Mass Transfer and Optical Properties of Active PET/PP Food-Grade Films Impregnated with Olive Leaf Extract

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.

Transcriptomics of Listeria monocytogenes Treated With Olive Leaf Extract

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.

Polylactide Films with the Addition of Olive Leaf Extract—Physico-Chemical Characterization

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.

Study of Therapeutic Effects of Olive Leaf Extract on Phenylhydrazine-Induced Anemia Mice Model

Introduction Anemia is the most common blood disorder which affects billions of people, especially young adults and women. However, currently available treatments of anemia are with limitations and adverse effects. Therefore, natural resources have been receiving considerable attention as complementary or alternative hematinic agents in recent years. In this regard, olive leaf extract (OLE) is rich in bioactive phenolic compounds and has been reported to have anti-inflammatory, antioxidant and neuroprotective effects (Vogel et al., 2015). Our previous study showed treatment with water extract of olive leaf (WOL) for 12 days could induce erythroid differentiation in human hematopoietic stem cells (hHSCs) and showed potential in oxygen and iron homeostasis, haem metabolism, and hemoglobin (Hb) biosynthesis (Kondo et al., 2021). In the present study, we aimed to investigate the therapeutic effects of WOL on the phenylhydrazine (PHZ)-induced mice model of anemia and explore its underlying molecular mechanism. Methods Total 63 male ICR mice (four weeks old) were randomly divided into three groups: control, PHZ and WOL groups. Mice in the WOL group were orally administered with 150 mg/kg body weight of WOL (diluted by saline) every day, while mice in the other two groups received saline. After two weeks of WOL pretreatment, PHZ was injected intraperitoneally (60 mg/kg body weight) to PHZ and WOL groups. The mice were dissected on day0 (before PHZ injection), day1, day3, day5, and day7 after PHZ injection. We collected blood for hematologic tests during dissection and liver, kidney, intestine, bone marrow, and spleen samples. We next checked the iron homeostasis-related gene expressions by real-time PCR: hepcidin (Hamp) in liver, ferroportin (Fpn) in spleen and intestine. Results and Discussion After anemia was induced, WOL group showed a significant increase in the number of reticulocytes, the erythroid progenitors, compared to that of in PHZ group on Day 5. Simultaneously, plasma iron level on Day 5 and Hb level on Day7 was significantly decreased in the WOL group compared to the PHZ group. These results suggest that during anemia, the WOL group had rapid erythropoiesis, which in turn caused a rapid consumption of Hb and iron. Additionally, mRNA expression of Hamp in liver was significantly decreased on Day 5, whereas Fpn expressions in spleen and intestine were significantly increased on Day 5 and Day 7 in the WOL group compared to the PHZ group. Hamp regulates plasma iron concentrations as well as systemic iron metabolism by interacting with its receptor Fpn, a transmembrane iron-exporter. In intestine, Fpn controls iron absorption from food intake, while in spleen, Fpn regulates phagocytosis of senescent erythrocytes by the macrophages. Decreased Hamp expression and increased Fpn expression by WOL treatment suggest increased levels of absorbed and recycled iron to meet the demand for erythropoiesis. Altogether, our findings indicate that WOL could regulate iron homeostasis in the early stage of anemia to promote the differentiation of erythroid progenitors. Conclusion Our study suggests that WOL treatment downregulates Hamp expression in liver and increased Fpn expressions in the intestine and spleen, leading to increased absorbed iron in the intestine and recycled iron in the spleen (Figure 1). Therefore, WOL may have therapeutic potential in anemia through regulating iron homeostasis and promoting erythroid differentiation. However, further studies are required to confirm these findings and to elucidate the molecular mechanisms. Our previous study showed that 12-day treatment of hHSCs with WOL could upregulate the expression of hypoxia-inducible factor 1-a (HIF1A) (Kondo et al., 2021), a key modulator of the transcriptional response to hypoxia and has been reported to regulate erythropoietin (Epo) production, which plays an important role in erythropoiesis. So, we hypothesize that WOL treatment would activate HIF1A in anemia-induced mice model, thus regulating Epo production to accelerate erythroid maturation. HIF2A is also reported to regulate Epo in kidney and Fpn in intestine to regulate erythropoiesis (Andrew J., et al., 2019). Therefore, we will investigate Epo expression in kidney, Hif1a and Hif2a expressions in kidney and intestine, and transferrin receptor (Tfrc, erythroid marker) in bone marrow. All gene expressions will be confirmed in protein levels also. Figure 1 Figure 1. Disclosures Suidasari: Nutrition Act Co. Ltd.: Current Employment. Yokozawa: Nutrition Act Co. Ltd.: Current Employment. Yamauchi: Nutrition Act Co. Ltd.: Current Employment.