RESUMO
Six new compounds, xylomexicanins K-N (1-4), granasteroid (5) and 5-methoxy-2-pentylbenzofuran-7-ol (6), along with nine known compounds were isolated from the leaves and twigs of Xylocarpus granatum. Among them, 1 was a biogenetic precursor of 1,8,9-phragmalin limonoid, and 4 represent the first example of degraded A-ring limonoid. The structures of them were elucidated on the basis of one- and two-dimensional NMR spectroscopic data (including 1H, 13C-NMR, DEPT, 1H-1H COSY, HSQC, HMBC, and NOESY) and confirmed by high-resolution mass spectrometry.[Formula: see text].
Assuntos
Limoninas , Meliaceae , Limoninas/química , Espectroscopia de Ressonância Magnética , Meliaceae/química , Estrutura Molecular , Folhas de PlantaRESUMO
Mono- and dianion species of 1,8-naphthalene diamide 2 were generated under sec-BuLi/TMEDA conditions and trapped with a variety of electrophiles to give 2- and 2,7- substituted products 3 and 4. Using Suzuki-Miyaura cross-coupling, mono- and di-iodinated products were converted into the corresponding 2-aryl (5) and 2,7-diaryl (6) products, respectively. The amide-amide rotation barrier of 2 was established by VT NMR, and the structure of fluorenone structure 9, obtained by remote metalation, was secured.
RESUMO
Twelve new compounds, aspergorakhins A-L (1-12) coupled with one known xanthone leptosphaerin D (13), were isolated from the extract of soil-derived fungus Aspergillus gorakhpurensis F07ZB1707. Their structures were elucidated by spectroscopic data analysis including UV, IR, NMR, and HRESIMS. The absolute configurations of 5 and 8-11 were identified using ECD and OR calculations. All compounds were tested by enzyme inhibitory activity assay in vitro. Aspergorakhin A (1) showed selective activities against PTP1B and SHP1 over TCPTP with IC50 values 0.57, 1.19, and 22.97 µM, respectively. Compounds 1 and 2 exhibited modest cytotoxicity against tumor cell lines A549, HeLa, Bel-7402, and SMMC-7721 with IC50 values in the range of 6.75-83.4 µM.
RESUMO
Dimesitylboron-functionalized stilbene derivatives have been found to undergo an unusual regioselective photoisomerization upon irradiation at 365 nm. Using NMR to follow the photoreaction, the structures of key reaction intermediates and the final products were established. This photoisomerization occurs in four steps: trans-cis isomerization, Diels-Alder reaction, di-π-methane rearrangement, and ring opening with [1,3]-H migration. This results in the formation of a rare structure with three fused five-membered rings and a six-membered one.
Assuntos
Compostos de Boro/química , Estilbenos/síntese química , Reação de Cicloadição , Estrutura Molecular , Processos Fotoquímicos , Estereoisomerismo , Estilbenos/químicaRESUMO
New chiral N,C-chelate organoboron compounds based on benzylideneamines (bza) with the general formula of B(bza-R)Mes2 (R=H or Me; Mes=mesityl) are reported. A chiral substituent group R- or S-CH(CH3 )Ph (Ph=phenyl) was introduced to the imine center, which imposed a previously unobserved pseudo- or axial-chirality on the BMes2 , creating distinct diastereomers. NMR spectroscopic studies established that the diastereomers undergo slow exchange in solution at ambient temperature. The chiral N,C-chelate B(bza-R)Mes2 molecules undergo photoisomerization in the same manner as their non-chiral analogues, generating chiral BN-cyclooctatriene (BN-COT) derivatives. Most significantly, by tracking the photoisomerization with circular dichroism (CD) and 1 Hâ NMR spectra along with time-dependent density functional theory (TD-DFT) computational studies, the photoisomerization was established to proceed in a highly stereoselective manner, that is, one diastereomer converts exclusively to the corresponding diastereomer product in the photoreaction.
RESUMO
Tambjamines are natural products that consist of a conserved bipyrrole core functionalized with different imines giving rise to many derivatives. The core structure of tambjamines allows ion coordination through the nitrogen atoms, which is a key aspect in many of their observed antimicrobial, anticancer, and antimalarial bioactivities. Minor variances in the compound structure have a considerable impact on the potency of these activities, so identifying new analogues is valuable for maximizing tambjamine biological potential. In this work, we describe the isolation and structure elucidation of the first naturally occurring macrocyclized tambjamine, tambjamine MYP1, from the marine microbe Pseudoalteromonas citrea. We also compare the apparent pK a of cyclic and linear tambjamine analogues and discuss how structural strain may effect the compound's ion coordination abilities.
RESUMO
The key intermediate, 4a,4b-dihydrophenanthrene (DPH), involved in the photocyclization of stilbene and derivatives is known to be unstable, and is therefore poorly characterized/understood. We have found that functionalising stilbenes with NMe2 and BMes2 groups can greatly enhance the stability of 4a,4b-DPHs, allowing quantitative isolation and full characterization of these rare species. Furthermore, we discovered that the new amino-borane decorated 4a,4b-DPHs can undergo thermal [1,5] H sigmatropic shift, forming isomers 4a,10a-DPHs. Both 4a,4b-DHPs and 4a,10a-DHPs are stable towards air and moisture, while only the former were found to undergo oxidative dehydrogenation upon irradiation at 365 nm under air, yielding brightly blue/green fluorescent NMe2 and BMes2 functionalised phenanthrene analogues. Control studies established that the trans-Mes2B-Ph-NMe2 unit is responsible for the stability of these isolated 4a,4b-DHPs and their [1,5]-H shift isomers.
RESUMO
We report herein a series of triarylboron-functionalized Pt(II) dinuclear complexes using a photoactive bis(4-pyridyl)ethylene (bpe) bridging unit. The new Pt(II) complexes display phosphorescence at both room temperature and 77 K. Depending on the conditions under which crystals of the complexes were grown, either the cis- or trans-isomers could be obtained. The trans and cis isomers were found to undergo light-induced isomerization in solution with the trans isomer being the dominant species.
RESUMO
Two tetranortriterpenoids with new skeletons, xylomexicanins I and J (1 and 2), were isolated during the investigation of chemical constituents from seeds of the Chinese mangrove, Xylocarpus granatum. Xylomexicanin I (1) is an unprecedented limonoid with bridged B- and C-rings. A biosynthesis pathway for 1 from xylomexicanin F is proposed.
Assuntos
Limoninas/isolamento & purificação , Meliaceae/química , Sementes/química , Limoninas/química , Estrutura MolecularRESUMO
A rotational barrier study was performed on eight tertiary biaryl 2-amides using variable-temperature (VT) NMR and exchange (EXSY) spectroscopy experiments. Seven out of the eight 2-amido-2'-methylbiphenyls with additional 3- and 6-substitution patterns (1-7) were found to have approximately similar rotational barriers (ΔG⧧Tc = 56.5-67.5 kJ/mol). However, for both 3- and 6-substitution (8), the rotational barrier was found to be significantly higher (ΔG⧧ = 102.6-103.8 kJ/mol). Computational studies performed on all eight compounds gave results in good agreement with the experimental rotational barriers. A transition state in which atropisomerism occurs by a cooperative rotation of the Ar-CO and Ar-Ar' bonds depending on substituent location is proposed.
RESUMO
A 1-phosphonium-8-borane-decorated naphthalene molecule 2 has been found to react with N,N'-dimethylimidazol-2-ylidene (IMe), a popular member of the N-heterocyclic carbene (NHC) family, which converts it into two vinyl-amine fragments one of which is trapped between the phosphonium and borane unit by the formation of a C-C and a B-N bond. The same reactivity was not observed for larger NHC molecules. Control experiments and mechanistic studies have established the involvement of an ylide-borane molecule and an imidazolium salt in addition to IMe carbene in this new transformation of an NHC.
RESUMO
Eupatorium (family: Compositae), which comprises nearly 1200 species, is distributed throughout tropical America, Europe, Africa, and Asia. Up to now, the reported constituents from the genus Eupatorium involve flavonoids, terpenoids, pyrrolizidine alkaloids, phenylpropanoids, quinonoids, essential oils, and some others, altogether more than 300 compounds. Studies have shown that Eupatorium and its active principles possess a wide range of pharmacological activities, such as cytotoxic, antifungal, insecticidal, antibacterial, anti-inflammatory, and antinociceptive activities. Currently, effective monomeric compounds or active parts have been screened for pharmacological activities from Eupatorium in vivo and in vitro. Increasing amount of data supports application and exploitation for new drug development.
Assuntos
Analgésicos/farmacologia , Anti-Infecciosos/farmacologia , Anti-Inflamatórios/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Eupatorium/química , Compostos Orgânicos/farmacologia , Extratos Vegetais/farmacologia , Analgésicos/química , Analgésicos/isolamento & purificação , Anti-Infecciosos/química , Anti-Infecciosos/isolamento & purificação , Anti-Inflamatórios/química , Anti-Inflamatórios/isolamento & purificação , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Humanos , Compostos Orgânicos/química , Compostos Orgânicos/isolamento & purificação , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificaçãoRESUMO
A new sesquiterpene, eudesm-11-ene-4alpha,7beta,9beta-triol, was isolated from the EtOH extract of aerial parts of Dichrocephala integrifolia. Its structure was determined on the basis of spectral analysis of 1D and 2D NMR data.
Assuntos
Asteraceae/química , Sesquiterpenos de Eudesmano/isolamento & purificação , Espectroscopia de Ressonância Magnética , Sesquiterpenos de Eudesmano/químicaRESUMO
Highly fluorescent π-conjugated polycyclic azaborines can be prepared from B,N-heterocyclic compounds with a BR2 -CH2 unit through the elimination of an R-H molecule (see scheme). These clean photoelimination reactions occur both in solution and in polymers doped with the precursors.
RESUMO
Two new limonoids, named xylomexicanins C and D, were isolated from a dichloromethane extract of the seeds of Xylocarpus granatum cultivated in Hainan, China, and their structures were elucidated on the basis of one- and two-dimensional NMR (including 1H, 13C-NMR, DEPT, 1H-1H COSY, HSQC, HMBC, and NOESY) and confirmed by high-resolution mass spectrometry. Xylomexicanin C exhibited antiproliferative activity against human breast carcinoma cells (KT).
Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Limoninas/química , Limoninas/farmacologia , Meliaceae/química , Antineoplásicos/isolamento & purificação , Linhagem Celular Tumoral , Humanos , Limoninas/isolamento & purificaçãoRESUMO
A phytochemical investigation of Chromolaena odorata resulted in the isolation of five new compounds, 5aα,6,9,9aß,10-pentahydro-10ß-hydroxy-7-methylanthra[1,2-d][1,3]dioxol-5-one (1), 1,2-methylenedioxy-6-methylanthraquinone (2), 3-hydroxy-1,2,4-trimethoxy-6-methylanthraquinone (3), 3-hydroxy-1,2-dimethoxy-6-methylanthraquinone (4), and 7-methoxy-7-epi-medioresinol (5), together with 12 known compounds, odoratin (6), 3ß-acetyloleanolic acid (7), ursolic acid (8), ombuin (9), 4,2'-dihydroxy-4',5',6'-trimethoxychalcone (10), (-)-pinoresinol (11), austrocortinin (12), tianshic acid (13), cleomiscosin D (14), (-)-medioresinol (15), (-)-syringaresinol (16), and cleomiscosin A (17). All the compounds were evaluated for their PPARγ transactivation activity, and compound 6 showed moderate activity with an EC(50) value of 3.10 µM.
Assuntos
Antraquinonas/isolamento & purificação , Chromolaena/química , Dioxóis/isolamento & purificação , Dioxóis/farmacologia , Medicamentos de Ervas Chinesas/isolamento & purificação , Medicamentos de Ervas Chinesas/farmacologia , Flavonoides/isolamento & purificação , Flavonoides/farmacologia , Lignanas/isolamento & purificação , Lignanas/farmacologia , PPAR gama/agonistas , Antraquinonas/química , Antraquinonas/farmacologia , Dioxóis/química , Medicamentos de Ervas Chinesas/química , Flavonoides/química , Furanos/química , Furanos/isolamento & purificação , Hepatócitos/efeitos dos fármacos , Humanos , Lignanas/química , Luciferases/metabolismo , Estrutura Molecular , Sesquiterpenos/química , Sesquiterpenos/isolamento & purificação , Sesquiterpenos/farmacologia , EstereoisomerismoRESUMO
Expression of metastatic suppressor maspin is lost in advanced prostate cancer. Clinically relevant mutations in androgen receptor (AR) convert antiandrogens into AR agonists, promoting prostate tumor growth. We discovered tanshinone IIA (TS-IIA) is a potent antagonist of mutated ARs and induces maspin expression through AR. TS-IIA suppressed AR expression and induced apoptosis in LNCaP cells. Syntheses of TS-IIA derivatives (1-9) revealed that the 4,4-dimethyl group at ring A is important for TS-IIA's antiandrogenic and maspin induction activities.
Assuntos
Abietanos/farmacologia , Antagonistas de Androgênios/farmacologia , Antineoplásicos/farmacologia , Neoplasias da Próstata/patologia , Receptores Androgênicos/metabolismo , Serpinas/biossíntese , Abietanos/síntese química , Abietanos/química , Antagonistas de Androgênios/síntese química , Antagonistas de Androgênios/química , Antineoplásicos/síntese química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral/efeitos dos fármacos , Humanos , Masculino , Mutação , Antígeno Prostático Específico/metabolismo , Receptores Androgênicos/genética , Relação Estrutura-Atividade , Ativação Transcricional/efeitos dos fármacosRESUMO
A novel 6/8/6-membered taxane with a rare C-12(13)-double bond and rare 2(3â20)abeotaxane were isolated from the needles of Taxus canadensis. Their structures were characterized as 7ß,9α,10ß-triacetoxytaxa-4(20),12-diene-2α,5α,11ß-triol (1) and 2α,7ß,10ß-triacetoxy-5α-hydroxy-2(3â20)abeotaxa-4(20),11-diene-9,13-dione (2) on the basis of 1D and 2D spectroscopic data. 1 is the first example of a natural taxane without substitution at both C-13 and C-14.
Assuntos
Antineoplásicos/análise , Extratos Vegetais/análise , Taxoides/análise , Taxus/química , Antineoplásicos/química , Antineoplásicos/isolamento & purificação , Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Feminino , Humanos , Espectroscopia de Ressonância Magnética , Masculino , Estrutura Molecular , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Folhas de Planta/química , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/patologia , Taxoides/química , Taxoides/isolamento & purificação , Taxoides/farmacologia , Falha de Tratamento , Neoplasias do Colo do Útero/tratamento farmacológico , Neoplasias do Colo do Útero/patologiaRESUMO
Achillinin A (2ß,3ß-epoxy-1α,4ß,10α-trihydroxyguai-11(13)-en-12,6α-olide, 1), a new guaianolide isolated from the flower of Achillea millefolium, exhibited potential antiproliferative activity to A549, RERF-LC-kj and QG-90 cells with 50% inhibitory concentration (IC(50)) values of 5.8, 10 and 0.31 µM, respectively.
Assuntos
Achillea/química , Adenocarcinoma/tratamento farmacológico , Antineoplásicos Fitogênicos/farmacologia , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Fitoterapia , Extratos Vegetais/farmacologia , Sesquiterpenos/farmacologia , Carcinoma de Pequenas Células do Pulmão/tratamento farmacológico , Adenocarcinoma/patologia , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/uso terapêutico , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Flores/química , Humanos , Concentração Inibidora 50 , Neoplasias Pulmonares/patologia , Espectroscopia de Ressonância Magnética , Extratos Vegetais/química , Extratos Vegetais/uso terapêutico , Sesquiterpenos/química , Sesquiterpenos/uso terapêutico , Carcinoma de Pequenas Células do Pulmão/patologiaRESUMO
Three new taxanes, 2 α,9 α,10 ß-triacetoxy-13 α-( ß-D-glucopyranosyloxy)taxa-4(20),11-dien-5 α-ol, 5 α,10 ß,13 α-triacetoxytax-11-ene-2 α,7 ß,9 α,20-tetraol, and 5 α,10 ß,13 ß-triacetoxy-2 α,7 ß-dihydroxy-2(3â20) abeotaxa-4(20),11-dien-9-one, were isolated from the leaves of the Japanese yew, Taxus cuspidata. Compound 1 is the first example of a taxane with 13-glycosidic linkage.