The dose-response relationships of the direct scavenging activity of amide-based local anesthetics against multiple free radicals

Abstract

This study aimed to illustrate the dose-response relationships of the direct scavenging activity of amide-based local anesthetics against multiple free radicals in vitro . We have demonstrated that amide-type local anesthetics selectively and directly scavenge some free radicals. Three kinds of free radicals were eliminated by all the four local anesthetics examined. Mepivacaine, lidocaine, bupivacaine, and dibucaine scavenged hydroxyl radicals in dose-dependent manners. Ascorbyl free radicals were also scavenged in dose-dependent manners, and lastly singlet oxygen was scavenged in dose-dependent manners. Three other free radicals were not scavenged by all of the four local anesthetics; tert -butoxyl radical was scavenged by all the anesthetics examined but dibucaine, nitric oxide by mepivacaine but not by the other three, and tyrosyl radical by mepivacaine and lidocaine but not by the other two. Some free radicals (superoxide anion, tert -butyl peroxyl radical, DPPH) were not scavenged by any of the four local anesthetics. The local anesthetics were also shown to inhibit lipid peroxidation by TBARS assay. These results suggest that local anesthetics have antioxidant properties through their free radical scavenging activities.

Effect of Dental Local Anesthetics on Reactive Oxygen Species: An In Vitro Study

“…Considering that the molecular weight of lidocaine is 288.81, its IC 50 (80 µM) corresponded to 0.0023%. Overall, the results of the present study are consistent with the previous reports (Figure 2A , 2D ) [ 26 , 27 ]. However, the concentrations at which the antioxidant effect against HO • was detected were lower than those typically used in clinical practice (0.5-2%).…”

“…Although several studies have shown the antioxidant effects of local anesthetics, reports on the direct capture of ROS are limited. For example, studies using the ESR spin-trapping technique showed that lidocaine scavenged HO • in a concentration-dependent manner, with IC 50 of approximately 80 µM [ 26 , 27 ]. Considering that the molecular weight of lidocaine is 288.81, its IC 50 (80 µM) corresponded to 0.0023%.…”

“…Considering that the IC 50 of lidocaine against HO • in the present study was approximately 0.029% (Figure 2D ), may sufficiently scavenge HO • even when injected locally. In contrast, lidocaine did not reportedly scavenge O 2 •− [ 26 , 27 ]. Additionally, a comparative study of eight different local anesthetics showed that high concentrations of local anesthetics are necessary to effectively scavenge O 2 •− in human neutrophils [ 29 ].…”