Phenolic Constituents of Elsholtzia blanda Benth

Objectives: Elsholtzia blanda Benth. is a Vietnamese medicinal plant, used to treat inflammation, cough, and flu. Therefore, this current study focused on the isolation of the active ingredients from this plant and their NO production inhibitory activity. Methods: E. blanda aerial parts were dried, minced, and ultrasonically extracted with methanol and further separated by various chromatographic methods. The chemical structures of isolates were revealed by nuclear magnetic resonance, high resolution lectrospray ionization mass spectrometry, and circular dichroism spectra. The nitric oxide inhibition effects were evaluated in lipopolysaccharide-activated RAW264.7 cells. Results: Ten phenolic components [1 new (1) and 9 known (2-10)] were isolated and their chemical structures determined. Compound 5 (innovanoside, IC 50 = 19.23 ± 1.43 µM) and 6 (maltol- O- β-D-glucopyranoside, IC 50 = 21.73 ± 1.27 µM) showed the highest activity, and 2-4 showed moderate inhibition (IC 50 = 47.36 ∼ 57.29 µM). The other compounds were inactive with IC 50 values >100 µM. Conclusions: One previously undescribed and 9 known phenolic components isolated from E. blanda have been screened for their nitric oxide inhibitory activity. Compounds 2-6 showed moderate to significant inhibition with IC 50 values of 19.23∼57.29 µM.