Rosmarinic Acid Levels, Phenolic Contents, Antioxidant and Antimicrobial Activities of the Extracts from S alvia verbenaca L. Obtained with Different Solvents and Procedures

Abstract

The present paper investigated the quantities of total polyphenols, tannins, flavonoids, hydroxycinnamic derivatives, rosmarinic acid and thujone, as well as the antioxidant and antimicrobial activities in 12 Salvia verbenaca L. extracts. The sample, prepared with 80% methanol using ultrasound extraction (UE) contained the highest levels of total polyphenols (236.44 ± 12.80 mg catechin equivalents (CE)/g, 190.27 ± 9.89 mg gallic acid equivalent (GAE)/g), tannins (187.81 ± 12.93 mg CE/g, 148.95 ± 10.00 mg GAE/g) and hydroxycinnamic derivatives (13.52 ± 0.24%), and was superior in the antimicrobial activity test. The highest amount of total flavonoids (10.55 ± 0.44 μg of rutin/mg) was quantified in the ethanolic extract prepared using UE. The extract made with 80% ethanol using UE had the highest rosmarinic acid level (94.00 ± 1.58 μg/mg) and was the most active in the β-carotene/linoleic acid system. The 80% methanolic extract made by maceration was the most active in 2,2-diphenyl-1-picrylhydrazyl assay. Thujone was absent from all extracts. Practical Applications The use of plants and products derived from plants has increased in the food industry in the past decade because of the comforts and advantages they provide when used as natural antioxidants and antimicrobials. The genus Salvia L. has been proven to be a relevant source of powerful natural antioxidant agents and preservatives used in food and medical products for centuries. The results indicate that Salvia verbenaca extracts are rich in polyphenolics, particularly in rosmarinic acid. The alcoholic extracts exerted significant levels of antioxidant and antimicrobial activities; therefore, the extracts of S. verbenaca could be potential sources of natural antimicrobial agents for food preservation. In addition, thujone, a neurotoxic monoterpene commonly present in Salvia species, was absent from all samples, which would allow extracts to be orally applicable. As an outcome of the proposed beneficial effects, S. verbenaca extracts could be used in functional foods and dietary supplements.