RESUMO
INTRODUCTION: Traditional Chinese medicine (TCM) revolves around complex mixtures bound to specific roles within the formulation, among which saponin-containing plants with alleged properties of harmonising or detoxifying other compounds present in the preparations. OBJECTIVE: This article deals with the study of these interactions with, as a model, the interaction between saponins and selected active principles. METHODS: The measurement of the partition coefficient between water and octanol (logP) was used as an indicator and determined by nuclear magnetic resonance (NMR) for these active principles in the presence of saponins. For each compound, a graph was constructed showing the evolution of logP with increasing concentrations of saponins. RESULTS: Four distinct patterns of interactions were distinguished. Pattern A showed a constant decrease of logP, pattern B showed a decrease followed by a plateau, in pattern C the logP did not vary until the critical micellar concentration (CMC) and decreased afterwards, and pattern D exhibited an increase of logP. These properties were linked to the ability of saponins to form micelles in water once the CMC is reached. The interaction of aconitine and saponins followed pattern D, thus explaining the detoxification of herbal preparations using Aconitum with licorice. The licorice facilitated the extraction of the notoriously water-insoluble artemisinin from Artemisia annua. CONCLUSION: This investigation confirms that the physical properties of micelle forming saponins are intimately linked to a modification of behaviour of the other molecules in solution, as seen with the alteration of logP and the four types of interactions presented.
Assuntos
Medicamentos de Ervas Chinesas , Saponinas , Medicina Tradicional Chinesa , Micelas , Medicamentos de Ervas Chinesas/química , Água/químicaRESUMO
Nine non-phenolic compounds, including four furanylmethyl glycosides, angularides A-D, one ent-kaurane diterpene glycoside, angularin A, and four triterpenoid saponins, angulasaponins A-D, were isolated from seeds of Vigna angularis, together with eight known compounds. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic analysis as well as chemical methods. Angularin A, angulasaponins A-C, and azukisaponins III and VI showed inhibition of nitric oxide production in LPS-activated RAW264.7 macrophages, with IC50 values ranging from 13µM to 24µM.
Assuntos
Anti-Inflamatórios/isolamento & purificação , Anti-Inflamatórios/farmacologia , Diterpenos do Tipo Caurano/isolamento & purificação , Diterpenos do Tipo Caurano/farmacologia , Medicamentos de Ervas Chinesas/isolamento & purificação , Medicamentos de Ervas Chinesas/farmacologia , Fabaceae/química , Saponinas/isolamento & purificação , Saponinas/farmacologia , Animais , Anti-Inflamatórios/química , Diterpenos do Tipo Caurano/química , Medicamentos de Ervas Chinesas/química , Técnicas In Vitro , Concentração Inibidora 50 , Lipopolissacarídeos/farmacologia , Macrófagos/efeitos dos fármacos , Camundongos , Estrutura Molecular , Óxido Nítrico/biossíntese , Saponinas/química , Sementes/químicaRESUMO
Six dichapetalins named dichapetalins N-S were isolated from Dichapetalum mombuttense, Dichapetalum zenkeri and Dichapetalum leucosia. They were accompanied in the same plants by the known dichapetalins A, B, C, I, L and M. The structures of the compounds were elucidated by 1D and 2D NMR experiments and mass spectrometry. They all possessed the dammarane skeleton substituted at position C-3 by a C6-C2 unit forming a 2-phenylpyran moiety. All contained a lactone ring in the side chain except dichapetalins O, Q and R, in which this ring was replaced by a lactol. Dichapetalin Q and R were also the first dichapetalins bearing a tertiary methyl and a double bond instead of the cyclopropane of the dammaranes. All these compounds were assayed against cancer cell lines HCT116 and WM 266-4 and displayed cytotoxic and anti-proliferative activities in the 10(-6) to 10(-8)M range.
Assuntos
Antineoplásicos Fitogênicos/química , Magnoliopsida/química , Extratos Vegetais/química , Raízes de Plantas/química , Antineoplásicos Fitogênicos/isolamento & purificação , Antineoplásicos Fitogênicos/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Células HCT116 , Células HL-60 , Compostos Heterocíclicos de 4 ou mais Anéis/química , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Humanos , Espectroscopia de Ressonância Magnética/métodos , Magnoliopsida/classificação , Estrutura Molecular , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Especificidade da Espécie , Compostos de Espiro/química , Compostos de Espiro/farmacologia , Relação Estrutura-AtividadeRESUMO
Six carvotanacetone derivatives (1- 6), amongst which four new compounds (1- 4), were isolated from the aerial parts of Sphaeranthus ukambensis Vatke & O. Hoffm. The structures of the molecules were elucidated by complementary spectroscopic methods, and their biological properties were investigated using human DLD-1 colon cancer cells engineered to stably express a 4 ubiquitin-luciferase (4 Ub-Luc) reporter protein. Five of the isolated carvotanacetone derivatives (2- 6) were found to inhibit the proliferation of the colon cancer cells and interfere with the ubiquitin-proteasome pathway, with potencies in a micromolar range.
Assuntos
Asteraceae/química , Extratos Vegetais/química , Inibidores de Proteases/farmacologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Terpenos/farmacologia , Ubiquitina/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Quênia , Componentes Aéreos da Planta/química , Terpenos/química , Terpenos/isolamento & purificaçãoRESUMO
Six protoflavonoids, including two new compounds, were isolated during a large scale screening of fern extracts for original interaction with mitosis. The new compounds isolated from PHEGOPTERIS decursive-pinnata and EQUISETUM fluviatile were 2',3'-dihydroprotogenkwanone (1) and 2',3'-dihydro-2'-hydroxyprotoapigenone (2). Known compounds were: protoapigenone, protogenkwanone, protoapigenin, and 4'- O- ß-D-glucopyranosyl protoapigenin. They showed a cytotoxic activity against HeLa cells at a micromolar level. IC50 values were 2 µM for compound 1 > 10 µM for compound 2, and respectively 2.4, 0.6, > 10 µM for the known compounds. Their cytotoxic effects were associated with phenotypic changes never observed before and characterized by the loss of centrosomal γ-tubulin labelling in both mitotic and interphasic cells.
Assuntos
Antineoplásicos Fitogênicos/toxicidade , Centrossomo/efeitos dos fármacos , Gleiquênias/química , Flavonoides/toxicidade , Extratos Vegetais/toxicidade , Tubulina (Proteína)/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cicloexanonas/farmacologia , Flavonas/farmacologia , Células HeLa , Humanos , Concentração Inibidora 50 , Mitose/efeitos dos fármacos , FenótipoRESUMO
Eighteen new meroterpene derivatives, dichrostachines A-R (1-18), have been isolated from the root and stem barks of Dichrostachys cinerea, and their structures determined by spectroscopic means and molecular modeling. From a biosynthetic standpoint these compounds arise from a Diels-Alder reaction between a labdane diene of the raimonol type and a flavonoid B-ring-derived quinone. The hypothesis was tested by the partial synthesis of similar compounds by simply mixing methyl communate and a synthetic flavonoid quinone. The hemisynthetic compounds were shown by NMR to have configurations different from those of the natural products, thus allowing a refinement of the biosynthesis hypothesis. Most of the compounds were assayed for their ability to inhibit the enzyme protein farnesyl transferase. The most active compounds exhibited IC50 and cytotoxicity values in the 1 microM range.
Assuntos
Alquil e Aril Transferases/antagonistas & inibidores , Fabaceae/química , Plantas Medicinais/química , Terpenos/isolamento & purificação , Terpenos/farmacologia , República Democrática do Congo , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Casca de Planta/química , Terpenos/químicaRESUMO
Antitumor activities of substances from natural sources apart from vascular plants and micro-organisms have been poorly investigated. Here we report on a pharmacological screening of a bryophyte extract library using a phenotypic cell-based assay revealing microtubules, centrosomes and DNA. Among the 219 moss extracts tested, we identified 41 extracts acting on cell division with various combinations of significant effects on interphasic and mitotic cells. Seven extracts were further studied using a cell viability assay, cell cycle analysis and the phenotypic assay. Three distinct pharmacological patterns were identified including two unusual phenotypes.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Briófitas/química , Extratos Vegetais/farmacologia , Neoplasias do Colo do Útero/tratamento farmacológico , Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/patologia , Ciclo Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Centrossomo/efeitos dos fármacos , Centrossomo/metabolismo , DNA/efeitos dos fármacos , DNA/metabolismo , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Células HeLa , Humanos , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Fenótipo , Neoplasias do Colo do Útero/patologiaRESUMO
The ubiquitin-proteasome pathway plays a critical role in the degradation of proteins involved in tumor growth and has therefore become a target for cancer therapy. In order to discover novel inhibitors of this pathway, a cellular assay reporter of proteasome activity was established. Human DLD-1 colon cancer cells were engineered to express a 4 ubiquitin-luciferase (DLD-1 4Ub-Luc) reporter protein, rapidly degraded via the ubiquitin-proteasome pathway and designed DLD-1 4Ub-Luc cells. Following treatment with reference proteasome inhibitors, the 4Ub-Luc protein accumulated in DLD-1 4Ub-Luc cells and a 80-fold increase in luciferase-produced bioluminescence signal was measured, as compared to untreated cells. The screening of over 30,000 compounds using this DLD-1 4Ub-Luc assay led to the identification of physalin B as a novel inhibitor of the ubiquitin-proteasome pathway. Indeed, physalin B induced an increase in bioluminescence from DLD-1 4Ub-Luc cells, at concentrations also producing an accumulation of ubiquitinated proteins and inhibiting TNFalpha-induced NF-kappaB activation. Physalin B did not inhibit catalytic activities of purified proteasome and interfered with cellular proteasomal catalytic activities at 4- to 8-fold higher concentrations than that required to induce significant increase in bioluminescence and accumulation of ubiquitinated proteins in DLD-1 4Ub-Luc cells. Furthermore, physalin B proved to be cytotoxic, triggered apoptosis in DLD-1 4Ub-Luc cells and induced the proapoptotic protein NOXA, characteristic of the proteasome signaling pathway. Therefore, the use of the DLD-1 4Ub-Luc assay allowed the identification of a novel inhibitor of the ubiquitin-proteasome pathway that might interfere with proteasome functions in a different way from reference proteasome inhibitors.
Assuntos
Apoptose/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Secoesteroides/farmacologia , Ubiquitina/metabolismo , Proteínas Reguladoras de Apoptose/genética , Linhagem Celular Tumoral , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Extratos Vegetais/química , Inibidores de Proteases/farmacologia , Proteínas Proto-Oncogênicas c-bcl-2/fisiologia , Transdução de SinaisRESUMO
To discover original inhibitors of the ubiquitin-proteasome pathway, the authors have developed a cell-based bioluminescent assay and used it to screen collections of plant extracts and chemical compounds. They first established a DLD-1 human colon cancer cell line that stably expresses a 4Ubiquitin-Luciferase (4Ub-Luc) reporter protein, efficiently targeted to the ubiquitin-proteasome degradation pathway. The assay was then adapted to 96- and 384-well plate formats and calibrated with reference proteasome inhibitors. Assay robustness was carefully assessed, particularly cell toxicity, and the statistical Z factor value was calculated to 0.83, demonstrating a good performance level of the assay. A total of 18,239 molecules and 15,744 plant extracts and fractions thereof were screened for their capacity to increase the luciferase activity in DLD-1 4Ub-Luc cells, and 21 molecules and 66 extracts inhibiting the ubiquitin-proteasome pathway were identified. The fractionation of an active methanol extract of Physalis angulata L. aerial parts was performed to isolate 2 secosteroids known as physalin B and C. In a cell-based Western blot assay, the ubiquitinated protein accumulation was confirmed after a physalin treatment confirming the accuracy of the screening process. The method reported here thus provides a robust approach to identify novel ubiquitin-proteasome pathway inhibitors in large collections of chemical compounds and natural products.
Assuntos
Inibidores Enzimáticos/análise , Inibidores Enzimáticos/farmacologia , Luciferases/metabolismo , Extratos Vegetais/análise , Extratos Vegetais/farmacologia , Inibidores de Proteassoma , Ubiquitina/antagonistas & inibidores , Contagem de Células , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Fracionamento Químico , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Inibidores Enzimáticos/química , Humanos , Lactonas/química , Lactonas/farmacologia , Luciferases/antagonistas & inibidores , Proteínas de Neoplasias/metabolismo , Oligopeptídeos/farmacologia , Extratos Vegetais/química , Reprodutibilidade dos Testes , Secoesteroides , Esteroides/química , Esteroides/farmacologia , Especificidade por Substrato/efeitos dos fármacos , Fatores de Tempo , TransfecçãoRESUMO
Five new acylphloroglucinol derivatives, mahureones A-E (1, 3-6), have been isolated from the leaves of Mahurea palustris, and their structures determined by spectroscopic means. During the isolation process, several byproducts (7-9) were formed by reaction of one of the isoprenyl side chains with TFA, water, and acetonitrile. All the compounds were assayed for their ability to inhibit human DNA polymerase beta. The most active compounds, mahureones A (1) and D (5), exhibited IC50 values in the 10 microM range.
Assuntos
Clusiaceae/química , DNA Polimerase beta/antagonistas & inibidores , Inibidores Enzimáticos/isolamento & purificação , Floroglucinol , Plantas Medicinais/química , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Guiana Francesa , Humanos , Concentração Inibidora 50 , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Floroglucinol/análogos & derivados , Floroglucinol/química , Floroglucinol/isolamento & purificação , Floroglucinol/farmacologia , Folhas de Planta/químicaRESUMO
Two isocoumarins have been isolated from the ethyl acetate extract of the root of Pituranthos scoparius: 3-n-propyl-5-methoxy-6-hydroxy-isocoumarin and 3-n-propyl-5,7-dimethoxy-6-hydroxy-isocoumarin. Their structures were assigned by spectral analysis.
Assuntos
Apiaceae , Cumarínicos/química , Fitoterapia , Extratos Vegetais/química , Humanos , Raízes de PlantasRESUMO
Bio-guided fractionation of an extract from Tanacetum parthenium showing activity as mitotic blocker allowed the isolation and identification of santin 3, jaceidin 2 and centaureidin 1. The latter two closely related flavonols, which, to the best of our knowledge, are isolated here together for the first time, form a mixture difficult to resolve and which is probably the reason for the confusion in the literature regarding their occurrence. Centaureidin 1 had an IC50 of 1 microM while jaceidin 2 and santin 3 were 200 times less active.