Sea fennel (Crithmum maritimum L.):a culinary herb with nutraceutical potential. Extraction, purification and chemical characterization of polar extracts.

Crithmum maritimum L., also known as sea fennel, rock samphire and locally as ‘paccasassi’, is a perennial halophyte, thrives on maritime rocks and sometimes in sandy beaches along the Mediterranean, Pacific and Atlantic coasts. Its potential for commercial cultivation has not yet been fully exploited though it is considered a promising biosaline crop [1]. Sea fennel has been used since ancient times in folk medicine as antiscorbutic, tonic, carminative, diuretic, depurative and vermifuge. Today it is believed as an emerging edible vegetable crop, famous for its culinary and not culinary properties [2]. C. maritimum has lots of food uses due to its aromatic traits, for instance to make pickles and to flavour and season soups, sauces and salads. The plant is reported in the Belfrit list, including plants that could be used for food supplements due to sufficient scientific evidence. The use of the plant in the diet is also confirmed by its presence in the “List of Traditional Agri-Food Product” by the Italian Ministry of Agriculture as a traditional agri-food product of Puglia [3]. According to the medicinal use, sea fennel is also considered a source of human health compounds, namely fatty acids such as linoleic (C18:2 ω6) and linolenic (C18:3 ω3) acids [4], and phenolics compounds with well documented antioxidant effects [5]. Due to the growing interest in this vegetable as a source of nutraceutical compounds [6], different studies have been performed to understand the total chemical profile of the vegetable. This work aims to provide a complete quantitative and qualitatively overview of the extract obtained from the aerial parts of C. maritimum. For this purpose: aerial parts were dried, ground and extracted by percolation with ethanol 70% at 60°C. The purification was done using an Amberlite® XAD7HP sorbent resin. For the quantification, HPLC-DAD-MS/MS system, equipped with electrospray ionization (ESI) and a Zorbax ODS (250 x 4.6 mm, 5 μm) column, was used. The extract was mainly composed of phenolic compounds, among which hydroxycinnamic acids and flavonoids were the two main chemical classes. Among the former, chlorogenic acids, including 5-O-caffeoylquinic acid (32.04-166.21 mg g-1), 3,5-di-O-caffeoylquinic acid (8.44-38.86 mg g-1) and 4,5-di-O-caffeoylquinic acid (5.70-25.85 mg g-1), were the most abundant ones. Among flavonoids, rutin (1.60-4.33 mg g-1) and kaempferol-3-O-rhamnoside (0.07- 0.33 mg g-1) were the main constituents. These results support the use of this plant as a functional food or in nutraceuticals due to the abundance of antioxidant compounds.