*4.2. Participants*

Between December 2011 and December 2016, patients, presenting with pelvic pain and an ultrasonographically that identified an adnexal ovarian mass, were referred to our endometriosis care unit for laparoscopy. Only women classified as having endometriosis by histological examination of surgical specimens were put in the endometriosis group (*n* = 18, aged 34.1 ± 8.5 years). Following surgery, the stage of the disease was defined according to the classification system of the revised American Society for Reproductive Medicine (rASRM) as stage I (minimal, *n* = 4), stage II (mild, *n* = 7), stage III (moderate, *n* = 4), and stage IV (severe, *n* = 3).

Patients met the following criteria: no hormone therapy for at least 3 months; regular menstruation; non-smoker; no signs of other inflammatory disease (as assessed by leucocytes, body temperature, or other specific symptoms). Fresh blood was collected from patients undergoing laparoscopy and also from a group of 12 volunteers, mean age 34.9 (SD 9.2) years, whose clinical and ultrasound tests identified as being healthy (Table S1).

Clinical data and peripheral blood samples were collected from both PG and CG subjects only after explaining the objectives of the study and obtaining signed informed consent, according to the Italian Law for Privacy 675/96 prior to enrolment.

All participants were asked to take licorice sweets containing licorice extract up to 25 mg /day, a dose by far lower than what is recommended by the Scientific Committee which considered it prudent that regular ingestion should not exceed 100 mg/day [43].

This study was conducted in accordance with the ethical standards of the Ethics Committee for Research and Clinical Trials of our University (Em. n. 7, 13 February 2012) and in accordance with the Helsinki Declaration.
