Herba Ecliptae Protects against Hydroxyl Radical-induced Damages to DNA and Mesenchymal Stem Cells via Antioxidant Mechanism

Herba Ecliptae (HE) is a typical Chinese herbal medicine used in China for 1500 years. In the study, HE was extracted by various solvents to prepare five HE extracts. They were observed to possess a protective effect against ×OH-induced DNA damage, and scavenging effects on ×OH radical, ×O 2 − radical, DPPH×(1,1-diphenyl-2-picrylhydrazyl) radical, and ABTS× + (2,2′-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) radical, and reduce Cu 2+ ion. The contents of total phenolics and wedelolactone in five extracts were determined respectively using Folin-Ciocalteu method and HPLC method. To identify which chemical component can be responsible for its effects, the correlation graphs between chemical contents and antioxidant abilities (1/IC 50 values) were plotted to calculate correlation coefficients (R values). Finally, MTT assay revealed that two HE extracts could effectively protect mesenchymal stem cells (MSCs) against ×OH-induced damage at 3-30 μg/mL. On the basis of mechanistic analysis, we concluded that: ( i ) HE can effectively protect against ×OH-induced damages to DNA and MSCs, thereby HE may have a therapeutic potential in MSCs transplantation or prevention of many diseases; ( ii ) the effects can be mainly attributed to total phenolics (R = 0.678) especially wedelolactone (R = 0.618); ( iii ) they exert antioxidant action via hydrogen atom transfer (HAT) and sequential electron proton transfer (SEPT) mechanisms.