Isolation and characterization of phellodendronoside A, a new isoquinoline alkaloid glycoside with anti-inflammatory activity from Phellodendron chinense Schneid.

Bark of Phellodendron chinense Schneid. (Rutaceae), called "Huang Bai" in China, is one of the 50 most used Chinese medicines in clinical practice. In this paper, a new isoquinoline alkaloid glycoside was isolated from P. chinense, and its structure was elucidated using spectroscopic method. The compound was eventually identified as (1S, 3"S)-1, 2, 3, 4-tetrahydro-7-hydroxy-1-[(4-hydroxybenzyl) methyl]-2-methyl-8-O-isoquinolinyl-[3-hydroxy-3-methylglutaryl]-β-D-glucopyranoside and named as Phellodendronoside A (PDA). The results of molecular docking showed that PDA could stably bind to an extracellular signal-regulated kinase (ERK), stress-activated protein kinase (JNK) and p38 mitogen-activated protein kinase (p38MAPK) proteins that are closely related to inflammation. Further, the anti-inflammatory activity of PDA was evaluated using the lipopolysaccharide (LPS) induced RAW264.7 macrophage model. We observed that PDA can effectively reduce the levels of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and decrease the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, we found that PDA inhibits the activation of ERK, JNK and p38MAPK proteins in the MAPK signaling pathway. Collectively, the present study demonstrates that PDA has excellent anti-inflammatory effect in vitro by inhibiting the overproduction of pro-inflammatory mediators, and its mechanism of action involves suppressing the activation of MAPK pathways, suggesting that PDA may be a potential agent for the treatment of inflammatory illness.