The inclusion complex of heptakis(2,6-di-O-methyl)-β-cyclodextrin (DIMEB) with euplotin C (EC), a cytotoxic metabolite isolated from the protistan strains composing the marine ciliate Euplotes crassus, has been investigated by 1H NMR techniques, electrospray ionization mass spectrometry (ESI/MS)and molecular mechanics (MM) calculations. The results suggest that DIMEB preferentially includes the side chain of this sesquiterpenoid with the terminal methyl groups exposed at the narrower rim of the cyclodextrin (CD). The dihydropyranic ring of EC is also well enclosed in the host cavity, whereas the acetyl group and the ring protons at C-4 and C-5 lie outside the larger rim. A kinetic degradation study of EC and its inclusion complex (EC-DIMEB) in aqueous solution has been performed by HPLC-UV-MS measurements obtaining structural data for the hydrolysis end-products. A significant increase in the chemical stability of complexed EC compared with free EC has also been determined.
Chemical and structural properties of the inclusion complex of euplotin C with heptakis (2,6 di-O-methyl)-beta-cyclodextrin through NMR, electrospray mass spectrometry and molecular mechanics investigations
UCCELLO BARRETTA, GLORIA;BALZANO, FEDERICA;DINI, FERNANDO
2004-01-01
Abstract
The inclusion complex of heptakis(2,6-di-O-methyl)-β-cyclodextrin (DIMEB) with euplotin C (EC), a cytotoxic metabolite isolated from the protistan strains composing the marine ciliate Euplotes crassus, has been investigated by 1H NMR techniques, electrospray ionization mass spectrometry (ESI/MS)and molecular mechanics (MM) calculations. The results suggest that DIMEB preferentially includes the side chain of this sesquiterpenoid with the terminal methyl groups exposed at the narrower rim of the cyclodextrin (CD). The dihydropyranic ring of EC is also well enclosed in the host cavity, whereas the acetyl group and the ring protons at C-4 and C-5 lie outside the larger rim. A kinetic degradation study of EC and its inclusion complex (EC-DIMEB) in aqueous solution has been performed by HPLC-UV-MS measurements obtaining structural data for the hydrolysis end-products. A significant increase in the chemical stability of complexed EC compared with free EC has also been determined.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
