Synthesis of analogs of amathamide A and their preliminary antimicrobial activity

Syntheses of three non-brominated analogs of amathamide A (1), a natural alkaloid isolated from the Tasmanian marine bryozoan Amathia wilsoni, are described. Antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomona aeruginosa, and Candida albicans was tested. Test results for amathamide A (1) showed a weak activity against C. albicans and E. coli. The three non-natural analogs 2-4 proved to be inactive compounds.     

Synthesis of reported and revised structures of amathamide D and synthesis of convolutamine F, H and lutamide A, C

Total synthesis of the published structure of amathamide D is described. Methyl 2,3,4-tribromo-5-hydroxybenzoate was selected as starting compound because it is readily accessible via acid-mediated Grob fragmentation-aromatization reaction of 1,4,5,6-tetrabromo-7,7-dimethoxybicyclo[2.2.1]hept-5-en-2-one. The aforementioned ester was transformed into the reported structure of amathamide D through methylation of a hydroxyl group and conversion of the ester moiety to a β-aminoethyl side chain. The NMR data of the synthetic compound did not conform to the reported natural product structure possessing contiguously positioned β-aminoethyl side chain, a set of three adjacent bromines, and a methyl ether linkage on the phenyl ring. This prompted us to redefine the natural product structure by synthesizing a product whose spectral data exactly matched with the reported data of amathamide D. The convolutamine H, with completely substituted phenyl ring adorned with an extra methyl ether functional group, has also been synthesized by application of Grob fragmentation-aromatization strategy to 3-(benzyloxy)-1,4,5,6-tetrabromo-7,7-dimethoxybicyclo[2.2.1]hept-5-en-2-one. This approach furnished directly methyl 2,3,4-tribromo-5,6-dimethoxybenzoate, which was converted straightforwardly into convolutamine H. Further, synthesis of convolutamine F and lutamide A and C is also described.     

C19-二萜生物碱贡乌生的结构研究

毛茛科植物贡嘎乌头 ( Aconitum liljestrandii)具有镇痛、镇静、祛风湿等功效 ,产于我国西藏东部及四川西部 [1] .我们从其块根中分得 1 8个单体 ,其中 1 6个为已知生物碱 [2 ,3] ,2个为新生物碱 [3] .本文报道新的 C19-二萜生物碱贡乌生 ( Liljestrandisine) 1的结构 .1　实验部分1 .1　仪器与试剂　 Boetius微量熔点测定仪 ;Nicolet FTIR2 0 0 SXV型红外光谱仪 ,KBr压片 ;BrukerAC- E2 0 0和 Varian Unity INOVA40 0 /5 4核磁共振仪 ,溶剂为 CDCl3,TMS为内标 ;VG Autospec30 0 0型和 VG70 A型质谱仪 ;Pekin Polarimete…     

修饰金鸡纳碱催化的不对称烯丙基烷基化反应

以修饰金鸡纳碱的手性叔胺为催化剂,Morita-Baylis-Hillman碳酸酯与α-取代的β-酮酸酯经不对称烯丙基烷基化反应,以中等收率及较好的非对映选择性和对映选择性合成了一系列具有连续季碳叔碳手性中心的新型烷基取代β-酮酸酯类化合物,其结构经1H NMR和13C NMR表征。     

NMR spectral assignments of a new chlorotryptamine alkaloid and its analogues from Acacia confusa

A new chlorotryptamine alkaloid, N-chloromethyl-N,N-dimethyltryptamine, was isolated from a methanol extract of the Chinese shrub Acacia confusa Merr., together with its known hallucinogenic analogues, N-methyltryptamine, N,N-dimethyltryptamine and N,N-dimethyltryptamine-N-oxide. The new compound was an artefact of the isolation conditions. The complete (1)H and (13)C NMR assignments for these compounds were carried out using (1)H, (13)C, DEPT, gCOSY, gHSQC and gHMBC NMR experiments.     

Alfileramine : A new zanthoxylum alkaloid structurally related to tetrahydrocannabinol

A new alkaloid, named alfileramine, has been isolated from Zanthoxylum punctatum. It represents the first alkaloid which has a structure closely related to the tetrahydrocannabinols. The structure was assigned based upon ¹H and ¹³C NMR, UV and mass spectroscopy and by relating alfileramine structure to that of the rearranged dihydrobromide salt. The structure of the dihydrobromide was known from X-ray diffraction. A possible biosynthetic pathway from a dehydrocitral equivalent and two molecules of hordenine is suggested.     

远程二维NMR用于马尾杉碱M的结构测定

马尾杉碱是一种从华南马尾杉(新品科植物)中分得的新的生物碱。其分子式为C17H20N2O3, 通过紫外, 红外, ^1H和^1^3C NMR谱图分析发现其结构与最近文献报导的福定碱或石杉碱相类似, 本文还采用普通和远程的^1^3C-^1H COSY二维NMR新技术进行了研究, 所得结果与上述分析相符。     

Alkaloids ofThalictrum flavum

Chemistry of Natural Compounds - The roots ofTh. flavum L. have yielded thalicarpine and a new alkaloid, thalflavine, C12H13NO4, for which the structure of 1-oxo-5-methoxy-2-methyl-6,...     

Citropremide and Citropridone: A New Ceramide and a New Acridone Alkaloid from the Stem Bark of Citropsis gabunensis

The structure elucidation and complete ¹H‐ and ¹³C‐NMR assignments are reported for two new compounds: the ceramide citropremide ( 1 ), and the acridone alkaloid citropridone ( 2 ). Both of these secondary metabolites were isolated from the stem bark of Citropsis gabunensis. High‐resolution mass, IR and UV spectrometry, and NMR experiments including COSY, HMQC, and HMBC were used for the determination of the structures and NMR spectral assignments.     

海绵Phacelliafusca中含氮化合物的分离与结构鉴定

从采自中国南海西沙群岛海域的海绵Phacellia fusca Schmidt中得到4个含氮 化合物。经~1H NMR,~(13)C NMR,HMQC,HMBC,~1H-~1HCOSY,FABMS和EIMS等光谱分析 ，确证其结构分别为：N,N'-二[2-乙氧基-1（Z）-乙烯基]脲（1），2- Bromoaldisin(2),Aldisin(3)Dibromophakellin盐酸盐(4)。其中化合物1为一具有 对称结构的新脲类化合物，命名Phacelliaurea A；化合物4是首次从该海绵中分离 得到的已知胍基生物碱，首次报到了它的~(13)C NMR数据及其归属。     

A New Diterpenoid Alkaloid from the Roots of a White‐Flowering Aconitum orientale Sample

From the roots of a white‐flowering Aconitum orientale Miller sample, collected in Artvin‐?av?at, Turkey, a new diterpenoid alkaloid named aconitorientaline ( 1 ) was isolated, along with the known diterpenoid alkaloids septentiriodine, lappaconitine, finaconitine, ranaconitine, puberanidine and delstaphinine (Fig.). The structure of 1 was established on the basis of ¹H‐ and ¹³C‐NMR, DEPT, ¹H,¹H‐COSY, NOESY, HSQC, and HMBC studies. All the known compounds were identified by comparison of their ¹H‐ and ¹³C‐NMR data and co‐TLC behavior with those of authentic samples.     

青海翠雀化学成分的研究

用柱层析、制备薄层层析等对青海翠雀的化学成份进行了分离，并用IR，FA， MS，1HNMR，13C NMR及DEPT等光谱确定了化合物的结构，共分得5种二萜生物碱， 其中一种为新化合物，还分得一种非生物碱β-谷甾醇．     

Photoinduced Copper‐Catalyzed C−H Arylation at Room Temperature

Room‐temperature azole C?H arylations were accomplished with inexpensive copper(I) compounds by means of photoinduced catalysis. The expedient copper catalysis set the stage for site‐selective C?H arylations of non‐aromatic oxazolines under mild reaction conditions, and provides step‐economical access to the alkaloid natural products balsoxin and texamine.     

Indole Alkaloids and Chromones from the Stem Bark of Cassia alata and Their Antiviral Activities

The Cassia (Leguminosae) genus has attracted a lot of attention as a prolific source of alkaloids and chromones with diverse structures and biological properties. The aim of this study is to screen the antiviral compounds from Cassia alata. The extract of the stem bark of this plant was separated using silica gel, MCI, ODS C18, and Sephadex LH-20 column chromatography, as well as semi-preparative HPLC. As a result, three new indole alkaloids, alataindoleins A–C (1–3); one new chromone, alatachromone A (4); and a new dimeric chromone-indole alkaloid, alataindolein D (5) were isolated. Their structures were determined by means of HRESIMS and extensive 1D and 2D NMR spectroscopic studies. Interestingly, alataindolein D (5) represents a new type of dimeric alkaloid with an unusual N-2−C-16’ linkage, which is biogenetically derived from a chromone and an indole alkaloid via an intermolecular nucleophilic substitution reaction. Compounds 1–5 were tested for their anti-tobacco mosaic virus (TMV) and anti-rotavirus activities, and the results showed that compounds 2–4 showed high anti-TMV activities with inhibition rates of 44.4%, 66.5%, and 52.3%, respectively. These rates were higher than those of the positive control (with inhibition rate of 32.8%). Compounds 1 and 5 also showed potential anti-TMV activities with inhibition rates of 26.5% and 31.8%, respectively. In addition, compounds 1–5 exhibited potential anti-rotavirus activities with therapeutic index (TI) values in the range of 9.75~15.3. The successful isolation and structure identification of the above new compounds provided materials for the screening of antivirus drugs, and contributed to the development and utilization of C. alata.     

Sesquiterpenoid alkaloid from Acroptilon repens

One new sesquiterpenoid alkaloid, namely 3 beta,8 alpha-dihydroxy-13-pyrrolidine-4(15),10(14)-(1 alpha H,5 alpha H,6 beta H,11 beta H)-guaiadien-12,6-olide (1), together with two known guaiane-type sesquiternoids (2-3) was isolated from the aerial part of Acroptilon repens. The structure of 1 was established by spectroscopic methods, especially 2D NMR (HMQC, HMBC, and NOESY). Cytotoxic activity against tumor cell line was assessed for compounds 2-3, and found to show potent cytotoxic activities against tumor cell line P-388.     

A New Indole Alkaloid from Cleome droserifolia

The phytochemical investigations on Cleome droserifolia resulted in the isolation and characterization of a new indole alkaloid, 5‐hydroxy‐2‐methoxy‐1‐methyl‐1H‐indole‐3‐carbaldehyde ( 1 ). The structure elucidation was carried out on the basis of 1D‐ and 2D‐NMR techniques. In addition to 1 , two known aromatic derivatives, veratrol ( 2 ) and 2‐methoxy‐4‐methylacetophenone ( 3 ), were also obtained. All these compounds were purified by repeated column chromatography of the CH₂Cl₂ fraction obtained from MeOH extract of Cleome droserifolia. The structure of the new compound 1 was finally confirmed by the combined 1D (¹H‐ and ¹³C‐) and 2D (H? C correlations; HMBC and HSQC) NMR and IR spectroscopy, mass spectrometry (MS), and UV absorption spectroscopy techniques. The comparison of the physical and spectroscopic data with those in the literature provided evidence for the structure confirmation of known compounds. All the purified compounds were subjected to urease and α‐glucosidase enzymes inhibition. The results showed that compound 1 was more potent with an IC₅₀ value 11.97±2.067 μg/ml towards urease inhibition, while the activity of α‐glucosidase enzyme was marginal.     

高乌头根中新的二萜生物碱

从高乌头根中分离得到3个新的冉乌头型的C₁₈-二萜生物碱高乌宁己(1)、高乌宁庚(3)、高乌宁辛(5)和一个新的牛扁碱型C₁₉-二萜生物碱高乌宁壬(7). 它们的结构通过IR, ¹H NMR, ¹³C NMR, MS予以确证.     

A new C<Subscript>19</Subscript>-diterpenoid alkaloid,habaenine C,from <Emphasis Type="Italic">Aconitum habaense</Emphasis>

A new C₁₉-diterpenoid alkaloid, habaenine C (1), together with the two known compounds vilmorrianine C and crassicauline A, were isolated from Aconitum habaense. The structure of the new compound was elucidated on the basis of spectral analysis, including 2D NMR spectroscopy. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 265–266, May–June, 2008.     

Structure of lilidine

The new alkaloid lilidine, isolated for the first time from the epigeal part ofLilium martagon has been studied by special methods. It has the composition B₅H₆NO₂, mp 118–110°C, [α]_D-26.3°. The¹H and¹³C NMR spectra were studied in detail. The values of the direct and long-range spin-spin coupling constants between the¹³C carbon nuclei and the¹H nuclei of the alkaloid molecule were measured with the aid of¹³C-[{su1}H] selective heteronuclear double resonance. The structure of 5-hydroxy-3-methyl-3-pyrrolin-2-one is suggested for lilidine.     

Aspergicin,a new antibacterial alkaloid produced by mixed fermentation of two marine-derived mangrove epiphytic fungi

A new alkaloid designated as aspergicin (1), together with a previous secondary metabolite, neoaspergillic acid (2), and a common compound, ergosterol (3), were isolated from the mixed cultured mycelia of two marine-derived mangrove epiphytic Aspergillus sp. fungi. Extensive application of 1D and 2D NMR techniques was made to characterize the structure and to establish the ¹H and ¹³ C assignments of compound 1. In the antibacterial assays, both compounds 1 and 2 showed significant antibacterial activity against some selected Gram bacteria.