Heteronuclear Multiple Bond Connectivity Research Articles

Synthesis and structural elucidation of a series of isoflavones-based on FPR antagonists

Synthesis and structural elucidation of a series of isoflavones-based on FPR antagonists

A Cytotoxic Compound from n-Hexane Fraction of Lantana camara Linn Leaves

In this study, one triterpenoid compound from n-hexane fraction of Lantana camaraLinn leaves has cytotoxic activity was isolated. Isolation was carried out using gravity chromatographycolumnand purification by recrystallization method. Isolated compound was obtained white solid with melting point 252-253oC. The structure of isolated compound was elucidated using spectroscopic analysis Ultraviolet (UV), Infrared (IR), 1H-Nuclear Magnetic Resonance (1H-NMR), 13C-Nuclear Magnetic Resonance (13C-NMR) Heteronuclear Multiple Bond Connectivity (HMBC), Heteronuclear Multiple Quantum Correlation (HMQC), Distortionless Enhancement Polarization Transfer (DEPT) and comparative literature data, identified as Lantadene A (22β-angeloyloxy-3-oxoolean-12-en-28-oic-acid) with molecule formula C35H52O5. The Lantadene A compound was evaluated for cytotoxic activity against shrimp larvae Artemia SalinaLeach using Brine Shrimp Lethality Test(BSLT) method, showed strong cytotoxic activity with an LC50value of 48.97 µg/mL.

Cytotoxic Lathyrane-Type Diterpenes from Seeds of Euphorbia lathyris.

We isolated two new lathyrane-type diterpenes L27 (1) and L28 (2) along with seven known compounds (3-9) from the seeds of Euphorbia lathyris. These compounds were identified by NMR, high-resolution electrospray ionisation (HR-ESI)-MS as well as IR spectroscopy. Compounds 1 and 2 were assigned NMR spectrums with 1H-NMR, 13C-NMR, distortionless enhancement by polarization (DEPT), correlation spectroscopy (COSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear multiple bond connectivity (HMBC) and nuclear Overhauser effect spectroscopy (NOESY). Stereo configuration of 1 and 2 were confirmed by comprehensive interpretation of their nuclear Overhauser effect (NOE) relationship and showed they were first natural lathyrane-type diterpenes possessing α-configuration substitutes at C-3. Cytotoxicity assay of isolated compounds were evaluated against breast cancer cell lines MCF-7 or MDA-MB-231, 786-0 and liver cancer cell lines HepG2. As a result, Euphorbia factor L28 (2) showed strongly cytotoxicity to the 786-0 and HepG2 cell lines, with an IC50 value of 9.43 and 13.22 µM, respectively, which preliminarily suggested that the configuration of lathyrane-type diterpene at C-3 has a significant effect on its bioactivity.

Synthesis and Spectral Characterization of Benzo-[6,7][1,5]diazocino[2,1-a]isoindol-12-(14H)-one Derivatives.

A simple synthetic route affording 27%–85% yields of benzo[6,7][1,5]diazocino[2,1-a]isoindol-12(14H)-one ring systems from readily available 3-(2-oxo-2-phenylethyl) isobenzofuran-1(3H)-ones and 2-(aminomethyl)aniline starting materials in toluene and catalysed by p-toluene-sulfonic acid is developed. The 1H- and 13C-NMR spectra of the final products were assigned using a variety of one and two-dimensional NMR experiments. The distinction between the two potential isomers of the final products was made on the basis of heteronuclear multiple bond connectivity (HMBC) NMR spectra.

Trifasciatosides A-J, Steroidal Saponins from Sansevieria trifasciata.

Four previously unreported steroidal saponins, trifasciatosides A-D (1-4), three pairs of previously undescribed steroidal saponins, trifasciatosides E-J (5a, b-7a, b) including acetylated ones, together with twelve known compounds were isolated from the n-butanol soluble fraction of the methanol extract of Sansevieria trifasciata. Their structures were elucidated on the basis of detailed spectroscopic analysis, including (1)H-NMR, (13)C-NMR, (1)H-(1)H correlated spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC), total correlated spectroscopy (TOCSY), nuclear Overhauser enhancement and exchange spectroscopy (NOESY), electrospray ionization-time of flight (ESI-TOF)-MS and chemical methods. Compounds 2, 4, and 7a, b exhibited moderate antiproliferative activity against HeLa cells.

Synthesis of the Proposed Structure of Damaurone D and Evaluation of Its Anti-inflammatory Activity.

Concise and efficient synthesis of the proposed structure of damaurone D is accomplished in five steps without protection-deprotection operations. The key feature of our synthesis includes a versatile aldol reaction of the benzofuranone, provided by selective α-halogenation and intramolecular O-alkylation. However, the H- and C-NMR spectral data of the synthesized damaurone D did not agree with previous reports. The structure of the synthesized damaurone D was confirmed using combined two dimensional (2D)-NMR analysis, including heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC), and nuclear Overhauser effect spectroscopy (NOESY). The synthesized damaurone D was found to exhibit potent anti-inflammatory activity in murine macrophage RAW264.7 cells, which was demonstrated by the findings that damaurone D treatment in cells resulted in the inhibition of lipopolysaccharide (LPS)-stimulated inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression and nitrite production.

Re-evaluation of physicochemical and NMR data of triol ginsenosides Re, Rf, Rg2, and 20-gluco-Rf from Panax ginseng roots

Ginseng roots were extracted with aqueous methanol, and extracts were suspended in water and extracted successively with ethyl acetate and n-butanol. Column chromatography using the n-butanol fraction yielded four purified triol ginseng saponins: the ginsenosides Re, Rf, Rg2, and 20-gluco-Rf. The physicochemical, spectroscopic, and chromatographic characteristics of the ginsenosides were measured and compared with reports from the literature. For spectroscopic analysis, two-dimensional nuclear magnetic resonance (NMR) methods such as 1H-1H correlation spectroscopy, nuclear Overhauser effect spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond connectivity were employed to identify exact peak assignments. Some peak assignments for previously published 1H- and 13C-NMR spectra were found to be inaccurate. This study reports the complete NMR assignment of 20-gluco-Rf for the first time.

Three New Lignan Glycosides with IL-6 Inhibitory Activity from <i>Akebia quinata</i>

Three new lignan glycosides, akeqintoside A [(7S,8S)-7,8-dihydro-8-hydroxymethyl-7-(4-hydroxy-3-methoxyphenyl)-1'-benzofuranpropanol 2'-O-β-D-glucopyranoside] (1), akeqintoside B [(7R,8R)-7,8-dihydro-8-hydroxymethyl-7-(4-hydroxy-3-methoxyphenyl)-1'-(9'-methoxy-7'-propenyl) benzofuran 2'-O-β-D-glucopyranoside] (2), and akequintoside C [7R*,8R*-dihydroxy-7-(4-hydroxy-3-methoxyphenyl)-glycerol 9-O-β-D-(6'-O-caffeoyl)-glucopyranoside] (3) were isolated from Akebia quinata along with five known compounds, syringin (4), vanilloloside (5), salidroside (6), 3,4-dihydroxyphenylethyl alcohol 8-O-β-D-glucopyranoside (7), and calceolarioside B (8). The structures of the compounds were identified based on one dimensional (1D)- and 2D-NMR, including (1)H-(1)H correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and nuclear Overhauser effect spectroscopy (NOESY) spectroscopic analyses. The inhibitory activity of these isolated compounds against interleukin-6 (IL-6) production in tumor necrosis factor-alpha (TNF-α) stimulated MG-63 cells was also examined.

Characterization and Thermal Isomerization of (all-E)-Lycopene

A large amount of (all-E)-lycopene was successfully purified from tomato paste using an improved method that included a procedure to wash crystalline powder with acetone. The total yield of the pure (all-E) form was at least 30%. The melting point of (all-E)-lycopene was determined to be 176.35 °C by differential scanning calorimetry (DSC) measurements. Bathochromic shifts were observed in the absorption maxima of all solvents tested (at most a 36 nm shift for λ2 in carbon disulfide, as was observed in hexane) and were accompanied by absorbance decreases, namely, a hypochromic effect, showing a higher correlation between the position and the intensity of the main absorption bands. This bathochromic shift was dependent upon the polarizability of the solvent rather than its polarity. The structure of (all-E)-lycopene in CDCl3 and C6D6 was identified on the basis of one- and two-dimensional nuclear magnetic resonance (NMR) spectra, including (1)H and (13)C NMR, homonuclear correlation spectroscopy ((1)H-(1)H COSY), heteronuclear multiple-quantum coherence (HMQC), and heteronuclear multiple-bond connectivity (HMBC). The rate constants of the decrease in (all-E)-lycopene with hexane and benzene were calculated to be 3.19 × 10(-5) and 3.55 × 10(-5) s(-1), respectively. The equilibrium constants between (all-E) and (13Z) isomers were estimated to be 0.29 in hexane and 0.31 in benzene, respectively, from the point at which the amount of (13Z)-lycopene reached its maximum.

Anti-leishmanial Activities of Extracts and Isolated Compounds fromDrechslera rostrataandEurotium tonpholium

The fungal extract of Drechslera rostrata and Eurotium tonpholium showed a significant anti-leishmanial activity against Leishmania major; IC50 was 28.8 and 28.2 μg/mL, respectively. Seven compounds, five from D. rostrata (H1-H5) and two from E. tonpholium (H6 and H7), were isolated and identified using different spectroscopic analysis including (1) HNMR, (13) CNMR, Hetero-nuclear multiple bond connectivity (HMBC), Hetero-nuclear Multiple Quantum Correlation (HMQC), and EI-MS. The isolated compounds are: di-2-ethylhexyl phthalate (1), (22E)-5α,8α-epidioxyergosta-6,22-diene-3β-ol (2),1,3,8-trihydroxy-6-methyl-nthraquinone (3), aloe-emodine 8-O-glucopyranoside(4), 2R, 3R,4R,5R hexane 1, 2, 3, 4, 5, 6 hexole (Mannitol) (5), 1,8-dihydroxy-3-methoxy-6-methyl-anthraquinone (6) and 1, 4, 5-trihydroxy-7-methoxy-2-methyl-anthraquinone (7). However, compounds (1) and (6) showed activity against L. major with IC50 of 3.2 and 10.38 µg/mL, respectively. On the other hand, oral administration of the two extracts (100 mg/kg) and compounds 1 and 6 (50 mg/kg) showed very good activity when compared with the anti-leishmanial drug Pentostam (125 mg/kg). Interestingly, the complete heeling activity of the extracts and compounds (1) and (6) was obtained after 13-17 days of treatment, while complete healing activity of Pentostam was obtained after 28 days. No alteration on liver and kidney functions was recorded on animals treated with the two extracts for 15 consecutive days.

Isolation and Characterization of Phytotoxic Compounds Produced by Streptomyces sp. AMC 23 from Red Mangrove (Rhizophora mangle)

Natural products produced by microorganisms have been utilized as sources of new drugs possessing a wide range of agrochemical and pharmacological activities. During our research on Actinomycetes from Brazilian mangroves, the ethyl acetate extract of Streptomyces sp. AMC 23 isolated from the red mangrove (Rhizophora mangle) rhizosphere produced a highly active compound against the microalga Chlorella vulgaris, often used to assess the phytotoxic activity. As a result, the bioassay-guided fractionation led to the isolation of the mixture of the known compounds bafilomycin B1 and bafilomycin B2. The chemical structures of bafilomycin B1 and bafilomycin B2 were established based on their spectroscopic data by infrared (IR), mass spectrometry (MS), (1)H nuclear magnetic resonance (NMR), gradient-enhanced heteronuclear multiple quantum coherence (gHMQC), and gradient-enhanced heteronuclear multiple-bond connectivity (gHMBC) as well as comparison with reference data from the literature. Moreover, it was also possible to identify other bafilomycins using non-chromatographic-dependent techniques (Tandem mass spectrometry). Additionally, this is the first report on the phytotoxic activity of bafilomycin B1.

Triterpenoid Saponins of Pulsatilla koreana Root Have Inhibition Effects of Tumor Necrosis Factor-α Secretion in Lipopolysaccharide-Induced RAW264.7 Cells

In the present study, a new oleanane-type triterpenoid saponin, pulsatilloside F (1), along with 21 known compounds (2-22), were isolated from the root of Pulsatilla koreana. Their chemical structures were elucidated by mass, (1)H-, (13)C-NMR, correlation spectroscopy (COSY), heteronuclear multiple quantum coherence (HMQC) and heteronuclear multiple bond connectivity (HMBC) spectroscopy. Anti-inflammatory effects of the compounds were evaluated in terms of inhibitory of tumor necrosis factor α (TNF-α) secretion in the lipopolysaccharide (LPS)-stimulated murine RAW264.7 macrophage cell line. Compounds 19 and 20 exhibited particularly inhibitory effects with respective IC50 values of 0.32 and 0.65 µm. Compounds 1-4, 7 and 10-13 exhibited inhibitory effects with inhibition rates up to 41.55-73.76% at a concentration of 5 µm, respectively.

Sesquiterpene Coumarins from <i>Ferula fukanensis</i> and Their Pro-inflammatory Cytokine Gene Expression Inhibitory Effects

Six new sesquiterpene coumarin derivatives, fukanefuromarin H-M (1-6), were isolated from an 80% aqueous methanol extract of the roots of Ferula fukanensis. The structures were elucidated on the basis of spectroscopic evidence, particularly heteronuclear multiple-bond connectivity (HMBC) and high-resolution MS. The sesquiterpene coumarin derivatives inhibited nitric oxide (NO) and inducible NO synthase (iNOS), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) gene expression in a murine macrophage-like cell line (RAW264.7), which was activated by lipopolysaccharide (LPS) and recombinant mouse interferon-γ (IFN-γ).

2,3,22,23-Tetrahydroxyl-2,6,10,15,19,23-hexamethyl-6,10,14,18-tetracosatetraene, an Acyclic Triterpenoid Isolated from the Seeds of <i>Alpinia katsumadai</i>, Inhibits Acyl-CoA : Cholesterol Acyltransferase Activity

In order to isolate a cholesterol-lowering compound from Alpinia katsumadai, an inhibitor for acyl-CoA : cholesterol acyltransferase (ACAT), an enzyme responsible for the cholesterol ester formation in liver, was purified, its chemical structure was determined, and in vivo and in vitro inhibition activities were performed. In a high fat diet mouse model, we discovered that the ethanol extract of Alpinia katsumadai reduced plasma cholesterol, triglyceride, and low density lipoprotein (LDL) levels. An acyclic triterpenoid showing ACAT inhibitory activity was isolated from the extract of seeds of A. katsumadai. By NMR spectroscopic analysis of its (1)H-NMR, (13)C-NMR, (1)H-(1)H correlation spectroscopy, heteronuclear multiple bond connectivity (HMBC), hetero multiquantum coherence (HMQC) and nuclear Overhauser effect, chemical structure of 2,3,22,23-tetrahydroxyl-2,6,10,15,19,23-hexamethyl-6,10,14,18-tetracosatetraene (1), were elucidated. The acyclic triterpenoid was found to be responsible for the ACAT inhibition activities of rat liver microsomes with IC(50) values of 47.9 µM. It also decreased cholesteryl ester formation with IC(50) values of 26 µM in human hepatocyte HepG2 cell. The experimental study revealed that the ethanol extract of A. katsumadai has a hypolipemic effect in high fat diet mice, and the isolated acyclic triterpenoid has ACAT inhibition activity, showing a potential novel therapeutic approach for the treatment of hyperlipidemia and atherosclerosis.

Characterization of Chemical Constituents of <i>Luffa operculata</i>(Cucurbitaceae)

A mixture of new ceramides (1, 2, 3, 4 and 5) together with a binary mixture of ceramides with long chain alkyl (6 and 7), triterpenoid (10) and steroids (11 and 12) have been isolated from bark of the fruits and of the stems of Luffa operculata (Cucurbitaceae). The structures were elucidated by comprehensive spectro- scopic analysis including 1H and 13C NMR, DEPT (distortionless enhancement by polarization transfer), COSY (correlated spectroscopy), HMQC (heteronuclear multiple quantum coherence), HMBC (heteronu- clear multiple bond connectivity), IR (infrared), HR-ESI-MS (electrospray ionization-high resolution mass spectra) and LR-MS (low resolution electron ionization mass spectra) experiments. All the ceramides are reported for the first time in Cucurbitaceae and this is the first report of the rare triterpene 10 isolated from Luffa operculata. The ceramides 6 and 7 showed a high acetylcholine esterase inhibitory effect.

Novel Nortriterpenoids from Aphanamixis grandifolia

Four novel nortriterpenoids, 24,25-epoxy-tirucall-7,20(E)-diene-3,23-dione (1), 24,25,26,27-tetranortirucall-1,7-diene-23(21)-lactone (2), 3α-hydroxy-tirucall-7-ene-20-one (3), and 3-oxo-tirucall-7-ene-3,20-dione (4), together with one known compound mombasol (5) were isolated from the stem barks of Aphanamixis grandifolia. Their structures were elucidated on the basis of various spectroscopic analysis including electrospray ionization (ESI)-MS, high resolution (HR)-ESI-MS, IR, 1D- and 2D-NMR techniques (heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and rotating frame Overhauser enhancement spectroscopy (ROESY)), and by comparison of their spectral data with those reported. The absolute configuration of compound 1 was determined by circular dichroism (CD) exciton chirality.

A new prenylated xanthone from Garcinia xipshuanbannaensis Y.H. Li

A new prenylated xanthone, named bannaxanthone I (1), has been isolated from the leaves of Garcinia xipshuanbannaensis, along with five other known compounds, bannaxanthone E (2), mangostinone (3), tovophyllin A (4), garcinone E (5), and γ-mangostin (6). The structure of the new compound was elucidated on the basis of high-resolution fast atom bombardment mass spectra (HRFABMS), 1D-and 2D-NMR experiments, including heteronuclear multiple bond connectivity (HMBC), heteronuclear single quantum coherence (HSQC) and 1H–1H-COSY (correlated spectroscopy, COSY).

Molecular Identification of N-Acetylaspartylglutamate Synthase and β-Citrylglutamate Synthase

The purpose of the present work was to determine the identity of the enzymes that synthesize N-acetylaspartylglutamate (NAAG), the most abundant dipeptide present in vertebrate central nervous system (CNS), and β-citrylglutamate, a structural analogue of NAAG present in testis and immature brain. Previous evidence suggests that NAAG is not synthesized on ribosomes but presumably is synthesized by a ligase. As attempts to detect this ligase in brain extracts failed, we searched the mammalian genomes for putative enzymes that could catalyze this type of reaction. Mammalian genomes were found to encode two putative ligases homologous to Escherichia coli RIMK, which ligates glutamates to the C terminus of ribosomal protein S6. One of them, named RIMKLA, is almost exclusively expressed in the CNS, whereas RIMKLB, which shares 65% sequence identity with RIMKLA, is expressed in CNS and testis. Both proteins were expressed in bacteria or HEK293T cells and purified. RIMKLA catalyzed the ATP-dependent synthesis of N-acetylaspartylglutamate from N-acetylaspartate and l-glutamate. RIMKLB catalyzed this reaction as well as the synthesis of β-citrylglutamate. The nature of the reaction products was confirmed by mass spectrometry and NMR. RIMKLA was shown to produce stoichiometric amounts of NAAG and ADP, in agreement with its belonging to the ATP-grasp family of ligases. The molecular identification of these two enzymes will facilitate progress in the understanding of the function of NAAG and β-citrylglutamate.

ChemInform Abstract: Oligomeric Stilbenes from Caragana chamlagu Lamark Root

Caraganaphenol A (1), a new tetrameric stibene, was isolated from the root of Caragana chamlagu LAMARK (Leguminosae) along with (+)-α-viniferin (2) and kobophenol A (3). The stereostructure of 1 was suggested using NMR techniques (1H-detected heteronuclear multiple quantum coherence (HMQC), 1H-detected heteronuclear multiple bond connectivity (HMBC), and nuclear Overhauser effect (NOE) difference spectra).

Probing Ligand-binding Pockets of the Mevalonate Pathway Enzymes from Streptococcus pneumoniae

Diphosphomevalonate (Mev.pp) is the founding member of a new class of potential antibiotics targeting the Streptococcus pneumoniae mevalonate (Mev) pathway. We have synthesized a series of Mev.pp analogues designed to simultaneously block two steps in this pathway, through allosteric inhibition of mevalonate kinase (MK) and, for five of the analogues, by mechanism-based inactivation of diphosphomevalonate decarboxylase (DPM-DC). The analogue series expands the C(3)-methyl group of Mev.pp with hydrocarbons of varying size, shape, and chemical and physical properties. Previously, we established the feasibility of a prodrug strategy in which unphosphorylated Mev analogues could be enzymatically converted to the active Mev.pp forms by the endogenous MK and phosphomevalonate kinase. We now report the kinetic parameters for the turnover of non-, mono-, and diphosphorylated analogues as substrates and inhibitors of the three mevalonate pathway enzymes. The inhibition of MK by Mev.pp analogues revealed that the allosteric site is selective for compact, electron-rich C(3)-subsitutents. The lack of reactivity of analogues with DPM-DC provided evidence, counter to the existing model, for a decarboxylation transition state that is concerted rather than dissociative. The Mev pathway is composed of three structurally and functionally conserved enzymes that catalyze consecutive steps in a metabolic pathway. The current work reveals that these enzymes exhibit significant differences in specificity toward R-group substitution at C(3) and that these patterns are explained well by changes in the volume of the C(3) R-group-binding pockets of the enzymes.