RESUMO
Six new sesquiterpene coumarin ethers, namely turcicanol A (1), turcicanol A acetate (2), turcicanol B (3), turcica ketone (4), 11'-dehydrokaratavicinol (5), and galbanaldehyde (6), and one new sulfur-containing compound, namely turcicasulphide (7), along with thirty-two known secondary metabolites were isolated from the root of the endemic species Ferula turcica Akalin, Miski, & Tuncay through a bioassay-guided isolation approach. The structures of the new compounds were elucidated by spectroscopic analysis and comparison with the literature. Cell growth inhibition of colon cancer cell lines (COLO205 and HCT116) and kidney cancer cell lines (UO31 and A498) was used to guide isolation. Seventeen of the compounds showed significant activity against the cell lines.
Assuntos
Anestésicos Gerais , Antineoplásicos Fitogênicos , Antineoplásicos , Ferula , Sesquiterpenos , Ferula/química , Compostos de Enxofre/análise , Estrutura Molecular , Éteres , Antineoplásicos Fitogênicos/farmacologia , Antineoplásicos/análise , Cumarínicos/química , Sesquiterpenos/química , Enxofre/análise , Raízes de Plantas/químicaRESUMO
Plants have historically been a rich source of successful anticancer drugs and chemotherapeutic agents, with research indicating that this trend will continue. In this contribution, we performed high-throughput cytotoxicity screening of 702 extracts from 95 plant species, representing 40 families of the Brazilian Cerrado biome. Activity was investigated against the following cancer cell lines: colon (Colo205 and Km12), renal (A498 and U031), liver (HEP3B and SKHEP), and osteosarcoma (MG63 and MG63.3). Dose-response tests were conducted with 44 of the most active extracts, with 22 demonstrating IC50 values ranging from <1.3 to 20 µg/mL. A molecular networking strategy was formulated using the Global Natural Product Social Molecular Networking (GNPS) platform to visualize, analyze, and annotate the compounds present in 17 extracts active against NCI-60 cell lines. Significant cytotoxic activity was found for Salacia crassifolia, Salacia elliptica, Simarouba versicolor, Diospyros hispida, Schinus terebinthifolia, Casearia sylvestris var. lingua, Magonia pubescens, and Rapanea guianensis. Molecular networking resulted in the annotation of 27 compounds. This strategy provided an initial overview of a complex and diverse natural product data set, yielded a large amount of chemical information, identified patterns and known compounds, and assisted in defining priorities for further studies.
Assuntos
Ecossistema , Ensaios de Triagem em Larga Escala , Extratos Vegetais/análise , Extratos Vegetais/farmacologia , Brasil , Linhagem Celular Tumoral , Geografia , Humanos , Concentração Inibidora 50 , SolventesRESUMO
A high-throughput screening assay was developed and applied to a large library of natural product extract samples, in order to identify compounds which preferentially inhibited the in vitro 2D growth of a highly metastatic osteosarcoma cell line (MG63.3) compared to a cognate parental cell line (MG63) with low metastatic potential. Evaluation of differentially active natural product extracts with bioassay-guided fractionation led to the identification of lovastatin (IC50 = 11 µm) and the limonoid toosendanin (IC50 = 26 nm). Other statins and limonoids were then tested, and cerivastatin was identified as a particularly potent (IC50 < 0.1 µm) and selective agent. These compounds potently and selectively induced apoptosis in MG63.3 cells, but not MG63. Assays with other cell pairs were used to examine the generality of these results. Statins and limonoids may represent unexplored opportunities for development of modulators of osteosarcoma metastasis. As cerivastatin was previously approved for clinical use, it could be considered for repurposing in osteosarcoma, pending validation in further models.
Assuntos
Produtos Biológicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Ensaios de Triagem em Larga Escala/métodos , Produtos Biológicos/química , Produtos Biológicos/isolamento & purificação , Neoplasias Ósseas/metabolismo , Neoplasias Ósseas/patologia , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Medicamentos de Ervas Chinesas/química , Medicamentos de Ervas Chinesas/isolamento & purificação , Medicamentos de Ervas Chinesas/farmacologia , Humanos , Lovastatina/química , Lovastatina/isolamento & purificação , Lovastatina/farmacologia , Melia/química , Melia/metabolismo , Monascus/química , Monascus/metabolismo , Osteossarcoma/metabolismo , Osteossarcoma/patologia , Extratos Vegetais/química , Piridinas/química , Piridinas/isolamento & purificação , Piridinas/farmacologia , Sementes/química , Sementes/metabolismoRESUMO
Several simple and prenylated coumarin derivatives were isolated from the dichloromethane extract of the root of Neocryptodiscus papillaris based on moderate cytotoxic activity of the extract in COLO205, KM12 and MCF7 cancer cells. While the major prenylated furanocoumarin derivatives and osthol isolated from the dichloromethane extract were responsible for the activity in the colon and breast cancer cell lines, the 4'-acylated osthol derivatives including a novel coumarino-alkaloid; neopapillarine) demonstrated selective cytotoxic activity in A498 and UO31 renal cancer cell lines.
Assuntos
Alcaloides/farmacologia , Antineoplásicos/farmacologia , Apiaceae/química , Apoptose , Carcinoma de Células Renais/patologia , Neoplasias Renais/patologia , Extratos Vegetais/farmacologia , Carcinoma de Células Renais/tratamento farmacológico , Proliferação de Células , Cumarínicos/farmacologia , Humanos , Neoplasias Renais/tratamento farmacológico , Células Tumorais CultivadasRESUMO
Seven known sesquiterpene coumarins and a new sesquiterpene coumarin, anatolicin (8), were isolated from the dichloromethane extract of the roots of Heptaptera anatolica. Structures of these compounds were elucidated based on their spectral properties. While some of these sesquiterpene coumarins showed modest cytotoxic activity against COLO205, KM12, A498, UO31, and TC32 cancer cell lines, selective cytotoxicity of anatolicin (8) and 14'-acetoxybadrakemin (7) were observed at nanomolar level against the UO31 kidney cancer cell line.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apiaceae/química , Extratos Vegetais/farmacologia , Sesquiterpenos/farmacologia , Antineoplásicos Fitogênicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cumarínicos/química , Cumarínicos/farmacologia , Humanos , Neoplasias Renais/tratamento farmacológico , Estrutura Molecular , Extratos Vegetais/química , Raízes de Plantas/química , Sesquiterpenos/químicaRESUMO
The new pentacyclic triterpene 11ß-hydroxypristimerin (1), along with the known metabolites pristimerin (2), 6-oxopristimerol (3) and vitideasin (4), were isolated from a Salacia crassifolia root wood extract, following a bioassay-guided fractionation approach. Both the extract and the purified triterpenes displayed pronounced cytotoxic activity against human cancer cell lines. The NCI-60 cell line screen revealed that compound 2 was the most active, with a mean GI50 of 0.17 µM, while compound 1 had a mean GI50 of 8.7 µM. A COMPARE analysis of the screening results showed that pristimerin is likely to be the main compound responsible for the cytotoxic activity of the extract (mean GI50 of 0.3 µg·mL−1). A targeted search for pristimerin and related derivatives using LC-MS/MS revealed the presence of pristimerin (2) and 6-oxopristimerol (3) in all Celastraceae species examined and in all plant parts tested, while vitideasin (4) was only detected in the genus Salacia.
Assuntos
Celastraceae/metabolismo , Metabolômica/métodos , Extratos Vegetais/química , Salacia/química , Triterpenos/química , Antineoplásicos/química , Antineoplásicos/isolamento & purificação , Antineoplásicos/metabolismo , Antineoplásicos/uso terapêutico , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Triterpenos Pentacíclicos , Raízes de Plantas/química , Relação Estrutura-Atividade , Triterpenos/isolamento & purificação , Triterpenos/metabolismo , Triterpenos/uso terapêuticoRESUMO
A simple and rapid method using high-speed counter-current chromatography (HSCCC), along with bioassay-guided fractionation based on the anti-proliferative activity against renal and colon cancer cells, has been developed for the preparative separation of aceroside VIII (1) and platyphylloside (2) from Betula platyphylla. A solvent system composed of ethyl acetate/acetonitrile/water (1:0.1:1, v/v/v) was optimized for the separation. The upper phase was used as the stationary phase, and the lower phase was used as the mobile phase. Among these isolated diarylheptanoids, platyphylloside (2) showed anti-proliferative activity in the COLO205 and KM12 colon cells and renal cancer cell lines A498, U031, as well as in MG63 and MG 63.3 osteosarcoma cells. In addition, it showed dose dependent inhibitory effects in the NCI 60 cell line assay. These results suggest that the diarylheptanoids isolated from B. platyphylla with an efficient HSCCC method could be potential multi-targeted therapeutic agents for cancer.
Assuntos
Betula/química , Proliferação de Células/efeitos dos fármacos , Diarileptanoides/isolamento & purificação , Extratos Vegetais/administração & dosagem , Linhagem Celular Tumoral , Neoplasias do Colo/tratamento farmacológico , Diarileptanoides/administração & dosagem , Diarileptanoides/química , Humanos , Neoplasias Renais/tratamento farmacológico , Extratos Vegetais/química , Solventes/químicaRESUMO
It is well known that activated microglia produce nitric oxide (NO), which has an important role in the pathophysiology of several neurodegenerative diseases such as Alzheimer's disease. In the course of searching for novel therapeutic agents from medicinal plants against neuroinflammatory diseases, the methanolic extract of Tetrapanax papyriferus was found to have significant NO inhibitory activity in lipopolysaccharide (LPS)-stimulated BV2 microglia cells. Nine oleanane-type triterpenes, including two new compounds, epipapyriogenin C-3-O-ß-d-glucopyranoside (6) and 11-O-butylpapyrioside LIIc (9), were isolated from the leaves and stems of Tetrapanax papyriferus. The structures of these compounds were elucidated with 1D- and 2D-NMR and MS data. Among these Δ(11,13) oleanane-type triterpenes, compound 3 showed significant NO inhibitory activity in BV-2 cells, reducing the LPS-induced expression of COX-2 and pro-inflammatory cytokines such as TNF-α and IL-6. Compounds 7 and 9 also showed NO inhibitory activities among the Δ(12) oleanane-type triterpene saponins. These results show that oleanane-type triterpenes isolated from T. papyriferus could be a potential natural resource of NO inhibitors used in the treatment of neurodegenerative disorders.
Assuntos
Anti-Inflamatórios/química , Óxido Nítrico/biossíntese , Ácido Oleanólico/química , Extratos Vegetais/química , Anti-Inflamatórios/administração & dosagem , Araliaceae/química , Ciclo-Oxigenase 2 , Citocinas/biossíntese , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Inflamação/induzido quimicamente , Inflamação/tratamento farmacológico , Lipopolissacarídeos/toxicidade , Microglia/efeitos dos fármacos , Microglia/metabolismo , Microglia/patologia , Doenças Neurodegenerativas/tratamento farmacológico , Óxido Nítrico/antagonistas & inibidores , Ácido Oleanólico/administração & dosagem , Ácido Oleanólico/isolamento & purificação , Extratos Vegetais/administração & dosagem , Folhas de Planta/química , Plantas Medicinais/químicaRESUMO
A high throughput screen for inhibitors of the oncogenic transcription factor activator protein-1 (AP-1) was applied to the NCI repository of natural product extracts. The liphophilic extract of the plant Nothospondias staudtii (Simaroubaceae) displayed significant AP-1 inhibition. Bioassay-guided fractionation of the extract lead to a new quassinoid named nothospondin (1), and the known compound glaucarubinone (2). The structure of 1 was elucidated by spectroscopic methods. Compounds 1 and 2 showed potent, dose-dependent AP-1 inhibition at noncytotoxic concentrations.
Assuntos
Cumarínicos/química , Fenantrenos/química , Simaroubaceae/química , Fator de Transcrição AP-1/antagonistas & inibidores , Camarões , Cumarínicos/isolamento & purificação , Cumarínicos/farmacologia , Espectroscopia de Ressonância Magnética , Conformação Molecular , Fenantrenos/isolamento & purificação , Fenantrenos/farmacologia , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Fator de Transcrição AP-1/metabolismoRESUMO
CONTEXT: Acquired immune deficiency syndrome (AIDS) is a severe pandemic disease especially prevalent in poor and developing countries. Thus, developing specific, potent antiviral drugs that restrain infection by human immunodeficiency virus type 1 (HIV-1), a major cause of AIDS, remains an urgent priority. OBJECTIVE: This study evaluated 32 extracts and 23 compounds from Vietnamese medicinal plants for their inhibitory effects against HIV-1 ribonuclease H (RNase H) and their role in reversing the cytopathic effects of HIV. MATERIALS AND METHODS: The plants were air-dried and extracted in different solvent systems to produce plant extracts. Natural compounds were obtained as previously published. Samples were screened for RNase H inhibition followed by a cytopathic assay. Data were analyzed using the Microsoft Excel. RESULTS AND DISCUSSION: At 50 µg/mL, 11 plant extracts and five compounds inhibited over 90% of RNase H enzymatic activity. Methanol extracts from Phyllanthus reticulatus and Aglaia aphanamixis leaves inhibited RNase H activity by 99 and 98%, respectively, whereas four extracts showed modest protection against the cytopathic effects of HIV. CONCLUSION: The screening results demonstrated that the butanol (BuOH) extract of Celastrus orbiculata leaves, methanol (MeOH) extracts of Glycosmis stenocarpa stems, Eurya ciliata leaves, and especially P. reticulatus leaves showed potential RNase H inhibition and protection against the viral cytopathic effects of HIV-1. Further chemical investigations should be carried out to find the active components of these extracts and compounds as potential anti-HIV drug candidates.
Assuntos
Fármacos Anti-HIV/farmacologia , Avaliação Pré-Clínica de Medicamentos , HIV-1/efeitos dos fármacos , Extratos Vegetais/farmacologia , Plantas Medicinais/química , Ribonuclease H/antagonistas & inibidores , Síndrome da Imunodeficiência Adquirida/tratamento farmacológico , Síndrome da Imunodeficiência Adquirida/epidemiologia , Aglaia/química , Fármacos Anti-HIV/uso terapêutico , Antivirais/farmacologia , Antivirais/uso terapêutico , Efeito Citopatogênico Viral/efeitos dos fármacos , Citoproteção , Países em Desenvolvimento , Infecções por HIV/tratamento farmacológico , HIV-1/fisiologia , Humanos , Fitoterapia , Extratos Vegetais/química , Extratos Vegetais/uso terapêutico , Folhas de Planta , Caules de Planta , Plantas Medicinais/metabolismoRESUMO
Two new monoterpene glycosides, distyloside A-B (1-2), and a new megastigmane glucoside, iso-dihydrodendranthemoside A (3) were isolated from twigs and leaves of Distylium racemosum, along with five known phenolic compounds (4-8). The structures were established via spectroscopic techniques and chemical transformations, and the absolute stereochemistry of 3 was determined by Mosher's esterification. A homogeneous fluorescence resonance energy transfer (FRET) quenching assay was used to determine the inhibitory activity of isolates (1-8) on the ribonuclease H enzymes from HIV-1, 2, human, and Escherichia coli. Among them, 6â³-O-galloylsalidroside (6) showed potent inhibitory effects with an IC(50) value of 3.5 µM on HIV-2, and 1.7 µM on human RNase H, respectively.
Assuntos
Ativação Enzimática/efeitos dos fármacos , Glicosídeos , Hamamelidaceae/química , Monoterpenos , Extratos Vegetais/farmacologia , Caules de Planta/química , Ribonuclease H/antagonistas & inibidores , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Transferência Ressonante de Energia de Fluorescência , Glicosídeos/análise , Glicosídeos/farmacologia , HIV-1/enzimologia , HIV-2/enzimologia , Humanos , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Monoterpenos/análise , Monoterpenos/farmacologia , Fenóis/análise , Fenóis/farmacologia , Folhas de Planta/químicaRESUMO
Neurofibromatosis type 1 (NF1) is the most common genetic disease affecting the nervous system. Patients typically develop many tumors over their lifetime, leading to increased morbidity and mortality. The NF1 gene, mutated in NF1, is also commonly mutated in sporadic glioblastoma multiforme (GBM). Because both NF1 and GBM are currently incurable, new therapeutic approaches are clearly needed. Natural products represent an opportunity to develop new therapies, as they have been evolutionarily selected to play targeted roles in organisms. Schweinfurthin A is a prenylated stilbene natural product that has previously shown specific inhibitory activity against brain and hematopoietic tumor lines. We show that patient-derived GBM and NF1 malignant peripheral nerve sheath tumor (MPNST) lines, as well as tumor lines derived from the Nf1-/+;Trp53-/+ (NPcis) mouse model of astrocytoma and MPNST are highly sensitive to inhibition by schweinfurthin A and its synthetic analogs. In contrast, primary mouse astrocytes are resistant to the growth inhibitory effects of schweinfurthin A, suggesting that schweinfurthin A may act specifically on tumor cells. Stable transfection of the GTPase-activating protein related domain of Nf1 into Nf1-/-;Trp53-/- astrocytoma cells confers resistance to schweinfurthin A. In addition, the profound effect of schweinfurthin A on dynamic reorganization of the actin cytoskeleton led us to discover that schweinfurthin A inhibits growth factor-stimulated Rho signaling. In summary, we have identified a class of small molecules that specifically inhibit growth of cells from both central and peripheral nervous system tumors and seem to act on NF1-deficient cells through cytoskeletal reorganization correlating to changes in Rho signaling.
Assuntos
Neoplasias Encefálicas/patologia , Proliferação de Células/efeitos dos fármacos , Genes da Neurofibromatose 1 , Glioma/patologia , Neurofibromatose 1/patologia , Estilbenos/farmacologia , Proteínas rho de Ligação ao GTP/metabolismo , Animais , Animais Recém-Nascidos , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Células Cultivadas , Avaliação Pré-Clínica de Medicamentos , Genes da Neurofibromatose 1/fisiologia , Glioma/genética , Glioma/metabolismo , Humanos , Camundongos , Camundongos Transgênicos , Modelos Biológicos , Neurofibromatose 1/metabolismo , Neurofibromina 1/química , Neurofibromina 1/metabolismo , Neurofibromina 1/fisiologia , Estrutura Terciária de Proteína/genética , Estrutura Terciária de Proteína/fisiologia , Transdução de Sinais/efeitos dos fármacos , Especificidade por Substrato/efeitos dos fármacos , Proteínas rho de Ligação ao GTP/fisiologiaRESUMO
Demand for the experimental antineoplastic agent schweinfurthin A, for developmental testing, prompted a re-collection of leaf material of Macaranga schweinfurthii from the original collection site in Cameroon. During chromatographic purification of the organic solvent extract, analytical UPLC-PDA-TOFMS of stilbene-enriched fractions revealed the presence of six known schweinfurthins and two previously unknown stilbenes. The structures of these new compounds, schweinfurthins I and J (1 and 2), were elucidated by 1D- and 2D-NMR techniques.
Assuntos
Antineoplásicos Fitogênicos/isolamento & purificação , Euphorbiaceae/química , Plantas Medicinais/química , Estilbenos/isolamento & purificação , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Camarões , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Folhas de Planta/química , Estilbenos/química , Estilbenos/farmacologiaRESUMO
Several quassinoids were identified in a high-throughput screening assay as inhibitors of the transcription factor AP-1. Further biological characterization revealed that while their effect was not specific to AP-1, protein synthesis inhibition and cell growth assays were inconsistent with a mechanism of simple protein synthesis inhibition. Numerous plant extracts from the plant family Simaroubaceae were also identified in the same screen; bioassay-guided fractionation of one extract (Ailanthus triphylla) yielded two known quassinoids, ailanthinone (3) and glaucarubinone (4), which were also identified in the pure compound screening procedure.
Assuntos
Ailanthus/química , Citotoxinas/isolamento & purificação , Citotoxinas/farmacologia , Inibidores da Síntese de Proteínas/isolamento & purificação , Inibidores da Síntese de Proteínas/farmacologia , Quassinas/isolamento & purificação , Quassinas/farmacologia , Fator de Transcrição AP-1/antagonistas & inibidores , Citotoxinas/química , Glaucarubina/análogos & derivados , Humanos , Estrutura Molecular , Inibidores da Síntese de Proteínas/química , Quassinas/químicaRESUMO
An extract from Phyllanthus engleri was identified in a bioinformatic analysis of NCI 60-cell natural product extract screening data that selectively inhibited the growth of renal cancer cell lines. Bioassay-guided fractionation yielded two new guaiane sesquiterpenes, englerins A (1) and B (2). Englerin A showed 1000-fold selectivity against six of eight renal cancer cell lines with GI(50) values ranging from 1-87 nM. The structures of 1 and 2 and their relative stereochemistry were established by spectroscopic methods.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Neoplasias Renais/patologia , Phyllanthus/química , Extratos Vegetais/farmacologia , Sesquiterpenos de Guaiano/farmacologia , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Bioensaio , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética/normas , Conformação Molecular , Casca de Planta/química , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Caules de Planta/química , Padrões de Referência , Sesquiterpenos de Guaiano/química , Sesquiterpenos de Guaiano/isolamento & purificação , EstereoisomerismoRESUMO
Natural products have provided chemical leads for the development of many drugs for diverse indications. While most U.S. pharmaceutical firms have reduced or eliminated their in-house natural product groups, there is a renewed interest in this source of new chemical entities. Many of the reasons for the past decline in popularity of natural products are being addressed by the development of new techniques for screening and production. The aim of this unit is to review current strategies and techniques that increase the value of natural products as a source for novel drug candidates.
Assuntos
Produtos Biológicos/farmacologia , Descoberta de Drogas/métodos , Biodiversidade , Produtos Biológicos/química , Produtos Biológicos/provisão & distribuição , Descoberta de Drogas/economia , Indústria Farmacêutica/economia , Interações Medicamentosas , Etnofarmacologia/métodos , Ensaios de Triagem em Larga Escala , Humanos , Publicações Periódicas como Assunto , Apoio à Pesquisa como AssuntoRESUMO
Three new galloyl arbutins, hyemalosides A-C (1-3), along with nine known compounds were isolated from the evergreen tree Eugenia hyemalis. The structures of compounds 1-3 were determined by analysis of NMR and MS data. Compounds 1-3 inhibited HIV-1 RNase H in vitro with IC50 values of 1.46, >18, and 1.19 microM, respectively. However, in a XTT-based cell viability assay using the human T-cell line CEM-SS infected with HIV-1 RT, none of the compounds inhibited the cytopathic effect of HIV-1 infection at the highest dose tested (20 microg/mL).
Assuntos
Fármacos Anti-HIV/isolamento & purificação , Fármacos Anti-HIV/farmacologia , Arbutina/análogos & derivados , Arbutina/isolamento & purificação , Arbutina/farmacologia , Ácido Gálico/análogos & derivados , Ácido Gálico/isolamento & purificação , Ácido Gálico/farmacologia , HIV-1/efeitos dos fármacos , HIV-1/enzimologia , Plantas Medicinais/química , Ribonuclease H do Vírus da Imunodeficiência Humana/antagonistas & inibidores , Syzygium/química , Fármacos Anti-HIV/química , Arbutina/química , Ácido Gálico/química , HIV-1/genética , Humanos , Estrutura Molecular , ParaguaiRESUMO
High-throughput screening technologies have revolutionized the manner in which potential therapeutics are identified. Although they are the source of lead compounds for ~65% of anticancer and antimicrobial drugs approved by the Food and Drug Administration between 1981 and 2002, natural products have largely been excluded from modern screening programs. This is due, at least in part, to the inherent difficulties in testing complex extract mixtures, which often contain nuisance compounds, in modern bioassay systems. In this article, the authors present a novel electrochemiluminescent assay system for inhibition of MDM2 activity that is suitable for testing natural product extracts in high-throughput screening systems. The assay was used to screen more than 144,000 natural product extracts. The authors identified 1 natural product, sempervirine, that inhibited MDM2 auto-ubiquitination, MDM2-mediated p53 degradation, and led to accumulation of p53 in cells. Sempervirine preferentially induced apoptosis in transformed cells expressing wild-type p53, suggesting that it could be a potential lead for anticancer therapeutics.
Assuntos
Produtos Biológicos/farmacologia , Misturas Complexas/farmacologia , Avaliação Pré-Clínica de Medicamentos/métodos , Medições Luminescentes/métodos , Proteínas Proto-Oncogênicas c-mdm2/antagonistas & inibidores , Animais , Bioensaio , Caspase 3/metabolismo , Morte Celular , Linhagem Celular Transformada , Camundongos , Poli(ADP-Ribose) Polimerases/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Alcaloides de Triptamina e Secologanina/química , Proteína Supressora de Tumor p53/metabolismo , Ubiquitinação/efeitos dos fármacosRESUMO
A new compound, 1,3,4,5-tetragalloylapiitol ( 1), was isolated from the aqueous extract of the plant Hylodendron gabunensis and was found to be a potent inhibitor of RNase H enzymatic activity. The structure of 1 was elucidated by NMR analyses to be an apiitol ( 2) sugar moiety substituted with four gallic acid residues. Optical rotation measurements of the free sugar following basic hydrolysis indicated that the 3 S absolute configuration was the same as that of d-apiitol. Compound 1 inhibited HIV-1, HIV-2, and human RNase H with IC 50 values of 0.24, 0.13, and 1.5 microM, respectively, but it did not show inhibition of E. coli RNase H at 10 microM.