In vitro Antifungal Activity of Olive (Olea europaea) Leaf Extracts Loaded in Chitosan Nanoparticles

Abstract

Olive leaf extract is characterized by a high content of phenols and flavonoids (oleuropein, luteolin, and their derivatives). These compounds are defined as secondary metabolites and exert such as anti-inflammatory, antioxidant, and antimicrobial activities. We investigated the in vitro antifungal activity of two olive leaf extracts (named EF1 and EF2) against a Fusarium proliferatum (AACC0215) strain that causes diseases to many economically important plants and synthesizing diverse mycotoxins. In this work, we aimed to identify the most appropriate concentration between the tested two olive leaf extracts to develop a safe, stable and efficient drug delivery system. Qualitative and quantitative analyses of the two olive leaf extracts by (HPLC) were performed. Furthermore, we also evaluated the antifungal effects of the two leaf extracts when encapsulated in chitosan-tripolyphosphate nanoparticles. The major compound in both EF1 and EF2 was oleuropein, with 336 and 603 mg/g, respectively, however, high concentrations of flavonoid were also present. EF1 and EF2 showed a concentration depended effect on F. proliferatum (AACC0215) viability. Our results showed a great efficacy of EF1/nanoparticles at the higher concentration tested (12X) against the target species. In this case, we observed an inhibition rate to both germination and growth of 87.96 and 58.13%, respectively. We suggest that EF1 olive leaf extracts, as free or encapsulated in chitosan-tripolyphosphate nanoparticles, could be used as fungicides to control plant diseases. Finally, future application of these findings may allow to reduce the dosage of fungicides potentially harmful to human health.

Antimicrobial Actions and Applications of Chitosan

“…Chitosan has been shown to have fungicidal effects on several fungal pathogens in plants and humans [ 82 , 83 , 108 , 135 , 136 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 147 ]. Its antifungal properties are mainly related to the interaction of chitosan with the cell wall or cell membrane.…”

Encapsulation of Olive Pomace Extract in Rocket Seed Gum and Chia Seed Gum Nanoparticles: Characterization, Antioxidant Activity and Oxidative Stability

“…Furthermore, de Campo et al (2017) [12] found that size of the chia seed oil NPs was 205 ± 4.24 nm by using chia seed mucilage. The particle size of chitosan-oleuropein, chitosan-two different olive leaf extracts were found between the range of 250-270 nm by using chitosan as wall material [27].…”

“…The high EE% indicated that OPE was encapsulated in gum nanoparticles which enhanced the stability against harsh environmental conditions. Muzzalupo et al (2020) [27] found that the EE% of the two types of olive leaf extract in chitosan nanoparticles was 94.5% and 73.1%, respectively. The values of EE% of the OPE in the literature were higher than the present study, e.g., Kesente et al (2017) [25] for encapsulation of olive leaf extract in polylactic acid.…”

“…After 24 h of the incubation, it was observed that the release of OPE reached 96.45 ± 1.89% for OPE-RSGNP and 85.61 ± 3.85% for OPE-CSGNP. Initial burst release occurred probably due to the OPE on the surface, followed by an accumulative release [27,53].…”

“…RSG and CSG are natural hydrophilic biopolymers and could have the potential to be utilized as wall materials. Many studies have been developed and evaluated for olive pomace and olive leaf phenolics encapsulation with different wall materials such as chitosan, maltodextrin, whey protein concentrate, and polylactic acid [1,[24][25][26][27]. Nevertheless, there are no reports about olive pomace encapsulation by using RSG and CSG as wall materials.…”