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Polyphenolic profile of bay leaves (Laurus nobilis L.)collected in two coastal regions of Croatia

The growing demand on naturally derived ingredients has brought the need for finding new sources of biologically active molecules which can be isolated and used as functional ingredients in food. Bay leaf is a Mediterranean shrub well known in the folk medicine for its many health beneficial effects that can be largely attributed to the content of polyphenols. In order to enable efficient industrial utilization of these valuable compounds, it is necessary to isolate them from plant material. Various green extraction technologies, such as pressurized liquid extraction (PLE), have emerged in recent years due to many advantages over conventional techniques including the shorter extraction time, lower energy and solvent consumption as well as higher extraction efficiency and lower degradation of targeted compounds. Combined chromatographic and spectral techniques, such as ultra-performance liquid chromatography tandem mass spectrometry (UPLC/MS-MS) allow effective polyphenolic characterization of the obtained extracts, enabling the optimal choice of the extraction methodology as well as plant material whose chemical composition may vary significantly depending on the environmental factors, harvesting season and storage conditions. The aim of this research was to compare the polyphenolic content of bay leaves collected in November 2021 in the region of Rijeka, Croatia and Dubrovnik, Croatia and stored in the same conditions. The extracts were obtained from finely grinded dry leaf samples by PLE at previously established optimal conditions (50% ethanol, 150°C, 1 extraction cycle and 5 min static time) and analyzed by UPLC/MS-MS. The results showed that the sample collected in the region of Dubrovnik, Croatia had a higher content of total polyphenols (45, 09 202 ± 0, 21 mg g-1) than the sample collected in the region of Rijeka, Croatia (36, 12 ± 0, 17 mg g1). Flavonols were the most abundant group of compounds in both samples, followed by flavan-3-ols, phenolic acids, proanthocyanidins and flavones. Significant differences were observed in the content of individual polyphenols, showing that environmental growth factors have an important effect on the polyphenolic profile of bay leaf and should be further researched in order to produce extracts of maximum quality, while using less plant material, resulting in a more sustainable process.

Laurus nobilis L. ; polyphenols ; pressurized liquid extraction (PLE) ; UPLC-MS/MS, habitat

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