Assessment of Antioxidant and Antibacterial Potential of Phenolic Extracts from Post-Distillation Solid Residues of Oregano, Rosemary, Sage, Lemon Balm, and Spearmint

Abstract

Medicinal and aromatic plants (MAPs) are potential sources of natural polyphenols. Solid residues (SRs) from the essential oil (EO) industry are produced in significant volumes and may be used as natural sources of bioactive compounds. Therefore, this work was designed to examine the antioxidant and antibacterial characteristics of phenolic extracts obtained from SRs that have remained after EO distillation. SR extracts of Greek oregano, rosemary, spearmint, lemon balm, and Greek sage were assessed for their total phenolic content (TPC), antioxidant activity, and antimicrobial activity against Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes, Staphylococcus aureus, Bacillus subtilis, Bacillus licheniformis, and Bacillus cereus in the concentration range of 500-3000 mg/L. The rosemary and Greek sage extracts exhibited the strongest antibacterial activities against all the Gram-positive species, while the spearmint and oregano extracts were less effective and only had an effect at the highest concentration used. The lemon balm extract did not show any inhibitory effect; however, it had the highest TPC, showing moderate antioxidant activity, along with spearmint. The oregano extract exhibited the strongest antioxidant activity, followed by Greek sage and rosemary. The experimental findings pointed to the potential use of extracts from post-distillation residues of MAPs as antimicrobials in the food industry, in addition to being rich sources of bioactive compounds.

Green Solvent Extraction of Antioxidants from Herbs and Agro-Food Wastes: Optimization and Capacity Determination

“…Similarly, Bouloumpasi et al [6] reported that among five studied ethanolic extracts of post-distillation solid residues, lemon balm presented the highest antioxidant activity determined using ABTS, DPPH, and FRAP assays, followed by spearmint, Greek oregano, Greek sage, and rosemary, respectively.…”

“…The following regression Equations ( 4)- (6) The ANOVA results for the predicted response PCM are presented in Table 5. The ANOVA test revealed that the PCMs adequately represent responses of AC values for LB extracts.…”

“…Interestingly, herb residues and agro-food by-products still contain high amounts of bioactive components, such as polyphenols, vitamins, carotenoids, tannins, and other phytochemicals (minerals, dietary fibers, fatty acids, amino acids, prebiotics) with high nutritional value and antioxidant properties. Recently, the antioxidant potential of phenolic extracts from various by-products such as the distillation solid wastes of Greek oregano, rosemary, Greek sage, lemon balm, and spearmint [6], chestnut shell [7][8][9], berry biowaste [10], chokeberry pomace [11], grape pomace and skin [9,12], rapeseed, mustard, sesame meals and cakes [13,14], olive pomace and leaves, spent coffee grounds, brewer's spent grain, fruit and vegetable leaves, pulp, peel, pomace and seeds [9,15,16], gray and black alder bark [17], and buckwheat hulls [18,19] have been investigated.…”

“…These antioxidant properties of biologically active substances isolated from plant wastes can also be of interest to cosmetic and pharmaceutical applications for the enhancement of therapeutic agent stability, photostability and protection of skin from UV rays, and formulation of new functional cosmetic and pharmaceutical ingredients [9]. It is known that different techniques and solvents, including traditional procedures and innovative processes, can be applied to extract antioxidant compounds from plant materials and by-products of agro-food industries [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Among them, solid-liquid extraction, Soxhlet extraction, heating-stirring extraction, ohmic heating extraction, homogenization-assisted extraction, heat refluxing extraction, high hydrostatic pressure-assisted extraction, supercritical and subcritical extraction, accelerated solvent extraction (ASE), microwave-assisted extraction (MAE), and ultrasound-assisted extraction (UAE) were employed.…”

Ethnopharmacological survey of medicinal plants used in traditional treatment of respiratory system disorders in the Southeast region of Morocco

“…Additionally, plants from the Lamiaceae, Apiaceae, and Asteraceae families can be easily found in the surrounding nature, making them accessible and economically viable for local communities as a source of traditional treatment for respiratory disorders. Lastly, Lamiaceae, Apiaceae, and Asteraceae are renowned for containing a variety of bioactive compounds (36), such as terpenoids, flavonoids, sesquiterpenes, and phenolic compounds, which are often associated with beneficial pharmacological properties for treating respiratory disorders. These compounds may have anti-inflammatory, antioxidant, expectorant, and antimicrobial effects, all of which are useful in addressing respiratory ailments (37)(38)(39).…”