RESUMO
We recently reported that propolis suppresses tumor-induced angiogenesis through tube formation inhibition and apoptosis induction in endothelial cells. However, molecular mechanisms underlying such angiogenesis suppression by propolis have not been fully elucidated. The aim of this study was to investigate the effects of ethanol extract of Brazilian propolis (EEBP) on two major survival signals, extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt, and to elucidate whether changes in these signals were actually involved in antiangiogenic effects of the propolis. Detection by western blotting revealed that EEBP suppressed phosphorylation of ERK1/2, but not that of Akt. Pharmacological inhibition by U0126 demonstrated that ERK1/2 inactivation alone was enough to inhibit tube formation and induce apoptosis. It was also shown that EEBP and U0126 similarly induced activation of caspase-3 and cleavage of poly ADP-ribose polymerase (PARP) and lamin A/C, all of which are molecular markers of apoptosis. These results indicate that inhibition of survival signal ERK1/2, and subsequent induction of apoptosis, is a critical mechanism of angiogenesis suppression by EEBP.
RESUMO
Propolis, a resinous substance collected by honeybees from various plant sources, possesses various physiological activities such as antitumor effects. We have previously shown that propolis of Brazilian origin was composed mainly of artepillin C and that its constituents were quite different from those of propolis of European origin. In this report, we examined an antiangiogenic effects of Brazilian propolis and investigated whether artepillin C was responsible for such effects. In an in vivo angiogenesis assay using ICR mice, we found that the ethanol extract of Brazilian propolis (EEBP) significantly reduced the number of newly formed vessels. EEBP also showed antiangiogenic effects in an in vitro tube formation assay. When compared with other constituents of EEBP, only artepillin C was found to significantly inhibit the tube formation of HUVECs in a concentration-dependent manner (3.13-50microg/ml). In addition, artepillin C significantly suppressed the proliferation of HUVECs in a concentration-dependent manner (3.13-50microg/ml). Furthermore, artepillin C significantly reduced the number of newly formed vessels in an in vivo angiogenesis assay. Judging from its antiangiogenic activity in vitro and in vivo, we concluded that artepillin C at least in part is responsible for the antiangiogenic activity of EEBP in vivo. Artepillin C may prove useful in the development of agents and foods with therapeutic or preventive activity against tumor angiogenesis.
Assuntos
Proliferação de Células/efeitos dos fármacos , Endotélio Vascular/efeitos dos fármacos , Neoplasias/irrigação sanguínea , Neovascularização Patológica/prevenção & controle , Fenilpropionatos/farmacologia , Própole/química , Animais , Brasil , Células Cultivadas , Endotélio Vascular/citologia , Humanos , CamundongosRESUMO
Propolis is a resinous substance collected by honeybees from various plant sources. It is extensively used in food and beverages to improve health and prevent diseases such as heart disease, diabetes, and cancer. To investigate the absorption and metabolism of the components in propolis, in the present study, we administered ethanol extracts of Uruguayan propolis (poplar type propolis) orally to rats and analyzed their plasma and urine by high-performance liquid chromatography with photodiode array and mass spectrometric detection. After deconjugation of the components by beta-glucuronidase/sulfatase treatment of the specimen, pinobanksin 5-methyl ether, pinobanksin, kaempferol, chrysin, pinocembrin, and galangin were detected in plasma of rats orally administered propolis. These compounds were detected also in urine after beta-glucuronidase/sulfatase treatment. Furthermore, pinobanksin 5-methyl ether, pinobanksin, chrysin, pinocembrin, and galangin were present in the urine also in free form. These results suggest that flavonoids in propolis are metabolized and circulate in the body after oral administration of propolis.
Assuntos
Própole/farmacocinética , Animais , Cromatografia Líquida de Alta Pressão , Dieta , Masculino , Espectrometria de Massas , Própole/sangue , Própole/urina , Ratos , Ratos Sprague-DawleyRESUMO
To identify the plant origin of Brazilian propolis directly, we observed the behavior of honeybees in Minas Gerais State of Brazil. Honeybee workers bit and chewed leaves of the plant, Baccharis dracunculifolia, packed the material into their pollen basket, brought it back to their nest, and used it as propolis. We collected the leaves of B. dracunculifolia and propolis, and compared their constituents by liquid chromatography-mass spectrometry (LC/MS) analysis. There was no difference between the chemical constituents of the ethanol extracts of B. dracunculifolia and those of propolis. This indicates directly that the plant origin of Brazilian propolis is B. dracunculifolia.
Assuntos
Baccharis/química , Abelhas/fisiologia , Comportamento Animal/fisiologia , Própole/química , Animais , Brasil , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas , Extratos Vegetais/isolamento & purificação , Folhas de Planta/químicaRESUMO
Eighteen flavonoids including two new compounds, four aromatic carboxylic acids, and eleven phenolic acid esters including one new compound were isolated and identified from the ethyl acetate soluble fraction of the 70% ethanol extract of Uruguayan propolis. The new compounds were elucidated as pinobanksin 3-(2-methyl)butyrate (1; recently reported in Usia, T.; Banskota, A. H.; Tezuka, Y.; Midorikawa, K.; Matsushige, K.; Kadota, S. J. Nat. Prod. 2002, 65, 673-676) pinobanksin 3-isobutyrate (2), and 2-methyl-2-butenyl ferulate (24). The constituents isolated from Uruguayan propolis in this study were similar to those of propolis of European and Chinese origin. Thus, it is suggested that the Uruguayan propolis has a plant origin similar to those of propolis from Europe and China.