Anti-Inflammatory Flavonoids from Agrimonia pilosa Ledeb: Focusing on Activity-Guided Isolation

Area of Science:

• Phytochemistry
• Pharmacology
• Immunology

Background:

• Inflammation is a key process in many diseases.
• Natural products are a rich source of anti-inflammatory agents.
• Agrimonia pilosa (A. pilosa) is traditionally used for medicinal purposes.

Purpose of the Study:

• To isolate and identify anti-inflammatory compounds from A. pilosa.
• To evaluate the nitric oxide (NO) inhibitory activity of isolated compounds.
• To conduct a structure-activity relationship (SAR) analysis of A. pilosa flavonoids.

Main Methods:

• Activity-guided isolation was employed to identify bioactive constituents.
• In vitro nitric oxide assay using lipopolysaccharide (LPS)-treated RAW 264.7 macrophage cells.
• Structure-activity relationship (SAR) analysis of eight flavonoids.

Main Results:

• Seven compounds were isolated and identified: quercetin-7-O-β-d-rhamnoside, apigenin-7-O-β-d-glucopyranoside, kaempferol-7-O-β-d-glucopyranoside, quercetin, kaempferol, apigenin, and apigenin-7-O-β-d-glucuronide-6″-butylester.
• All compounds exhibited significant NO inhibitory activity (IC50: 1.4–31 µM).
• Apigenin (6) showed the most potent NO inhibition; apigenin-7-O-β-d-glucuronide-6″-butylester (7) was identified as a novel anti-inflammatory agent.

Conclusions:

• A. pilosa is a valuable source of anti-inflammatory compounds.
• Flavones are more potent NO inhibitors than flavonols, and aglycones are more potent than glycones.
• A. pilosa holds potential as a dietary supplement and therapeutic material for inflammatory conditions.