Extraction yield, phenolic profile and in vitro antioxidant and enzyme-inhibitory activities of hydroalcoholic tincture extracts from fresh and dried Myrtus communis L. leaves

Myrtle (Myrtus communis L., Myrtaceae) is an aromatic Mediterranean shrub whose leaves are a traditional source of polyphenols. In this study, forty hydroalcoholic tincture extracts were prepared from fresh and dried myrtle leaves by combining two leaf conditions, five plant-to-solvent ratios (1:4-1:8, w/v) and four ethanol concentrations (20, 40, 60 and 80%, v/v) in order to evaluate how these factors govern extraction yield, phenolic composition and biological activity. Extraction yield ranged from 3.76 to 19.86%, with dried leaves and higher solvent ratios generally giving higher yields. Six phenolics were quantified by HPLC-DAD; epicatechin (up to 136.26 mg/g) and rutin (up to 32.36 mg/g) were the dominant constituents, accompanied by gallic acid, catechin, quercetin 3-O-galactoside and trace kaempferol. The extracts exhibited strong antioxidant activity in the ABTS, DPPH and CUPRAC assays, with several extracts being more potent than the reference antioxidants butylated hydroxytoluene (BHT) and α-tocopherol (α-TOC), particularly in the ABTS and DPPH assays. In contrast, none of the extracts showed appreciable inhibition of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-amylase or α-glucosidase (all IC50 > 200 µg/mL). The results indicate that hydroalcoholic tincture extracts of M. communis leaves, especially those obtained from dried leaves at higher ethanol concentrations, are an efficient and selective source of antioxidant polyphenols, while their cholinesterase- and carbohydrate-hydrolysing-enzyme-inhibitory potential is negligible under the tested conditions.