Control of the Verticillium Wilt on Tomato Plants by Means of Olive Leaf Extracts Loaded on Chitosan Nanoparticles.

In this research, a new ecofriendly and sustainable fungicide agent, with the ability to control Verticillium wilt, was developed. To this purpose, a green extract of olive leaf (OLE) was prepared by ultrasound-assisted extraction (UAE) and characterized in terms of polyphenol content and antioxidant activity. Then, OLE was loaded in chitosan nanoparticles (CTNPs) to combine the antifungal activity of CTNPs and phenolic compounds to obtain an important synergic effect. Nanoparticles were synthetized using the ionic gelation technique and characterized in terms of sizes, polydispersity index, Z-potential, encapsulation efficiency, and release profile. Qualitative and quantitative analyses of OLE were performed by the HPLC method. OLE-loaded CTNPs exhibited good physicochemical properties, such as a small size and positive surface charge that significantly contributed to a high antifungal efficacy against Verticillum dahliae. Therefore, their antifungal activity was evaluated in vitro, using the minimal inhibition concentration (MIC) assay in a concentration range between 0.071 and 1.41 mg/mL. Free OLE, blank CTNPs, and OLE-loaded CTNPs possessed MIC values of 0.35, 0.71, and 0.14 mg/mL, respectively. These results suggest an important synergic effect when OLE was loaded in CTNPs. Thereafter, we tested the two higher concentrations on tomato plants inoculated with V. dahliae, where no fungal growth was observed in the in vitro experiment, 0.71 and 1.41 mg/mL. Interestingly, OLE-loaded CTNPs at the higher concentration used, diminished the symptoms of Verticillium wilt in tomato plants inoculated with V. dahliae and significantly enhanced plant growth. This research offers promising results and opens the possibility to use OLE-loaded CTNPs as safe fungicides in the control strategies of Verticillium wilt at open field.

Extra Virgin Olive Oil Phenols Dilate the Rat Mesenteric Artery by Activation of BKCa2+ Channels in Smooth Muscle Cells.

Accumulating evidence has shown the beneficial health effects of extra virgin olive oil (EVOO) consumption in reducing blood pressure and preventing the risk of developing hypertension. Some studies associate the hypotensive activity of EVOO to a minor component-the phenols. This study was designed to investigate the effects of EVOO phenols on the rat resistance mesenteric artery (MA) and to find out the possible vascular pathways involved. The experiments were carried out using a pressurized myograph, which allowed the effects of phenols on isolated MA to be tested under different conditions: (a) with endothelium removed; (b) with inhibition of nitric oxide synthase by Nω-Nitro-l-arginine methyl ester hydrochloride (l-NAME, 10-4 M) + Nω-Nitro-l-arginine (l-NNA, 10-4 M) ; (c) with inhibition of cyclooxygenase by indomethacin (10-5 M); (d) with inhibition of guanylate cyclase by 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ,10-5 M) or adenylate cyclase by 9-(Tetrahydro-2'-furyl)adenine (SQ, 10-5 M); (e) with depolarization by high potassium chloride (40 mM); and (f) with inhibition of the large conductance Ca2+-potassium channels (BKCa2+) with paxilline (10-5 M). EVOO phenols induce vasodilation of the endothelium, mediated by a direct effect on smooth muscle cells (SMC) by activation of BKCa2+ channels, an action by which phenols can regulate the vascular tone of the resistance artery. Phenols can be regarded as bioactive molecules that may contribute to the antihypertensive effects of EVOO.

LOX Gene transcript accumulation in olive (Olea europaea L.) fruits at different stages of maturation: relationship between volatile compounds, environmental factors, and technological treatments for oil extraction.

The quality of olive oil is influenced by genetic and environmental factors and by the maturation state of drupes, but it is equally affected by technological treatments of the process. This work investigates the possible correlation between olive LOX gene transcript accumulation, evaluated in fruits collected at different stages of maturation, and chemical biomarkers of its activity. During olive fruit ripening, the same genotype harvested from two different farms shows a positive linear trend between LOX relative transcript accumulation and the content of volatile compounds present in the olive oil aroma. Interestingly, a negative linear trend was observed between LOX relative transcript accumulation and the content of volatile compounds present in the olive pastes obtained from olive fruits with and without malaxation. The changes in the olive LOX transcript accumulation reveal its environmental regulation and suggest differential physiological functions for the LOXs.

Transcript levels of CHL P gene, antioxidants and chlorophylls contents in olive (Olea europaea L.) pericarps: a comparative study on eleven olive cultivars harvested in two ripening stages.

The effects of ripening stage on the antioxidant content in olive pericarps were evaluated in eleven olive genotypes grown in the same bioagronomic conditions in Southern Italy. We examined the transcript levels of geranylgeranyl reductase (CHL P) gene and the content of tocopherols, phenolic compounds and chlorophylls in the pericarps. The examined genotypes showed an increase of CHL P transcripts during pericarps ripening. Significant differences were reported in the antioxidant proportions in the same cultivars at different pericarp ripening stage. We show an inverse correlation between phenols and tocopherols content. In particular, during the ripening phase, tocopherols increased rapidly in olive pericarps while phenolic compounds and chlorophyll levels declined significantly. The significant amounts of these antioxidants confirm the nutritional and medicinal value of olive drupes and its products (table olives and olive oil). We suggest, for the first time, a link between CHL P transcript levels and tocopherols content during the ripening of olive pericarps. Besides, we revealed that this trend of CHL P transcript levels during pericarps ripening is independent from the olive genotypes.