http://hdl.handle.net/1834/2487 Sat, 25 May 2013 21:13:17 GMT 2013-05-25T21:13:17Z http://hdl.handle.net/1834/3866 Title: Acanthifoliosides, minor steroidal saponins from the Caribbean marine sponge Pandaros acanthifolium Authors: Regalado, E.L.; Jiménez-Romero, C.; Genta-Jouve, G.; Tasdemir, D.; Amade, P.; Nogueiras, C.; Thomas, O.P. Abstract: Seven novel steroid glycosides, acanthifoliosides A-F (1-6) and the methyl ester of 6 (7), were isolated from the marine sponge Pandaros acanthifolium as minor components. Acanthifoliosides are characterized by a rare C-15 and C-16 oxidized D ring which was previously found in saponins produced by starfishes. Very uncommon is the presence of additional sugar residues at C-15 or C-16. Their structures were determined on the basis of extensive spectroscopic analyses, including two-dimensional NMR and HRESIMS data. The absolute configurations of the aglycones were assigned by comparison between experimental and TDDFT calculated CD spectra of 1, whereas the absolute configurations of the monosaccharide units were determined by chiral GC analyses of the acid methanolysates. Some of the acanthifoliosides exhibit moderate antiprotozoal activity but to a lesser extent than the most potent pandarosides. Sat, 01 Jan 2011 00:00:00 GMT http://hdl.handle.net/1834/3866 2011-01-01T00:00:00Z http://hdl.handle.net/1834/3910 Title: Efecto antioxidante y contenido polifenólico de Syringodium filiforme (Cymodoceaceae) Authors: González García, K.L.; Valdés Iglesias, O.; Laguna, A.; Díaz Martínez, M.; González Lavaut, J.A. Abstract: The marine phanerogam Syringodium filiforme, known as “manatee grass”, is a common species that grows in coastal areas associated to Thalassia testudinum. With the aim to describe some of its possible chemical characteristics, this study was performed with a sample of 1.2kg, collected in March 2009, in Guanabo beach, Havana, Cuba. The sample was dried (less than 12% humidity) and a total extract prepared; other three extracts were prepared with the use of solvents of increasing polarity. The phytochemical screening and analytical determinations of each fraction were undertaken Total polyphenol content was determined using pyrogallol as reference´s standard; chlorophyll a and b and anthocyanin content were also quantified. Total extract and fractions antioxidant activity were evaluated by using the free radical scavenging activity assay with 1,1-Diphenyl-2-Picrylhydrazyl reactive (knowing as DPPH´s method). The phytochemical screening of the different extracts detected the presence of high concentrations of flavonoids, phenols, terpenes, antocyaninns, reducing sugars and alkaloids. The total extract and methanol fraction showed significant free radical scavenging properties, while the petroleum ether fraction showed moderate activity, and the chloroform fraction and the aqueous soluble precipitate (residual salt) obtained didn’t show antioxidant properties against free radicals. The results of this work confirmed the potentialities of this species for biological purposes Sat, 01 Jan 2011 00:00:00 GMT http://hdl.handle.net/1834/3910 2011-01-01T00:00:00Z http://hdl.handle.net/1834/3861 Title: Volatile constituents of Thalassia testudinum Banks ex König leaves Authors: Pino, J.A.; Regalado, E.L. Abstract: The volatile constituents from the sea grass Thalassia testudinum Banks ex König was analyzed by GC and GC/MS. One hundred and forty-three constituents were identified which constitute more than 95% of the composition. All of them reported for the first time in this species. The most prominent volatile compound was ethyl (Z)-1-propenyl disulfide (31% of the total composition). Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/1834/3861 2010-01-01T00:00:00Z http://hdl.handle.net/1834/3863 Title: Antiprotozoal steroidal saponins from the marine sponge Pandaros acanthifolium Authors: Regalado, E.L.; Tasdemir, D.; Kaiser, M.; Cachet, N.; Amade, P.; Thomas, O.P. Abstract: The chemical composition of the Caribbean sponge Pandaros acanthifolium was reinvestigated and led to the isolation of 12 new steroidal glycosides, namely, pandarosides E-J (1-6) and their methyl esters (7-12). Their structures were determined on the basis of extensive spectroscopic analyses, including two-dimensional NMR and HRESIMS data. Like the previously isolated pandarosides A-D (13-16), the new compounds 1-12 share an unusual oxidized D-ring and a cis C/D ring junction. The absolute configurations of the aglycones were assigned by interpretation of CD spectra, whereas the absolute configurations of the monosaccharide units were determined by chiral GC analyses of the acid methanolysates. The majority of the metabolites showed in Vitro activity against three or four parasitic protozoa. Particularly active were the compounds 3 (pandaroside G) and its methyl ester (9), which potently inhibited the growth of Trypanosoma brucei rhodesiense (IC50 values 0.78 and 0.038 μM, respectively) and Leishmania donoVani (IC50’s 1.3 and 0.051 μM, respectively). Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/1834/3863 2010-01-01T00:00:00Z