Unravelling the potential of the medicinal halophyte Eryngium maritimum L.: In vitro inhibition of diabetes-related enzymes, antioxidant potential, polyphenolic profile and mineral composition

Abstract This work searched for the biotechnological potential and chemical characterisation of the medicinal halophyte Eryngium maritimum L. as source of bioactive natural products with enzymatic inhibitory properties and antioxidant capacity. With that aim, herbal formulations traditionally used in folk medicine, namely tisanes (infusions and decoctions) and tinctures, were prepared from four different anatomical organs (roots, stems, leaves and flowers) and assessed for in vitro inhibition of enzymes related with diabetes and for antioxidant potential. Phenolic fingerprinting and mineral contents were also assessed. Sea holly's tisanes, particularly from flowers and leaves, had the highest phenolic content although tinctures were comparatively richer considering the ingestion dosage. The main constituents identified were carvacrol, 2,3-dimethoxybenzoic acid, naringenin, catechin and t -cinnamic acid; from the several compounds identified, naringin, naringenin and 2,3-dimethoxybenzoic acid are here firstly described in the genus and epicatechin and carvacrol in the species. In all extracts, sodium was the most abundant mineral, followed by potassium, calcium and magnesium, pointing to possible nutritional applications of these beverages/tinctures as macronutrients supplementary source. Sea holly's tinctures (stems, leaves and flowers) were capable of inhibiting dietary carbohydrate digestive enzymes (α-glucosidase and α-amylase) and had in vitro antioxidant potential, particularly flowers. Altogether, results highlight that sea holly extracts, especially tinctures from stems, leaves and flowers, could be a novel source of α-glucosidase and α-amylase inhibitors, antioxidant compounds and also phenolic and mineral constituents, thus suggesting they may be interesting to further explore as potential health-promoting herbal beverages, food additives or other products.