Platycodonis Radix Alleviates LPS-Induced Lung Inflammation through Modulation of TRPA1 Channels.

Platycodonis Radix (PR), a widely consumed herbal food, and its bioactive constituents, platycodins, have therapeutic potential for lung inflammation. Transient Receptor Potential Ankyrin 1 (TRPA1), which is essential for the control of inflammation, may be involved in the development of inflammation in the lungs. The aim of this study was to determine the TRPA1-targeted effects of PR against pulmonary inflammation and to investigate the affinity of PR constituents for TRPA1 and their potential mechanisms of action. Using a C57BL/6J mouse lipopolysaccharides (LPS) intratracheal instillation pneumonia model and advanced analytical techniques (UPLC-Q-TOF-MS/MS, molecular docking, immuno-fluorescence), five platycodins were isolated from PR, and the interaction between these platycodins and hTRPA1 was verified. Additionally, we analyzed the impact of platycodins on LPS-induced TRPA1 expression and calcium influx in BEAS-2B cells. The results indicated that PR treatment significantly reduced the severity of LPS-triggered inflammation in the mouse model. Interestingly, there was a mild increase in the expression of TRPA1 caused by PR in healthy mice. Among five isolated platycodins identified in the PR extract, Platycodin D3 (PD3) showed the highest affinity for hTRPA1. The interaction between platycodins and TRPA1 was verified through molecular docking methods, highlighting the significance of the S5-S6 pore-forming loop in TRPA1 and the unique structural attributes of platycodins. Furthermore, PD3 significantly reduced LPS-induced TRPA1 expression and calcium ion influx in BEAS-2B cells, substantiating its own role as an effective TRPA1 modulator. In conclusion, PR and platycodins, especially PD3, show promise as potential lung inflammation therapeutics. Further research should explore the precise mechanisms by which platycodins modulate TRPA1 and their broader therapeutic potential.

The investigation of detection and sensing mechanism of spicy substance based on human TRPV1 channel protein-cell membrane biosensor.

The transient receptor potential vanilloid 1 (TRPV1) is a key target for the spicy taste sensor and analgesic drug development. However, the human TRPV1-associated signaling remains to be obscure. In this study, we overexpressed human TRPV1 (hTRPV1) in HEK293T cells and explored its signaling activated by spicy substances. A cell membrane biosensor was constructed by using the cells highly expressed hTRPV1 through a layer-by-layer assembly. Our results showed that the activation constants by capsaicin, allicin and sanshool, the active components of chili pepper, garlic and mountain pepper, were Ka, capsaicin = 3.5206 × 10-16 mol/L, Ka, allicin = 5.0227 × 10-15 mol/L, Ka, sanshool = 1.7832 × 10-15 mol/L. Obviously, the order of the sensitivity mediated by hTRPV1 was capsaicin > sanshool > allicin. The affinity values of the three spicy substances with hTRPV1 analyzed by molecular docking simulation also displayed the same law. Most importantly, some amide bonds and their similar groups and even benzene rings of spicy compounds were fund to be critical in the spicy sensing process. In addition, Glu570 in the active pocket of hTRPV1 plays an important role in identifying spicy substances. The elucidation of the detailed mechanism mediated by hTRPV1 in spicy sensing will lay a theoretical foundation to design rational strategies for screening of potential analgesics.