Studies on Alkaloids of Cephalotaxus sinensis (Rehd et Will.)Li

Seven alkaloids were isolated from Cephalotaxus sinensis (Rehd. et Wils.) Li and were identified by elements analysis, melting point and spectral data. Six of them are known alkaloids: cephalotaxine (Ⅰ), Ⅱ-hydroxyeephalotaxine (Ⅱ), drupaeine (Ⅲ), demethylcephalotaxinone (Ⅳ), c-3epi-witsonine (Ⅴ) and wilsonine (Ⅵ). Cephalo- taxine is the major alkaloid of this plant. (Ⅰ–Ⅳ) are alkaloid of Cephalotaxus type and another two (Ⅴ–Ⅵ) are alkaloid of homoerythrina type. (Ⅶ) seems to be a new alkaloid. Its strueture will be studied further.     

内生真菌Paraconiothyrium brasiliense代谢产物β-咔啉生物碱及其黄嘌呤氧化酶抑制活性研究

本研究通过前体介导调控一株内生真菌的次级代谢产物,采用正相硅胶柱色谱和制备型HPLC等方法分离纯化,利用NMR、MS等波谱学方法鉴定化合物结构,从中分离鉴定了10个生物碱类化合物,鉴定结果为:川芎哚(1)、1-(1',2'-二脱氧-α-D-核吡喃糖基)-β-咔啉(2)、flazin(3)、tangutorid E(4)...     

Indole alkoloids from Nauclea officinalis with weak antimalarial activity

Five indole alkaloids (naucleofficines A-E) were isolated from the stems (with bark) of Nauclea officinalis: (E)-2-(1-beta-d-glucopyranosyloxybut-2-en-2-yl)-3-(hydroxymethyl)-6,7-dihydro-indolo[2,3-a]quinolizin-4(12H)-one (1), (E)-1-propenyl-12-beta-d-glucopyranosyloxy-2,7,8-trihydro-indolo[2,3-a]pyran[3,4-g]quinolizin-4,5(13H)-dione (2), (E)-2-(1-hydroxybut-2-en-2-yl)-11-beta-d-glucopyranosyloxy-6,7-dihydro-indolo[2,3-a]quinolizin-4(12H)-one (3), (E)-1-propenyl-4-hydroxy-2,4a,7,8,13b,14,14a-hepthydro-(4alpha,4abeta,13balpha,14abeta)indolo[2,3-a]pyran[3,4-g]quinolizin-5(13H)-one (4) and 1-(1-hydroxyethyl)-10-hydroxy-7,8-dihydro-indolo[2,3-a]pirydine[3,4-g]quinolizin-5(13H)-one (10-hydroxyangustoline) (5), together with two known compounds, naucleidinal (6) and angustoline (7). All of the structures of the seven compounds above were elucidated by spectroscopic methods including use of 1D- and 2D-NMR spectroscopic analyses. Compounds 2 and 3 are rare examples of monoterpene indole alkaloids with a glucopyranosyloxy group attached to position C-12. In vitro activity screening of the above seven compounds showed weak to moderate inhibitory activity against Plasmodium falciparum.     

Isoquinoline and isoindole alkaloids from Menispermum dauricum

Three isoquinoline alkaloids and an isoindole alkaloid, along with eight known compounds, were isolated from the roots of Menispermum dauricum (Menispermacese). The alkaloids were characterized as 7-hydroxy-6-methoxy-1(2H)-isoquinolinone, 6,7-dimethoxy-N-methyl-3,4-dioxo-1(2H)-isoquinolinone, 1-(4-hydroxybenzoyl)-7-hydroxy-6-methoxy-isoquinoline and 6-hydroxy-5-methoxy-N-methylphthalimide, on the basis of spectral evidence including 1D- and 2D-NMR and MS analyses.     

Potent anti-metastatic activity of dimeric sesquiterpene thioalkaloids from the rhizome of Nuphar pumilum

The methanolic extract and its alkaloid fraction from the rhizomes of Nuphar pumilum inhibited invasion of B16 melanoma cells across collagen-coated filters in vitro. Dimeric sesquiterpene thioalkaloids with the 6-hydroxyl group, 6-hydroxythiobinupharidine, 6,6′-dihydroxythiobinupharidine, and 6-hydroxythionuphlutine B, showed potent activity with IC₅₀ values of 0.029, 0.087, and 0.36 μM, respectively, but dimeric sesquiterpene thioalkaloids lacking the 6-hydroxyl group (thiobinupharidine, neothiobinupharidine, syn-thiobinupharidine sulfoxide, thionuphultine B β-sulfoxide, and neothiobinupharidine β-sulfoxide) and monomeric sesquiterpene alkaloids (nupharidine, deoxynupharidine, 7-epideoxynupharidine, and nupharolutine) showed weak activity. The alkaloid fraction (20 mg/kg/d, po) and the principal dimeric sesquiterpene thioalkaloid 6-hydroxythiobinupharidine (5 mg/kg/d, po) significantly inhibited lung tumor formation by more than 90% 10 days after injection of B16 melanoma cells in mice.     

Insecticidal and antifeedant effects of two alkaloids from Cynanchum komarovii against larvae of Plutella xylostella L

A bioassay‐guided fractionation of Cynanchum komarovii crude alkaloid extract led to the isolation of two alkaloids. The isolated alkaloids were identified as 7‐demethoxytylophorine (1) and 6‐hydroxyl‐2,3‐dimethoxy phenanthroindolizidine (2) based on the comparison of their spectroscopic characteristics with the literature data. Insecticidal, antifeedant and growth inhibitory effects of these two alkaloids against the 3rd instar larvae of Plutella xylostella L. (Lepidoptera: Plutellidae) were examined. The results showed that alkaloid 1 was more toxic than alkaloid 2 against the 3rd instar larvae of Plutella xylostella L., but both alkaloids were less toxic than the total alkaloid fraction. For antifeedant activity, alkaloid 1 showed AFC₅₀ of 1.82 mg/ml at 24 h after treatment, alkaloid 2 showed 3.89 mg/ml, while total alkaloids showed 1.56 mg/ml. In dipping toxicity test, alkaloids 1 and 2 produced 93.3% and 63.3% mortality at 72 h after treatment, respectively, while total alkaloids produced 96.7% mortality. The LC₅₀ values for alkaloids 1, 2 and the total alkaloids were 3.54, 9.21 and 2.63 mg/ml, respectively. The development of larvae was also inhibited, and the growth inhibition rates at the concentration of 15.00 mg/ml were 92.8%, 78.2% and 98.6% for alkaloids 1, 2 and total alkaloids, respectively, at 72 h after treatment. Compared with antifeedant and dipping effect, the alkaloids 1, 2 and total alkaloid fraction revealed weak feeding toxicity, and their corrected mortality rates at the concentration of 15.00 mg/ml were 60.0%, 40.0% and 63.3% at 7 days after treatment. The LC₅₀ values for alkaloids 1, 2 and total alkaloids were 12.58, 32.37 and 8.88 mg/ml, respectively, at 7 days after treatment.     

Nuphar alkaloids with immediately apoptosis-inducing activity from Nuphar pumilum and their structural requirements for the activity

The methanolic extract and its alkaloid fraction from the rhizomes of Nuphar pumilum showed cytotoxic effects on human leukemia cell (U937), mouse melanoma cell (B16F10), and human fibroblast (HT1080). Dimeric sesquiterpene thioalkaloids with the 6-hydroxyl group (6-hydroxythiobinupharidine, 6,6'-dihydroxythiobinupharidine, 6-hydroxythionuphlutine B) showed substantial cytotoxic activity at a concentration of 10 microM, but dimeric sesquiterpene thioalkaloids lacking the 6-hydroxyl group (thiobinupharidine, thionuphlutine B, 6'-hydroxythionuphlutine B, neothiobinupharidine, thionuphlutine B beta-sulfoxide, and neothiobinupharidine beta-sulfoxide) and monomeric sesquiterpene alkaloids (nupharidine, 7-epideoxynupharidine, and nupharolutine) showed weak activity. Next, apoptosis-inducing activity of a principal active constituent, 6-hydroxythiobinupharidine, on U937 was examined using morphological observation and DNA fragmentation assay (TUNEL method). Apoptosis of U937 was immediately observed within 1 h after treatment of 6-hydroxythiobinupharidine at 2.5-10 microM.     

峨眉翠雀花中生物碱成分的研究

从峨眉翠雀花(Delphinium omeiense)块根中分得12个已知生物碱氨茴酰基牛扁碱(anthranoyllycoctonine)1、牛扁碱(lycoctonine)2、甲基牛扁碱(methyllycaconitine)3、德尔塔生(deltatsine)4、德尔色明甲(delsemine A)5、德尔色明乙(delsemine B)6、delsoline 7、potanine 8、delectine 9、delectinine 10、isodelectine11、kusnesoline 12,除1、2和3外,其余化合物均系首次自该植物中分得.应用光谱学和化学方法鉴定了报告的所有化合物的结构.     

Inhibitory alkaloids from Dictamnus dasycarpus root barks on lipopolysaccharide-induced nitric oxide production in BV2 cells

The methanolic extract of Dictamnus dasycarpus root barks afforded one new glycosidic quinoline alkaloid, 3-[1β-hydroxy-2-(β-D-glucopyranosyloxy)-ethyl)-4-methoxy-2(1H)-quinolinone (1), together with nine known compounds, preskimmianine (2), 8-methoxy-N-methylflindersine (3), dictamine (4), γ-fagarine (5), halopine (6), skimmianine (7), dictangustine-A (8), iso-γ-fagarine (9), isomaculosidine (10). The isolated alkaloids significantly inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated BV2 cells. Among them, compounds 3 and 7 showed the most potent inhibitory activities on LPS-induced NO production.     

Indole Alkaloids of Melodinur henryi Craib

The fruits of Melodinus henryi Craib (Apocynaceae) are used in folk medicine for the treatment of children meningitis and fractureetc. Eight indole alkaloids have been isolated from the roots and fruits of Melodinus henryi Craib by aluminum oxide and silica gel chro- matography. Seven of them were identified as tabersonine (1), 11-methoxy-tabersonine (2), lo- chnerinine (3), △14-vincamine (4), 16-epi-△14-vincamine (5), △14-eburnamine (6) and 19, 20- dihydrocondylocapine (7). The other one, namely, tenuicausine (8), is a dimeric indole alkaloid. Their structures were elucidated by spectral and chemical methods.     

Honatisine, a novel diterpenoid alkaloid, and six known alkaloids from Delphinium honanense and their cytotoxic activity

A novel diterpene alkaloid named honatisine (1) has been isolated from the whole plants of Delphinium honanense, along with six known alkaloids, siwanine E (2), isoatisine (3), atisine (4), delcorinine (5), uraphine (6), and nordhagenine A (7). Their structures were deduced on the basis of their spectral data. All of them were evaluated by a SRB assay for their cytotoxicity, and compound 1 showed a significant cytotoxic activity (IC(50) =3.16 μM) against the MCF-7 cell line.     

Diterpenoid Alkaloids from the Roots of Aconitum kongboense Lauener

Four diterpenoid alkaloids were obtained form the roots of Aconitum kongboense Lauener. Among them, one is a new alkaloid, kongboensine (1), and the structure has been elucidated by spectral evidence. The others were identified as guayewuanine A (2), indaconitine (3) and talatisamine (4) respictevely. 2 and 3 were isolated from this plant for the first time.     

THE ALKALOIDS OF RAUWOLFIA YUNNANENSIS TSIANG

Four alkaloids had been isolated from the roots of Rauwolfia yunnanensis Tsiang. Three of them are identified as reserpine, ajmaline and ajmalicine res-pectively by comparing their physical and chemical properties with those of the authentic samples. It seems that the other remained alkaloid is a new compound which has the formula C22H26O4N2 on the elementary analysis of base and it's hydrochloride salf, [α]D+l06' (CHCl3). It should be decomposed by heating without characteristic meltinq point. According to it's IR spectrum it has indole group, hydroxyI group and αβunsaturafed carboxylic metbyl ester and seems to be a serpentine derivative.     

工布乌头根中的二萜生物碱

工布乌头（ＡｃｏｎｉｔｕｍｋｏｎｇｂｏｅｎｓｅＬａｕｅｎｅｒ）系毛茛科乌头属植物,分布于西藏及四川西部,其块根有剧毒,泡酒外用可治疗跌打损伤和毒虫咬伤［１］。Ｙｕｅ等［２］、王锋鹏等［３］和庞志功等［４］曾从该植物分离到５个二萜生物碱。本文报道从四川产工布乌头的块根分离出的４个二萜生物碱。根据ＭＳ、１Ｈ－ＮＭＲ、１３Ｃ－ＮＭＲ等波谱分析,确定其中一个微量成分为新Ｃ１９－二萜生物碱,命名为工布生（ｋｏｎｇｂｏｅｎｓｉｎｅ,１）另外３个已知化合物分别鉴定为瓜叶乌碱甲素（２）、印乌碱（３）和它拉乌头胺…     

Three New O-Methyltransferases Are Sufficient for All O-Methylation Reactions of Ipecac Alkaloid Biosynthesis in Root Culture of Psychotria ipecacuanha

The medicinal plant Psychotria ipecacuanha produces ipecac alkaloids, a series of monoterpenoid-isoquinoline alkaloids such as emetine and cephaeline, whose biosynthesis derives from condensation of dopamine and secologanin. Here, we identified three cDNAs, IpeOMT1–IpeOMT3, encoding ipecac alkaloid O-methyltransferases (OMTs) from P. ipecacuanha. They were coordinately transcribed with the recently identified ipecac alkaloid β-glucosidase Ipeglu1. Their amino acid sequences were closely related to each other and rather to the flavonoid OMTs than to the OMTs involved in benzylisoquinoline alkaloid biosynthesis. Characterization of the recombinant IpeOMT enzymes with integration of the enzymatic properties of the IpeGlu1 revealed that emetine biosynthesis branches off from N-deacetylisoipecoside through its 6-O-methylation by IpeOMT1, with a minor contribution by IpeOMT2, followed by deglucosylation by IpeGlu1. The 7-hydroxy group of the isoquinoline skeleton of the aglycon is methylated by IpeOMT3 prior to the formation of protoemetine that is condensed with a second dopamine molecule, followed by sequential O-methylations by IpeOMT2 and IpeOMT1 to form cephaeline and emetine, respectively. In addition to this central pathway of ipecac alkaloid biosynthesis, formation of all methyl derivatives of ipecac alkaloids in P. ipecacuanha could be explained by the enzymatic activities of IpeOMT1–IpeOMT3, indicating that they are sufficient for all O-methylation reactions of ipecac alkaloid biosynthesis.     

小果博落回的生物碱分离与鉴定

以D101大孔吸附树脂为吸附剂,将对小果博落回全草的酸水提取物分为50%乙醇洗脱部分和丙酮洗脱部分.对两部分洗脱物分别进行硅胶柱色谱分离,由50%乙醇洗脱部分得到5个生物碱:二氢血根碱(1),二氢白屈菜红碱(2),6-乙氧基血根碱(3),6-丙酮基血根碱(4)和Bocconarborine A (5).由丙酮洗脱部分得到原阿片碱(6),α-别隐品碱(7),β-别隐品碱(8)和小檗红碱(9).采用波谱分析对化合物进行了结构表征,结果表明,化合物3、4、5、9是首次从该植物中分离得到.     

Mechanistic studies on trans-2,3-dihydro-2,3-dihydroxybenzoate dehydrogenase (Ent A) in the biosynthesis of the iron chelator enterobactin

The enzyme 2,3-dihydro-2,3-dihydroxybenzoate dehydrogenase (2,3-diDHB dehydrogenase, hereafter Ent A), the product of the enterobactin biosynthetic gene entA, catalyzes the NAD(+)-dependent oxidation of the dihydroaromatic substrate 2,3-dihydro-2,3-dihydroxybenzoate (2,3-diDHB) to the aromatic catecholic product 2,3-dihydroxybenzoate (2,3-DHB). The catechol 2,3-DHB is one of the key siderophore units of enterobactin, a potent iron chelator secreted by Escherichia coli. To probe the reaction mechanism of this oxidation, a variety of 2,3-diDHB analogues were synthesized and tested as substrates. Specifically, we set out to elucidate both the regio- and stereospecificity of alcohol oxidation as well as the stereochemistry of NAD+ reduction. Of those analogues tested, only those with a C3-hydroxyl group (but not a C2-hydroxyl group) were oxidized to the corresponding ketone products. Reversibility of the Ent A catalyzed reaction was demonstrated with the corresponding NADH-dependent reduction of 3-ketocyclohexane- and cyclohexene-1-carboxylates but not the 2-keto compounds. These results establish that Ent A functions as an alcohol dehydrogenase to specifically oxidize the C3-hydroxyl group of 2,3-diDHB to produce the corresponding 2-hydroxy-3-oxo-4,6-cyclohexadiene-1-carboxylate (Scheme II) as a transient species that undergoes rapid aromatization to give 2,3-DHB. Stereospecificity of the C3 allylic alcohol group oxidation was confirmed to be 3R in a 1R,3R dihydro substrate, 3, and hydride transfer occurs to the si face of enzyme-bound NAD+.     

Benzophenanthridine alkaloids from Zanthoxylum nitidum (Roxb.) DC, and their analgesic and anti-inflammatory activities

Seven benzophenanthridine alkaloids, 1-7, were isolated from the roots of Zanthoxylum nitidum. Among them, two novel alkaloids, named (R)-8-[(R)-1-hydroxyethyl]dihydrochelerythrine (1) and 8-methoxynorchelerythrine (2), were structurally identified as new compounds on the basis of the spectroscopic analysis. Bioactivity evaluation showed that nitidine (3), dihydrochelerythrine (4), oxyavicine (5), 8-methoxychelerythrine (6), and 8-hydroxydihydrochelerythrine (7) exhibit comparable analgesic and anti-inflammatory effects as hydrocortisone.     

E/Z-Thesinine-O-4'-alpha-rhamnoside, pyrrolizidine conjugates produced by grasses (Poaceae)

Based on direct infusion mass spectrometry we identified a novel alkaloid as a major component of perennial ryegrass (Lolium perenne). Initial mass spectral data suggested it to be a pyrrolizidine conjugate. As this class of alkaloids has not been described before from grasses, we isolated it to elucidate its structure. The isolated alkaloid proved to be a mixture of two stereoisomers. The structures of the two compounds as determined by 1D and 2D NMR spectroscopy, were E-thesinine-O-4'-alpha-rhamnoside (1) and Z-thesinine-O-4'-alpha-rhamnoside (2). These identifications were supported by the characterisation by GC-MS and optical rotation of (+)-isoretronecanol as the necine base released on alkaline hydrolysis of these alkaloids. 1 and 2 together with the aglycone and a hexoside were also detected in tall fescue (Festuca arundinacea). This is the first report of pyrrolizidine alkaloids produced by grasses (Poaceae).