Natural Compound from Panax Flowers Eases Cough by Blocking Key Pain Channels

Jenn Hoskins
25th August, 2024

Natural Compound from Panax Flowers Eases Cough by Blocking Key Pain Channels

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Yangzhou University found that Panax notoginseng flowers can effectively suppress coughs
  • The main active compound, 20S-ginsenoside Rh2, was identified as a key contributor to these antitussive effects
  • The study suggests that 20S-ginsenoside Rh2 works by targeting specific channels involved in cough reflexes, offering a potential new treatment for chronic cough
Refractory chronic cough (RCC) is a persistent and debilitating condition that lacks effective, licensed treatments. Recent research conducted by Yangzhou University has investigated the antitussive (cough-suppressing) properties of Panax notoginseng flowers, a traditional Chinese medicinal herb known for its therapeutic effects on both acute and chronic coughs[1]. This study aimed to identify the active compounds responsible for these effects and to elucidate their underlying mechanisms. The researchers first analyzed the chemical constituents of aqueous extracts of Panax notoginseng flowers using advanced techniques like liquid chromatography-mass spectrometry. They identified that the primary active components were protopanaxadiol-type saponins, with 20S-ginsenoside Rh2 being the most abundant (51.46 mg/g). This compound was then quantitatively analyzed using high-performance liquid chromatography. The antitussive effects of Panax notoginseng flowers were evaluated using two animal models: a cough reflex model in healthy mice and an ovalbumin-induced, highly sensitive guinea pig cough model. These models helped verify the suppressive effects of the flowers and their saponin constituents on coughing. The study found that Panax notoginseng flowers exhibited antitussive effects comparable to those of pentoxyverine citrate, a known cough suppressant. Although 20S-ginsenoside Rh2 showed slightly weaker effects, it still demonstrated a concentration-dependent inhibition of channel activity. To explore the mechanisms of action, the researchers employed whole-cell patch-clamp techniques and molecular docking. These methods revealed that 20S-ginsenoside Rh2 might exert its effects by directly binding to NaV1.7 and TRPV1 channels. NaV1.7 and NaV1.8 are voltage-gated sodium channels crucial for the initiation and conduction of action potentials, making them attractive targets for antitussive therapies[2]. Previous studies have shown that NaV1.7 and NaV1.8 inhibitors can significantly reduce cough responses induced by capsaicin and citric acid in animal models[2]. The current study aligns with these findings, suggesting that 20S-ginsenoside Rh2 may inhibit cough by targeting these channels. In the guinea pig model, Panax notoginseng flowers and their saponin components not only reduced cough frequency and prolonged the latency period before cough onset but also significantly inhibited tracheal and pulmonary inflammation and the overexpression of TRPV1. TRPV1 is a receptor known to be involved in cough reflex sensitivity. Prior research has indicated that TRPV1 antagonists like XEN-D0501 can reduce capsaicin-evoked cough but not spontaneous cough frequency, highlighting the complexity of targeting this receptor for cough treatment[3]. The Yangzhou University study provides new insights by showing that 20S-ginsenoside Rh2 can downregulate TRPV1 expression, offering a potential mechanism for its antitussive effects. The findings from this study suggest that 20S-ginsenoside Rh2, the major bioactive saponin in Panax notoginseng flowers, exhibits potent antitussive effects. The potential mechanism involves inhibiting NaV1.7 and TRPV1 channel currents through direct binding to core protein active sites and downregulating TRPV1 expression. This research not only supports the traditional use of Panax notoginseng flowers for cough relief but also provides a scientific basis for developing new antitussive therapies targeting NaV1.7 and TRPV1 channels.

MedicineHealthBiochem

References

Main Study

1) 20S-Ginsenoside Rh2, the major bioactive saponin in Panax notoginseng flowers, ameliorates cough by inhibition of NaV1.7 and TRPV1 channel currents and downregulation of TRPV1 expression.

Published 21st August, 2024

https://doi.org/10.1016/j.jep.2024.118716

Related Studies

2) Influence of combined voltage-gated sodium channel NaV1.7 and NaV1.8 inhibitors on cough in a guinea pig model.

https://doi.org/10.1016/j.resp.2023.104043

3) XEN-D0501, a Novel Transient Receptor Potential Vanilloid 1 Antagonist, Does Not Reduce Cough in Patients with Refractory Cough.

https://doi.org/10.1164/rccm.201704-0769OC


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