was detected in ethanolic extract of Lastovka, while almost two-fold lower amounts were obtained using water extracts, both hot water and room temperature water. The extremely significant correlation between the FRAP and oleuropein/phenolic content points out the importance of these compounds in the total reducing activity of the extracts. All tested extracts provided good chelating activity probably due to the high concentrations of oleuropein but also the presence of other compounds with catechol structure, which is the most important structural feature of strong chelating activity. According to the obtained results it can be concluded that the extraction of polyphenols from olive leaves, especially from Lastovka cultivar, could present an interesting means of increasing the value of this cheap plant material that often remains unused after the harvest

In vitro Antioxidant and Antibacterial Activity of Lamiaceae Phenolic Extracts: A Correlation Study

U radu je spektrofotometrijski određen udjel ukupnih fenola i fenolnih podgrupa u ekstraktima pet biljaka iz porodice Lamiaceae (kadulja, majčina dušica, matičnjak, menta i mravinac), a udjel je pojedinih fenola utvrđen pomoću visokodjelotvorne tekućinske kromatografije. Antioksidacijska je aktivnost ekstrakata ispitana pomoću različitih metoda, a njihov antibakterijski učinak s pomoću najvažnijih patogenih bakterija prisutnih u hrani, kao što su: Campylobacter coli, Salmonella Infantis, Escherichia coli, Bacillus cereus, Listeria monocytogenes i Staphylococcus aureus. Najveći su udjeli ukupnih fenola i neflavonoida pronađeni u ekstraktu kadulje, koji je imao i najbolji antibakterijski učinak, osobito na Gram-pozitivne bakterije i C. coli. Najbolja je reducirajuća snaga i sposobnost uklanjanja molekula slobodnih radikala dokazana za ekstrakt matičnjaka, koji je imao najveći udjel ružmarinske kiseline. Nadalje, analizom glavnih komponenata ispitan je utjecaj fenola, osobito ružmarinske kiseline, na biološka svojstva ekstrakata biljaka iz porodice Lamiaceae. Udjel je ružmarinske kiseline bio u pozitivnoj korelaciji sa svim antioksidacijskim parametrima, što potvrđuje njezin značajan doprinos antioksidacijskoj aktivnosti ispitanih ekstrakata.Total phenols and phenolic subgroups of five Lamiaceae plant extracts (sage, thyme, lemon balm, peppermint and oregano) were determined spectrophotometrically, whereas the individual phenolics were determined by high-performance liquid chromatography. The antioxidant activity of the extracts was evaluated by means of a multiple method approach, while the antibacterial activity was tested against major foodborne pathogens such as Campylobacter coli, Escherichia coli, Salmonella Infantis, Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus. The highest content of total phenolics and non-flavonoids was detected in the sage extract, which also showed the best antibacterial activity, especially against Gram-positive bacteria and C. coli. The best reducing power and free radical scavenging activity were obtained in lemon balm extract, with the highest content of rosmarinic acid. Additionally, the effect of the phenolics, especially rosmarinic acid, on biological properties of Lamiaceae plant extracts was investigated using principal component analysis. Rosmarinic acid showed good correlation with all antioxidant parameters, confirming its significant contribution to antioxidant activity of investigated plant extracts