The absolute stereostructures of cyanogenic glycosides, hydracyanosides A, B, and C, from the leaves and stems of Hydrangea macrophylla

Three new cyanogenic glycosides named hydracyanosides A (1), B (2), and C (3) were isolated from the leaves and/or stems of Hydrangea macrophylla in China. The absolute stereostructures of hydracyanosides were characterized on the basis of chemical and physiochemical evidence including single crystal X-ray crystallographic analysis. To the best of our knowledge, this is the first scientific report of cyanogenic glycosides from Hydrangea plants.     

Structure of tecophilin,a tri-caffeoylanthocyanin from the blue petals of Tecophilaea cyanocrocus, and the mechanism of blue color development

The pigment, tecophilin, in blue flowers of Tecophilaea cyanocrocus was isolated and the structure was determined to be 3-O-(6-O-α-l-rhamnopyranosyl-β-d-glucopyranosyl)-7-O-(6-O-(4-O-(2-O-(4-O-β-d-glucopyranosyl-(E)-caffeoyl)-6-O-(4-O-β-d-glucopyranosyl-(E)-caffeoyl)-β-d-glucopyranosyl)-(E)-caffeoyl)-β-d-glucopyranosyl)delphinidin. The reproduction experiment of the same color as petals according to the results of chemical analysis and measurement of vacuolar pH of blue cells clarified that the blue color solely develops by tecophilin without interaction of metal ions nor co-pigments. ¹H NMR analysis and CD spectrum indicate the co-existence of clockwise intermolecular self-association of the delphinidin nuclei and intramolecular π–π stacking between the chromophore and caffeoyl residues to derive bathochromic shift of the absorption spectrum and stabilize the color by preventing hydration reaction.     

Total synthesis of cimiracemate B and analogs

The synthesis of the biologically active cimiracemate B and some analogs is described. The key step of the synthesis is a coupling between a bromoketone and a cinnamic acid derivative.     

3-Oxyanthranilic acid derivatives from Actinomadura sp. BCC27169

Eight new compounds including 9′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy) phenyl]nonanoic acid (1), 9′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl] nonanoic acid (2), 11′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy)phenyl]undecanoic acid (3), 11′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl]undecanoic acid (4), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (5), 8-(4′-O-methyl-α-ribopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (6), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-2-methyquinoline (7), and 8-(4′-O-methyl-α-ribopyranosyloxy)-2-methylquinoline (8) were isolated from Actinomadura sp. BCC27169. The chemical structures of these compounds were determined based on NMR and high-resolution mass spectroscopy. The absolute configurations of these monosaccharides were revealed by the hydrolysis of compounds 7 and 8. Compounds 3 and 8 exhibited antitubercular activity at MIC 50 μg/mL. Only compound 3 showed cytotoxicity against KB cell at IC₅₀ 18.63 μg/mL, while other isolated compounds were inactive at tested maximum concentration (50 μg/mL).     

A nonenzymatic optical immunoassay strategy for detection of Salmonella infection based on blue silica nanoparticles

A novel nonenzymatic optical immunoassay strategy was for the first time designed and utilized for sensitive detection of antibody to Salmonella pullorum and Salmonella gallinarum (S. pullorum and S. gallinarum) in serum. The optical immunoassay strategy was based on blue silica nanoparticles (Blue-SiNps) and magnetic beads (MB). To construct such an optical immunoassay system, the Blue-SiNPs were first synthesized by inverse microemulsion method, characterized by SEM, Zeta potential and FTIR. Two nanostructures including Blue-SiNPs and MB were both functionalized with antibody against S. pullorum and S. gallinarum (anti-PG) without using enzyme labeled antibody. Anti-PG functionalized blue silica nanoparticles (IgG-Blue-SiNps) were used as signal transduction labels, while anti-PG functionalized magnetic beads (IgG-MB) were selected to separate and enrich the final sandwich immune complexes. In the process of detecting negative serum, a sandwich immunocomplex is formed between the IgG-MB and IgG-Blue-SiNPs. With the separation of the immunocomplex using an external magnetic field, the final plaque displayed bright blue color. While in the detection of infected serum, IgG-MB and anti-PG formed sandwich immunocomplexes, IgG-Blue-SiNPs were unable to bind to the limited sites of the antigen, and a light brown plaque was displayed in the bottom of microplate well. Stable results were obtained with an incubation time of 60 min at room temperature, and different colors corresponding to different results can be directly detected with naked eye. The reaction of IgG-Blue-SiNPs with S. pullorum was inhibited by 1:100 dilution of positive chicken serum. Such a simple immunoassay holds great potential as sensitive, selective and point-of-care (POC) tool for diagnosis of other biological molecules.     

Novel tetranortriterpenoid derivatives from Munronia henryi

Six novel tetranortriterpenoid derivatives were isolated from the methanolic extract of the whole bodies of Munronia henryi, namely, munronins A-F (1-6). In compounds (3-6), the side chains are rare in tetranortriterpenoids. Their structures were established by extensive NMR experiments. Based on the diversity of the side chains, possible biodegradations for the side chains of compounds 1-6 from euphane or tirucallane skeleton are proposed. Munronins A-E exhibited moderate antifeeding activity against Pieris brassicae L, while munronin F showed negative activity.     

Isolation of secondary metabolites from Hortia oreadica (Rutaceae) leaves through high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) with a two-phase solvent system (hexane–ethanol–acetonitrile–water 10:8:1:1, v/v) was applied to examine the leaves of Hortia oreadica, which afforded the known limonoid guyanin (1), the alkaloids rutaecarpin (2) and dictamnine (6), the dihydrocinnamic acid derivatives methyl 5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran-6-propanoate (3), 5,8-dimethoxy-2,2-dimethyl-2H-1-benzopyran-6-propanoic acid (4), together with the new E-3,4-dimethoxy-α(3-hydroxy-4-carbomethoxyphenyl)cinnamic acid (5). The recovery of compounds 1–6 was determined by comparison with LC-atmospheric pressure chemical ionization MS/MS data: 66.2%, 93.1%, 102.5%, 101.2%, 99.0% and 84.9%, respectively. Compound 3 showed IC₅₀ of 23.6 μM against Plasmodium falciparum and 15.6 μM against Trypanosoma brucei rhodesienses and was not toxic to KB cells (IC₅₀ > 100 μM).     

Four new ginkgolic acids from Ginkgo biloba

Four new compounds, 2-hydroxy-6-(12′-hydroxyheptadec-13′(E)-en-1-yl)benzoic acid (1), 2-hydroxy-6-(13′-hydroxyheptadec-11′(E)-en-1-yl)benzoic acid (2), 2-hydroxy-6-(10′-hydroxypentadec-11′(E)-en-1-yl)benzoic acid (3), and 2-hydroxy-6-(11′-hydroxypentadec-9′(E)-en-1-yl)benzoic acid (4) were isolated from the leaves of Ginkgo biloba and the structures of new ginkgolic acids were deduced on the basis of spectroscopic methods and chemical means. Compounds 1 and 2, and 3 and 4 examined as an inseparable mixture of hydroxyl and double bond positional isomers, were ultimately defined by total synthesis. Compounds 1–4 showed moderate lipid droplets accumulation inhibitory activity on mouse pre-adipocyte cell line, MC3T3-G2/PA6.     

Feeding attractants for the muricid gastropod Drupella cornus, a coral predator

The muricid gastropods genus Drupella are known to be voracious coral predator. Outbreaks of them have accelerated significant destruction on coral reefs, but its precise mechanism is poorly understood. Here, we describe the identification of montiporic acids C (1) and A (2) isolated from sea water extracts of the coral Montipora sp., which showed potent feeding-attractant activity toward D. cornus.     

VioE, a prodeoxyviolacein synthase involved in violacein biosynthesis, is responsible for intramolecular indole rearrangement

Indole-3-pyruvic acid is transformed to prodeoxyviolacein by the novel enzyme VioE, which is involved in the violacein biosynthetic pathway in Chromobacterium violaceum ATCC12472. VioE catalyzes the decarboxylation and indole-ring rearrangement of a nascent compound that is produced from indole-3-pyruvic acid and by the action of chromopyrrolic acid synthase (VioB or StaD), and ultimately the reaction yields prodeoxyviolacein.     

The first total synthesis of (±)-4-methoxydecanoic acid: a novel antifungal fatty acid

The hitherto unknown (±)-4-methoxydecanoic acid was synthesized in six steps and in 25% overall yield starting from commercially available 4-penten-1-ol. The title compound demonstrated 17-fold higher antifungal activity (MIC = 1.5 mM) against Candida albicans ATCC 60193 and Cryptococcus neoformans ATCC 66031 when compared to unsubstituted n-decanoic acid. Our results demonstrate that mid-chain methoxylation appears to be a viable strategy for increasing the fungitoxicity of fatty acids.     

Aurilide, a cytotoxic depsipeptide from the sea hare Dolabella auricularia: isolation, structure determination, synthesis, and biological activity

The bioassay-guided fractionation of the cytotoxic constituents of the Japanese sea hare Dollabella auricularia led to the isolation of aurilide (1), a 26-membered cyclodepsipeptide. The gross structure of 1 was established by spectroscopic analysis including 2D NMR techniques. The absolute stereostructure was determined by chiral HPLC analysis of acid hydrolysates of 1 and by the enantioselective synthesis of a degradation product arising from a dihydroxylated fatty acid portion. The enantioselective synthesis of 1 was achieved in 12% overall yield (16 steps) and confirmed the absolute stereostructure of 1. The cytotoxicity of 1 was evaluated using a synthetic sample, which was found to exhibit potent cytotoxicity against HeLa S₃ cells with an IC₅₀ of 0.011 μg/mL. Further biological and pharmacological studies of 1 have been carried out by using synthetic 1.     

Synthesis and binding properties of carboxylphenyl-modified calix[4]arenes and cytochrome c

Two novel carboxylphenyl-modified calix[4]arenes, tetrakis-carboxylphenylcalix[4]arene (TCPC) and 1,3-bis-carboxylphenylcalix[4]arene (BCPC), as well as a corresponding analogue for comparison, tetrakis-phenylcalix[4]arene (TPC), have been synthesized by palladium-catalyzed Suzuki cross-coupling of arylboronic acid and tetrabromocalix[4]arene as a key step. The binding properties of these calix[4]arene derivatives with bovine heart cytochrome c (cyt c) in dimethylformamide (DMF) was investigated by fluorescence spectroscopy. The binding affinity in the order of TCPC > BCPC ? TPC reflects a clear dependence on the number of carboxyl ligating groups attached onto a receptor and suggests the electrostatic force may be the predominant factor driving the complexing process. The stable 1:1 complexes of TCPC and BCPC with cyt c were evidenced with the binding constants of 3.15 × 10⁶ and 5.85 × 10⁵ L mol⁻¹, respectively. Due to a large overlap between the emission spectrum of TCPC and the absorption spectrum of cyt c, and a short interaction distance (estimated to be 5.6 nm) between them, the fluorescence quenching of TCPC upon complexation with cyt c is attributed to an efficient energy transfer.     

Two novel blue pigments with ellagitannin moiety, rosacyanins A1 and A2, isolated from the petals of Rosa hybrida

Two novel blue pigments, rosacyanins A1 and A2, were isolated from the petals of Rosa hybrida cv. ‘M'me. Violet’. Their structures were elucidated on the basis of high-resolution Fourier transform ion cyclotron resonance mass spectroscopy (HR-FT-ICR-MS), FABMS/MS/MS, ¹H, ¹³C and two-dimensional NMR. The molecular formulas of rosacyanin A1 (1) and A2 (2) are C₅₆H₃₇O₃₁ and C₆₃H₄₁O₃₅, respectively. The structures of rosacyanins A1 and A2 consisted of a common chromophore containing cyanidin with a galloyl group link between positions 4 and 5 of the hydroxyl group of the flavylium nucleus and tellimagrandins (1 or 2). These pigments in which anthocyanidin nuclei linked to ellagitannin through an ether bond are the first compounds isolated from natural sources.     

Synthesis and structure of novel closo-dodecaborate-based glycerols

The reactions of oxonium derivatives of [B₁₂H₁₂]²⁻ with different glycerol-based nucleophiles were studied. A series of novel closo-dodecaborate-based glycerols with different net charges on the molecules were prepared. A structure of {2-[2-(4-(2, 3-dihydroxypropyl)-dipiperazinium-1-yl)-ethoxy]-ethoxy}-undecahydro-closo-dodecaborate was determined and the existence of different intermolecular H-bonds was shown.     

New iodotyramine derivatives from Didemnum rubeum

The study of an aqueous extract from the ascidian Didemnum rubeum permitted the isolation of a previously reported derivative diiodo-tyramine derivative together with six new iodo-tyramine derivatives. Their structures were elucidated by NMR and MS analysis.     

Revised structure of tetrapetalone A and its absolute stereochemistry

The chemical structure of tetrapetalone A (1), a novel lipoxygenase inhibitor from Streptomyces sp., was revised by using the ¹H-¹⁵N HMBC technique. Furthermore, the absolute stereochemistry of all the asymmetric carbons in 1 was determined based on the detailed NOE data of 1 and its derivative.     

Evaluation of the nanofibrillar structure of Dioscorea opposite extract for cell attachment

Dioscorea opposite has been widely used in traditional herbal medicine in the Far East, ameliorating symptoms ranging from abdominal swelling to pain. Previous studies have focused on understanding the chemical components that lead to the medicinal effects of the extract. In this study, we examined the nanostructures formed by the soluble and insoluble parts of the sticky excretion from the mucilaginous rhizome of Dioscorea opposite and evaluated their cellular response. Using atomic force microscopy, we found that the soluble extract of the excretion had the capacity to form a nanofibrillar scaffold composed of uniform ～10 nm nanofibers with a typical pore size of ～40 nm, while the insoluble extract formed some nanofibers without specific structure. Cellular response to the two types of nanostructures was tested by seeding with HeLa and MC3T3 cells. The observations suggested that the nanofibrillar scaffold formed from the soluble extract provided an excellent platform for HeLa cell attachment and growth and to a lesser degree for MC3T3 cells, while nanofibers from the insoluble extract displayed no cell attachment and growth. Further analysis by direct incubation of the soluble extract with growing cells indicated that components from the extract preferentially bound to HeLa cells, but not to MC3T3 cells, which might help explain the observed preference of HeLa cells on the nanofibrillar scaffold. The nanofibrillar scaffold created from the Dioscorea opposite extract and its ability to sustain the attachment of specific cell types demonstrate the potential for this natural nanomaterial in tissue engineering applications.     

Synthesis,crystal structure,and blue photoluminescence of a 3D coordination polymer based on a Ag10 cluster with the versatile 2-mercapto-5-benzimidazolesulfonic acid ligand

The solvothermal reaction of 2-mercapto-5-benzimidazolesulfonic acid (H₃MBZD), which has imidazole, –SH, and –SO₃H groups, with Ag₂SO₄ led to the 3D coordination polymer {Ag₅[(HMBZD)₂(H₂MBZD)(H₂O)]} _n (1). X-ray single-crystal analysis showed that five independent Ag atoms are connected by the bridging mercapto group to generate asymmetric pentanuclear clusters, which are joined together to form a large Ag₁₀ ringed subunit. The Ag₁₀ subunits are linked together by the –SO₃H groups to give the complex 3D framework. Strong blue photoluminescence of 1 can be assigned to the intraligand fluorescent emission.     

Novel environmentally-benign methods for green-colour protection of bamboo culms and leaves

The objective of this study was to search for appropriate environmental-benign preservatives as green-colour protectors for the culms and leaves of ma bamboo (Dendrocalamus latiflorus), moso bamboo (Phyllostachys pubescens) and makino bamboo (Phyllostachys makinoi). Five water-borne copper-based preservatives, namely ammoniacal copper quaternary compound-type B (ACQ-B), copper azole-type A (CBA-A), copper azole-type B (CA-B), tanalith CY (TCY) and micronized copper quaternary (MCQ), were tested as green-colour protectors. Results revealed that excellent green-colour protection (a* values of −13.2, −7.6 and −6.3, respectively) was obtained when the culms and leaves of ma bamboo, moso bamboo and makino bamboo culms were treated with 0.25% aqueous TCY solution in a 100 °C water bath for 2 h. Furthermore, to evaluate the effects of 0.25% TCY treatment on the green-colour fastness of bamboo culms, two exposure tests including indoor exposure and outdoor weathering were employed in this study. Results from the 6-month exposure tests in both indoor and outdoor environment demonstrated that specimens treated with 0.25% TCY exhibited good colourfastness. To improve the treatment efficacy in bamboo culms, both atmospheric pressure impregnation and vacuum pressure impregnation were used. The results indicated that green-colour protection could be obtained by the two impregnation treatments in 0.25% TCY solution.