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Rose-scented geranium (Pelargonium sp.) have been the subject of many studies concerning essential oil, unlike the edible flowers of scent Pelargonium despite the beneficial properties of chemical compounds present in such organ and the fragrances produced. Therefore, we investigated organic compounds, total phenols and the antioxidant activity of the flowers with particular attention to the volatile compounds emitted by flowers of Pelargonium ‘Endsleigh’ at three stages of development. We identified several major phenols and organic compounds that revealed significative difference compared with other Pelargonium flowers, and employing the solid-phase micro extraction (SPME) methodology we determined that the production of volatile compounds decreases during the flower development. In addition, the emission of volatiles is accomplished mainly by the sepals. In conclusion, to use Pelargonium ‘Endsleigh’ flowers, it is important in ensuring that they have not yet opened and that the sepals are in place.

Plant extracts are a rich source of natural compounds with antimicrobial properties, which are able to prevent, at some extent, the growth of foodborne pathogens. The aim of this study was to investigate the potential of polyphenolic extracts from cladodes of Opuntia ficus-indica (L.) Mill. to inhibit the growth of some enterobacteria and the biofilm formation by Staphylococcus aureus. Opuntia ficus-indica cladodes at two stages of development were analysed for total phenolic content and antioxidant activity by Oxygen Radical Absorbance Capacity (ORAC) and Trolox equivalent antioxidant capacity (TEAC) (in vitro assays) and by cellular antioxidant activity in red blood cells (CAA-RBC) (ex vivo assay). The Liquid Chromatography Time-of-Flight Mass Spectrometry (LC/MS&ndash, TOF) analysis of the polyphenolic extracts revealed high levels of piscidic acid, eucomic acid, isorhamnetin derivatives and rutin, particularly in the immature cladode extracts. Opuntia cladodes extracts showed a remarkable antioxidant activity (in vitro and ex vivo), a selective inhibition of the growth of Gram-positive bacteria, and an inhibition of Staphylococcus aureus biofilm formation. Our results suggest and confirm that Opuntia ficus-indica cladode extracts could be employed as functional food, due to the high polyphenolic content and antioxidant capacity, and used as natural additive for food process control and food safety.

Plant cell cultures are valuable tools for the production of bioactive compounds. Recently, many efforts have been made in order to develop and optimize strategies for increasing the yields of the desired plant metabolites by eliciting their biosynthesis or improving the efficiency of product recovery. We established Artemisia annua L. (Asteraceae) cell suspension cultures to investigate the biosynthesis of the antimalarial artemisinin (AN) [1] and other healthful phytochemicals such as carotenoids and quinones. The use of culture supplementation with cyclic oligomers ?-cyclodextrins was successful to significantly increase intracellular and extracellular levels of AN, lutein, Q9 and Q10 [2, 3]. In order to investigate the mechanism underlying these effects, other oligosaccharides having a linear structure were explored as putative elicitors in A. annua cell suspension cultures. For this purpose, oligogalacturonides (OGA) were obtained by hydrolysis of polygalacturonic acid with pectolyase from Aspergillus japonicus. Various OGA fractions were used for culture medium supplementation at different concentrations. The results showed that the 4-5 OGA fraction induced significant increases of AN and the intermediate dihydroartemisinic acid. These results suggest that the ability of ?-CDs to elicit the production of bioactive compounds in A. annua cell cultures could be due to their chemical similarity to pectic oligosaccharides often occurring in plants after fungal infection.

Glutathione S-transferases (GST) are multifunctional proteins encoded by a large gene family, divided on the basis of sequence identity into phi, tau, theta, zeta and lambda classes. The phi and tau classes are present only in plants. GSTs appear to be ubiquitous in plants and are involved in herbicide detoxification and stress response, but little is known about the precise role of GSTs in normal plant physiology and during biotic and abiotic stress response. Two cDNAs representing the two plant classes tau and phi, AtGSTF9 and AtGSTU26, were expressed in vitro and the corresponding proteins were analysed. Both GSTs were able to catalyse a glutathione conjugation to 1-chloro-2,4-dinitrobenzene (CDNB), but they were inactive as transferases towards p-nitrobenzylchloride (pNBC). AtGSTF9 showed activity towards benzyl isothiocyanate (BITC) and an activity as glutathione peroxidase with cumene hydroperoxide (CumHPO). AtGSTU26 was not active as glutathione peroxidase and towards BITC. RT-PCR analysis was used to evaluate the expression of the two genes in response to treatment with herbicides and safeners, chemicals, low and high temperature. Our results reveal that AtGSTU26 is induced by the chloroacetanilide herbicides alachlor and metolachlor and the safener benoxacor, and after exposure to low temperatures. In contrast, AtGSTF9 seems not to be influenced by the treatments employed.

Anthocyanin-producing callus cultures from in vitro sour cherry (Prunus cerasus L.) leaf tissues were established. As in the parent leaf tissues, the calli extracts showed the synthesis of a prevalent anthocyanin, cyanidin 3-glucoside. When the dark grown callus cultures were exposed to the light, cyanidin 3-glucoside content was increased from 0.1 to 4.5 mg 100 g 1 fresh weight. Thus, of the available strategies for the enhancement of pigment production light resulted the triggering factor in this cell system. The addition of 50 lM jasmonic acid to the culture medium stimulated cyanidin 3-glucoside synthesis which resulted in an earlier appearance of pigment on the calli. � 2005 Elsevier Ltd. All rights reserved.

Three different Arabidopsis thaliana transgenic lines overexpressing AtHXK1, AtHXK2 and yeast HXK2 genes, respectively, were analyzed with regard to their hexokinase activity. The methodology employed was a non-denaturing electrophoresis followed by activity-staining. Three distinct hexokinase activities were detected and named, respectively, AtHXK1, AtHXK2 and YHXK2. Arabidopsis HXK1 and HXK2 showed high affinity for glucose, minor affinity for mannose, and very low specificity for fructose. In comparison, YHXK2 exhibited a higher affinity for both mannose and fructose. Galactose, 3-O-methyl glucose and 6-deoxyglucose showed no influence on hexokinase activity, while glucosamine and 2- deoxyglucose produced a clear inhibition at high concentrations. Trehalose did not cause inhibition. Instead, trehalose 6- phosphate (T6P) was an effective inhibitor of YHXK2 but not of AtHXK1 and AtHXK2. As a whole, these results indicate important differences between the properties of plant and yeast HXKs and provide useful information for a discussion concerning the sugar response of transgenic plants overexpressing AtHXK or YHXK2 genes.