小柴胡黄酮的分离及结构鉴定

本文对贵州产小柴胡(B.tenue Buch.-Ham.ex D.Don)黄酮成分进行了研究。从其乙醇浸膏的水溶性物质中分离出四种黄酮醇类成分。根据光谱分析、衍生物制备、酸水解及理化常数测定,分别鉴定为芸香甙(槲皮素-3-芸香糖甙)、水仙甙(异鼠李素-3-芸香糖甙)、山萘酚和槲皮素。此类成分在该种植物中首次分离得到。     

山奈酚与水的氢键作用对其抗氧化活性影响的理论研究

本文用密度泛函理论在(RO)B3LYP/6-31G(2d,2p)水平上对山奈酚及其与水分子之间形成的氢键复合物进行结构优化,通过热力学计算研究了不同位置的酚羟基发生抽氢反应的键离解能(BDE)、质子解离反应过程的质子解离能(DPE)受分子间氢键的影响。结果表明:与H2O形成的分子间氢键会影响化合物结构,改变化合物B环与AC环的二面角,A5位酚羟基更容易发生抽氢反应和质子解离反应,此位点的BDE和DPE均明显降低,同时也降低C3位质子解离的DPE。分子间氢键的形成促使酚羟基的抽氢和质子解离反应,提高化合物抗氧化活性。     

Anti‐HSV‐1 and HSV‐2 Flavonoids and a New Kaempferol Triglycoside from the Medicinal Plant Kalanchoe daigremontiana

Kalanchoe daigremontiana (Crassulaceae) is a medicinal plant native to Madagascar. The aim of this study was to investigate the flavonoid content of an aqueous leaf extract from K. daigremontiana (Kd), and assess its antiherpetic potential. The major flavonoid, kaempferol 3‐O‐β‐d ‐xylopyranosyl‐(1 → 2)‐α‐l ‐rhamnopyranoside ( 1 ), was isolated from the AcOEt fraction (Kd‐AC). The BuOH‐soluble fraction afforded quercetin 3‐O‐β‐d ‐xylopyranosyl‐(1 → 2)‐α‐l ‐rhamnopyranoside ( 2 ) and the new kaempferol 3‐O‐β‐d ‐xylopyranosyl‐(1 → 2)‐α‐l ‐rhamnopyranoside‐7‐O‐β‐d ‐glucopyranoside ( 3 ), named daigremontrioside. The crude extract, Kd‐AC fraction, flavonoids 1 and 2 were evaluated using acyclovir‐sensitive strains of HSV‐1 and HSV‐2. Kd‐AC was highly active against HSV‐1 (EC₅₀ = 0.97 μg/ml, SI > 206.1) and HSV‐2 (EC₅₀ = 0.72 μg/ml, SI > 277.7). Flavonoids 1 and 2 showed anti‐HSV‐1 (EC₅₀ = 7.4 μg/ml; SI > 27 and EC₅₀ = 5.8 μg/ml; SI > 8.6, respectively) and anti‐HSV‐2 (EC₅₀ = 9.0 μg/ml; SI > 22.2 and EC₅₀ = 36.2 μg/ml; SI > 5.5, respectively) activities, suggesting the contribution of additional substances to the antiviral activity.     

Acylated flavonol diglucosides from Lotus polyphyllos

Three acylated flavonol diglucosides, kaempferol 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside; quercetin 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside; isorhamnetin 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside were isolated from the whole plant aqueous alcohol extract of Lotus polyphyllos. The known 3,7-di-O-glucosides of the aglycones kaempferol, quercetin and isorhamnetin were also characterized. All structures were established on the basis of chemical and spectral evidence.     

Antioxidant activity of compounds from the medicinal herb Aster tataricus

A number of compounds were isolated from the medicinal plant Aster tataricus including shionone, epifriedelinol, quercetin, kaempferol, scopoletin, emodin, aurantiamide acetate and 1,7-dihydroxy-6-methyl-anthraquinone. The compounds were compared with regard to their ability in inhibiting hemolysis of rat erythrocytes induced by 2'-2' azobis (2-amidinopropane) dihydrochloride, lipid peroxidation using the FeSO(4)-ascorbic acid system, and generation of superoxide radicals using a phenazine methosulfate-nicotinamide adenine dinucleotide system. The effects on the Fe-bleomycin-induced DNA damage reflected pro-oxidant activity. Quercetin and kaempferol were most potent in inhibiting hemolysis, lipid peroxidation and superoxide radical generation. Scopoletin and emodin were similar to quercetin and kaempferol in inhibiting superoxide radical generation and second to them in inhibiting lipid peroxidation. Aurantiamide acetate exhibited some inhibitory activity toward superoxide radical generation. 1,7-dihydroxy-6-methyl-anthraquinone exerted an inhibitory activity only on superoxide radical generation. Shionone and epifriedelinol did not display any antioxidant activity. Quercetin and kaempferol, but not the remaining compounds, exhibited some pro-oxidant activity.     

Flavonols and an indole alkaloid skeleton bearing identical acylated glycosidic groups from yellow petals of Papaver nudicaule

From yellow petals of Iceland poppy, besides the known flavonoid gossypitrin, seven kaempferol derivatives were isolated. In addition to kaempferol 3-O-beta-sophoroside and kaempferol 3-O-beta-sophoroside-7-O-beta-glucoside, known from other plants, the mono- and dimalonyl conjugates of the latter were identified by MS and NMR spectroscopy. Structure analyses of a set of co-occurring pigments, the nudicaulins, revealed that they have the identical acylated glycoside moieties attached to a pentacyclic indole alkaloid skeleton for which the structure of 19-(4-hydroxyphenyl)-10H-1,10-ethenochromeno[2,3-b]indole-6,8,18-triol was deduced from MS and NMR as well as chemical and chiroptical methods.     

Glucosylation of the flavonoid, astragalin by Leuconostoc mesenteroides B-512FMCM dextransucrase acceptor reactions and characterization of the products

Astragalin (kaempferol-3-O-β-d-glucopyranoside, Ast) glucosides were synthesized by the acceptor reaction of a dextransucrase produced by Leuconostoc mesenteroides B-512FMCM with astragalin and sucrose. Each glucoside was purified and their structures were assigned as kaempferol-3-O-β-d-glucopyranosyl-(1 → 3)-O-α-d-glucopyranoside (or kaempferol-3-O-β-d-nigeroside, Ast-G1′) and kaempferol-3-O-β-d-glucopyranosyl-(1 → 6)-O-α-d-glucopyranoside (or kaempferol-3-O-β-d-isomaltoside, Ast-G1) for one glucose transferred, and kaempferol-3-O-β-d-isomaltooligosacharide (Ast-IMO or Ast-Gn; n = 2-8). The astragalin glucosides exhibited 8.3-60.6% higher inhibitory effects on matrix metalloproteinase-1 expression, 18.8-20.3% increased antioxidant effects, and 3.8-18.8% increased inhibition activity of melanin synthesis compared to control (without the addition of compound), depending on the number of glucosyl residues linked to astragalin. These novel compounds could be used to further expand the industrial applications of astragalin glucosides, in particular in the cosmetics industry.     

Signaling pathways of kaempferol-3-neohesperidoside in glycogen synthesis in rat soleus muscle

Kaempferol 3-neohesperidoside is one of the several compounds that have been reported to have insulin-like properties in terms of glucose lowering. We studied the effect of kaempferol 3-neohesperidoside in glycogen synthesis in rat soleus muscle through the incorporation of ¹⁴C-d-glucose in glycogen. Kaempferol 3-neohesperidoside stimulates glycogen synthesis in rat soleus muscle by approximately 2.38-fold. Insulin at 100 nM showed a stimulatory effect on glycogen synthesis when compared with the control group. The stimulatory effect of kaempferol 3-neophesperidoside on glycogen synthesis was inhibited by wortmannin, the phosphatidylinositol 3-kinase (PI3K) inhibitor, and enhanced by lithium chloride, a glycogen synthase kinase 3 (GSK-3) inhibitor. Moreover, the stimulatory effect of kaempferol 3-neohesperidoside was also nullified by PD98059, a specific inhibitor of mitogen-activated protein kinase (MEK) and by calyculin A, an inhibitor of protein phosphatase 1 (PP1) activity. It was concluded that the PI3K – GSK-3 pathway and MAPK – PP1 pathway are involved in the stimulatory kaempferol 3-neohesperidoside effect on glycogen synthesis in rat soleus muscle.     

山萘酚通过增强Treg细胞免疫抑制功能延长移植物生存时间

目的:探讨应用山萘酚增强Treg细胞免疫抑制功能,从而抑制大鼠移植物排斥反应并改善移植物生存的作用和机制。方法:以Wister大鼠和SD大鼠分别为供、受体,建立同种异体皮肤移植排斥反应动物模型。观察受体老鼠皮肤移植物的情况,记录移植物失功时间(移植物皮片80%面积发生排斥)。RT-PCR检测移植7天后脾细胞、淋巴细胞FOXP3、CTLA-4和IL-10的mRNA水平,用HE染色组织病理学观察术后7天移植皮片的淋巴细胞浸润程度。体外实验T细胞增殖抑制试验加入山萘酚作为对照,观察Treg功能情况。结果:1.山萘酚能增强移植后同种异体移植物的生存时间(DMSO组6.3±0.3天,山萘酚组13.7±0.39天,P<0.01);2.RT-PCR显示山萘酚可增强细胞CTLA-4(对照组9.24±0.17,山萘酚组12.48±0.145,P<0.05)、FOXP3(对照组0.96±0.07,山萘酚组1.41±0.07,P<0.01)和IL-10(对照组0.95±0.12,山萘酚组1.50±0.16,P<0.05)的mRNA水平;3.体外T细胞增殖抑制实验中,山萘酚可增强Treg细胞的免疫抑制功能。结论:在大鼠皮肤移植模型中,山萘酚可延长皮肤移植物的生存时间,提高Treg细胞相关IL-10、FOXP3和CTLA-4的mRNA水平;体外实验中,能抑制效应T细胞的增殖,表明山萘酚在提高移植物生存方面存在一定的价值。     

Kaempferol induces cell death through ERK and Akt-dependent down-regulation of XIAP and survivin in human glioma cells

The present study was undertaken to determine the molecular mechanism by which kaempferol induces cell death in human glioma cells. Kaempferol resulted in loss of cell viability and inhibition of proliferation in a dose- and time-dependent manner, which were largely attributed to cell death. Kaempferol caused an increase in reactive oxygen species (ROS) generation and the kaempferol-induced cell death was prevented by antioxidants, suggesting that ROS generation is involved in kaempferol-induced cell death. Kaempferol caused depolarization of mitochondrial membrane potential. Western blot analysis showed that kaempferol treatment caused a rapid reduction in phosphorylation of extracellular signal-regulated kinase (ERK) and Akt. The ERK inhibitor U0126 and the Akt inhibitor LY984002 increased the kaempferol-induced cell death and overexpression of MEK, the upstream kinase of ERK, and Akt prevented the cell death. The expression of anti-apoptotic proteins XIAP and survivin was down-regulated by kaempferol and its effect was prevented by overexpression of MEK and Akt. Kaempferol induced activation of caspase-3 and kaempferol-induced cell death was prevented by caspase inhibitors. Taken together, these findings suggest that kaempferol results in human glioma cell death through caspase-dependent mechanisms involving down-regulation of XIAP and survivin regulating by ERK and Akt.