Cytotoxic Activity of Semi-Synthetic Derivatives of Elatol and Isoobtusol
作者:Karen L. Lang、Izabella T. Silva、Lara A. Zimmermann、Cíntia Lhullier、Maria V. Mañalich Arana、Jorge A. Palermo、Miriam Falkenberg、Cláudia M. O. Simões、Eloir P. Schenkel、Fernando J. Durán
DOI:10.3390/md10102254
日期:——
In the present study, the in vitro cytotoxic effects of six semi-synthetic derivatives of elatol (1) and isoobtusol (2) were investigated. Chemical modifications were performed on the hydroxyl groups aiming to get derivatives of different polarity, namely the hemisuccinate, carbamate and sulfamate. The structural elucidation of the new derivatives was based on detailed NMR and MS spectroscopic analyses. The in vitro cytotoxicity of compounds 1 to 8 was evaluated against A459 and RD tumor cell lines with CC50 values ranging from 4.93 to 41.53 µM. These results suggest that the structural modifications performed on both compounds could be considered a good strategy to obtain more active derivatives.
Conformational Studies of Marine Polyhalogenated ?-Chamigrenes Using Temperature-dependent NMR spectra inverted-chair and twist-boat cyclohexane moieties in the presence of an axial halogen atom at C(8)
α-Chamigren-3-one (+)-8 bearing an axial CI-atom at C(8) exists as a largely dominant conformer with Me—C(5) at the envelope-shaped enone ring pointing away from CIax−C(8) at the cyclohexane ring (= B) in the ‘normal’ chair conformation, as shown by 1H-NMR. In contrast, the α-chamigren-3-ols (+)-9 and (+)-10, obtained from hydride reduction of (+)-8, show a temperature-dependent equilibrium of conformers where
Enantioselective ring construction: synthesis of halogenated marine natural spiro[5.5]undecane sesquiterpenes
作者:Julio D. Martin、Cirilo. Perez、Jose L. Ravelo
DOI:10.1021/ja00284a052
日期:1986.11
(-)-33, and (8R,9R)-8-bromo-9-hydroxy-(E)-y-bisabolene, (+)-33, as the basic building blocks. This asymmetric methodology represents a general strategy for the enantioselectiveconstruction of spiro[5S]undecane systems containing a chiral quaternarycenter. This approach should be generally useful for the preparation of a wide variety of six-membered spirocycle-containing natural compounds. The compounds
agreement, with (+)-9 and (+)-10, which have a trigonal C(2), two conformers can be directly observed by NMR. The kinetic barriers, which are seen to arise mainly from steric repulsions between Hax–C(14) and the axial H or halogenatoms at C(8) and C(10), are calculated and discussed with respect to well documented exocycliemethylidene-substituted cyclohexane(ene) systems. This helps to rationalize why in rogiolol