Department of Pharmaceutical and Toxicological Chemistry Named after Arzamastsev of the Institute of Pharmacy, I.M. Sechenov First Moscow State Medical University (Sechenov University), 119991 Moscow, Russia.
School of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Sciences, La Trobe University, Edwards Rd, Bendigo 3550, Australia.
Molecules. 2021 Nov 16;26(22):6892. doi: 10.3390/molecules26226892.
The aim of this study was to analyse the effect of spontaneous microbial maceration on the release and extraction of the flavonoids and phenolics from olive leaves. Bioprofiling based on thin-layer chromatography effect-directed detection followed by ATR-FTIR spectroscopy proved to be a reliable and convenient method for simultaneous comparison of the extracts. Results show that fermentation significantly enhances the extraction of phenolic compounds and flavonoids. The polyphenolic content was increased from 6.7 µg GAE (gallic acid equivalents) to 25.5 µg GAE, antioxidants from 10.3 µg GAE to 25.3 µg GAE, and flavonoid content from 42 µg RE (rutin equivalents) to 238 µg RE per 20 µL of extract. Increased antioxidant activity of fermented ethyl acetate extracts was attributed to the higher concentration of extracted flavonoids and phenolic terpenoids, while increased antioxidant activity in fermented ethanol extract was due to increased extraction of flavonoids as extraction of phenolic compounds was not improved. Lactic acid that is released during fermentation and glycine present in the olive leaves form a natural deep eutectic solvent (NADES) with significantly increased solubility for flavonoids.
本研究旨在分析橄榄叶中天然微生物浸渍对类黄酮和酚类物质释放和提取的影响。基于生物分析的薄层色谱效应导向检测结合衰减全反射傅里叶变换红外光谱（ATR-FTIR）证明是一种可靠且方便的方法，可用于同时比较提取物。结果表明，发酵显著提高了酚类化合物和类黄酮的提取率。多酚含量从 6.7 µg GAE（没食子酸当量）增加到 25.5 µg GAE，抗氧化剂从 10.3 µg GAE 增加到 25.3 µg GAE，类黄酮含量从 42 µg RE（芦丁当量）增加到 238 µg RE，每 20 µL 提取物。发酵乙酸乙酯提取物抗氧化活性的增加归因于提取的类黄酮和酚类萜烯的浓度增加，而发酵乙醇提取物抗氧化活性的增加则是由于类黄酮的提取增加，而酚类化合物的提取没有得到改善。发酵过程中释放的乳酸和橄榄叶中的甘氨酸形成了具有显著增加的类黄酮溶解度的天然深共晶溶剂（NADES）。
