Prevete Giuliana, Donati Enrica, Ruggiero Anna Paola, Fardellotti Silvia, Lilla Laura, Ramundi Valentina, Nicoletti Isabella, Mariani Francesca, Mazzonna Marco
Institute for Biological Systems (ISB), Consiglio Nazionale delle Ricerche (CNR), Territorial Research Area Rome 1, Strada Provinciale 35d, no. 9, 00010 Montelibretti, Rome, Italy.
ACS Appl Mater Interfaces. 2024 Dec 18;16(50):68850-68863. doi: 10.1021/acsami.4c13302. Epub 2024 Dec 4.
According to the innovative and sustainable perspective of the circular economy model, leaves, a solid byproduct generated every year in large amounts by the olive oil production chain, are considered a valuable source of bioactive compounds, such as polyphenols, with many potential applications. In particular, the following study aimed to valorize olive leaves in order to obtain products with potential antibacterial activity. In this study, olive leaf extracts, rich in polyphenols, were prepared by ultrasound-assisted extraction using green solvents, such as ethanol and water. The extracts were found to be rich in polyphenols up to 26.7 mg/g; in particular, hydroxytyrosol-hexose isomers (up to 6.6 mg/g) and oleuropein (up to 324.1 mg/g) turned out to be the most abundant polyphenolic compounds in all of the extracts. The extracts were embedded in liposomes formulated with natural phosphocholine and cholesterol, in the presence or in the absence of a synthetic galactosylated amphiphile. All liposomes, prepared according to the thin-layer evaporation method coupled with an extrusion protocol, showed a narrow size distribution with a particle diameter between 79 and 120 nm and a good polydispersity index (0.10-0.20). Furthermore, all developed liposomes exhibited a great storage stability up to 90 days at 4 °C and at different pH values, with no significant changes in their size and polydispersity index. The effect of the encapsulation in liposomes of leaf extracts on their antimicrobial activity was examined against two strains of : ATCC 25923 (wild-type strain) and ATCC 33591 (methicillin-resistant , MRSA). The extracts demonstrated good antimicrobial activity against both bacterial strains under investigation, with the minimum inhibitory concentration ranging from 140 to 240 μg/mL and the minimum bactericidal concentration ranging from 180 to 310 μg/mL, depending on the specific extract and the bacterium tested. Moreover, a possible synergistic effect between the bioactive compounds inside the extracts tested was highlighted. Notably, their inclusion in galactosylated liposomes highlighted comparable or slightly increased antimicrobial activity compared to the free extracts against both bacterial strains tested.
根据循环经济模式的创新和可持续发展理念，橄榄油生产链每年产生大量固体副产品——橄榄叶，被视为生物活性化合物（如多酚）的宝贵来源，具有许多潜在应用。特别是，以下研究旨在使橄榄叶增值，以获得具有潜在抗菌活性的产品。在本研究中，使用乙醇和水等绿色溶剂通过超声辅助提取制备了富含多酚的橄榄叶提取物。发现提取物中多酚含量高达26.7毫克/克；特别是，羟基酪醇己糖异构体（高达6.6毫克/克）和橄榄苦苷（高达324.1毫克/克）是所有提取物中含量最丰富的多酚化合物。提取物被包封在由天然磷脂酰胆碱和胆固醇配制的脂质体中，有无合成半乳糖化两亲物。所有根据薄层蒸发法结合挤压方案制备的脂质体均显示出窄的尺寸分布，粒径在79至120纳米之间，且具有良好的多分散指数（0.10 - 0.20）。此外，所有制备的脂质体在4℃和不同pH值下长达90天均表现出良好的储存稳定性，其尺寸和多分散指数无显著变化。研究了叶提取物包封在脂质体中对其抗菌活性的影响，针对两种菌株：ATCC 25923（野生型菌株）和ATCC 33591（耐甲氧西林金黄色葡萄球菌，MRSA）。提取物对所研究的两种细菌菌株均表现出良好的抗菌活性，最低抑菌浓度范围为140至240微克/毫升，最低杀菌浓度范围为180至310微克/毫升，具体取决于特定提取物和测试的细菌。此外，还突出了测试提取物中生物活性化合物之间可能的协同作用。值得注意的是，与游离提取物相比，它们包含在半乳糖化脂质体中对两种测试细菌菌株的抗菌活性相当或略有增加。
