槲皮素、异鼠李素对Cu2+介导极低密度脂蛋白氧化修饰的影响

目的　观察槲皮素 (Que)及异鼠李素 (Iso)对 Cu2 +介导的极低密度脂蛋白 (VL DL)氧化修饰的影响。方法　采用一次性密度梯度离心法分离人血浆 VL DL,用 Cu2 +进行体外氧化修饰 ,抗氧化组在温育前加入不同浓度的 Que和 Iso。分别检测脂蛋白中丙二醛 (MDA)、维生素 E(Vit E)及超氧化物歧化酶 (SOD)活性。结果　Que和 Iso可明显降低 OX- VL DL 中 MDA含量 ,延缓 OX- VL DL 中 Vit E含量的减少 ;显著提高脂蛋白中 SOD活性。结论　 Que和 Iso可显著抑制 Cu2 +诱导的 VL DL 的氧化修饰 ,且二者的作用相近 ,这与其抗自由基氧化活性密切相关。     

槲皮素,异鼠李素对Cu^2＋介导的LDL氧化修饰的抑制作用

目的：观察槲皮素（Ｑｕｅ）、异鼠李素（Ｉｓｏ）对Ｃｕ＾２＋介导的低密脂蛋白（ＬＤＬ）氧化修饰的影响。方法：采用一次性密度梯度离心法分离正常人血浆脂蛋白,用Ｃｕ＾２＋进行体外氧化修饰,温育前加不同浓度的Ｑｕｅ及Ｉｓｏ。检测脂蛋白中脂质过氧化物（ＬＰＯ）、维生素Ｅ（ＶｉｔＥ）含量及超氧化物歧化酶（ＳＯＤ）活性。结果：在Ｃｕ＾２＋与ＬＤＬ温育前加入Ｑｕｅ、Ｉｓｏ可使ＬＤＬ中ＬＰＯ生成减少,明显延缓 ,Ｖ     

New flavonol glycosides from leaves ofSymplocarpus renifolius

A study was carried out to evaluate flavonol glycosides in leaves ofSymplocarpus renifolius (Araceae). From the water fraction of the MeOH extract, three new flavonol glycosides were isolated along with three known compounds, kaempferol-3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-7-O-β-D-glucopyranoside, quercetin-3-O-β-D-glucopyranosy-l-(1→2)-β-D-glucopyranoside, and caffeic acid. The structures of the new flavonol glycosides were elucidated by chemical and spectral analyses as quercetin-3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-7-O-β-D-glucopyranoside, isorhamnetin-3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-7-O-β-D-glucopyranoside, and quercetin-3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-7-O-(6^IIII-trans-caffeoyl)-β-D-glucopyranoside.     

Protective effects of isorhamnetin on apoptosis and inflammation in TNF-α-induced HUVECs injury

Little is known about the role of isorhamnetin on endothelial cell apoptosis and inflammation when insulted by TNF-α injury. In our study, HUVECs were treated with TNF-α for 6 hours. HUVECs apoptosis were detected using flow cytometry. The expressions of ICAM-1, VCAM-1, E-selectin, NF-κB, AP-1 and eNOS were determined with western blotting or flow cytometry. The results showed TNF-α increased of apoptosis and the expression of ICAM-1, VCAM-1 and E-selectin in HUVECs, accompanied by significant augmentation of NF-κB and AP-1 expression. Pretreatment with isorhamnetin significantly reduced apoptosis in TNF-α-treated HUVECs. Moreover, isorhamnetin significantly attenuated TNF-α-induced upregulation of ICAM-1, VCAM-1, AP-1, E-selectin and NF-κB expression. Meanwhile, isorhamnetin also increased the expression of eNOS. So, isorhamnetin could suppress TNF-α-induced apoptosis and inflammation by blocking NF-κB and AP-1 signaling in HUVECs, which might be one of the underlying mechanisms for treatment of coronary heart disease.     

Transport characteristics of isorhamnetin across intestinal Caco-2 cell monolayers and the effects of transporters on it

Flavonoid isorhamnetin occurs in various plants and herbs, and demonstrates various biological effects in humans. This work will clarify the isorhamnetin absorption mechanism using the Caco-2 monolayer cell model. The isorhamnetin transport characteristics at different concentrations, pHs, temperatures, tight junctions and potential transporters were systemically investigated. Isorhamnetin was poorly absorbed by both passive diffusion and active transport mechanisms. Both trans- and paracellular pathways were involved during isorhamnetin transport. Active transport under an ATP-dependent transport mechanism was mediated by the organic anion transporting peptide (OATP); isorhamnetin’s permeability from the apical to the basolateral side significantly decreased after estrone-3-sulfate was added (p < 0.01). Efflux transporters, P-glycoproteins (P-gp), breast cancer resistance proteins (BCRP) and multidrug resistance proteins (MRPs) participated in the isorhamnetin transport process. Among them, the MRPs (especially MRP2) were the main efflux transporters for isorhamnetin; transport from the apical to the basolateral side increased 10.8-fold after adding an MRP inhibitor (MK571). This study details isorhamnetin’s cellular transport and elaborates isorhamnetin’s absorption mechanisms to provide a foundation for further studies.     

高效液相色谱法测定复方银杏叶片中银杏总黄酮的含量

目的建立复方银杏叶片中银杏总黄酮含量测定方法。方法采用高效液相色谱法,用Symmetry-C18色谱柱(250mm×4.6 mm,5μm),以甲醇-0.4%磷酸溶液(52∶48)为流动相,流速为1.0 ml.min-1,检测波长360 nm,柱温35℃。结果该法线性关系良好,平均加样回收率为98.35%,RSD为1.17%(n=5)。结论该法操作简便,分离效果好,结果准确,专属性强,可作为复方银杏叶片的质量控制方法。     

异鼠李素及橙皮甙抑制LDL氧化修饰作用的研究

目的:研究黄酮类中药异鼠李素及橙皮甙是否具有抑制LDL氧化修饰的作用。方法:按一次性密度梯度超速离心法分离人血清LDL,分别加入5.0μmol/L异鼠李素及橙皮甙与LDL温育3 h,然后利用Cu2 介导体外氧化修饰脂蛋白的方法,观察LDL氧化修饰不同时间,其A234、REM、TBARS及蛋白质羰基的动力学改变,并与对照组比较。结果:Cu2 介导LDL氧化修饰时,在2、4、6、8、12及24 h后,其A234、REM、TBARS及蛋白质羰基含量均逐步增加;加入5.0μmol/L异鼠李素及橙皮甙的实验组,Cu2 LDL的氧化修饰分别延迟2~4 h和2 h,其A234、REM、TBARS及载脂蛋白羰基含量较对照组降低;异鼠李素实验组分别较对照组降低23.5%~40.4%、20.5%~37.7%、18.6%~30.3%及20.1%~52.4%(P<0.001);橙皮甙实验组分别降低11.1%~21.2%、9.2%~28.3%、13.7%~21.3%及5.0%~43.8%(P<0.001,P<0.01,P<0.001及P<0.05)。结论:异鼠李素及橙皮甙均可抑制Cu2 诱导的LDL的氧化修饰,且异鼠李素的抗氧化作用较及橙皮甙强。     

Ginkgolide A contributes to the potentiation of acetaminophen toxicity by Ginkgo biloba extract in primary cultures of rat hepatocytes

The present cell culture study investigated the effect of Ginkgo biloba extract pretreatment on acetaminophen toxicity and assessed the role of ginkgolide A and cytochrome P450 3A (CYP3A) in hepatocytes isolated from adult male Long-Evans rats provided ad libitum with a standard diet. Acetaminophen (7.5-25 mM for 24 h) conferred hepatocyte toxicity, as determined by the lactate dehydrogenase (LDH) assay. G. biloba extract alone increased LDH leakage in hepatocytes at concentrations > or =75 mug/ml and > or =750 mug/ml after a 72 h and 24 h treatment period, respectively. G. biloba extract (25 or 50 mug/ml once every 24 h for 72 h) potentiated LDH leakage by acetaminophen (10 mM for 24 h; added at 48 h after initiation of extract pretreatment). The effect was confirmed by a decrease in [(14)C]-leucine incorporation. At the level present in a modulating concentration (50 mug/ml) of the extract, ginkgolide A (0.55 mug/ml), which increased CYP3A23 mRNA levels and CYP3A-mediated enzyme activity, accounted for part but not all of the potentiating effect of the extract on acetaminophen toxicity. This occurred as a result of CYP3A induction by ginkgolide A because triacetyloleandomycin (TAO), a specific inhibitor of CYP3A catalytic activity, completely blocked the effect of ginkgolide A. Ginkgolide B, ginkgolide C, ginkgolide J, quercetin, kaempferol, isorhamnetin, and isorhamnetin-3-O-rutinoside did not alter the extent of LDH leakage by acetaminophen. In summary, G. biloba pretreatment potentiated acetaminophen toxicity in cultured rat hepatocytes and ginkgolide A contributed to this novel effect of the extract by inducing CYP3A.     

鸭脚木叶中药材的质量标准研究

目的对鸭脚木叶中药材进行质量标准研究,采用显微鉴别和高效液相法测定含量.方法使用中药材粉末显微鉴定方法,寻找鸭脚木叶在显微镜下的最常见的特征性细胞;采用高效液相法测定鸭脚木叶中槲皮素和异鼠李素进行含量测定.结果显微鉴定:具有一定的特征性;含量测定方法槲皮素在1.2752~81.6104g;异鼠李素在1.35~180.0g范围内线性关系良好,槲皮素的回收率为99.58%,异鼠李素的回收率为98.41%.结论定性、定量方法简便、准确,该研究为鸭脚木叶药材质量性评价提供一定的依据.     

HPLC法测定垂盆草配方颗粒中黄酮类成分的含量

目的:建立高效液相色谱法测定垂盆草配方颗粒中槲皮素、山奈素及异鼠李素含量的方法.方法:流动相为甲醇:0.4％磷酸溶液(45∶ 55),色谱柱为Diamonsil C18(200 mm× 4.6 mm,5μm),检测波长为360 nm,柱温为30℃,流速为1.0ml·min-1.结果:三种黄酮类成分分离度好,不受杂质干扰,线性范围:槲皮素在2.982 ～29.820 μg· ml-1,r =0.9997,山奈素在0.966～9.660μg·ml-1,r =0.9998,异鼠李素在0.982～9.820 μg·ml-1,r =0.9994;平均回收率:槲皮素99.26％,RSD=0.66％(n=6),山奈素99.21％,RSD=1.24％ (n =6),异鼠李素99.44％,RSD =0.40％(n=6).结论:该测定方法操作简便,快捷,可靠性高,重复性好,可作为垂盆草配方颗粒的质量控制方法之一.