Vasorelaxant properties of Vernonia amygdalina ethanol extract and its possible mechanism

Figures & data

Figure 1. Fingerprint of VAE in (a) conventional FTIR, (b) second derivative in the range of 1800–700 cm⁻¹, and (c) 2D-correlation IR spectra in the range of 1200–1800 cm⁻¹.

Table 1. Peak assignments on the FTIR spectrum of VAE.

Peak (cm^−1)
VAE	Primary assignment	Possible compounds
3378	O–H and N–H, ν	Various and alkaloid
2921	C–H, νas	Various
2850	C–H, νs	Various
1733	C = O, ν	Ester
1619	O–H, δ and Ring	Ester and aromatic
1445	Ring	Aromatic
1380	C–H, δ	–
1259	(O) C–H, δ	Saccharides
1163	C–O, ν	Saccharides
1074	C–O, ν	Saccharides
1037	C–O, ν	Saccharides

ν: stretching; ν_s: symmetrical stretching; ν_as: asymmetrical stretching; δ: bending.

Figure 2. Original isometric force recordings showing the contraction evoked by PE in endothelium-intact (a) and endothelium-denuded (b) rat aortic rings treated with various concentrations of VAE. Effect of VAE on PE-induced contraction in endothelium-intact aortic rings and endothelium-denuded aortic rings (n = 8) (c). *, **, and *** indicate significance at p < 0.05, p < 0.01, and p < 0.001, respectively, compared to the group of endothelium-intact aortic rings.

Figure 3. Original isometric force recordings showing influence of L-NAME (a), indomethacin (b), and atropine (c) on the vasorelaxant effect of VAE in endothelium-intact aortic rings. Effect of VAE on PE-induced contraction in endothelium-intact aortic rings (n = 8) in the presence of L-NAME, indomethacin, and atropine (d). *, **, and *** indicate significance at p < 0.05, p < 0.01, and p < 0.001, respectively, compared to the group of endothelium-intact aortic rings.

Figure 4. Original isometric force recordings showing influence of propranolol (a), methylene blue (b), and ODQ (c) on the vasorelaxant effect of VAE in endothelium-intact aortic rings. Effect of VAE on PE-induced contraction in endothelium-intact aortic rings (n = 8) in the presence of propranolol, methylene blue, and ODQ (d). *, **, and *** indicate significance at p < 0.05, p < 0.01, and p < 0.001, respectively, compared to the group of endothelium-intact aortic rings.

Figure 5. Original isometric force recordings showing the influence of TEA (a), glibenclamide (b), 4-AP (c), and BaCl₂ (d) on the vasorelaxant effect of VAE in endothelium-intact aortic rings. Effect of VAE on PE-induced contraction in endothelium-intact aortic rings (n = 8) in the presence of TEA, glibenclamide, 4-AP, and BaCl₂ (e). *, **, and *** indicate significance at p < 0.05, p < 0.01, and p < 0.001, respectively, compared to the group of endothelium-intact aortic rings.

Figure 6. Effect of VAE on CaCl₂-induced vasocontraction in isolated aortic rings (n = 8). *, **, and *** indicate significance at p < 0.05, p < 0.01, and p < 0.001, respectively, compared to the group without incubation of antagonist (control).

Figure 7. Vasorelaxant effect of VAE on PE pre-contracted endothelium-denuded aortic rings in Ca²⁺-free Krebs solution (n = 8). *, **, and *** indicate significance at p < 0.05, p < 0.01, and p < 0.001, respectively, compared to the control group.