Conifer Bark Extracts as Modulators of Endothelial Function: Evidence from Abies alba and Cedrus brevifolia

Conifer bark extracts have attracted growing interest for their potential to protect and support endothelial function. The objective of this study was to evaluate the effects of <i>Abies alba</i> Mill. and <i>Cedrus brevifolia</i> (Hook. f.) Henry bark extracts on vascular endothelial function. The bark extracts were characterized by liquid chromatography coupled to high-resolution mass spectrometry. Bioactivity studies were first conducted in EA.hy926 endothelial cells to investigate the effects of bark extracts on cell viability and proliferation, nitric oxide production, oxidative stress, and angiogenesis. The vasorelaxant effects of bark extracts in rat aortic rings, as well as their impact on in vitro arginase activity, were further assessed. <i>Abies alba</i> bark extract was more effective in enhancing nitric oxide production (8.8-fold vs. 7.4-fold at 0.1 mg/mL), reducing oxidative stress (by 33% vs. 26% at 0.1 mg/mL), and inhibiting angiogenesis in EA.hy926 endothelial cells. It also exhibited stronger arginase inhibitory activity (IC₅₀ = 68.30 µg/mL vs. 115.31 µg/mL). Both bark extracts showed marked vasorelaxant activity (EC₅₀ < 15 µg/mL), mainly mediated by an endothelial nitric oxide synthase-related mechanism, with the <i>Cedrus brevifolia</i> bark extract being more active. Overall, our findings indicate that both bark extracts are promising candidates for supporting endothelial function.