In Vitro and In Vivo Studies of Crategus and Inula helenium extracts: Their Effects on Rat Blood Pressure
Authors: Inomjonov Dolimjon , Abdullaev Izzatullo , Omonturdiev Sirojiddin , Abdullaev Azizbek , Maxmudov Lazizbek , Zaripova Mehrangiz , Abdullayeva Muyassar , Abduazimova Dildora , Menglieva Shakhnoza , Gayibova Sabina , Sadbarxon Mavlanova , Gayibov Ulugbek , Aripov Takhir 
Published: February 2025

The contraction of aortic tissues induced by 50 mM KCl is primarily mediated through the activation of voltage-dependent L-type Ca2+ channels in smooth muscle cells. In this study, the effects of Crategus Rosaceae and Inula helenium extracts on KCl-induced contraction were investigated. Extracts of Crataegus attenuated the KCl-induced contraction by 15.0 ± 2.6 and 70.0 ± 2.8 % at concentrations ranging from 20 - 70 μg/mL, while Inula helenium extract reduced the contraction by 5.0 ± 3.1 and 80.0 ± 2.8 % at concentrations of 10 - 50 μg/mL. These findings suggest that the extracts inhibit KCl-induced contraction by modulating L-type Ca2+ channels. Further experiments were conducted in Ca2+-free Krebs solution and in the presence of the L-type Ca2+ channel blocker, verapamil. Crategus Rosaceae and Inula helenium extracts significantly reduced aortic contractions in the presence of KCl and Ca2+, with reductions of 45.0 ± 2.2 and 38.0 ± 2.4 %, respectively, suggesting that the relaxant effects are mediated by reduced Ca2+ influx through L-type Ca2+ channels. Additionally, Crataegus and Inula helenium extracts inhibited phenylephrine (1 μM)-induced contraction, with reductions of 75.0 ± 2.4 and 88.0 ± 2.2 %, respectively, further suggesting an effect on both receptor-controlled and L-type Ca2+ channels. When combined with the α-adrenoceptor blocker phentolamine, the extracts reduced phenylephrine-induced contraction by 20.0 ± 2.1 and 10.0 ± 2.3 %, respectively. Endothelium-dependent relaxant effects of the extracts were confirmed in experiments with L-NAME (100 μM), where the relaxant effects of Crataegus and Inula helenium were significantly reduced to 15.0 ± 2.9 and 24.3 ± 2.4 %, respectively, in the absence of the endothelial layer. These findings suggest that the relaxant effects are mediated through the nitric oxide (NO)-cGMP-PKG signaling pathway. In vivo experiments using the tail cuff method demonstrated a dose-dependent decrease in systolic blood pressure (SBP) in hypertensive rats treated with Crataegus extract at doses of 50, 100 and 200 µg/mL, further supporting the extract’s potential antihypertensive effects.
HIGHLIGHTS

Modulation of L-type Ca2+ channels: Crataegus Rosaceae and Inula helenium extracts significantly reduced KCl-induced aortic contractions, suggesting modulation of voltage-dependent L-type Ca2+
Dual mechanism of relaxation: Both extracts inhibited contractions induced by phenylephrine, indicating effects on receptor-controlled and L-type Ca2+
Endothelium-dependent relaxation: Relaxant effects were mediated via the NO-cGMP-PKG pathway, confirmed through reduced efficacy in the presence of L-NAME.
In vivo antihypertensive activity: Crataegus extract produced a dose-dependent reduction in systolic blood pressure in hypertensive rats, demonstrating its antihypertensive potential.
Concentration-dependent effects: Crataegus and Inula helenium extracts showed a graded response, with contractions reduced by up to 80 % at varying concentrations.

GRAPHICAL ABSTRACT