The effect of extraction solvents, temperature and time on the composition and mass fraction of polyphenols in dalmatian wild sage (Salvia officinalis L.) extracts

Abstract

The effect of extraction solvents (30, 50 and 70 % aqueous solutions of ethanol and acetone, and 100 % distilled water), extraction temperature (60 and 90 °C) and extraction time (30, 60 and 90 min) on the composition and mass fraction of polyphenolic compounds in Dalmatian wild sage (Salvia officinalis L.) extracts has been investigated. The total polyphenolic content of sage extracts was determined spectrophotometrically using Folin-Ciocalteu method, whereas the individual polyphenols were determined by HPLC UV/PDA method. Results indicated that the main polyphenols in sage extracts were vanillic, caffeic, syringic, salvianolic K and salvianolic I acids, methyl rosmarinate, 6-hydroxyluteolin-7-glucoside, luteolin-7-glucuronide, luteolin-7-glucoside, apigenin-7-glucunoride, apigenin-7-glucoside, with rosmarinic acid and luteolin-3-glucuronide as predominant compounds. The mass fractions of total and individual polyphenols significantly depend on the type of extraction solvent, solvent composition and extraction temperature. The results showed that binary solvent systems are more efficient than mono-solvent systems in the extraction of polyphenolic compounds in regard to their relative polarity. The aqueous solutions of ethanol or acetone (30 %), extraction temperature of 60 °C and extraction time of 30 min were the most efficient for the extraction of polyphenols from dry sage leaves.