JOURNAL OF HERBAL MEDICINE, cilt.27, 2021 (SCI-Expanded)
In the current work, the ethanol extracts of (36 samples from various locations) 21 species of Geranium were investigated for their tyrosinase (TYR) inhibitory and antioxidant activity. G. glaberrimum (GG) (31.41 +/- 1.11 %), G. macrostylum (31.15 +/- 1.35 %), and G. lasiopus (30.01 +/- 0.09 %) had the highest inhibition against TYR, which were proceeded to further phytochemical analyses. The major compounds were gallic and ellagic acids. G. glaberrimum Boiss. & Heldr. were further fractioned by preparative-LC, in which the second fraction (GG-2) resulted in the highest inhibition, which was analyzed by LC-MS-MS. Geraniin and corilagin in GG-2 and quinic acid, gallic acid, 3,4-dihydroxy benzoic acid, 4-O-methyl gallate, geraniin, corilagin, ellagic acid, and quercetin were shown to be present in GG-EtOH extract. Quercetin (IC50 = 54.11 +/- 1.92 mu g/mL) was the most active inhibitor. Molecular interactions of the compounds with TYR were examined. Structure-activity relationship was achieved by PASS and Swiss Target Prediction programs. Ellagic acid and quercetin also displayed good molecular connections with the active site of TYR through pi-pi interactions and binding with two Cu atoms at the center of the enzyme. Thus, these two compounds appeared to be the most promising TYR inhibitors approved by both in vitro and in silico results.