Subcritical Water Extraction of Rosmarinic Acid from Lemon Balm (Melissa officinalis L.) and Its Effect on Plant Cell Wall Constituents

Abstract

Rosmarinic acid (RA), an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid, is a potent radical scavenger, a chelator of prooxidant ions, and an inhibitor of lipid peroxidation. RA-containing extracts are widely used natural antioxidants in food products, and many herbal preparations and food supplements, containing RA, are marketed with claims of beneficial health effects. The current study investigated the effectiveness of subcritical water extraction (SWE) for the recovery of RA from lemon balm (Melissa officinalis), as a “green” alternative to conventional hydro-alcoholic extraction. Different durations (10 min and 20 min) and extraction temperatures (100 °C and 150 °C) were applied. Subcritical water applied at a temperature of 100 °C was equally efficient as 50% ethanol in extracting RA. However, the further elevation of temperature to 150 °C decreased RA content by up to 20% due to thermal degradation. The content of RA in dried extracts was between 2.36% and 5.55% and the higher temperature of SWE increased extract yield by up to 41%. The higher extraction yield resulted from the degradation of plant material by subcritical water as evidenced by the increased extraction and degradation of proteins, pectin, and cellulose. These results reveal that SWE is an efficient technology for the extraction of RA and other antioxidants from lemon balm at reduced extraction time and without the use of toxic organic solvents. Furthermore, by modification of SWE conditions, dry extracts with different purity and content of RA are obtained. These extracts could be used in the food industry as food antioxidants, or in the development of food supplements and functional foods.

Phytochemical Characterization of Purple Coneflower Roots (Echinacea purpurea (L.) Moench.) and Their Extracts

“…extraction methods can be employed to assist polysaccharide extraction more fully, especially of the uronic acid-containing one. A good example of this is our very recent study on subcritical water extraction, which found that the yields of lemon-balm extracts and polysaccharides increased significantly with an increase in temperature and duration [21]. In fact, a detailed study on how subcritical water affects the yield and composition of echinacea extracts is being undertaken by us.…”

Teucrium montanum L.—Unrecognized Source of Phenylethanoid Glycosides: Green Extraction Approach and Elucidation of Phenolic Compounds via NMR and UHPLC-HR MS/MS

“…Nastić et al (2018b) [40] reported higher DPPH values for SWE extract in the range of 60-160 • C while significantly lower antioxidant capacity was observed at 180 • C, which may be due to the degradation of antioxidants via pyrolysis. Since there is not always a positive correlation between the antioxidant capacity results and the individually recovered phenolic compounds when SWE is applied [43,44], the hydrolysis of phenolic compounds under the influence of specific SWE conditions could lead to the formation of Maillard products, whose radical scavenging properties are preserved [45].…”

Biologically Active Compounds from Probiotic Microorganisms and Plant Extracts Used as Biopreservatives

“…The presence of an outer membrane in Gram-negative bacteria impairs the diffusion through the membrane The numerous studies conducted with plant extracts and essential oils containing various biologically active substances have shown effective results in controlling the colonial growth of pathogenic microorganisms. For example, rosmarinic acid-containing extracts have been widely investigated as natural antioxidants and biopreservatives in food products [35]. Similarly, eugenol has been found to play an important role in the inhibition of L. monocytogenes in meat [36].…”