In Vitro Enzyme Inhibitory and Antioxidant Properties, Cytotoxicity, and LC-DAD-ESI-MS/MS Profile of Extracts from the Halophyte Lotus creticus L.

The halophyte Lotus creticus L. (creta trefoil, Fabaceae) belongs to a family and genus containing several medicinal species, and is considered a promising crop for saline Mediterranean areas. However, to the best of our knowledge, information regarding the biological properties of this species that could increase its biotechnological value is particularly scarce.

We aimed to evaluate the potential use of creta trefoil collected in Southern Portugal (Algarve) as a source of bioactive products.

Food-grade extracts (water, acetone, ethanol) were obtained by ultrasound-assisted extraction from aerial parts (stems and leaves) and fruits (pods), and evaluated for acute toxicity on mammalian cells. In vitro enzymatic inhibition was appraised on enzymes related to neurodegeneration (acetyl- and butyryl-cholinesterase: AChE and BuChE), type-2 diabetes (T2DM,α-glucosidase, and α-amylase), and hyperpigmentation/food browning (tyrosinase). In vitro, antioxidant activity included radical scavenging towards 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), ferric-reducing antioxidant power (FRAP), and metal chelating activity on iron and copper. Chemical composition was established by liquid chromatography coupled with a diode array detector (LC-DAD-ESI-MS/MS).

Samples were not toxic and were active towards AChE (especially acetone extracts) and BuChE (particularly ethanol and acetone fruits’ extracts). Acetone and water fruit extracts and ethanol extract from aerial organs displayed significant inhibition on α-glucosidase, but low capacity towards amylase. All extracts exhibited a high capacity to inhibit tyrosinase, except water extract from aerial organs. Fruit extracts had, in general, the highest antioxidant capacity, especially ethanol. Fruits exhibited the highest diversity of polyphenols, especially flavonols, catechins, quercetin, myricetin, and its derivatives.

Overall, our results suggested that creta trefoil should be further explored as a source of natural products for the management of T2DM, hyperpigmentation disorders, or food additive to prevent food oxidation and browning.