Olive Leaf
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2022 ◽  
Vol 10 (1) ◽  
pp. 136
Elisabetta Mazzotta ◽  
Rita Muzzalupo ◽  
Adriana Chiappetta ◽  
Innocenzo Muzzalupo

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.

2021 ◽  
Vol 14 (1) ◽  
pp. 391
Yiannis G. Zevgolis ◽  
Efstratios Kamatsos ◽  
Triantaphyllos Akriotis ◽  
Panayiotis G. Dimitrakopoulos ◽  
Andreas Y. Troumbis

Conservation of traditional olive groves through effective monitoring of their health state is crucial both at a tree and at a population level. In this study, we introduce a comprehensive methodological framework for estimating the traditional olive grove health state, by considering the fundamental phenotypic, spectral, and thermal traits of the olive trees. We obtained phenotypic information from olive trees on the Greek island of Lesvos by combining this with in situ measurement of spectral reflectance and thermal indices to investigate the effect of the olive tree traits on productivity, the presence of the olive leaf spot disease (OLS), and olive tree classification based on their health state. In this context, we identified a suite of important features, derived from linear and logistic regression models, which can explain productivity and accurately evaluate infected and noninfected trees. The results indicated that either specific traits or combinations of them are statistically significant predictors of productivity, while the occurrence of OLS symptoms can be identified by both the olives’ vitality traits and by the thermal variables. Finally, the classification of olive trees into different health states possibly offers significant information to explain traditional olive grove dynamics for their sustainable management.

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 84
Cristina Cejudo Bastante ◽  
Marlene J. Cran ◽  
Lourdes Casas Cardoso ◽  
Casimiro Mantell Serrano ◽  
Stephen W. Bigger

A supercritical solvent impregnation (SSI) technique was employed to incorporate, by batch- and semicontinuous-modes, bioactive olive leaf extract (OLE) into a food-grade multilayer polyethylene terephthalate/polypropylene (PET/PP) film for active food packaging applications. The inclusion of OLE in the polymer surfaces significantly modified the colour properties of the film. A correlation of 87.06% between the CIELAB colour parameters and the amount of the OLE impregnated in the film was obtained which suggests that colour determination can be used as a rapid, non-destructive technique to estimate the OLE loading in the impregnated matrices. The UV barrier and water permeability properties of the films were not significantly modified by the incorporation of OLE. The migration of OLE into a 50% (v/v) ethanol food simulant demonstrated faster release of OLE from the PP surface than from the PET surface which may be due to the different interactions between OLE and each polymer.

2021 ◽  
Vol 12 ◽  
Yanhong Liu ◽  
Ting Fang ◽  
Yujuan Suo ◽  
Shigang Gao ◽  
Gian Marco Baranzoni ◽  

Listeria monocytogenes is a regulated foodborne pathogen that is known to cause listeriosis, a disease associated with high mortality rates in humans. Olive leaf extract (OLE) has been shown to act as a plant antimicrobial and inhibit the growth of pathogens, such as L. monocytogenes, although its mode of action has not been defined. To help identify the cellular mechanisms important for conveying these beneficial traits, RNA-Seq was used to study the transcriptome of L. monocytogenes upon exposure to a sublethal level of OLE. Results obtained from cells cultured both with and without OLE at two different time points (3.5-h and 24-h) revealed 661 genes that were differentially expressed. Of the differentially expressed genes (DEGs) identified, transcription was altered for 171 genes in response to the 3.5-h OLE treatment while 490 genes were altered in response to the 24-h OLE treatment. These DEGs included but were not limited to genes encoding for signal transduction, ATP-binding cassette (ABC) transporters, and the phosphotransferase system. Interestingly, several virulence-related genes were downregulated including an ABC transporter permease previously shown to negatively regulate biofilm formation, genes involved in flagella assembly and binding/entry into host cells as well as those regulating acid resistance suggesting that OLE may decrease the virulence potential of L. monocytogenes. Furthermore, quantitative reverse-transcription PCR was used to validate the data obtained via RNA-Seq. Our study provides insight into the mode of action of OLE treatment against L. monocytogenes and may aid in identifying synergetic strategies to inhibit L. monocytogenes in food.

2021 ◽  
Vol 55 (4) ◽  
pp. 379-384
Miyuki Ogata ◽  
Keiko Yashiki ◽  
Akinori Kiso ◽  
Yoko Hashii ◽  
Yoshihito Kawashima

Antioxidants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2030
Jose Manuel Silvan ◽  
Esperanza Guerrero-Hurtado ◽  
Alba Gutiérrez-Docio ◽  
Teresa Alarcón-Cavero ◽  
Marin Prodanov ◽  

Helicobacter pylori (H. pylori) is one of the major human pathogens and the main cause of pathological damages that can progress from chronic gastritis to gastric cancer. During the colonization of gastric mucosa, this bacterium provokes a strong inflammatory response and subsequent oxidative process, which are associated with tissue damage. Therefore, the objective of this research was to evaluate the ability of two olive-leaf extracts (E1 and E2) to modulate the inflammatory response and oxidative stress in H. pylori-infected human gastric AGS cells. The obtained results showed that both extracts significantly decreased interleukin-8 (IL-8) secretion and reactive oxygen species (ROS) production in human gastric AGS cells. Both extracts also showed antibacterial activity against different H. pylori strains. HPLC-PAD-MS characterization demonstrated that extract E1 was mainly composed of highly hydrophilic compounds, such as hydroxytyrosol (HT) and its glucosides, and it was the most effective extract as an antibacterial agent. In contrast, extract E2 was composed mostly of moderately hydrophilic compounds, such as oleuropein (OLE), and it was more effective than extract E1 as an anti-inflammatory agent. Both extracts exhibited similar potential to decrease ROS production. These results show the importance of standardizing the extract composition according to the bioactive properties that should be potentiated.

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7623
Sylwia Grabska-Zielińska ◽  
Magdalena Gierszewska ◽  
Ewa Olewnik-Kruszkowska ◽  
Mohamed Bouaziz

The aim of this work was to obtain and characterize polylactide films (PLA) with the addition of poly(ethylene glycol) (PEG) as a plasticizer and chloroformic olive leaf extract (OLE). The composition of OLE was characterized by LC-MS/MS techniques. The films with the potential for using in the food packaging industry were prepared using a solvent evaporation method. The total content of the phenolic compounds and DPPH radical scavenging assay of all the obtained materials have been tested. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (FTIR-ATR) allows for determining the molecular structure, while Scanning Electron Microscopy (SEM) indicated differences in the films’ surface morphology. Among other crucial properties, mechanical properties, thickness, degree of crystallinity, water vapor permeation rate (WVPR), and color change have also been evaluated. The results showed that OLE contains numerous active substances, including phenolic compounds, and PLA/PEG/OLE films are characterized by improved antioxidant properties. The OLE addition into PLA/PEG increases the material crystallinity, while the WVPR values remain almost unaffected. From these studies, significant insight was gained into the possibility of the application of chloroform as a solvent for both olive leaf extraction and for the preparation of OLE, PLA, and PEG-containing film-forming solutions. Finally, evaporation of the solvent from OLE can be omitted.

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