Antioxidant and Antimicrobial Activity of Hydroethanolic Leaf Extracts from Six Mediterranean Olive Cultivars

• Main Authors: Vida Šimat (Author), Danijela Skroza (Author), Giulia Tabanelli (Author), Martina Čagalj (Author), Federica Pasini (Author), Ana María Gómez-Caravaca (Author), Carmen Fernández-Fernández (Author), Meta Sterniša (Author), Sonja Smole Možina (Author), Yesim Ozogul (Author), Ivana Generalić Mekinić (Author)
• Format: Book
• Published: MDPI AG, 2022-08-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/antiox11091656; 2076-3921
• Keywords: olive leaves; antioxidant activity; antimicrobial activity; phenolic compounds; Therapeutics. Pharmacology; RM1-950
• Source: Antioxidants, Vol 11, Iss 9, p 1656 (2022)

Phenolic profiles, antioxidant, and antimicrobial activities of hydroethanolic olive leaf extracts from six Mediterranean olive cultivars (Croatian: <i>Lastovka</i>, <i>Levantinka</i>, <i>Oblica</i>; Italian: <i>Moraiolo</i>, <i>Frantoio</i>, <i>Nostrana di Brisighella</i>) were investigated. As expected, various distributions of phenolic levels were observed for each cultivar and the total phenolic content showed high variability (ranging from 4 to 22 mg GAE/g of dry extract), with the highest amount of phenolics found in the <i>Oblica</i> sample, which also provided the highest antiradical (ORAC) and reducing activity (FRAP). The screening of individual compounds was performed by HPLC-PDA-ESI-QTOF-MS and the main detected compounds were oleuropein, hydroxytyrosol, oleoside/secologanoside, verbascoside, rutin, luteolin glucoside, hydroxyoleuropein, and ligstroside. While the antioxidant activity of the samples was relatively high, they showed no bactericidal and bacteriostatic activity against <i>E. coli</i> and <i>S.</i> Typhimurium; weak activity against <i>Staphylococcus aureus</i>, <i>Bacillus cereus</i>, and <i>Listeria innocua</i>; and inhibitory effects against <i>Campylobacter jejuni</i> at 0.5 mg dry extract/mL. The obtained results support the fact that olive leaf extracts, and especially those from the <i>Oblica</i> cultivar, could potentially be applied in various industries as natural preservatives and effective and inexpensive sources of valuable antioxidants.