Volatile components of grape pomaces from different cultivars of Sicilian Vitis vinifera L.

The volatile components of grape pomace coming from the processing of some of the most important varieties of grape (Vitis vinifera L.) cultivated in Sicily, namely Nero d'Avola, Nerello Mascalese, Frappato and Cabernet Sauvignon, have been determined by gas-chromatography (GC) and gas-chromatography-mass spectrometry (GC-MS). According to the winemaking procedure that entails the removal of stalks before fermentation, two kinds of grape pomace are obtained. The first consists of skins, pulp residues and seeds, the proper grape pomace, which is partially used for grappa, a typical Italian spirit, and alcohol production, the second consists almost exclusively of stalks. On the whole, 38 components have been characterized in the samples of grape pomaces, with Frappato cv. showing the richest composition; instead, 88 components have been detected in the stalks of Frappato, Nero d'Avola, Nerello Mascalese and Cabernet Sauvignon varieties. In order to make a comparison between the grape varieties easier, the volatile components detected in the two sets of samples (grape pomaces and stalks) have been grouped in different classes. Significant differences among varieties have been detected and statistical treatment of data is also reported. This study is part of a wider project aimed at the possible exploitation of the main agro-industrial by-products. At the same time it is one of the first reports on the volatile components of this waste material.

Polyphenols distribution in juices from Citrus allotetraploid somatic hybrids and their sexual hybrids.

The polyphenol profile of an interspecific allotetraploid somatic hybrid, achieved by protoplast fusion, the 'Valencia' sweet orange ( Citrus sinensis L. Osbeck) + 'Femminello' lemon ( Citrus limon L. Burm), and three sexual hybrids obtained by backcrosses between Femminello lemon and the allotetraploid somatic hybrid ('Valencia' + 'Femminello') was studied by liquid chromatography-ultraviolet-diode array detector-mass spectrometry (LC-UV-DAD-MS). The aim of the work was to evaluate whether superior traits and improved performance can be observed in these new genotypes. Ten flavonoids (TF), comprising seven flavanones and three flavones, and four hydroxycinnamic acids (HCA) have been characterized and quantified in all hybrids and compared with those of the respective parents. The 'Valencia' + 'Femminello' somatic hybrid shows an intermediate polyphenol composition with respect to those of the parents, with a slight prevalence of lemon influence. The three sexual hybrids show, instead, different and more complex chromatographic profiles.

Citrus limonoids and their semisynthetic derivatives as antifeedant agents against Spodoptera frugiperda larvae. A structure-activity relationship study.

The antifeedant activity of Citrus-derived limonoids limonin (1), nomilin (2), and obacunone (3) and their semisynthetic derivatives 4-26 was evaluated against a commercially important pest, Spodoptera frugiperda. Simple chemical conversions were carried out on the natural limonoids obtained from seeds of Citrus limon. These conversions focused on functional groups considered to be important for the biological activity, namely the C-7 carbonyl and the furan ring. In particular, reduction at C-7 afforded the related alcohols, and from these their acetates, oximes, and methoximes were prepared. Hydrogenation of the furan ring was also performed on limonin and obacunone. The known antifeedant properties of the Citrus limonoids are confirmed. Comparison with previously reported data shows that insect species vary in their behavioral responses to these structural modifications. Highly significant antifeedant activity (P < 0.01) for two natural (1 and 3) and three semisynthetic limonoids (4, 8, and 10) was observed against S. frugiperda.