Green and Sustainable extraction of bioactive compounds from Salicornia ramosissima

Halophytes are salinity–sensitive plants that tolerate extremely high salt concentrations, being mainly found in saltmarshes and coastal areas worldwide, including Portugal [1]. Halophytes, such as Salicornia spp., are used by human due to commercial, ecological and gastronomic values [2]. Inside this genus, Salicornia ramosissima is of particular interest, being considered an alternative to salt [3]. The valorization of S. ramosissima may be a sustainable and environmental-friendly way to obtain extracts with interest for nutraceutical industry. Nevertheless, extraction is a key step to acquire bioactive compounds from plants, with emphasis on the extraction technique and solvent employed, which should maximize the extraction yield [13]. The aim of this study was to recover bioactive compounds from S. ramosissima by conventional extraction (CE) and Microwave-assisted extraction (MAE) techniques using water as extractor solvent.

In this study, the total phenolic and flavonoid contents (TPC and TFC, respectively), antioxidant/antiradical activities (through FRAP and ABTS assays) as well as the phenolic profile and the in-vitro effects on intestinal cells were screened. Briefly, CE was performed as a decoction preparation while MAE was executed at selected temperatures (72 – 94 ºC) during 1 to 5 min with constant medium stirring. After extractions, samples were filtrated and lyophilized for further assays.

The values of TPC ranged between 8.34 and 15.02 mg of gallic acid equivalents (GAE)/g for CE and MAE extracts, respectively. In same line, CE extract exhibited the highest TFC value (8.44 mg of catechin equivalents (CAE)/g). Regarding ABTS and FRAP assays, the MAE extract showed the highest values (60.61 μmol FSE/g dw and 16.06 % inhibition for FRAP and ABTS assays, respectively). On the other hand, the total amount of phenolic compounds identified and quantified in both extracts were similar, being the phenolic acids and flavonols the principal constituents. For both extracts, myricetin was the compound present in highest amounts (0.4250 and 0.4655 mg myricetin/g dw for CE and MAE extracts, respectively) and gallic acid was the major phenolic acid present in extracts (0.2105 and 0.1553 mg gallic acid/g dw for CE and MAE extracts, respectively). The cell effects demonstrated that both extracts did not lead to a decrease of HT29-MTX viability. In Caco-2 cell line, only the highest concentration of MAE (1000 µg/mL) led to a decrease of viability (86.55%). In this sense, S. ramosissima extracted by CE or MAE can be classified as non-toxic and rich in bioactive compounds. However further studies, such as in-vitro intestinal permeation assays and in-vivo studies, are needed to underline this potential.

References:

[1] Flowers, T.J.; Colmer, T.D. Salinity Tolerance in Halophytes. New Phytol. 2008, 179, 945–963.

[2] Lima, A.R.; Castañeda-Loaiza, V.; Salazar, M.; Nunes, C.; Quintas, C.; Gama, F.; Pestana, M.; Correia, P.J.; Santos, T.; Varela, J.; et al. Influence of Cultivation Salinity in the Nutritional Composition, Antioxidant Capacity and Microbial Quality of Salicornia Ramosissima Commercially Produced in Soilless Systems. Food Chem. 2020, 333, 127525.

[3] Ferreira, D.; Pinto, D.C.G.A.; Silva, H.; Girol, A.P.; de Lourdes Pereira, M. Salicornia ramosissima J. Woods Seeds Affected the Normal Regenerative Function on Carbon Tetrachloride-induced Liver and Kidney Injury. Biomed. Pharmacother. 2018, 107, 283–291.

[4] Panja, P. Green Extraction Methods of Food Polyphenols from Vegetable Materials. Curr. Opin. Food Sci. 2018, 23, 173–182.