RESUMEN
Cell mortality is a key mechanism that shapes phytoplankton blooms and species dynamics in aquatic environments. Here we show that sterol sulfates (StS) are regulatory molecules of a cell death program in Skeletonema marinoi, a marine diatom-blooming species in temperate coastal waters. The molecules trigger an oxidative burst and production of nitric oxide in a dose-dependent manner. The intracellular level of StS increases with cell ageing and ultimately leads to a mechanism of apoptosis-like death. Disrupting StS biosynthesis by inhibition of the sulfonation step significantly delays the onset of this fatal process and maintains steady growth in algal cells for several days. The autoinhibitory activity of StS demonstrates the functional significance of small metabolites in diatoms. The StS pathway provides another view on cell regulation during bloom dynamics in marine habitats and opens new opportunities for the biochemical control of mass-cultivation of microalgae.
Asunto(s)
Diatomeas/metabolismo , Microalgas/metabolismo , Fitoplancton/metabolismo , Esteroles/metabolismo , Colestadienoles/metabolismo , Colestadienoles/toxicidad , Ésteres del Colesterol/metabolismo , Ésteres del Colesterol/toxicidad , Diatomeas/citología , Diatomeas/efectos de los fármacos , Ecosistema , Eutrofización/efectos de los fármacos , Eutrofización/fisiología , Microalgas/citología , Microalgas/efectos de los fármacos , Filogenia , Fitoplancton/citología , Fitoplancton/efectos de los fármacos , Fitosteroles/metabolismo , Fitosteroles/toxicidad , Transducción de Señal , Sitoesteroles/metabolismo , Sitoesteroles/toxicidad , Esteroles/toxicidad , Sulfatos/metabolismo , Sulfatos/toxicidad , Sulfotransferasas/genética , Sulfotransferasas/metabolismoRESUMEN
Two new compounds, 14-methyl stigmast-9(11)-en-3alpha-ol-3beta-D-glucopyranoside (1) and cholest-11-en-3beta, 6beta, 7alpha, 22beta-tetraol-24-one-3beta-palmitoleate (2), along with the known compound beta-sitosteryl-3beta-D-glucopyranosyl-6'-linoleiate (3), were isolated from the methanolic extract of rice (Oryza sativa) hulls. The structures of the two new compounds were elucidated using one- and two-dimensional NMR in combination with IR, EI/MS, FAB/MS, HR-EI/MS and HR-FAB/MS. In bioassays with blue-green algae, Microcystis aeruginosa UTEX 2388 and duckweed, Lemna paucicostata Hegelm 381, the efficacy of bioactivity of the two new compounds linearly increased as the concentration increased from 0.3 to 300 IgM. Compared with momilactone A, compounds 1 and 2 showed similar and higher inhibitory activities against the growth of M. aeruginosa at a concentration of 300 microM. However, compound 2 was similar to momilactone A in inhibiting L. paucicostata growth at a concentration of 300 microM. As a result, compound 2 appears to have a strong potential for the environmentally friendly control of weed and algae that are harmful to water-logged rice.
Asunto(s)
Colestadienoles/química , Colestadienoles/toxicidad , Cianobacterias/fisiología , Ácidos Grasos Monoinsaturados/química , Ácidos Grasos Monoinsaturados/toxicidad , Glucósidos/química , Glucósidos/toxicidad , Herbicidas , Ácidos Linoleicos/química , Ácidos Linoleicos/toxicidad , Oryza/química , Sitoesteroles/química , Sitoesteroles/toxicidad , Esteroides/química , Esteroides/toxicidad , Diterpenos/toxicidad , Hidrólisis , Lactonas/toxicidad , Espectroscopía de Resonancia Magnética , Microcystis/efectos de los fármacos , Extractos Vegetales/química , Extractos Vegetales/toxicidad , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masa Bombardeada por Átomos Veloces , Espectrofotometría InfrarrojaRESUMEN
BACKGROUND/AIMS: Biliary epithelial cells are exposed to highly concentrated oxysterols. Therefore, oxysterols may play a role in pathogenesis of biliary tract diseases. We investigated the cytotoxic effect and apoptosis inducing effect of oxysterol on gallbladder epithelial cells. METHODS: We studied the cytotoxic effect of 3,5- cholestadien-7-one, 5 beta-cholestan-3-one and 5,24-cholestadien-3 beta-OL which are identified in human bile and pigment gallstones on dog gallbladder epithelial cells (DGBE) and mouse gallbladder epithelial cells (MGBE). We used model bile to dissolve oxysterols as in vitro experiment and also used MTT, cell count, Diff-Quick stain, and flow cytometry to investigate cytotoxicity and apoptosis. RESULTS: Oxysterols dissolved in model bile have cytotoxic effects in a dose dependent fashion. In oxysterol containing model bile, viable cells are 51% in 500 microM 5 beta-cholestan-3-one (cholesterol:oxysterol 50:50) and 47% in 5 mM 3,5-cholestadien-7-one (90:10) on MGBE, and are 129% and 38% in 500 microM (50:50) 3,5-cholestadien-7-one and 5 beta-cholestan-3-one on DGBE, and are 74% and 71.5% in 5 mM (90:10) 3,5-cholestadien-7-one and 5 beta-cholestan-3-one on DGBE, respectively. 500 microM (50:50) 3,5- cholestadien-7-one, 5 beta-cholestan-3-one, and 5,24-cholestadien-3 beta-OL treated on DGBE increase the apoptotic cell number as 22.0+/-8.8, 30.2+/-12.6, and 45.5+/-13.2%, respectively, compared with control (14.6+/-10.0%). 500 microM (50:50) 3,5-cholestadien-7-one, 5 beta-cholestan-3-one, and 5,24-cholestadien-3 beta-OL also affect the changes in cell cycles compared with the control. CONCLUSIONS: We concluded that oxysterol containing model bile is useful as an in vitro experiment as model to analyze the effects of oxysterols on biliary epithelial cells and that adequate concentration of oxysterols can induce the cytotoxic effect and the apoptosis on gallbladder epithelial cells.
Asunto(s)
Apoptosis/efectos de los fármacos , Colestadienos/toxicidad , Colestadienoles/toxicidad , Colestanos/toxicidad , Células Epiteliales/efectos de los fármacos , Vesícula Biliar/citología , Animales , Bilis/química , Perros , Relación Dosis-Respuesta a Droga , Vesícula Biliar/efectos de los fármacos , Técnicas In Vitro , RatasRESUMEN
BACKGROUND/AIMS: Biliary epithelial cells are exposed to highly concentrated oxysterols. Therefore, oxysterols may play a role in pathogenesis of biliary tract diseases. We investigated the cytotoxic effect and apoptosis inducing effect of oxysterol on gallbladder epithelial cells. METHODS: We studied the cytotoxic effect of 3,5- cholestadien-7-one, 5beta-cholestan-3-one and 5,24-cholestadien-3beta-OL which are identified in human bile and pigment gallstones on dog gallbladder epithelial cells (DGBE) and mouse gallbladder epithelial cells (MGBE). We used model bile to dissolve oxysterols as in vitro experiment and also used MTT, cell count, Diff-Quick stain, and flow cytometry to investigate cytotoxicity and apoptosis. RESULTS: Oxysterols dissolved in model bile have cytotoxic effects in a dose dependent fashion. In oxysterol containing model bile, viable cells are 51% in 500 microM 5beta-cholestan-3-one (cholesterol : oxysterol 50:50) and 47% in 5 mM 3,5-cholestadien-7-one (90:10) on MGBE, and are 129% and 38% in 500 microM (50:50) 3,5-cholestadien-7-one and 5beta-cholestan-3-one on DGBE, and are 74% and 71.5% in 5 mM (90:10) 3,5-cholestadien-7-one and 5beta-cholestan-3-one on DGBE, respectively. 500 microM (50:50) 3,5- cholestadien-7-one, 5beta-cholestan-3-one, and 5,24-cholestadien-3beta-OL treated on DGBE increase the apoptotic cell number as 22.0+/-8.8, 30.2+/-12.6, and 45.5+/-13.2%, respectively, compared with control (14.6+/-10.0%). 500 microM (50:50) 3,5-cholestadien-7-one, 5beta-cholestan-3-one, and 5,24-cholestadien-3beta-OL also affect the changes in cell cycles compared with the control. CONCLUSIONS: We concluded that oxysterol containing model bile is useful as an in vitro experiment as model to analyze the effects of oxysterols on biliary epithelial cells and that adequate concentration of oxysterols can induce the cytotoxic effect and the apoptosis on gallbladder epithelial cells.
Asunto(s)
Animales , Perros , Ratas , Apoptosis/efectos de los fármacos , Bilis/química , Colestadienos/toxicidad , Colestadienoles/toxicidad , Colestanos/toxicidad , Relación Dosis-Respuesta a Droga , Resumen en Inglés , Células Epiteliales/efectos de los fármacos , Vesícula Biliar/citología , Técnicas In VitroRESUMEN
Four new polyoxygenated sterols 2-5 were isolated from the marine black coral Antipathes subpinnata. The structures of these compounds, including stereochemical details, were deduced by ms, 1H- and 13C-nmr, 1H-1H COSY, and nOe difference spectroscopy. Compounds 2-5 are lethal to brine shrimp (Artemia salina).