The relaxant and contractile effects of Verbascum speciosum extracts on rat trachea: phenolic and organic acid contents and acetylcholinesterase inhibition

İngilizce (OpenAlex)

Verbascum speciosum is traditionally used against respiratory system diseases such as asthma and bronchitis. This study investigated the effects of extracts prepared from V. speciosum Schrad. on isolated rat trachea. Plants collected in July 2023 were used to prepare flower methanol extract (FME), leaf methanol extract (LME), flower water extract (FWE), and leaf water extract (LWE). Phenolic and organic acid contents and acetylcholinesterase (AChE) inhibitory activity were measured. Methanol extracts had a more concentrated phenolic content. The IC50 values for AChE inhibition were higher in the methanol extracts. The extracts were directly tested on isolated rat trachea. LME did not produce contractile or relaxant responses. However, FME, FWE, and LWE elicited contractile responses in a dose- and extract-dependent manner. All extracts relaxed rat trachea pre-contracted with KCl and carbachol (CCh) in a dose- and extract-dependent manner. For trachea pre-contracted with ACh, LWE and FWE induced contraction, while LME and FME caused relaxation. LME exhibited the strongest relaxant effect at 100 mg, relaxing KCl-induced contraction by 103.81±7.94%, CCh-induced contraction by 109.21±2.64%, and ACh-induced contraction by 111.45±5.95%. The findings suggest that V. speciosum may contain various pharmacologically active compounds useful for treating respiratory diseases. However, the contractile response of water extracts to ACh-induced contraction may indicate potential risks of consuming Verbascum-containing herbal teas.