Thiosugars. X. Novel Nucleoside Analogues Derived from 4-Thio-L-lyxofuranose

Abstract

1-O-Acetyl-2,3,5-tri-O-benzyl-4-thio-L-lyxofuranose 1 was transformed into O-benzyl- and O-acetyl-protected 1-(4-thio-L-lyxofuranosyl) nucleoside derivatives by use of the TMSOTf method. Debenzylation with boron tribromide or deacetylation with sodium methoxide yielded the corresponding pyrimidine (7–11, 17, 18, 26 and 27) and purine (29 and 34) nucleoside analogues. The anomeric configurations were determined by NMR spectroscopy and, in the case of the 5-halo- (7–9) and nitrouridine derivative 11 and the 6-methylcytidine derivative 27, by X-ray structural analyses. – The unprotected nucleosides were not antivirically inhibitory at 250 µM.     

Plant regeneration from protoplasts ofCapsicum annuum L. cv. California Wonder

Plant regeneration from mesophyll protoplasts of pepper,Capsicum annuum L. cv. California Wonder has been demonstrated via shoot organogenesis. Protoplasts isolated from fully expanded leaves of 3-week-old axenic shoots when cultured in TM medium supplemented with 1 mg l ⁻¹ NAA, 1 mg l ⁻¹ 2,4-D, 0 5 mg l ⁻¹ BAP (CM 1) resulted in divisions with a frequency ranging from 20–25 %. Antioxidant ascorbic acid and polyvinylpyrrolidone (PVP) in the medium and incubation in the dark helped overcome browning of protoplasts. Microcalli and macrocalli were formed in TM medium containing 2 mg l ⁻¹ NAA and 0.5 mg l ⁻¹ BAP (CM II) and MS gelled medium containing 2 mg 1 ⁻¹ NAA and 0 5 mg 1 ⁻¹ BAP (CM III), respectively. Regeneration of plantlets was possible via caulogenesis. Microshoots, 2–5 percallus appeared on MS gelled medium enriched with 0.5 mg l ⁻¹ IAA, 2mg l ⁻¹ GA and l0mg l ⁻¹ BAP (CM IVc). Rooting of microshoots was obtained on half strength gelled medium containing 1 mg l ⁻¹ NAA and 0.5mg l ⁻¹ BAP. Protoplasts isolated from cotyledons failed to divide and degenerated eventually.     

Nucleotides. LXXIV Synthesis of a-D-Arabino-oligonucleotides

The 5 α-D-arabinofuranosylnucleosides α-araU (15), α-araT (18), α-araC (22), α-araA (25), and α-araG (28) have been synthesized by the modified silyl-method. The amino groups at the nucleobases and the 2′-hydroxy group at the sugar moiety were protected by the 2-(4-nitro-phenyl) ethoxycarbonyl (npeoc) group (37-40) and the amide function in α-araG was additionally blocked by the 2-(4-nitrophenyl)ethyl group (63) to improve solubility in organic solvents. Mono-and dimethoxytritylation of the 5′-OH group was performed in the usual manner to give 41-48, 64, and 65 in high yields and further substitution of the 3′-OH group led to the monomeric building blocks 66-75 as well as the 3′-O-succinoyl derivatives 76-85 functioning as starting units in solid-support oligonucleotide synthesis. A large number of oligo-α-arabinonucleotides have been prepared on modified CPG-material applying the npeoc/npe strategy as a very efficient synthetic tool for highly purified, homogenous oligomers. Hybridizations between α-arabinonucleotide strands revealed in analogy to earlier findings an antiparallel orientation whereas the combination of an oligo-α-D-arabinonucleotide with a complementary oligo-2′-deoxy-β-D-ribofuranosylnucleotide showed base-pairing only if a parallel polarity was present. The advantages in oligo-α-arabinonucleotide synthesis were furthermore demonstrated by the synthesis of the tα-ANA ^his a structural analog of the natural tRNA ^his of the phage T5.     

Nucleosides and Nucleotides. 98. Synthesis and Antitumor Activities of 5-Ethynylimidazole-4-carboxamide and -carbonitrile Derivatives

Abstract

5-Ethynyl-1-(2-deoxy-β-D-ribofuranosyl)imidazole-4-carbonitrile (4) and -carboxamide (5) and 5-ethynyl-1-(5-deoxy-β-D-ribofuranosyl)imidazole-4-carbonitrile (11) and -carboxamide (12) have been synthesized from the corresponding 5-iodo derivatives 2 and 7 by a palladium-catalyzed cross-coupling reaction with (tri-methylsilyl)acetylene. The aglycons, 5-ethynylimidazole derivatives 14 and 15 were synthesized by the hydrolytic cleavage of the corresponding nucleosides. The antileukemic activity of these nucleosides and base analogues are also described.     

Urease inhibitors from Hypericum oblongifolium WALL.

The bioassay-guided fractionation of H. oblongifolium has led to the isolation of potent urease inhibitors 1–3. The structures were elucidated by NMR and mass spectroscopic techniques. Compound 2 showed a potent enzyme inhibition activity (IC₅₀ 20.96?±?0.93), which is comparatively higher than that for the standard thiourea (IC₅₀ 21.01?±?0.51 μM). Compounds 1 and 3 also showed a significant activity, with IC₅₀ 37.95?±?1.93 and 138.43?±?1.23 μM, respectively. The sub crude fractions (F1, F2, F3, and F4) were tested in vitro for their urease inhibition activity. Fractions F2 and F4 showed significant activity with IC₅₀ 140.37?±?1.93 and 167.43?±?3.03 μM, respectively.     

海南栽培肾茶的化学成分研究

为了解肾茶(Clerodendranthus spicatus)的化学成分,从海南栽培肾茶地上部分分离得到11个化合物,经波谱分析分别鉴定为:吐叶醇(1)、丁香脂素(2)、3,4-二羟基苯乙醇(3)、甜橙素(4)、5,6,7,4′-四甲氧基黄酮(5)、5-羟基-6,7,3′,4′-四甲氧基黄酮(6)、6-羟基-5,7,4′-三甲氧基黄酮(7)、5-羟基-6,7,3′,4′-四甲氧基黄烷酮(8)、3,3′,5-三羟基-4′,7-二甲氧基-二氢黄酮(9)、松脂素(10)和熊果酸(11)。化合物3、9和10为首次从肾茶中分离得到。对化合物1~6进行活性测试,结果表明化合物3~5对乙酰胆碱酯酶具有一定的抑制活性。     

Abraracourcix curvivenatus n. gen. n. sp. from the Lowermost Eocene Oise amber (Hemiptera: Fulgoromorpha: Ricaniidae)

An extinct genus Abraracourcix n. gen. with A. curvivenatus n. sp. is described based on the specimen from the Lowermost Eocene Oise amber. The venation characters and possible hostplant relationships, as well as taxonomic position and biogeographical pattern of recent Pochazoides generic group are discussed.     

Folsomia (Collembola: Isotomidae) of China. II. heterocellata group

An annotated list of species of the Folsomia heterocellata group recorded in China is given. Folsomia cephalota n. sp., F. dorsomediaseta n. sp., F. longiseta n. sp., F. manubriopilosa n. sp., F. longdeica n. sp., and F. plenosensilla n. sp. are characterized by having a simple maxillary palp, four prelabral setae and no eyes. They differentiate mainly by characteristics of the furca. We report other species of the group which are recorded for the first time in China: Folsomia tianshanica Martynova, 1969, F. pseudovtorovi Potapov & Gulgenova, 2013, and F. pseudodecemoculata Stebaeva, 1971. This excludes F. wanxianensis Ji, Ding & Chen, 2007, for which we provide morphological remarks based on the type material. The group is mainly distributed in the central part of China (Chongqing, Gansu, southern part of Inner Mongolia, Ningxia and Shaanxi provinces). A key to all blind species with a simple maxillary palp is given.     

Studies in Neotropical Burseraceae. II. Generic limits in New World Protieae and Canarieae

Trattinnickia is closely related toDacryodes and is transferred to the tribe Canarieae. Additional characters are proposed to supplement the weak characters that traditionally have been used to separateCrepidospermum andTetragastris fromProtium. The assumed “intermediate” genusParaprotium is shown to be an unnatural assemblage and is here merged withProtium. This revised concept of generic limits in the Neotropical Protieae and Canarieae leads to the following new combinations:Tetragastris occhionii (Rizzini) Daly,Protium pilosum (Cuatrec.) Daly,Protium nitidifolium (Cuatrec.) Daly,Protium vestitum (Cuatrec.) Daly, andDacryodes cuspidata (Cuatrec.) Daly. A key to the Neotropical genera of Burseraceae is provided.     

I. Introduction

Background: Past research and ecological theory supports the hypothesis that alpine plants should be predominantly clonal, long-lived and reproduce by seed infrequently.

Aims: To challenge the entrenched view that alpine seedling establishment is uncommon and perhaps unsuccessful in maintaining alpine plant populations.

Methods: We looked for patterns in seedling establishment across a stress gradient of alpine sites and tested the notion that natural seedling recruitment would be reduced at higher altitudes due to a combination of stressful environmental conditions such as frosts, wind and extended snow cover.

Results: Seedlings were common at all study sites and there was a partial trend in mean seedling density with altitude. Seedling emergence was best predicted by a combination of altitude, plant litter and soil wilting point. Many seedlings survived to become established plants (37–61%) but there was no significant relationship between establishment and altitude. There was low similarity between the seedling flora and the standing vegetation, suggesting that patterns in seedling establishment are unlikely to be driving the patterns in the standing vegetation assemblage.

Conclusions: Although Australian alpine species predominantly reproduce vegetatively, this study shows that many plants depend on recruitment from seed in order to become established.     

New Acyclic Quinoxaline Nucleosides. Synthesis and Anti-Hiv Activity

A series of acyclonucleosides substituted 1-(4,5-dihydroxypentyl) (13-8) and 2-(4,5-dihydroxypentyloxy)quinoxalines (19-24) were synthesized by the sharpless asymmetric dihydroxylation of the derivatives 1-6 and 7-12, respectively. Treatment of the quinoxaline base 26 with (R)-2,2-dimethyl-1,3-dioxolan-4-ylmethyl-p-toluenesulfonate (27) in the presence of NaH/DMF furnished 28. Acid hydrolysis of 28 gave 1-(2,3-dihydroxypropyl)-6,7-dimethyl-quinoxaline-2-one (29). Alternatively, 29 was prepared by sharpless dihydroxylation of 30. All the compounds were evaluated for their in vitro anti-HIV-1 and HIV-2 in MT-4 cell and found inactive, except 29, which showed inhibition of HIV-1 with EC₅₀ value of 0.15 ± 0.1 μg/ml and a therapeutic index (SI) of 73.     

The low-molecular-weight glutenin subunit proteins of primitive wheats. II. The genes from A-genome species

 Three accessions of T. boeoticum were selected for the cloning and sequencing of novel low-molecular-weight glutenin subunit (LMW-GS) genes, based on the results of SDS-PAGE and PCR analyses of the LMW-GS diversity in A-genome wheat (Lee et al. 1998 a). A comparison of the nucleotide and deduced amino-acid sequences of three cloned genes, LMWG-E2, LMWG-E4 and LMWG-AQ1, both to each other and to other known LMW-GS genes was carried out. The N-terminal domains showed one variable position; GAG (coding for a glutamic acid) for the E-type, and GAT (coding for an aspartic acid) for the Q-type. The comparisons of the LMW-GSs in the literature and this paper define three different types of N-terminal sequences; METSCIPGLERPW and MDTSCIPGLERPW from the durum and A-genome wheats, and METRCIPGLERPW from the hexaploid and D-genome wheats. The repetitive domains were AC-rich at the nucleotide level and coded for a large number of glutamine residues; this region showed 16 variable positions changing 12 amino-acid residues, three triple nucleotide deletions/additions, a large deletion of 18 nucleotides in LMWG-E4 and a deletion of 12 nucleotides in LMWG-E2. In the C-terminal domains 26 variable positions were found and 12 of these mutations changed amino-acid residues; no deletions/ additions were present in this region. It was shown that the LMWG-E2 and LMWG-E4 genes could be expressed in bacteria and this allowed the respective protein products to be related back to the proteins defined as LMW-GSs in vivo. Received: 24 November 1997 / Accepted: 18 August 1998     

Erratum to: Singh R.K. and Gunjan A. Histone tyrosine phosphorylation comes of age. Epigenetics 2011; 6:153-60.

We recently noticed that there is a major error in Figure 1 of our review published in Epignetics 2010, Volume 6, Issue 2. During the preparation of the figure, the human and yeast H2B tyrosines were numbered the same, making the human numbering incorrect. The correct Figure 1 with proper numbering of human tyrosines is below.

Erratum to:

Singh R.K. and Gunjan A. Histone tyrosine phosphorylation comes of age.Epigenetics 2011; 6:153-60.     

Riccia rhenana Lorb. ex. K.Mill. in Britain

Abstract

A single, small moss leaf has been found among very small amounts of contents extracted from the Tyrolean Iceman's colon. It belongs to the species Neckera complanata Hedw., a woodland moss of low to moderate altitudes. The leaf was accidently ingested and not consumed as food.     

Robert Alexander Falla K.B.E., C.M.G., M.A., D.Sc., F.R.S.N.Z.

Abstract

On 23 February 1979 Sir Robert Falla collapsed and died at his home in Eastbourne. He was 77. His sudden death came as a great shock to his multitude of friends and colleagues, many of whom were still sharing with Sir Robert a deep sense of loss at the death on 31 May 1978, shortly after the couple's golden wedding anniversary, of his charming wife Molly.     

Fatty Acid n-Propyl and Ethyl Esters in the Volatile Oil from Dentcorn,Zea mays L. var. indentata,Silage

(+)-Marmelo Lactones A(VA) and B (VB) were synthesized from erythro-γ-methyl-l-glutamic acid (IA) and threo acid (IB), respectively. The absolute configurations of natural marmelo lactones were thus determined to be (2R, 4S) for (+)-marmelo lactone A and (2R, 4R) for ( – )-marmelo lactone B.     

Terminal Fluoroolefins. The Synthesis of Novel Carboacyclic Nucleosides

Abstract

A facile preparation of ketone 7 from butanetriol acetonide 5 is reported, and its utility for the synthesis of novel carboacyclic nucleosides 3E, 3Z, 4E and 4Z by the selective manipulation of multiple functionalities is demonstrated.     

Pohlia andrewsii J. Shaw in the U.S.S.R.

Abstract

P. andrewsii appears to be widespread in the arctic regions of the U.S.S.R. and also in mountains of southern Siberia, the Altai Mountains. Except in the mountains of Central and Northern Europe the range of P. andrewsii does not overlap with P. annotina and P. camptotrachela.     

Synthesis and Antileishmanial Activity of 3-Imidazolylalkylindoles. Part I

The present study was designed to investigate conazoles as new antileishmanial agents. Several 3-imidazolylalkylindoles were prepared under mild reaction conditions and pharmacomodulation at N1 and C5 of the indole ring and at the level of the alkyl chain (R) was carried out starting from the corresponding 3-formylindoles 7–10. All target imidazolyl compounds 38–52 were evaluated in vitro against Leishmania mexicana promastigotes; ketoconazole, amphotericin B and meglumine antimoniate were used as references. Eight out of fifteen compounds (40, 43, 44, 47, 48, 50, 51 and 52) exerted similar activity to ketoconazole, with IC₅₀ values in the range of 2.10–3.30?μg/mL. However the most potent compound, 1-(2-bromobenzyl)-3-(1H-imidazol-1-ylmethyl)-1H-indole (38), exhibited IC₅₀ value (0.011±0.003?μg/mL) 270-fold lower than that of ketoconazole. Four compounds (38, 43, 50 and 52) were also tested against intracellular amastigotes of L. mexicana; compound 38 exhibited the highest activity with an IC₅₀ value of 0.018±0.004?μg/mL.