**1. Introduction**

One of the most common gynecological pathologies in reproductive age women is endometriosis, characterized by the presence of endometrial-like tissue in the uterine cavity [1,2].

Both heme and cellular debris contribute consistently to the formation of local [3] and systemic [4] inflammation status, thus promoting the increased production of reactive oxygen species (ROS) and reactive nitrogen species, cytokines, growth factors, and prostaglandins [5].

The presence of oxidative stress status markers in circulating red blood cells (RBCs) has been recently pointed out as a systemic feature of endometriosis [4]. Due to their fundamental role in oxygen transport, RBCs are particularly exposed to the oxidant threat, which represents a limiting factor of the lifespan of RBCs because no new proteins can be synthesized [6]. Therefore, oxidative-related damage is critical in the regulation of RBC's proper functioning and aging.

Besides ensuring deformability, which is determined by membrane protein-protein and lipid-protein interactions, membranes also provide cellular ion exchange and the expression of aging-related epitopes for RBC senescence recognition and removal.

In the RBC membrane, one of the most important integral proteins is protein band 3 (or anion exchanger, AE1), a 100 kDa protein with 12–14 transmembrane segments, mainly involved in the maintaining of the biconcave-shape and the CO2/HCO<sup>3</sup> − homeostasis through chloride and bicarbonate (Cl−/HCO<sup>3</sup> −) anion exchange [7]. The presence of phosphorylatable residues in the cytoplasmic domain (including both the *N*- and *C*-terminal ends of the molecule) provides band 3 the peculiarity of being considered as a redox stress sensor [8] in many prooxidant disorders [8–10], such as in glucose-6-phosphate dehydrogenase deficiency (G6PDd) [10,11]. The band 3 Tyr-P level regulates many of the physiological processes in RBCs, from glycolysis [12] to morphology [13], but it is also involved in erythrocyte aging [11,14] and antibody recognition [15].

Dapsone (DDS) is an aniline compound commonly used for many indications [16,17], including the treatment of leprosy, varied skin conditions, *Pneumocystis carinii* infection, and a variety of immuno-related conditions [18,19]. Unfortunately, DDS shares a welldocumented toxicity, related to its routes of biotransformation [20,21] leading to the formation of dapsone hydroxylamine (DDS-NHOH), the powerful oxidizing dapsone metabolite [20,22]. In in vitro studies, DDS-NHOH has been demonstrated to shorten RBC lifespan through the progressive oxidative alteration pathway starting from methemoglobin formation, glutathione oxidation, [22–25], and band 3 high molecular weight aggregates (HMWA) [26], which leads to autologous antibody recognition [24].

Among the antioxidants assumed with the diet, such as vitamins, carotenoids, and minerals, which have been shown to contribute to maintaining the redox homeostasis, glycyrrhizin, the glycoside extracted from roots of the liquorice, known for its characteristic sweetness (about 30–50 times sweeter than sucrose), is widely used in the treatment of many diseases, such as chronic hepatitis [27], erythrodermic psoriasis [28], a variety of human viruses such as avian infectious bronchitis virus [29], HIV [30,31], and SARS-CoV-2 [32,33], as a few examples. Orally administered glycyrrhizin is metabolized by intestinal bacteria into 18β-glycyrrhetinic acid (GA) [34], a pentacyclic triterpenoid, whose structure is similar to those of the mineralocorticoid and glucocorticoid hormones secreted by the adrenal cortex. In in vitro experiments in human RBCs, GA prevented oxidative-induced alterations, greatly reducing both band 3 Tyr-P and band 3 high molecular weight aggregate (HMWA) formation [35].

The aim of this study was to evaluate the effect of the licorice intake on the oxidative stress generated by DDS-NHOH in RBCs from PG by monitoring band 3 Tyr-P levels and HMWA as parameters for the detection of RBC membrane denaturation. In addition, we analyzed the state and the activity of cytosolic carbonic anhydrase (CA), to investigate if GA could mitigate DDS-NHOH side-effects involving this enzyme, a useful parameter of the potential worsening of RBC oxidative status [36].
