| 摘要: | 香楠（Machilus zuihoensis Hayata）為樟科（Lauraceae）楨楠屬（Machilus）之常綠中喬木，是臺灣特有種植物，廣泛地分佈於全島低中海拔山區。於初篩試驗中，香楠葉的乙醇萃取物顯示具有顯著清除DPPH自由基能力（IC50 = 7.9 μg/mL），因此本實驗的目的是希望從香楠葉中分離出具有相關活性的成分。目前從香楠葉中分離一個新的化合物，屬於biflavonol glycoside結構的quercetin-3-O-β-D-glucopyranoside-(4''→O-3"'')-quercetin-3-O-β-D-glucopyranoside (9)，以及八個已知化合物分別為屬於flavonols結構的化合物quercetin (1)、hyperoside (2)、quercitrin (3)和afzelin (4)；屬於phenyl derivative結構的化合物4-hydroxybenzaldehyde (5)；和屬於caffeoyl derivatives結構的化合物ethyl caffeate (6)、ethyl 3-O-caffeoylquinate (7)和clorogenic acid methyl ester (8)。在抗氧化活性分析中，和正對照組 [(+)-catechin, IC50 = 41.6 μM] 相較下，我們發現quercetin-3-O-β-D-glucopyranoside-(4''→O-3"'')-quercetin-3-O-β-D-glucopyranoside (9) 顯示清除superoxide anion radical (O2-˙)的效果為最佳，其IC50為30.4 μM。在抗發炎活性分析中，以quercetin及ethyl caffeate顯示對於RAW264.7巨噬細胞具有明顯的抑制nitric oxide產生，IC50分別為27.6及42.9 μM。針對ethyl caffeate，其可能透過抑制NF-?羠的訊息傳遞路徑，進而降低iNOS、IL-1β及IL-10的mRNA表現。而在針對六種不同的腫瘤細胞株NCI-H838、MCF-7、HCT-116、MES-SA、MKN-45及HL-60的毒性分析中，以quercetin對於NCI-H838細胞毒性效果為佳，IC50為83 μM；另外ethyl caffeate 對於NCI-H838、MCF-7、HCT-116、MES-SA腫瘤細胞毒殺性效果為佳，IC50 分別為 79、90、81及76 μM。
Machilus zuihoensis Hayata (Lauraceae) is an endemic species in Taiwan. It was found widely throughout the island and from the low lands up to an altitude of 1500 m. In our screening test, the 95% EtOH extract of the leaves of M. zuihoensis shows the free-radical scavenging activity against DPPH radical (IC50 = 7.9 μg/mL). Therefore, the related bioactive constituents from the leaves of M. zuihoensis were isolated in the present study. A new biflavonol glycoside, quercetin-3-O-β-D-glucopyranoside- (4''→O-3"'')-quercetin-3-O-β-D-glucopyranoside (9), together with 8 known compounds including four flavonols, quercetin (1), hyperoside (2), quercitrin (3), and afzelin (4); one phenyl derivative, 4-hydroxybenzaldehyde (5); as well as three caffeoyl derivatives, ethyl caffeate (6), ethyl 3-O-caffeoylquinate (7), and clorogenic acid methyl ester (8) were isolated from the leaves of M. zuihoensis. In superoxide anion radical scavenging activity, compared with positive control [(+)-catechin, IC50 = 41.6 μM], we found the isolated new compound 9 showed the significant scavenging activity (IC50 = 30.4 μM). In anti-inflammatory activity, quercetin and ethyl caffeate were found to markedly suppress the lipopolysaccharide (LPS)-induced nitric oxide (NO) production (IC50 = 27.6, and 42.9 μM) in RAW264.7 macrophages. Additionally, we found ethyl caffeate maybe via suppressed NF-?羠 pathway to down regulated mRNA expressions of inducible nitric oxide synthase (iNOS), IL-1β, and IL-10 production in RAW264.7 macrophages. In anti-tumor activity, quercetin (IC50 = 83, >100, >100, and 99 μM) and ethyl caffeate (IC50 = 79, 90, 81, and 76 μM) showed cytotoxic activities against NCI-H838, MCF-7, HCT-116, and MES-SA cancer cell lines in vitro. |
