Total Phenolic Content and Polyphenolic Profile of Tunisian Rosemary (Rosmarinus officinalis L.) Residues

Plants, especially herbs and spices, have always been the major sources of numerous natural compounds with antioxidant activity and other beneficial properties and, specifically, Rosemary (Rosmarinus officinalis L.) has been widely accepted as one of the spices with highest antioxidant activities which appear to be related to their richness of phenolic compounds. This study was undertaken with the aim to estimate the total phenolic content, identify and quantify the polyphenolic compounds of the methanolic extracts from post-distilled rosemary, collected from two different bioclimatic areas from Tunisia. Total phenolic content (TPC) was determined by Folin–Ciocalteu method. Identification and quantification of polyphenolic compounds was performed using high-performance liquid chromatography (HPLC) analysis. TPC ranged from 85.8 to 137.3 mg GAE/g DE in rosemary extracts. HPLC analysis showed the presence of carnosic acid and carnosol, wich were found to be the most abundant compounds in all analyzed extracts (46.3 to 76.4 and 22.4 to 43.5 mg/g of plant dry weight respectively), rosmarinic acid and caffeic acid as phenolic acids, besides some flavonoids such as apigenin, luteolin, genkwanin and hesperidin. This study revealed that rosemary post-distilled residues were shown to be promising with regard to their incorporation into various foods, cosmetics and fragrances.Therefore, supplementing a balanced diet with herbs may have beneficial health effects.