Bioactivity evaluation of ingredients identified from the fruits of Amomum tsaoko Crevost et Lemaire, a Chinese spice

Abstract

In this work, a phytochemical investigation was conducted on Amomum tsaoko Crevost et Lemaire, a traditional Chinese spice. Based on spectroscopic methods including MS, ¹H-NMR, ¹³C-NMR, DEPT135 and HMQC spectroscopy, eight main chemical compositions, sitosterol, daucosterol, meso-hannokinol, quercetin, epicatechin, quercetin-7-O-β-glucoside, quercetin-3-O-β-glucoside, and catechol, were isolated and identified from A. tsaoko, among which quercetin, quercetin-7-O-β-glucoside and quercetin-3-O-β-glucoside were first found in A. tsaoko. Their bioactivities were evaluated by the inhibitory effect on NO production in LPS-stimulated macrophage RAW 264.7 cells, the protective effect on H₂O₂-induced apoptosis of PC-12 cells and the DPPH radical scavenging assay. Epicatechin exhibited excellent anti-inflammatory properties; its inhibition rate was up to 63.65% at a concentration of 100 μg mL⁻¹. In addition, quercetin showed the strongest neuroprotective effect of PC-12 cells induced by H₂O₂, and the cell viability was up to 78.9% at a concentration of 50 μg mL⁻¹. Quercetin also exhibited excellent DPPH radical-scavenging activity at a concentration of 100 μg mL⁻¹ (DPPH radical inhibition rate > 80%), which was very close to V_c at the same concentration. It is concluded that, in A. tsaoko, different ingredients have their own health functions.