Abstract
A new biflavonol glycoside, quercetin-3-O-β-D-glucopyranoside-(3′→O-3‴)- quercetin-3-O-β-D-galactopyranoside (9), together with eight known compounds was isolated for the first time from the leaves of Machilus zuihoensis Hayata (Lauraceae). The structure of compound 9 was elucidated by various types of spectroscopic data analysis. Analysis of the biological activity assay found that compound 9 showed significant superoxide anion scavenging activity (IC50 is 30.4 μM) and markedly suppressed LPS-induced high mobility group box 1 (HMGB-1) protein secretion in RAW264.7 cells. In addition, the HMGB-1 protein secretion was also inhibited by quercitrin (3), ethyl caffeate (6), and ethyl 3-O-caffeoylquinate (7) treatment. In the LPS-stimulated inducible nitric oxide synthase (iNOS) activation analysis, two known compounds, quercetin (1) and ethyl caffeate (6), were found to markedly suppress nitric oxide (NO) production (IC50 value, 27.6 and 42.9 μM, respectively) in RAW264.7 cells. Additionally, it was determined that ethyl caffeate (6) down-regulated mRNA expressions of iNOS, IL-1β, and IL-10 in the LPS-treatment of RAW264.7 cells via a suppressed NF-κB pathway. These results suggested for the first time that the new compound 9 and other constituents isolated from M. zuihoensis have potential anti-inflammatory and superoxide anion scavenging effects. These constituents may be useful for treating various inflammatory diseases.
Highlights
Reactive oxygen free radical species (ROS) induce oxidative stress, which causes a wide variety of pathological effects, such as DNA damage and cellular degeneration related to aging [1] and diseases [2], including inflammatory diseases, cancer, and neurodegenerative diseases
Macrophages play a central role in mediating many different immunopathological phenomena, such as the overproduction of pro-inflammatory cytokines and inflammatory mediators, such as IL-1β, IL-6, nitric oxide (NO), iNOS, tumor necrosis factor-α (TNF-α), and high mobility group box 1 (HMGB-1) [6,7]
We have previously reported that a 95% EtOH extract of the leaves of M. zuihoensis showed significant free-radical scavenging activity [19]
Summary
Reactive oxygen free radical species (ROS) induce oxidative stress, which causes a wide variety of pathological effects, such as DNA damage and cellular degeneration related to aging [1] and diseases [2], including inflammatory diseases, cancer, and neurodegenerative diseases. Chronic and acute inflammation is a complex process mediated by activating inflammatory or immune cells [5,6]. Macrophages play a central role in mediating many different immunopathological phenomena, such as the overproduction of pro-inflammatory cytokines and inflammatory mediators, such as IL-1β, IL-6, nitric oxide (NO), iNOS, tumor necrosis factor-α (TNF-α), and high mobility group box 1 (HMGB-1) [6,7]. The stem wood of M. zuihoensis showed cytotoxic activity against NUGC-3 and HONE-1 cancer cell lines in vitro [18]. We have previously reported that a 95% EtOH extract of the leaves of M. zuihoensis showed significant free-radical scavenging activity [19]. To identify the active constituents from the leaves of M. zuihoensis, several isolation methods were used to purify the constituents and to evaluate their anti-inflammatory and free radical scavenging activities
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