Bioavailability of Phenolic Compounds in Californian-Style Table Olives with Tunisian Aqueous Olive Leaf Extracts

Abstract

Recent advances in biotechnology have ensured that one of the main olive tree by-products is olive leaf extract (OLE), a rich source in bioactive compounds. The aim of this work was to study the phenolic composition in different OLEs of three Tunisian varieties, namely, ‘Sayali’, ‘Tkobri’, and ‘Neb Jmel’. The in vitro biodigestibility effect after ‘Sayali’ OLE addition to Californian-style ‘Hojiblanca’ table olives was also studied. This OLE contained bioactive molecules such as hydroxytyrosol, tyrosol, oleropeine, Procianidine B1 (PB1), and p-cumaric acid. These compounds were also found in fresh olives after OLE was added. Furthermore, from fresh extract to oral digestion, the detected amount of bioavailable phenol was higher; however, its content decreased according to each phase of gastric and intestinal digestion. In the final digestion phase, the number of phenols found was lower than that of fresh olives. In addition, the phenolic content of Californian-style ‘Hojiblanca’ table olives decreased during the in vitro digestion process. The antioxidant activity of this variety decreased by 64% and 88% after gastrointestinal digestion, being the highest antioxidant capacity found in both simulated gastric and intestinal fluid, respectively. The results show us that the ‘Sayali’ variety is rich in phenolic compounds that are bioavailable after digestion, which could be used at an industrial level due to the related health benefits.

Updated Mineral Composition and Potential Therapeutic Properties of Different Varieties of Olive Leaves from Olea europaea

“…Zinc concentration showed significant correlation with the N, K, and Mn concentrations of the leaves, while Ca, Cu, and Na uptake exhibited a significant negative correlation with N concentration [ 16 ]. All this rich potentiality of olive leaf extract (OLE) hangs on the quantity of molecule/compound that is absorbed and metabolized in an organism after ingestion, in which the latest progress in biotechnology allows to understand and find ways to create supplementation that potentiates the maximal absorption of those bioactives such as the design of ion-nanoparticles (ion-NPs) [ 17 , 18 ]. For this reason, it is crucial to understand the biochemical composition of olive tree leaves from the most relevant cultivars.…”

Phytochemical and anticandidal efficacy of Olea europaea leaf extract from different cultivars and seasonal variation

“…OLEs are rich in phenolic and flavonoid compounds, therefore they present great potential as natural antioxidants for functional food, nutraceutical, and pharmaceutical applications (28). However, significant differences in phenolic compounds have been found in the biochemical or genetic characteristics of olive leaves and fruits (19).…”

Valorization of Olive Leaves through Polyphenol Recovery Using Innovative Pretreatments and Extraction Techniques: An Updated Review

“…Olive leaves are also rich in lignins, constituting up to 35.72% of their composition [21]. The surfaces of olive leaves contain a high quantity of triterpenes, especially oleanolic and maslinic acids, known for their antimicrobial, antitumor, anti-inflammatory, and anti-HIV activities [22] The diversity of bioactive compounds depends on different factors, e.g., the genotype [23,24] and the cultivar [25][26][27], climate variations, collection season, etc. For example, the highest polyphenol content was detected in different cultivars (Arbequina, Manzanilla, and Picual) during the summer season.…”