Ion Trandafir

Mesoporous silica functionalized with 1-furoyl thiourea urea for Hg(II) adsorption from aqueous media.

New organic-inorganic hybrid materials were prepared by covalently anchoring 1-furoyl thiourea on mesoporous silica (SBA-15). By means of various characterization techniques (X-ray diffraction, nitrogen adsorption-desorption, thermogravimetric analysis, and FTIR spectroscopy) it has been established that the organic groups were successfully anchored on the SBA-15 surfaces and the ordering of the inorganic support was preserved during the chemical modifications. The hybrid sorbents exhibited good ability to remove Hg(II) from aqueous solution. Thus, at pH 6, the adsorption capacity of mercury ions reached 0.61 mmol g(-1).

HPLC determination of phenolic acids, flavonoids and juglone in walnut leaves.

A high-performance liquid chromatographic method with gradient elution and diode-array detection was developed to quantify free phenolic acids (gallic, vanillic, chlorogenic, caffeic, syringic, p-coumaric, ferulic, sinapic, salycilic, elagic and trans-cinnamic), flavonoids (catechin, epicatechin, rutin, myricetin and quercetin) and juglone in walnut leaves. Chromatographic separation was performed on a Hypersil Gold C18 column (5 µm particle size, 250 × 4.6 mm) and detection was conducted at three different wavelengths (254, 278 and 300 nm) according to the absorption maxima of the analyzed compounds. Validation procedures were conducted and the method was proven to be precise, accurate and sensitive. The developed method has been applied to analyze walnut leaves samples from nine different cultivars, with the same agricultural, geographical and climatic conditions. The experimental results revealed high concentrations of myricetin, catechin hydrate and rutin, and low concentrations of quercetin and epicatechin aglycones. Ellagic acid was established as the dominating phenolic acid of walnut leaves, followed by trans-cinnamic, chlorogenic and caffeic acids. Juglone content varied between 44.55 and 205.12 mg/100 g fresh weight. Significant differences were detected among cultivars for the concentration levels of phenolics.

Seasonal variation of the main individual phenolics and juglone in walnut (Juglans regia) leaves

Abstract Context: Walnut [Juglans regia L. (Juglandaceae)] is a rich source of phenolic compounds, including phenolic acids, naphtoquinones and flavonoids. The increasing interest in the powerful biological activities of plant phenolics has outlined the necessity of determining their content in leaves of different walnut cultivars. Objective: In this study, walnut leaves from walnut cultivars, originating from the same orchard and from the same year of production, were analyzed for their content in ellagic acid, rutin, myricetin and juglone. In addition, the seasonal variation of these major individual phenolics from June to August was determined. Materials and methods: An HPLC method was used for identification and quantification of ellagic acid, rutin, myricetin and juglone contained in the methanol extract of walnut leaves in nine different cultivars grown under the same agricultural, geographical and climatic conditions. Results: Cultivars and sampling date had statistically significant influence on the phenolics contents in walnut leaves. The results showed that ellagic acid, rutin, myricetin and juglone were more abundant in July 15th samples (average content is 84.62 mg/100 g FW, 98.9 mg/100 g FW, 178.09 mg/100 g FW and 73.81 mg/100 g FW, respectively). Their contents increases similarly in all the cultivars; therefore, the walnut leaves should preferentially be collected until early August, when phenolics content is higher. Discussion and conclusion: The results reported here show that genotype and its interaction with the environment could make significant differences in leaf polyphenols. Walnut leaves may become a noticeable source of compounds with health protective potential.

Ultraviolet Irradiation of Trans-Resveratrol and HPLC Determination of Trans-Resveratrol and Cis-Resveratrol in Romanian Red Wines

A reversed-phase high-performance liquid chromatography method with diode array detection was developed for the determination of trans- and cis-resveratrol in red wines. Separation was achieved after direct injection by the use of a BDS Hypersil C18 column (250 × 4.6 mm) with gradient elution (solvent A: acetic acid 2%, solvent B: acetonitrile). Detection of trans- and cis-resveratrol was performed at 306 and 286 nm, respectively. The retention times of trans- and cis-resveratrol were 22.2 and 26.1 min, respectively. Good linearity and precision were obtained for the two isomers. Detection limits of 0.004 mg/L for trans-resveratrol and 0.02 mg/L for cis-reveratrol were obtained. The developed method was applied to determine cis- and trans-resveratrol in 30 red wines produced in Oltenia (southwestern Romania). The wines came from different vineyards harvested in various vintages. The concentration of trans-resveratrol ranged from 0.287 to 7.188 mg/L, while the content of cis-resveratrol ranged from 0.718 to 6.587 mg/L. The highest amount of trans-resveratrol was found in Merlot from Vanju Mare, Mehedinti (7.188 mg/L), followed by Sirah from Corcova, Mehedinti (4.738 mg/L), both from the 2010 harvest. The paper also approaches the study of the transformation of trans-resveratrol into the cis form after ultraviolet irradiation through glass and quartz. At the irradiation of a trans-resveratrol solution through quartz, the formation of another two compounds apart from cis-resveratrol was observed.

Phenolic acids and flavonoids profiles of extracts from edible wild fruits and their antioxidant properties

ABSTRACT In this study, the total phenolic, total flavonoids, phenolic compounds, the mineral content, and antioxidant activity of fruit extracts of seven wild species (Crataegus monogyna Jacq., Prunus spinosa L., Rosa canina L., Hippophaë rhamnoides L., Rubus fruticosus L., Prunus padus, Cornus mas L.) were investigated. The results indicated significant differences (p < 0.05) in the total phenolics and total flavonoids content, between the seven analyzed species. These ranged from 184.69 to 727.29 mg GAE/100 g FW and 17.27 to –165.55 mg QE/100 g FW, respectively. The antioxidant activity found in fruits was not directly affected by the total phenolic content (TPC). This activity was linked to a larger extent to the type of individual phenolic compounds and to a lesser extent to the TPC, because fruits with higher TPC have not always presented the highest values of antioxidant activity. HPLC analysis of methanolic extract showed the presence of phenolic acids (i.e. gallic, vanillic, chlorogenic, caffeic, syringic, p-coumaric, ferulic, sinapic, salycilic, elagic, and trans-cinnamic) and flavonoids (i.e. catechin, epicatechin, rutin, myricetin, and quercetin). Significant differences (p < 0.05) were observed in each individual mineral between fruits from wild flora. The fruits tissues of wild species turned out to be a good source of calcium (Ca), magnesium (Mg), sodium (Na), iron (Fe), manganese (Mn), copper (Cu), chromium (Cr), zinc (Zn), and boron (B). The results demonstrated that wild species possessed great potential for food production as sources of bioactive compounds such as phenolic compounds and minerals, for food supplements or functional foods.

Optimization of ultrasound-assisted hydroalcoholic extraction of phenolic compounds from walnut leaves using response surface methodology

Abstract Context Walnut leaves are highly appreciated for their pharmacological effects and therapeutic properties which are mainly attributed to their high content of phenolic compounds. Objective This study optimizes ultrasound assisted hydroalcoholic extraction (UAE) of phenolic compounds from dried walnut leaves by the maximization of total phenolics content (TPC) and total flavanoids content (TFC) of the extracts. Materials and methods Optimal conditions with regard to ethanol concentration (X1: 12.17–95.83% v/v), extraction time (X2: 8.17–91.83 min) and liquid-to-solid ratio (X3: 4.96–25.04 v/w) were identified using central composite design combined with response surface methodology. A high-performance liquid chromatography method with diode-array detection was used to quantify phenolic acids (gallic, vanillic, chlorogenic, caffeic, syringic, p-coumaric, ferulic, sinapic, salicylic, ellagic and trans-cinnamic), flavonoids (catechin, epicatechin, rutin, myricetin and quercetin) and juglone in the extracts. Results Liquid-to-solid ratio and ethanol concentration proved to be the primary factors affecting the extraction efficiency. The maximum predicted TPC, under the optimized conditions (61% ethanol concentration, 51.28 min extraction time and 4.96 v/w liquid-to-solid ratio) was 10125.4 mg gallic acid equivalents per liter while maximum TFC (2925 mg quercetin equivalents per liter) occurred at 67.83% ethanol concentration, 4.96 v/w liquid-to-solid ratio and 49.37 min extraction time. High significant correlations were found between antioxidant activity and both TPC (R2 = 0.81) and TFC (R2 = 0.78). Discussion and conclusion Extracts very rich in polyphenols could be obtained from walnut leaves by using UAE, aimed at preparing dietary supplements, nutraceuticals or functional food ingredients.

Phenolic Profile and Antioxidant Capacity of Walnut Extract as Influenced by the Extraction Method and Solvent

Abstract Total phenolic content, total flavonoid content, antioxidant activity and individual phenolic compounds were assessed in full fat and defatted walnut kernel. For quantification of phenolic fraction of walnut kernels, two different solvents (methanol and ethanol) and two methods of extraction (ultrasonic-assisted extraction and Soxhlet extraction) were tested. Total phenolics, flavonoid content and antioxidant capacity of alcoholic extracts varied depending on the solvent used and extraction methods. Seventeen phenolic compounds were detected and the study provides evidence on high phenolic contents and high antioxidant potential of full fat walnut kernel and defatted walnut kernel. The Soxhlet extraction is the best in terms of the amounts of total phenolic content (2,089.2 mg gallic acid equivalent/100 g dry matter), while the ultrasonic assisted extraction is a fast method but resulted in significantly lower phenolic content (667.3–1,426.8 mg gallic acid equivalent /100 g dry matter). The concentrations of phenolics (especially (+)-catechin hydrate, juglone, vanillic acid, caffeic acid, ferulic acid, sinapic acid, salicylic acid and ellagic acid) are many fold lower in ultrasonic-assisted extraction as compare to the Soxhlet method using the same extraction solvent. The results of this study provide evidence on high phenolic contents and high antioxidant potential of full fat and defatted walnut kernel.

Evolution of antioxidant activity and bioactive compounds in tomato (Lycopersicon esculentum Mill.) fruits during growth and ripening

The interest in the consumption of tomato (Lycopersicon esculentum Mill.) is, to a large extent, due to its content of bioactive compounds and their importance as dietary antioxidants. During the growth and ripening process, there are quantitative and qualitative changes in the fruit composition which determine the nutritional quality and antioxidant potential at each stage.Two halfdeterminate early hybrids cultivars (Prekos and Balkan) and one indeterminate mid-early hybrid cultivar (Reyana) were considered for this study. Fruits from plants grown on sandy soil in an unheated greenhouse were collected at three growth and six maturity stages. Antioxidant activity, dry matter, soluble solids, titratable acidity, ascorbic acid, lycopene, beta-carotene, chlorophylls and total phenolic contents were monitored. During fruit growth, dry matter, soluble solids and titratable acidity recorded a slight decrease, polyphenols and beta-carotene contents remained almost the same while ascorbic acid content and antioxidant activity increased continuously. The stage of ripening significantly influenced the content of all bioactive compounds as well as the antioxidant activity of tomato fruits. The first stages of ripening were characterized by a slight decrease of the dry matter content and by an increase of the titratable acidity, while in the last two stages of ripening these variations reversed. Ascorbic acid and total phenolics content increased as maturity progressed from mature green to pink or light red stage and decreased afterward. Lycopene started to accumulate since turning and sharply increased in the last three stages, on average 36%of the lycopene content being accumulated in the last stage of ripening. In terms of hydrophilic antioxidant activity, depending on the cultivar, the pink or light red stages were the ones with the greatest potential. Althoughthere weresignificant differences among the contents of bioactive compounds and antioxidant activity of the three cultivars studied, their patterns of variation during the nine stages were quite similar.

Nutritional and bioactive compounds in dried tomato processing waste

ABSTRACT This research investigated the nutritional and antioxidant composition of tomato processing waste with the aim to enable the development of new alternatives for the recycling of this by-product. The samples of dried tomato waste were found to contain 176.2 g/kg protein, 21.9 g/kg fat, 524.4 g/kg crude fiber and 42.1 g/kg ash. The essential amino acids represented 34.2% of total protein, the most abundant being leucine, followed by lysine and isoleucine. Unsaturated fatty acids represent 77.04% of the total fatty acids, linoleic being the major one. The results confirmed that dried tomato wastes contain considerable amounts of lycopene (510.6 mg/kg) and β-carotene (95.6 mg/kg) and exhibited good antioxidant properties. Total phenolics showed average contents of 1229.5 mg GAE/kg, of which flavonoids accounted for 415.3 mg QE/kg. Ellagic and chlorogenic acids were the most abundant phenolic acids while among flavonoids only rutin and myricetin were quantified.

Bioactive compounds and antioxidant activity of hot pepper fruits at different stages of growth and ripening

The evolution of some bioactive compounds and antioxidant activity has been investigated during fruit growth and ripening of five pepper cultivars: ‘Dracula’, ’Pintea’, ‘Pepperone’, ‘Bulgarian carrot’ (C. annuum) and ‘Christmas bell’ (C. baccatum var. pendulum). High-performance liquid chromatography was used to quantify the content of capsaicin in the fruit in order to determine the pungency level of analyzed peppers. Pepper fruits were collected at five stages of growth and ripening. Dry matter, soluble solids, ascorbic acid, total phenolics, including total flavonoids, capsaicin content and antioxidant activity were determined at each stage. There were major differences among the cultivars in the accumulation of the bioactive compounds in the fruit during their growth and ripening, although the quantitative accumulation pathway of various components had a similar trend during phenophases. Antioxidant activity and ascorbic acid content increased during growth and ripening of hot peppers, the highest levels being found in the last stage of ripening. The pattern of variation of total flavonoid content was cultivar dependent. In most cultivars, an important increase of the total phenolic and total flavonoid content was observed in the last stage of ripening. Capsaicin content recorded a maximum level in F3 or F4 depending on cultivar, and decreased afterwards until the complete ripening of the pepper fruits. ‘Dracula’ cultivar was classified as “non-pungent” (fruits are not spicy) while ‘Pintea’ was classified as “highly pungent”, the other analyzed cultivars having an average level of pungency.