Patrizia Pinelli

Antimicrobial and antiviral activity of hydrolysable tannins.

Hydrolysable tannins (HTs), secondary metabolites widely distributed in the plant kingdom, are generally multiple esters of gallic acid with glucose. HTs have been shown to be effective antagonists against viruses, bacteria and eukaryotic microorganisms. The present review examines the antimicrobial and antiviral activity of HTs, the mechanism(s) of action, and some structure-activity relationships.

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.

Identification and Quantitation of Polyphenols in Leaves of Myrtus communis L.

SummaryA liquid-solid extraction and purification procedure (LSE) was developed to identify and quantify polyphenols in the leaf tissue ofMyrtus communis L. Identification and quantitation of individual compounds was performed using HPTLC, HPLC-DAD and HPLC-MS analysis. Leaves ofMyrtus communis L. contain small amounts of phenolic acids (caffeic, ellagic and gallic acids) and quercetin derivatives (quercetin 3-O-galactoside and quercetin 3-O-rhamnoside), whereas catechin derivatives (epigallocatechin, epigallocatechin 3-O-gallate, epicatechin 3-O-gallate) and myricetin derivatives (myricetin 3-O-galactoside, myricetin 3-O-rhamnoside) are present in large amounts. This is the first report on the occurrence of galloyl-derivatives of catechin and gallo-catechin inMyrtus communis L. 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).

Commercial and laboratory extracts from artichoke leaves: estimation of caffeoyl esters and flavonoidic compounds content

Artichoke leaf extracts are widely used alone or in association with other herbs for embittering alcoholic and soft drinks and to prepare herbal teas or herbal medicinal products. Despite this wide diffusion, the European Pharmacopoeia does not report an official method for the determination of the active principles of artichoke leaf extracts. This work reports a quali-quantitative determination by HPLC/DAD and HPLC/MS techniques of both cynnamic acids and flavonoids present in some artichoke leaf commercial extracts (Com) compared with two different laboratory extracts (Lab). Most of the commercial extracts showed a similar quali-quantitative pattern with a single exception having five-six times higher value. The quantitative data from the Italian Pharmacopoeia(IP) official method does not evaluate the flavonoidic fraction and showed an overestimation of the caffeoyl esters with respect to the HPLC/DAD results. The proposed HPLC/DAD method was able to completely characterize and quantify this matrix and represents a contribution to better quality control of these herbal extracts.

Characterization of Matricaria recutita L. Flower Extracts by HPLC-MS and HPLC-DAD Analysis

SummaryMatricaria recutita L. is a spontaneous herbaceous perennial plant and its drug is largely used, as an infusion, for its anti-inflammatory properties, especially for respiratory and gastroenteric tracts. Granular soluble extracts of this drug are also used in children’s diets.The purpose of this work was to investigate the polyphenolic content of different parts of chamomile flowers. Methanolic extracts were compared and directly analysed by HPLC-DAD and HPLC-MS. The comparison between UV-Vis and MS spectra, carried out in positive and negative ionisation mode, allows identification of all the main polyphenolic compounds present in different parts of the flowers.The findings reported herein both confirm the presence of several flavonoids, described previously, and evidence large amounts of caffeic and ferulic acid derivatives. No other evidence of the presence of these compounds in chamomile flowers has been previously reported.Quantitative comparison of the flavonoid and phenolic acid derivatives present in receptacles, ligulate, tubular and total flowers was also performed.

Self-assembling and antioxidant activity of some vitamin C derivatives

Abstract Vitamin C behaves as a very powerful radical scavenger in aqueous media and can be successfully used to prevent peroxidation of important unsaturated organic molecules. Its hydrophobic derivatives (i.e. alkyl-esters and ethers) perform the same antioxidant activity in self-assembled structures such as micelles and microemulsion systems. In this work the study on the micellar properties obtained from these hydrophobic derivatives by viscosity, light-scattering, and small-angle neutron-scattering (SANS) experiments, and a comparison between the antioxidant activity of the vitamin C derivatives and the most common natural antioxidants are reported.