Antioxidant activity of lidocaine, bupivacaine, and ropivacaine in aqueous and lipophilic environments: an experimental and computational study.

Introduction: Local anesthetics are widely recognized pharmaceutical compounds with various clinical effects. Recent research indicates that they positively impact the antioxidant system and they may function as free radical scavengers. We hypothesize that their scavenging activity is influenced by the lipophilicity of the environment. Methods: We assessed the free radical scavenging capacity of three local anesthetics (lidocaine, bupivacaine, and ropivacaine) using ABTS, DPPH, and FRAP antioxidant assays. We also employed quantum chemistry methods to find the most probable reaction mechanism. The experiments were conducted in an aqueous environment simulating extracellular fluid or cytosol, and in a lipophilic environment (n-octanol) simulating cellular membranes or myelin sheets. Results: All local anesthetics demonstrated ABTS˙+ radical scavenging activity, with lidocaine being the most effective. Compared to Vitamin C, lidocaine exhibited a 200-fold higher half-maximal inhibitory concentration. The most thermodynamically favorable and only possible reaction mechanism involved hydrogen atom transfer between the free radical and the -C-H vicinal to the carbonyl group. We found that the antioxidant activity of all tested local anesthetics was negligible in lipophilic environments, which was further confirmed by quantum chemical calculations. Conclusion: Local anesthetics exhibit modest free radical scavenging activity in aqueous environments, with lidocaine demonstrating the highest activity. However, their antioxidant activity in lipophilic environments, such as cellular membranes, myelin sheets, and adipose tissue, appears to be negligible. Our results thus show that free radical scavenging activity is influenced by the lipophilicity of the environment.

Platysma muscle additionally innervated by a variant anterior branch of the great auricular nerve.

Damage to the great auricular nerve, with consequent clinical deficits, is a common surgical complication in facial aesthetic and in head and neck procedures such as parotidectomy, neck dissection, rhytidectomy and platysma flap operations. Hence, a thorough knowledge of nerve anatomy, particularly its potential variations, is critical in reducing the associated operative morbidity. Accordingly, we report an unusual variation of the anterior branch of the great auricular nerve noted in an 81-year-old female cadaver. The nerve was observed to course into the submandibular region anterior and superficial to the internal jugular vein, communicating with the cervical branch of the facial nerve, while independently innervating the platysma muscle. Although several anatomical variations of the branches of the cervical plexus have been documented, our report describes unique innervation of the platysma muscle by the great auricular nerve, which provides a new insight on the motor component of the nerve.

Variant course of the submental vein.

Superficial head and neck vessels are increasingly used in surgical procedures and are especially important in facial transplantation surgeries. We report a variant course of the submental vein observed during a dissection of a 79-year-old-male embalmed cadaver: a left submental vein running caudally across the intermediate tendon of the digastric muscle, separating from the course of the submental artery and emptying directly into the common facial vein in the carotid triangle. Such course may complicate submental island flap harvesting, as well as the graft manipulations and reattachment, since the vein could be damaged during the conventional procedure. This report therefore extends current knowledge of the variations of the vascular anatomy of the head and neck.

Cross-over type of supernumerary digastric muscle.

A cross-over type asymmetric anomaly of the anterior belly of the right digastricmuscle was observed during a cadaveric dissection of the submental region.Three irregularly-shaped supernumerary muscle bundles were found between theanterior bellies of the digastric muscles. Although the anomalies of the digastricmuscles are often observed, this complicated pattern has not been previouslyreported. Our findings and previous reports illustrate the morphogenetic complexityof the anterior belly of the digastric muscle, and their potential importancein confounding clinical evaluation or complicating surgical procedures in thesubmental region.