Methyl Carnosate Research Articles

Extraction of sage ( Salvia officinalis L.) by pressurized hot water and conventional methods: antioxidant activity of the extracts

The effectiveness of the extraction of antioxidative compounds from sage (Salvia officinalis L.) by pressurized hot water extraction, ultrasonication-assisted methanol extraction, hydrodistillation, and maceration with 70% ethanol was evaluated by determining the capability of the extracts to scavenge the free radical DPPH· (1,1-diphenyl-2-picrylhydrazyl) in vitro. Pressurized hot water extraction was found to be the most effective extraction procedure, followed by maceration with 70% ethanol, hydrodistillation, and ultrasonication-assisted methanol extraction. In addition to the total extract, special attention was paid to rosmarinic and carnosic acids, carnosol and methyl carnosate. The extracts were analyzed by reversed-phase high-performance liquid chromatography (RP-HPLC). The identification of compounds was confirmed by coupling RP-HPLC to mass spectrometry with electrospray ionization.

Phenolic antioxidant compounds produced by in vitro shoots of sage ( Salvia officinalis L.)

In vitro shoots of sage ( Salvia officinalis L.) were established under four different cytokinin supplementations by culturing nodal segments excised from aseptically germinated seedlings. The highest rates of shoot proliferation and linear shoot growth occurred with the supplementation of 1.5 mg/l benzyladenine and 0.05 mg/l dichlorophenoxyacetic acid. However, under these conditions, the specific production of total antioxidant phenolics was the lowest. Variation in kinetin (KIN) concentration (1.5; 2.0; 4.0 mg/l), in the presence of 0.05 mg/l 2,4-D, did not influence significantly the rates of shoot proliferation and linear shoot growth but influenced the production of antioxidant phenolics and biomass. Seventeen compounds were identified in the antioxidant phenolic extracts from shoots: gallic acid, 3- O-caffeoylquinic acid, 5- O-caffeoylquinic acid, caffeic acid, and rosmarinic acid, as phenolic acids; hesperetin, apigenin, hispidulin, cirsimaritin, and genkwanin, as flavonoids; epirosmanol, epirosmanol methyl ether, carnosol, epiisorosmanol ethyl ether, rosmadial, carnosic acid, and methyl carnosate, as phenolic diterpenes. With exception of carnosic acid and methyl carnosate, all the other phenolic compounds (15) were also identified in a commercial sample of this species. Rosmarinic acid and carnosol were the main compounds in all the antioxidant phenolic extracts. The increase in concentration of KIN decreased the accumulation of the most of phenolic diterpenes, particularly that of carnosol.

Supercritical Fluid Extraction of Natural Antioxidants from Rosemary: Comparison with Liquid Solvent Sonication

Supercritical fluid extraction (SFE) and liquid solvent sonication, in combination with two different sample treatments, were compared for the extraction of natural antioxidants from rosemary leaves. Dried, ground, and sieved rosemary leaves (20 mg) were subjected to SFE with CO(2) at 355 bar at 100 °C (CO(2) density 0.72 g/mL) for 20 min at a liquid flow rate of 4 mL/min. The analytes were concentrated on an ODS trap and subsequently eluted with acetone. Antioxidants in the SF and liquid solvent extract were analyzed by HPLC. Compounds of known antioxidant activity such as carnosol, carnosic acid, and methyl carnosate were identified by mass spectrometry of the HPLC fractions collected. Freezing and grinding the samples in liquid nitrogen resulted in decreased carnosic acid recoveries. Supercritical CO(2) extraction provided the highest recovery of carnosic acid from rosemary leaves (35.7 mg/g), the lowest relative standard deviation (4.4%), and the cleanest extract [Formula: see text] no cleanup prior to HPLC was required. Among the liquid solvents studies, only acetone provided comparable results (73% recovery relative to SC-CO(2) extraction); however, it required decoloration with active carbon prior to HPLC analysis.

Antioxidant Activity of Carnosic Acid and Methyl Carnosate in Bulk Oils and Oil-in-Water Emulsions

This study was aimed at evaluating the antioxidant activities of carnosic acid and its methyl ester, methyl carnosate, in inhibiting the formation and decomposition of hydroperoxides in bulk and emulsified corn oil triglycerides at 60 °C. In both lipid systems, methyl carnosate was a better antioxidant than carnosic acid, and both were more active than α-tocopherol. The difference in antioxidant activity between methyl carnosate and carnosic acid was greater in emulsion than in bulk systems. Carnosic acid was less stable than methyl carnosate and α-tocopherol in bulk corn oil and 1% Tween 20 micelle solution. The partitioning of carnosic acid into the water phase may explain its low activity in emulsions. The measurement of antioxidant depletion may not be a valid method to evaluate antioxidant activities because the antioxidant activities of carnosic acid and methyl carnosate were not related to their oxidative stability in bulk oil and Tween 20 solution. Keywords: Antioxidants; carnosic acid; methyl carnosate; α-tocopherol; corn oil triglycerides; emulsion; mechanism; interfacial oxidation; hydroperoxides; hexanal; partition coefficient; oxidative stability of antioxidants

Antioxidant Constituents in Sage (Salvia officinalis)

The antioxidant compounds of oleoresin of sage (Salvia officinalis) were separated by column chromatography and high-performance liquid chromatography. Sir major compounds were purified and identifred by IR, MS, and 1 H NMR spectrometry as carnosol, carnosic acid, rosmadial, rosmanol, epirosmanol, and methyl carnosate. Their antioridative activity was measured with an accelerated test, and their content was quantified in sage and in four commercial rosemary extracts