Flavonoid galetin 3,6-dimethyl ether attenuates guinea pig ileum contraction through K(+) channel activation and...

Area of Science:

• Pharmacology
• Natural Products Chemistry
• Gastroenterology

Background:

• Flavonoid galetin 3,6-dimethyl ether (FGAL) is a compound isolated from Piptadenia stipulaceae.
• FGAL has demonstrated a spasmolytic effect on guinea pig ileum.
• Understanding the precise mechanism of action is crucial for potential therapeutic applications.

Purpose of the Study:

• To elucidate the detailed relaxant mechanism of FGAL on guinea pig ileum.
• To investigate the specific ion channels and receptors involved in FGAL's spasmolytic activity.
• To characterize the effects of FGAL on cellular calcium levels.

Main Methods:

• Pharmacological characterization of FGAL's relaxant effects on isolated guinea pig ileum pre-contracted with various agonists (histamine, KCl, carbachol, S-(-)-Bay K8644).
• Investigation of FGAL's interaction with calcium influx pathways and specific potassium channels (SKCa, BKCa, KV, KATP) using selective modulators.
• Assessment of FGAL's effect on cytosolic calcium concentration using Fluo-4 fluorescence and cell viability using MTT assay.

Main Results:

• FGAL showed potent relaxant effects, particularly against histamine-induced contractions, and inhibited calcium-induced contractions.
• The relaxant effect was modulated by 4-aminopyridine and glibenclamide, indicating involvement of voltage-gated (KV) and ATP-sensitive (KATP) potassium channels.
• FGAL significantly reduced cytosolic calcium levels without affecting myocyte viability, suggesting a mechanism involving calcium channel blockade (CaV1) and K+ channel activation.

Conclusions:

• The relaxant mechanism of FGAL involves a pseudo-irreversible noncompetitive antagonism of histaminergic receptors.
• FGAL activates KV and KATP channels and blocks CaV1 channels, leading to decreased cytosolic calcium.
• These findings highlight FGAL as a promising natural compound for managing smooth muscle spasms.