Compounds
HSG4112 and all other glabridin-derivative compounds were prepared at Glaceum Inc. (Suwon, Republic of Korea) following the protocols from US9783551B2 (Yoo, 2017). Glaceum Inc. holds all IPs for synthesis, method, and use of all compounds in this paper as well as other unmentioned glabridin-derivatives. Commercially available glabridin (Sigma-Aldrich Co., St. Lousi, MO, USA) was used. Absolute configuration nomenclature (R /S ) was used instead of optical rotation nomenclature (+/−) because (R ) form of C-4’ methylated dihydro-glabridin and HSG4112 showed levorotary (−) optical rotation while (R ) form of glabridin and 3”,4”-dihydro-glabridin showed dextrorotary (+). The preparation of vehicle and test substances were carried out once a week during the administration period.