Microwave-Assisted Extraction (MAE) of Dalmatian Sage Leaves for the Optimal Yield of Polyphenols: HPLC-DAD Identification and Quantification

Abstract

Dalmatian sage (Salvia officinalis L.) is a Croatian medicinal herb with important biological and pharmacological properties due to diverse polyphenolic composition. Therefore, this study aimed at evaluating the effects of three solvents (30 % ethanol/water, v/v; 30 % acetone/water, v/v; water), time (3, 5, 7, 9, and 10 min), temperature (30, 50, 60, and 80 °C), and acidity (addition of 10 % HCl) with advanced extraction techniques such as microwave-assisted extraction (MAE) on phenolic compounds in Dalmatian sage extracts. Total polyphenols were better extracted with 30 % aqueous media with acetone (v/v), without HCl at 80 °C for 10 min. Considering individual phenolic compounds, in all extracts, rosmarinic acid was predominant and better extracted with 30 % ethanol/added HCl at 80 °C. The optimal polyphenol extraction conditions were methyl rosmarinate (30 % ethanol/added HCl/32 °C), syringic acid (30 % ethanol/without HCl/80 °C), salvianolic acid (any solvent/without HCl/80 °C), caffeic acid (water/added HCl/78 °C), and vanillic acid (30 % ethanol/added HCl/80 °C).