Pavela R., Kaffková K., Kumšta M. (2014): Chemical composition and larvicidal activity of essential oils from different Mentha L. and Pulegium species against Culex quinquefasciatus Say (Diptera: Culicidae). Plant Protect. Sci., 50: 36-42. Twenty samples of essential oils (EO) obtained from, and Pulegium vulgare were tested for larvicidal activity against Culex quinquefasciatus. EO were obtained via hydrodistillation and subsequently analysed by gas chromatography-mass spectrometry (GC-MS). Concentrations causing 50% or 90% larval mortality ranged from 17171 mg/l to 171 mg/l or 28171 mg/l to 577 mg/l, respectively. EO obtained from M. longifolia 2 and M. suaveolens, which were the only ones containing a majority share of piperitenone oxide, showed the highest effects. LD 50 was estimated as 17 mg/l for both EO, and LD 90 was estimated as 28 mg/l.

Abstract:Pavloušek P., Kumšta M. (2011): Profiling of primary metabolites in grapes of interspecific grapevine varieties: sugars and organic acids. Czech J. Food Sci., 29: 361-372.The quality of grapes is determined above all by the contents of the primary and secondary metabolites. The primary metabolites involve sugars and organic acids, and just these compounds are dealt with in this study. Its objective was to analyse and critically evaluate the primary metabolites in new interspecific varieties and, based on a comparison with European varieties of grapevine (Vitis vinifera L.), to find out the similarities and also possible differences between them. The study evaluates and compares 4 conventional varieties of Vitis vinifera with 11 new interspecific cultivars. The contents and compositions of the individual sugars and acids were estimated by means of the HPLC method. Most of these varieties belong to the group with either medium or low content of malic acid, i.e. with a medium to high β ratio. This corroborates the similarity of interspecific varieties to those of V. vinifera. The cluster analysis identified the existence of two interesting groups of varieties: the first one involved the varieties Riesling, Nativa, Marlen, and Kofranka while the other group consisted of varieties Blaufränkisch, Blauer Portugieser, and Laurot. This observation also indicates similarity between Vitis vinifera L. varieties and interspecific cultivars and demonstrates that the contents of the primary metabolites (i.e. sugars and organic acids) are also comparable.

The occurrence and content of some polyphenols and the antioxidant activity of compounds present in grape berries, stems and leaves of <i>Vitis vinifera</i> L. were evaluated. Three white and three blue varieties of grapevine were investigated. The contents were determined of <i>trans</i>-resveratrol, <i>trans</i>-piceid, caftaric acid, tryptophan, catechin, epicatechin, total polyphenols, and flavanols, both in healthy material and in the samples of the plant material infested with microorganisms (<i>Botryotinia fuckeliana</i> Whetzel anamorph <i>Botrytis cinerea</i> Pers.; Uncinula necator (Schw.) Burr; <i>Plasmopara viticola</i> (Berk. & M.A. Curtis) Berl & De Toni). The antioxidant activity of the extracts obtained was determined by different methods: FRAP (Ferric Reducing Antioxidant Power), DPPH (2,2-diphenyl-1-picrylhydrazyl radical) and TAC-PCL (Total Antioxidant Capacity of Photochemiluminescence). The content of <i>trans</i>-resveratrol varied between 0.3–2.3 mg/kg and 0.7–12.1 mg/kg in non-infested and infested grape berries, respectively. The content of <i>trans</i>-piceid between 0.6–2.9 mg/kg and 1.5–6.3 mg/kg in non-infested and infested grape berries, respectively. The content of trans-resveratrol varied between 2.5–10.3 mg/kg and 3.7–20.9 mg/kg in healthy and in infected leaves, respectively. The content <i>trans</i>-piceid varied between 11.3–58.4 mg/kg and 18.5–60.9 mg/kg in the healthy and in the infected leaves, respectively. The highest content of trans-resveratrol was found in stems (16.3–276.3 mg/kg). In young lateral shoots, the highest levels of <i>trans</i>-piceid (12.6–99.7 mg/kg) and caftaric acid (474–2257 mg/kg) were determined. The infested grape berries showed a higher antioxidant activity, which was most closely correlated with the content of total polyphenols (correlation coefficient = 0.8336–0.9952).

Pavloušek P., Kumšta M. (2013): Authentication of Riesling wines from the Czech Republic on the basis of the non-flavonoid phenolic compounds. Czech J. Food Sci., 31: 474-482.Eighteen non-flavonoid phenolic compounds comprising hydroxybenzoic acids, hydroxycinnamates, and stilbenes were analysed in 43 monovarietal wines originated from five wine-growing regions in the Czech Republic. The non-flavonoid phenolic compounds in wine were analysed by a HPLC method. The methods of multivariate statistical analysis were used for the wine discrimination on the basis of the geographical origin. The canonical discriminant analysis (CDA) proved the possibility to discriminate wines according to their provenance on the basis of the following parameters: protocatechuic acid, p-hydroxybenzoic acid, caftaric acid, p-coutaric acid, trans-resveratrol, and cis-resveratrol. On the basis of statistical analyses, 95.4% of the wine samples were correctly classified. The results therefore indicate that the non-flavonoid phenolic compounds can be used to discriminate the geographical origin of white wines.

Anthocyanins present in the grapes of nine grapevine (Vitis vinifera L.) varieties and ten interspecific hybrids were compared. Total anthocyanin levels were determined in fresh grapes and the values ranged from 0.50 g kg−1 to 4.99 g kg−1. A total of twenty-two different anthocyanins were identified. Malvidin 3-glucoside was the most abundant anthocyanin, with concentrations ranging from 30 % to 64 % of the totals observed. The ratio of acetylated to coumaroylated malvidin and peonidin derivatives ranged from 0.09 (variety: Regent) to 1.34 (variety: Cerason), depending on the variety. Diglucosylated anthocyanins were not found in particular interspecific hybrids such as the teinturier XIV 26–56, Laurot, Merlan, and Nativa.