Coupling sea lavender (Limonium algarvense Erben) and green tea (Camellia sinensis (L.) Kuntze) to produce an innovative herbal beverage with enhanced enzymatic inhibitory properties

Herbal beverages containing mixtures of L. algarvense (LA) flowers and C. sinensis (CS) were prepared and their inhibitory properties towards enzymes related with Alzheimer's (acetyl- and butyrylcholinesterase) and Type-2 diabetes mellitus (α-amylase and α-glucosidase) were evaluated for the first time. Samples were also appraised for antioxidant capacity and phenolic contents by high-performance liquid chromatography with diode-array detection (HPLC-DAD). Both synergistic and antagonistic interactions were observed: LA samples (infusion: IC₅₀ = 0.22 mg/mL; decoction: 0.39 mg/mL) had higher acetylcholinesterase inhibition than CS and mixtures resulted in stronger enzymatic inhibition. CS had the highest rat α-glucosidase inhibition (infusion: IC₅₀ = 3.91 mg/mL; decoction: IC₅₀ = 2.50 mg/mL), which decreased when combined with LA. LA and CS samples had strong antioxidant activity, whereas LA and CS mixtures exhibited higher OH[rad] radical-scavenging (0.56 ≤ SE ≤ 1.07) and anti-lipid peroxidation capacity (0.39 ≤ SE ≤ 0.81). CS had higher phenolic contents (infusion: 209 mg/g DW; decoction: 169 mg/g DW) and its combination with LA increased the phenolic diversity of the mixtures. Our results indicate that LA and CS infusions and decoctions and their combinations have relevant in vitro neuroprotective, antidiabetic and antioxidant properties and could be further explored as potential innovative functional beverages able to reduce the progression of neurodegenerative diseases and diabetic complications, and to prevent oxidative stress and lipid oxidation related diseases.