Melissa officinalis extracts obtained using maceration, ultrasoundand microwave-assisted extractions: Chemical composition, antioxidant capacity, and physical characteristics

Abstract

Even though Melissa officinalis L. (lemon balm, fam. Lamiaceae) is a well-known medicinal, aromatic, and spicy plant, and its physicochemical profile and biological activity have been investigated, there is no detailed research regarding the influence of solvent nature (polarity) on the extraction of active compounds (total polyphenols and total flavonoids) and antioxidant activities of the obtained extracts. Therefore, this study aimed to evaluate the polyphenol and flavonoid contents, as well as the antioxidant potential of lemon balm extracts obtained by varying the polarity of the extraction solvents (methyl alcohol, acetone, ethyl acetate, and deionized water) and using three extraction techniques (maceration-MAC, ultrasound-UAE, and microwave-assisted extraction-MAE). Two in vitro tests (ABTS and FRAP assays) were used to determine the antioxidant activity of the extracts. Total tannin and total protein contents, extraction yield, and physical properties of the selected extracts were measured as well. The highest content of polyphenols was found for the methanolic and water extracts obtained by all three extraction techniques, while the highest flavonoid yield was detected only in the mentioned methanolic extracts. The microwave reactor provided methanolic, ethyl acetate, and water extracts with the highest ABTS radical scavenging activity, while in the case of UAE, it was methanolic and water extracts, and in the case of MAC only water extracts. On the other hand, among lemon balm extracts from MAC, water extract possessed the highest ferric reducing power, whereas in UAE and MAE, it was ethyl acetate extract. Total tannin content determined in selected water extracts was 2.55, 4.53, and 1.83 mg tannic acid equivalent (TAE)/mL, while total proteins amounted to 1.34, 1.50, and 1.31 mg/mL using MAC, UAE, and MAE, respectively. The content of total extractive substances in the form of the extraction yield was also determined for selected water extracts and amounted to 12.6 % for MAC, 17.2 % for UAE, and 36.8 % for MAE. Further, this research has included the investigation of some physical properties of lemon balm water extracts, such as conductivity (3.68-4.14 mS/cm), pH (5.99-6.43), density (0.854-0.901 g/mL), surface tension (26.0-31.7 mN/m), and viscosity (1.18-1.21 mPa·s). This research represents the base for the future encapsulation of lemon balm extracts, enriched in polyphenol content, in a novel type of biofunctional carrier that potentially can be applied in the pharmacy, chemical industry, and biotechnics.

From Aloe vera Leaf Waste to the Extracts with Biological Potential: Optimization of the Extractions, Physicochemical Characterization, and Biological Activities

“…However, the differences in surface tension between the other three extracts with the same extraction solvent (70% ethanol) can be explained by the measured TPC in the mentioned extracts. As the polyphenol concentration in the extracts increases (HAE > UAE and MAE, Table 2 ), a decrease in surface tension can be noticed (HAE < UAE and MAE, Table 5 ), which is in agreement with the literature data [ 109 , 110 , 111 ]. Namely, lower surface tension provides faster penetration of the extraction solvent into the plant matrix and increased matrix–solvent contact surface, allowing further polyphenol release in the extract [ 110 ].…”

Phytochemical Analysis, Biological Activities, and Molecular Docking Studies of Root Extracts from Paeonia Species in Serbia

“…Compounds 32 and 33 (gibberellin and phloridzin) were found in the trees P. ostii, P. rockii, and P. suffruticosa [38][39][40]. 16), 447 (29), 599 (34), 601 (22), 617 (100) 193 (10), 313 (15), 429 (33), 291 (66), 301 (20), 409 (60), 427 (100) 247 (14), 275 (62), 287 (18), 301 (69), 409 (100) 257 (20), 287 (100), 299 (10) 95 (26), 109 (42), 113 (26), 127 (28), 137 (100) 69 (47), 81 (25), 95 (39), 106 (7) (20), 313 (10), 399 (10), 479 (12), 491 (23), 613 (100) 271 (100), 313 (33), 375 (16), 399 (27), 491 (67) 169 (8), 210 (7), 211 (18), 285 (13), 287 (47), 313…”

“…The binding modes of several protein-ligand complexes are presented in Figures 4 and 5, indicating the most important interactions that stabilize these structures. Ethyl gallate (7) and paeoniflorigenone ( 26) exhibited notable binding affinities toward AChE (-9.6 and -9.0 kcal/mol, respectively). Ethyl gallate interacts with Ser203 and His447 from the catalytic triad by serving as a hydrogen-bond donor (HBD) (Figure 4).…”

“…Ethyl gallate interacts with Ser203 and His447 from the catalytic triad by serving as a hydrogen-bond donor (HBD) (Figure 4). Additionally, it binds to Trp86 from the anionic site via HBD and π-π stacking interactions and to Tyr337 from the peripheral anionic site (PAS) through hydrogen-bond acceptor (HBA) in- Ethyl gallate (7) and paeoniflorigenone (26) exhibited notable binding affinities toward AChE (-9.6 and -9.0 kcal/mol, respectively). Ethyl gallate interacts with Ser203 and His447 from the catalytic triad by serving as a hydrogen-bond donor (HBD) (Figure 4).…”

“…The researchers are looking for the most efficient extraction protocol that captures and preserves all of the bio-constituents while retaining their healthy and nutritional properties. Regarding that, the extraction protocols, which include liquid and solid phases, are rudely divided into traditional and novel (eco-friendly) methods, referring to Soxhlet, maceration (M), CO 2 -extraction, heat- and microwave-assisted extraction (MAE), and ultrasound-assisted extraction (UAE) [ 6 , 7 , 8 ]. Some of these procedures require a high consumption of toxic extraction medium and prolonged extraction time, making them non-economic and harmful to the environment.…”