Optimization of Supercritical Fluid Extraction of Antioxidant Compounds from Venezuelan Rosemary Leaves

Abstract

Abstract The extraction of the antioxidant compounds from rosemary can be achieved by means of various processes, such as hydrodistillation, soxhlet extraction, microwave-accelerated hydrodistillation (MAHD) and supercritical fluid extraction (SFE). The aim of our study was to optimize SFE variables such as extraction pressure, extraction temperature and static extraction time for the maximum extraction of carnosol and carnosic acid from Venezuelan rosemary (Rosmarinus officinalis L.) leaves by using 23 full factorial and Box-Behnken designs and Response Surface Methodology (RSM). The chemical characterization of the supercritical fluid extracts was achieved by high-performance liquid chromatography (HPLC), and the antioxidant activity was determined by the peroxide index assay. For the extraction of carnosol, the variables of extraction temperature and static extraction time were statistically significant, and for the extraction of carnosic acid, only the extraction temperature-static extraction time interaction was significant. At a fixed pressure, the highest extraction of carnosol and carnosic acid were achieved when the operational extraction conditions of extraction temperature and static extraction time were set at 48°C for 69 min and 64°C for 57 min, respectively. SFE extracts presented higher antioxidant activities than commercial and soxhlet extracts, and pure dibutyl hidroxytoluene (BHT). Since the carnosic acid/carnosol ratios presented in our SFE extracts are higher than those from other countries, possibly it would be expected that higher antioxidant activity values would be obtained for the Venezuelan extracts.