Anti-inflammatory Activity of Total Alkaloids from Hypecoum leptocarpum Hook. f. et Thoms

Background: Hypecoum leptocarpum Hook. f. et Thoms., which is used in traditional Tibetan medicine as an antipyretic, antitussive, analgesic, and anti‑inflammatory agent, contains a variety of alkaloids that could be responsible for its analgesic and anti‑inflammatory properties. Objective: The present study was designed to investigate the anti‑inflammatory activity of the total alkaloids from H. leptocarpum (AHL) in vitro and to elucidate the chemical structure of the anti‑inflammatory components in AHL. Materials and Methods: Chemical characterization was performed using liquid chromatography/quadrupole‑time‑of‑flight mass and diode‑array detector‑high performance liquid chromatography. The anti‑inflammatory effects of AHL were investigated by measuring the production of inflammatory cytokines using enzyme‑linked immunosorbent assay and mRNA expression by real‑time polymerase chain reaction in lipopolysaccharide‑induced RAW 264.7 macrophages. Results: Chemical analysis of AHL revealed the presence of seven alkaloids, protopine (13.3%), cryptopine (1.5%), leptopidinine, leptocarpine, corydamine, dihydroleptopine, and oxohydrastinine. AHL significantly suppressed the production of nitric oxide (NO), interleukin‑1 beta (IL‑1 β), IL‑6, and tumor necrosis factor‑alpha (TNF‑α) in LPS‑induced RAW 264.7 cells. The maximum levels of suppression of NO, IL‑1 β, IL‑6, and TNF‑α were 86.8% ± 2.2%, 70.1% ± 1.5%, 100.1% ± 2.5%, and 50.8% ± 3.6%, respectively. IC50 values of suppression of cytokine production by AHL were 7.47 ± 2.81 μg/mL (NO), 0.12 ± 0.28 μg/mL (IL‑1 β), 0.56 ± 0.37 μg/mL (IL‑6), and 18.95 ± 5.23 μg/mL (TNF‑α). AHL was also shown to downregulate mRNA expression of inducible NO synthase, IL‑1 β, IL‑6, and TNF‑α in vitro. Conclusion: The study provides convincing evidence that AHL has strong anti‑inflammatory activity.