Carlotta Galardi

Evaluation of Antioxidant Effect of Different Extracts of Myrtus communis L.

Oxidative stress is involved in the pathogenesis of numerous diseases. Nevertheless, no optimal natural antioxidant has been found for therapeutics, therefore polyphenol antioxidants have been looked for in myrtle leaves, a plant that in folk medicine has been used as anti-inflammatory drug. Antioxidant-rich fractions were prepared from myrtle (Myrtus communis L.) leaves liquid–liquid extraction (LLE) with different solvents. All myrtle extracts were very rich in polyphenols. In particular, hydroalcoholic extracts contain galloyl-glucosides, ellagitannins, galloyl-quinic acids and flavonol glycosides; ethylacetate extract and aqueous residues after LLE are enriched in flavonol glycosides and hydrolysable tannins (galloyl-glucosides, ellagitannins, galloyl-quinic acids), respectively. Qualitative and quantitative analysis for the single unidentified compound was also performed. Human LDL exposed to copper ions was used to evaluate the antioxidant activity of the myrtle extracts. Addition of these extracts did not affect the basal oxidation of LDL but dose-dependently decreased the oxidation induced by copper ions. Moreover, the myrtle extracts reduce the formation of conjugated dienes. The antioxidant effect of three myrtle extracts decreased in the following order: hydroalcoholic extracts, ethylacetate and aqueous residues after LLE. The extracts had the following IC50: 0.36, 2.27 and 2.88 μM, when the sum of total phenolic compounds was considered after the correction of molecular weight based on pure compounds. Statistical analysis showed a significant difference among hydroalcoholic extracts vs. the ethylacetate and aqueous residues after LLE. These results suggest that the myrtle extracts have a potent antioxidant activity mainly due to the presence of galloyl derivatives.

Antioxidant Activity of Galloyl Quinic Derivatives Isolated from P. lentiscus Leaves

The antioxidant properties of galloyl quinic derivatives isolated from Pistacia lentiscus L. leaves have been investigated by means of Electron Paramagnetic Resonance spectroscopy (EPR) and UV-Vis spectrophotometry. Antioxidant properties have been also estimated using the biologically relevant LDL test. The scavenger activities of gallic acid, 5- O -galloyl, 3,5- O -digalloyl, 3,4,5- O -trigalloyl quinic acid derivatives, have been estimated against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, superoxide ( O 2 m ) radical, and hydroxyl (OH) radical. On the whole, the scavenger activity raised as the number of galloyl groups on the quinic acid skeleton increased. The half-inhibition concentrations (IC 50 ) of di- and tri-galloyl derivatives did not exceed 30 w M for all the tested free radicals. All the tested metabolites strongly reduced the oxidation of low-density lipoproteins (LDL), following a trend similar to that observed for the scavenger ability against OH radical.

Polyphenols in greenhouse and open-air-grown lettuce

Abstract Lactuca sativa L. plants (cv. Audran) developed in greenhouse or in open air, were analysed for their polyphenol compounds (caffeic acid derivatives, quercetin and kaempferol glycosides) to verify whether these two different growing environments affected both the qualitative and quantitative phenol patterns. The lettuce extracts from greenhouse and open-air samples were compared and directly analysed by HPLC/DAD, HPLC/MS and HPTLC. All open-air samples had higher flavonol contents than the greenhouse ones. The applied rapid and sensitive HPTLC method could be routinely employed to determine the leaf flavonol content of a large number of lettuce samples.

Flavonoid distribution in tissues of Phillyrea latifolia L. leaves as estimated by microspectrofluorometry and multispectral fluorescence microimaging.

Abstract A new method for detecting the tissue-specific distribution of flavonoids has been developed by coupling microspectrofluorometry and multispectral fluorescence microimaging techniques. Fluorescence responses of cross sections taken from 1 year old Phillyrea latifolia leaves exposed to full (sun leaves) or 15% (shade leaves) solar radiation in a coastal area of Southern Tuscany were analyzed. Fluorescence spectra of different tissue layers, each normalized at its fluorescence maximum, that were stained or not stained with Naturstoff reagent A (in ethanol), under excitation with UV light (λexc = 365 nm) or blue light (λexc = 436 nm) were recorded. The shape of the fluorescence spectra of tissue layers from shade and sun leaves differed only under UV excitation. The fluorescence of stained cross sections from sun and shade leaves as well as from different layers of sun leaves received a markedly different contribution from the blue (470 nm) and the yellow-red (580 nm) wavebands. Such changes in tissue fluorescence signatures were related to light-induced changes of extractable caffeic acid derivatives and flavonoid glycosides, namely quercetin 3-O-rutinoside and luteolin 7-O-glucoside. Wall-bound phenolics, i.e. hydroxycinnamic acids (p-coumaric, ferulic and caffeic acid) and flavonoids (apigenin and luteolin derivatives), did not substantially differ between sun and shade leaves. A Gaussian deconvolution analysis of fluorescence spectra was subsequently performed to estimate the contribution of flavonoids (emitting at 600 nm, F600 [red fluorescence contribution = signal integrated over a Gaussian band centered at about 600 nm]) relative to the tissue fluorescence (Ftot [total fluorescence = signal integrated over the whole fluorescence spectrum]). The F600/Ftot ratios sharply differed between analogous tissues of sun and shade leaves, as well as among tissue layers within each leaf type. A highly resolved picture of the tissue flavonoid distribution was finally provided through a fluorescence microimaging technique by acquiring fluorescence images at the blue (fluorescence at about 470 nm [F470]) and yellow-red (fluorescence at about 580 nm [F580]) wavelengths and correcting the F580 image for the contribution of nonflavonoids to the fluorescence at 580 nm. Monochrome images were elaborated by adequate computing functions to visualize the exclusive accumulation of flavonoids in different layers of P. latifolia leaves. Our data show that in shade leaves flavonoids almost exclusively occurred in the adaxial epidermal layer. In sun leaves flavonoids largely accumulated in the adaxial epidermal and subepidermal cells and followed a steep gradient passing from the adaxial epidermis to the inner spongy layers. Flavonoids also largely occurred in the abaxial epidermal cells and constituted the exclusive class of phenylpropanoids synthesized by the cells of glandular trichomes. The proposed method also allowed for the discrimination of the relative abundance of hydroxycinnamic derivatives and flavonoids in different layers of the P. latifolia leaves.

Minor polar compound and fatty acid analyses in monocultivar virgin olive oils from Tuscany

Virgin olive oil is a typical component of the Mediterranean diet, consumed unrefined and rich in important molecules, such as minor polar compounds (hydroxytyrosol, tyrosol, secoiridoids and flavonoids) and fatty acids. These molecules not only influence the sensorial properties of both olives and virgin oil but they are also important markers for typicity, biodiversity and quality determination of this product. The aim of this study was to evaluate the minor polar compound and fatty acid contents of 10 monocultivar virgin olive oils, typical of Tuscany, in order to have better knowledge about the quali-quantitative profiles of these compounds in samples obtained from both the same collecting season and same processing technique. Quali-quantitative analysis (performed by HPLC/DAD, HPLC/MS and GC) could be a useful tool to better correlate the typicity of the virgin olive oil with its minor polar compound and fatty acid pattern. Further studies are in progress to isolate the unknown compounds and to further investigate the quality index of this food product.

HPLC and HRGC analyses of polyphenols and secoiridoid in olive oil

SummaryPhenolic compounds influence the sensorial properties of both olives and virgin oil and are important markers for studying the characteristics of the fruits and controlling virgin oil production processes. The aim of this investigation was to evaluate the polyphenolic and secoiridoid content of various virgin olive oils from Abruzzo (Italy) to obtain knowledge on quali-quantitative profiles of these compounds in samples obtained from the same harvesting season (1998). These oils were collected from the most frequent Abruzzo cultivars, Gentile, Leccino and Dritta, by two different processing techniques: a process of milling and continuous washing with water or by traditional press. A quali-quantitative analysis was performed by HPLC-DAD, HPLC-MS and HRGC to characterize the different subclasses, and in particular the following compounds were identified and calibrated: tyrosol, hydroxytyrosol, phenolic acids (ferulic, syringic, caffeic and p-coumaric acids), oleuropein aglycone, deacetoxyoleuropein aglycone, elenolic acid and derivatives, other secoiridoid compounds and flavone aglycons (luteolin and apigenin).

HPLC quantification of flavonoids and biflavonoids inCupressaceae leaves

SummaryThe aim of this investigation was to obtain qualitative and quantitative profiles of the flavonoid and biflavonoid composition of six cypress species—Cupressus funebris L.,Cupressus sempervirens L.,Cupressus glabra L.,Cupressus arizonica L.,Cupressus goveniana L., andCupressus lusitanica L. HPLC-diode-array detection (DAD), HPLC-MS, and HPTLC were used to identify the individual compounds. A chromatographic method was optimized for identification and quantification of the main flavonoid glycosides and biflavonoids. The flavonoids identified and calibrated were: rutin, quercetin glucoside, quercetin rhamnoside, and kaempferol 3-O-rhamnoside. The biflavonoids identified and calibrated were: cupressuflavone, amentoflavone, robustaflavone, hinokiflavone, methylrobustaflavone, methylamentoflavone, and dimethylcupressuflavone.

Flavonoids from Olive Leaves ("Olea Europaea" L.) as Affected by Light

The effect of green house on the phenolic content of olive leaves (Olea europaea L.) in seven genotypes was studied. A decrease of flavonoids was found in plants grown in green house in comparison to those grown in open air. This was found in all the genotypes. The mainly involved compounds are luteolin and luteolin-7-glucoside. When olive leaves are used as starting material for phytochemical extracts the ecological conditions under which plants are grown should attentively be considered.