Flavonoids from Agrimonia pilosa Ledeb: Free Radical Scavenging and DNA Oxidative Damage Protection Activities and Analysis of Bioactivity-Structure Relationship Based on Molecular and Electronic Structures

• Published in: Molecules (Basel, Switzerland) Vol. 22; no. 3; p. 195
• Main Authors: Zhu, Liancai, Chen, Jinqiu, Tan, Jun, Liu, Xi, Wang, Bochu
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 26-02-2017; MDPI
• Subjects: Agrimonia - chemistry; Agrimonia pilosa Ledeb; Antioxidants; bioactivity-structure relationship; Biological activity; Catechin - chemistry; Catechin - pharmacology; Cocoa; Deoxyribonucleic acid; DNA; DNA Damage - drug effects; DNA oxidative damage; Flavonoids; Flavonoids - analysis; Flavonoids - chemistry; Flavonoids - pharmacology; free radical scavenging activity; Molecular Structure; Oxidative Stress - drug effects; Plant Extracts - chemistry; Plant Extracts - pharmacology; Quercetin - analogs & derivatives; Quercetin - chemistry; Quercetin - pharmacology; Rutin - chemistry; Rutin - pharmacology; Structure-Activity Relationship; DNA oxidative damage; Agrimonia pilosa Ledeb; flavonoids; bioactivity-structure relationship; free radical scavenging activity
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules22030195

To clarify the substantial basis of the excellent antioxidant capacity of
Ledeb. Fourteen flavonoids were isolated and identified from
Ledeb, seven of which have notable DPPH radical scavenging activities, i.e., catechin, luteolin, quercetin, quercitrin, hyperoside, rutin, luteolin-7-
-β-glucoside with IC
values of 5.06, 7.29, 4.36, 7.12, 6.34, 6.36 and 8.12 µM, respectively. The DNA nicking assay showed that five flavonoids from
Ledeb-taxifolin, catechin, hyperoside, quercitrin and rutin-have good protective activity against DNA oxidative damage. Further, we analyzed the bioactivity-structure relationship of these 14 flavonoids by applying quantum theory. According to their O-H bond dissociation enthalpy (BDE), C ring's spin density and stable molecular structure, the relationship between their structures and radical scavenging capacities was evaluated and clarified. We found that among flavonoid aglycones from
Ledeb, the O-H BDE of quercetin is lowest with the values of 69.02 and the O-H BDE of apigenin is highest with the values of 79.77. It is interesting that the O-H BDE value of isovitexin (78.55) with glycoside at C-6 position is lower than that of its aglycone (79.77) and vitexin (99.20) with glycoside at C-8 position. Further analysis indicated that the glycosidation of flavonoids at C-6 in the A-ring makes a more uniform distribution of spin density and improves the stability of free radicals leading to the increase in antioxidant capacity. Flavonoids with good antioxidant capacity might contribute to the pharmacological effects of
Ledeb.