Antiprotozoal activity of Melampyrum arvense and its metabolites

An activity guided isolation of the H₂O subextract of the crude extract of Melampyrum arvense L. afforded iridoid glucosides: aucubin (1), melampyroside (2), mussaenoside (3), mussaenosidic acid (4), 8‐epi‐loganin (5); flavonoids: apigenin (6), luteolin (7), luteolin 7‐O‐β‐glucopyranoside (8); a lignan glycoside dehydrodiconiferyl alcohol 9‐O‐β‐glucopyranoside (9); and benzoic acid (10). β‐Sitosterol (11) and a fatty acid mixture (12) were identified as the active principles of the CHCl₃ subextract. The structures of the isolates were elucidated by spectroscopic methods, while the composition of 12 was identified by GC‐MS after methylation. Luteolin (7) appeared as the most active compound against Trypanosoma brucei rhodesiense and Leishmania donovani (IC₅₀ values 3.8 and 3.0 μg/mL). Luteolin 7‐O‐β‐glucopyranoside (8) displayed the best antiplasmodial activity against Plasmodium falciparum (IC₅₀ value 2.9 μg/mL). This is the first detailed phytochemical study on Turkish M. arvense and the first report of the antiprotozoal effect of Melampyrum species and its constituents. Copyright © 2010 John Wiley & Sons, Ltd.     

The antiprotozoal activity of methylated flavonoids from Ageratum conyzoides L.

Aim of the study

The dichloromethane extract prepared from aerial parts of Ageratum conyzoides L. (Asteraceae), a plant commonly used in folk medicine for a number of illnesses including sleeping sickness, was recently found to exhibit a prominent activity (IC₅₀ = 0.78 μg/mL) against bloodstream forms of Trypanosoma brucei rhodesiense, the etiologic agent of East African Human Trypanosomiasis (East African Sleeping Sickness). This extract also exhibited noticeable activities against Leishmania donovani (Kala-Azar, IC₅₀ = 3.4 μg/mL) as well as Plasmodium falciparum (Malaria tropica, IC₅₀ = 8.0 μg/mL). In the current study, we sought for potentially active constituents of Ageratum conyzoides.

Materials and methods

Extracts prepared with solvents of different polarity were tested for activity against the above mentioned parasites as well as against Trypanosoma cruzi (Chagas’ disease) and for cytotoxicity using established protocols. The dicholoromethane extract showed the highest level of activity and was chosen for phytochemical studies aimed at the isolation of potential active constituents.

Results and conclusion

Five highly methoxylated flavonoids along with the chromene derivative encecalol methyl ether were isolated. All isolated compounds were previously reported from Ageratum conyzoides. While the chromene turned out to be inactive against the tested parasites, the flavonoids showed activity against the protozoan pathogens, some in the lower micromolar range. However, none of these isolated compounds was as active as the crude extract. This is the first report on antiprotozoal activity of this plant species and some of its constituents. The chemical principle accounting for the high activity of the crude extract, however, remains to be identified.     

Antiprotozoal effect of crude extracts and flavonoids isolated from Chromolaena hirsuta (asteraceae)

Phytochemical study of Chromolaena hirsuta (Hook. & Arn.) R. King & H. Robinson crude extract (collected in Furnas, MG-Brasil) produced fifteen flavonoids, two triterpenes and five steroids. IR, UV,(1)H and (13)C NMR spectroscopy and GC analysis were used for the identification of these compounds. The dichloromethanic and ethanolic crude extracts (flowers and leaves) and six flavonoids isolated from this specie have been assayed for antiprotozoal activity against tripomastigote forms of Trypanosoma cruzi and promastigote forms of Leishmania amazonensis. The crude extracts significantly reduced the viability of T. cruzi and Leishmania amazonensis, and the six flavonoids showed considerable antiproliferative effect of development of two parasites evaluated. This is the fi rst report of antiprotozoal activity of extracts of C. hirsuta.     

Antiparasitic,nematicidal and antifouling constituents from Juniperus berries

A bioassay‐guided fractionation of Juniperus procera berries yielded antiparasitic, nematicidal and antifouling constituents, including a wide range of known abietane, pimarane and labdane diterpenes. Among these, abieta‐7,13‐diene (1) demonstrated in vitro antimalarial activity against Plasmodium falciparum D6 and W2 strains (IC₅₀ = 1.9 and 2.0 µg/mL, respectively), while totarol (6), ferruginol (7) and 7β‐hydroxyabieta‐8,13‐diene‐11,12‐dione (8) inhibited Leishmania donovani promastigotes with IC₅₀ values of 3.5–4.6 µg/mL. In addition, totarol demonstrated nematicidal and antifouling activities against Caenorhabditis elegans and Artemia salina at a concentration of 80 µg/mL and 1 µg/mL, respectively. The resinous exudate of J. virginiana afforded known antibacterial E‐communic acid (4) and 4‐epi‐abietic acid (5), while the volatile oil from its trunk wood revealed large quantities of cedrol (9). Using GC/MS, the two known abietanes totarol (6) and ferruginol (7) were identified from the berries of J. procera, J. excelsa and J. phoenicea. Copyright © 2008 John Wiley & Sons, Ltd.     

Antibacterial activity of flavonoids from the stem bark of Erythrina caffra thunb.

The antibacterial activity of the stem bark of Erythrina caffra Thunb. was investigated against different bacterial strains. The antibacterial activity was determined by a micro broth dilution assay. Antibacterial compounds were isolated and identified using a Bruker Avance III LPO NMR spectrometer. Four known flavonoids, abyssione‐V 4′‐O‐methyl ether, 6,8‐diprenylgenistein, alpinumisoflavone and burttinone, were isolated. All the compounds were active against both Gram‐negative and Gram‐positive bacteria. The minimum inhibitory concentration values obtained (MIC) ranged from 3.9 μg/mL to 125 μg/mL. This is the first report of antibacterial activity of burttinone and the isolation of these compounds from E. caffra. Copyright © 2010 John Wiley & Sons, Ltd.     

Leishmanicidal and trypanocidal activity of extracts and secondary metabolites from basidiomycetes

Seventeen extracts and seven secondary metabolites isolated from basidiomycetes were tested in medium culture against promastigote forms of Leishmania spp. and bloodstream forms of Trypanosoma cruzi. Extracts from the culture filtrate or mycelium were generally inactive against the parasites except the Zucoagaricus genus mycelium extract which reduced by 47% the number of bloodstream forms. Striatin A, striatin B and podoscyphic acid exhibited in vitro activity at 10, 5 and 100 μg/mL, respectively. One compound showed activity against bloodstream forms of T. cruzi, the sesquiterpenoid naematolin, lysing the parasites by 79%. BALB/c mice infected with L. amazonensis were treated 3 weeks post-infection with striatin A and striatin B by subcutaneous route for 15 days at 10 mg/kg daily. The reference drug, N-methylglucamine antimonate, administered by subcutaneous injections at 28 mg Sbv/kg/day for 15 days reduced the parasite burden by 71.2% (p <0.05). Subcutaneous administration of straitin A at 10 mg/kg produced a weak decrease of the parasite burdens in the footpad by 17.6%. The treatment with striatin B had no effect and showed higher toxicity than striatin A. © 1997 John Wiley & Sons, Ltd.     

Antiprotozoal activity of quinoline alkaloids isolated from Galipea longiflora,a Bolivian plant used as a treatment for cutaneous leishmaniasis

The stem bark of Galipea longiflora is used by the Chimane Indians in Bolivia for the treatment of cutaneous leishmaniasis produced by Leishmania braziliensis. Petroleum ether and chloroform extracts of stem, root bark and leaves were found active in vitro against Leishmania ssp and Trypanosoma cruzi at 100 μg/mL. The activity guided fractionation of the extracts by chromatography afforded 12 active compounds identified as 2-substituted quinoline alkaloids. BALB/c mice were infected with Leishmania amazonensis (strain PH8 or H-142) and treated 24 h after infection with the major alkaloids from the crude alkaloidal extract; 2-phenylquinoline and 2-n-pentylquinoline. 2-phenylquinoline was as potent as Glucantime (Rhǒne-Poulenc) against the strain H-142, but less active than the reference drug against the virulent strain PH8 of L. amazonensis. 2-n-pentylquinoline did not exhibit any activity. Assays of single local treatments on the rear footpad infection, 2 weeks after the parasitic inoculation, indicated an effect for 2-phenylquinoline by reducing the severity of lesion. However, this activity was found to be slightly lower than that obtained using Glucantime.     

黄酮类化合物抗肿瘤活性及机制研究进展

黄酮类化合物是一类天然产物,在自然界中普遍存在,具有生理活性广泛,毒副作用低的特点。近年来,其抗肿瘤作用得到了广泛的关注和研究。研究结果表明,黄酮类化合物对多种常见癌症如肺癌、乳腺癌、结肠癌、前列腺癌、肝癌、白血病、卵巢癌、胃癌等皆有显著的防治效果。黄酮类化合物抗肿瘤的机制主要有:抗氧化抗自由基、诱导肿瘤细胞凋亡、影响细胞周期,调节免疫、抑制肿瘤新生血管、抑制环氧合酶2、抑制端粒酶活性等。该文综述了近年来国内外对黄酮化合物抗肿瘤活性及其机制的研究进展,以期为黄酮类化合物的进一步开发和临床应用提供理论基础和研究思路。     

Ulceroprotective activity of the flavonoids of Genista rumelica Vel

Ulceroprotective action of several flavonoid compounds isolated from Genista rumelica Vel. (total flavonoid mixture, luteoline-7-glycoside, genistine) was established on five models of gastric ulcer in rats, genistine being the most active. Comparison was made against several standard antiulcer durgs (Succus Liquiritiae, Caved S, Almagel). A combined drug Flavogastrol, containing total flavonoid mixture, Semmen Lini gel and antacid compounds, was prepared and demonstrated ulceroprotective activity and low toxicity.     

黄芪总黄酮生物学活性作用研究进展

黄芪总黄酮是黄芪中分离的抗氧化清除自由基的主要活性成分,具有明显的抗肿瘤、抗损伤和抗突变的作用,本文通过文献综述考证黄芪总黄酮的生物学活性及其作用机制,为该类中药成分临床研究提供了理论依据,从而更好地对其进行开发利用.     

鸡血藤黄酮类化合物的研究

目的:研究鸡血藤Spatholobus suberectus的化学成分。方法:用色谱法分离,用波谱法鉴定结构。结果:分离并鉴定了5个黄酮类化合物,分别为3-羟基-9-甲氧基紫檀烷(1)、芒柄花素钠(2,7-二羟基-4′-甲氧基异黄酮钠)(2)、芒柄花素(3)、大豆苷元(4)、7,4′-二羟基-3′-甲氧基异黄酮(5)。结论:化合物1,2,5为首次从本属植物中得到。     

Antioxidant activity of flavonoids in isolated mitochondria

Mitochondria are important intracellular sources and targets of reactive oxygen species (ROS), while flavonoids, a large group of secondary plant metabolites, are important antioxidants. Following our previous study on the energetics of mitochondria exposed to the flavonoids quercetin, taxifolin, catechin and galangin, the present work addressed the antioxidant activity of these compounds (1-50 micromol/L) on Fe(2+)/citrate-mediated membrane lipid peroxidation (LPO) in isolated rat liver mitochondria, running in parallel studies of their antioxidant activity in non-organelle systems. Only quercetin inhibited the respiratory chain of mitochondria and only galangin caused uncoupling. Quercetin and galangin were far more potent than taxifolin and catechin in affording protection against LPO (IC(50) = 1.23 +/- 0.27 and 2.39 +/- 0.79 micromol/L, respectively), although only quercetin was an effective scavenger of both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radicals. These results, together with the previous study, suggest that the 2,3-double bond in conjugation with the 4-oxo function in the flavonoid structure are major determinants of the antioxidant activity of flavonoids in mitochondria, the presence of an o-di-OH structure on the B-ring, as occurs in quercetin, favours this activity via superoxide scavenging, while the absence of this structural feature in galangin, favours it via a decrease in membrane fluidity and/or mitochondrial uncoupling.     

河北香菊中5种黄酮类化合物抗氧化活性的DFT研究

运用密度泛函理论(DFT)方法在B3LYP/6-311G(d)水平研究了河北香菊中5种黄酮类化合物木犀草素、芹菜素、金合欢素、木犀草苷、金合欢苷的电子结构、酚羟基氢原子的自然轨道电荷布局数(NBO)、酚羟基氢氧键离解能(BDE)、酚羟基氢氧键键级大小以及分子前线轨道的能级差。通过数据分析发现,B环邻位酚羟基分子内氢键的形成有利于增强分子的抗氧化活性;糖苷上的羟基并不具有消除自由基的活性,但是由于分子失去了7位酚羟基,从整体上降低了分子的抗氧化括性。初步判断出这5种黄酮类化合物抗氧化活性的大小顺序为:木犀草素木犀草苷芹菜素金合欢素金合欢苷。理论预测结果与文献报道的实验结果一致。该研究结果表明DFT方法可为天然黄酮类抗氧化剂的筛选提供理论指导。     

巴西甘薯叶黄酮类成分的研究

目的:研究巴西甘薯叶Ipomoea batatas的黄酮类成分.方法:乙醇提取后分别以氯仿、醋酸乙酯和正丁醇萃取,醋酸乙酯部位用硅胶柱色谱,Sephadex LH-20凝胶柱色谱等色谱法分离;通过理化性质和波谱方法鉴定结构.结果:分离并鉴定了5个黄酮类化合物:银椴苷(tiliroside)(Ⅰ),紫云英苷(astragalin)(Ⅱ),鼠李柠檬素(rhamnocitrin)(Ⅲ),鼠李素(rhamnetin)(Ⅳ),山柰酚(Ⅴ).结论:上述黄酮类成分均首次从该植物中分得.     

乌拉尔甘草根异戊烯基黄酮类成分的研究

目的 研究乌拉尔甘草Glycyrrhiza uralensis Fisch.根中异戊烯基黄酮类成分.方法 乌拉尔甘草95％乙醇提取物乙酸乙酯部位采用硅胶、聚酰胺、Sephadex LH-20、半制备HPLC等进行分离纯化,根据理化性质及波谱数据鉴定所得化合物的结构.结果 从中分离得到15个异戊烯基黄酮类化合物,分别鉴定...     

山豆根中黄酮化学成分研究

目的:对豆科槐属植物山豆根Sophora tonkinensis的黄酮类化学成分进行研究.方法:采用反复硅胶柱色谱法、Sephadex LH-20柱色谱法等进行分离纯化,并通过波谱分析鉴定了其化学结构.结果:分离得到8个黄酮类化合物,即山豆根色满二氢黄酮Ⅰ(tonkinochromane I,1),光甘草酚(glabrol,2),lupinifolin(3),tonkinensisol(4),8-C-prenylkaempferol (5),7,2'-dihydroxy-4'-methoxy-isoflavanol(6),芒柄花素(formononetin,7),金雀异黄素(genistein,8).结论:化合物1为新化合物,化合物6为首次从该属植物中分离得到,化合物2,3,5为首次从该植物中分离得到.     

枳壳中黄酮类成分的分离与鉴定

常用理气药枳壳来源于芸香科柑橘属酸橙Citrus aurantium及其栽培变种的干燥未成熟果实.研究枳壳中的化学成分,采用硅胶,Sephadex LH-20,HW-40凝胶,ODS柱色谱,制备HPLC以及制备TLC等方法进行分离纯化,根据理化性质和波谱数据如NMR,MS等鉴定化合物的结构.从枳壳乙醇提取物的石油醚层和乙酸乙酯层中分离得到14个黄酮类化合物,包括4个黄酮苷和10个多甲氧基黄酮,分别鉴定为(2R)和(2S)-6"-O-乙酸基洋李苷(1,2),柚皮素-7-O-β-D-葡萄糖苷(3)、5,7,4'-三羟基-8,3'-二甲氧基黄酮-3-O-6"-(3-羟基-3-甲基戊二酸单酯)-β-D-葡萄糖苷(4)、4'-羟基-5,6,7-三甲氧基黄酮(5)、柚皮黄素(6)、川陈皮素(7)、甜橙素(8)、5,6,7,4'-四甲氧基黄酮(9)、5,7,8,4'-四甲氧基黄酮(加)、3,5,6,7,8,3',4'-七甲氧基黄酮(11)、桔皮素(12)、5-去甲川陈皮素(13)、5-羟基-6,7,3',4'-四甲氧基黄酮(14),其中化合物1为新化合物,3～5为首次从酸橙植物中分离得到.     

苦荞麦黄酮对人食管癌细胞EC9706增殖的影响

目的研究苦荞麦黄酮在体外对EC9706细胞增殖的影响。方法 MTT法观察苦荞麦黄酮对EC9706细胞的毒性,荧光染色法观察细胞核的改变,流式细胞术观察细胞周期和细胞内活性氧水平,Western blotting分析凋亡蛋白表达。结果苦荞麦黄酮明显抑制EC9706细胞的增殖,其抑制率与药物浓度和作用时间呈正相关。经DAPI染色,电镜观察细胞核,可见多个凋亡小体的形成。流式细胞仪检测发现,苦荞麦黄酮使细胞发生G2/M期周期停滞,细胞内活性氧水平明显增加,且呈浓度依赖效应。Western blotting分析表明,苦荞麦黄酮能上调细胞内的促凋亡蛋白Bax,并下调抗凋亡蛋白Bcl-2的表达量。结论苦荞麦黄酮对人食管癌细胞株EC9706增殖具有明显的抑制作用,使细胞发生周期阻滞,并能通过调节活性氧水平及改变凋亡蛋白的表达量诱导其发生凋亡。     

黄芩中黄酮类成分活性作用的虚拟评价

目的利用理论对接方法研究黄芩中黄酮类化合物的潜在作用机制。方法选取黄芩中8个黄酮类化合物(包括苷元及其苷),收集现有靶标的晶体结构,利用Schrdinger软件进行计算,以分级标准评价选择性。结果文献报道黄芩黄酮类化合物药理作用共26种,其中与苷元及其苷类化合物对接结果相符的个数分别为9个和25个。表明苷元及其苷类化合物的靶标选择性与虚拟评价有差异,苷类化合物的结果与文献更接近。结论说明虚拟评价技术对于中药复杂作用系统的研究具有较大的实用性,苷元与苷类化合物体内作用效果相似,而体内代谢是药物虚拟评价过程中非常重要的影响因素。