1,721,029 research outputs found
New Diterpenes with Potential Antitumoral Activity Isolated from Plants in the Years 2017–2022
Full text linkDiterpenes represent a wider class of isoprenoids, with more than 18,000 isolated compounds, and are present in plants, fungi, bacteria, and animals in both terrestrial and marine environments. Here, we report on the fully characterised structures of 251 new diterpenes, isolated from higher plants and published from 2017, which are shown to have antitumoral activity. An overview on the most active compounds, showing IC50 < 20 μM, is provided for diterpenes of different classes. The most active compounds were extracted from 29 different plant families; particularly, Euphorbiaceae (69 compounds) and Lamiaceae (54 compounds) were the richest sources of active compounds. A better activity than the positive control was obtained with 33 compounds against the A549 cell line, 28 compounds against the MCF-7 cell line, 9 compounds against the HepG2 cell line, 8 compounds against the Hep3B cell line, 19 compounds against the SMMC-7721 cell line, 9 compounds against the HL-60 cell line, 24 compounds against the SW480 cell line, and 19 compounds against HeLa
Bicyclic g-butyrolactones. Relation between conformation of the lactone ring and chiroptical properties
No full textThe CD curves of a set of condensed gamma-butyrolactones have been investigated. A simple correlation between the sign of the Cotton effect (CE) and the configuration of C-alpha can be deduced from the resulting data
Isolation and characterization of major diterpenes from C. canephora roasted coffee oil
Full text linkA simple laboratory procedure for the isolation of pure cafestol and 16-O-methylcafestol together with beta-sitosterol from coffee is disclosed. Cafestol and 16-O-methylcafestol have been exhaustively characterized through 1D and 2D H-1, C-13 NMR, CD and X-ray diffraction. For the first time, the molecular structure of cafestol is reported and the assignment of the absolute configuration is unequivocally given by exploiting anomalous scattering of a brominated derivative
Chemoenzymatic synthesis of optically active 4-methyl-tetrahydro-5-oxo-Furancarboxylic acids and esters
No full textEnantiomerically pure 4-methyl-tetrahydro-5-oxo-2-furancarboxylic acids and esters are prepared by enzymatic resolution of the chiral racemic esters. Their stereochemistry as well as their absolute configurations have been established by chemical correlation. The influence of the alkoxycarbonyl group at C-2 and that of the methyl group at C-4 on the sign of the Cotton effect in their CD spectra have been investigated. Formation of enantiomerically pure hydroxydiesters, precursors of the above-mentioned gamma-lactones, by baker's yeast reduction of the corresponding ketodiesters was unsatisfactory
Interaction of chlorogenic acids and quinides from coffee with human serum albumin
No full textChlorogenic acids and their derivatives are abundant in coffee and their composition changes between
coffee species. Human serum albumin (HSA) interacts with this family of compounds with high
affinity. We have studied by fluorescence spectroscopy the specific binding of HSA with eight compounds
that belong to the coffee polyphenols family, four acids (caffeic acid, ferulic acid, 5-O-caffeoyl quinic
acid, and 3,4-dimethoxycinnamic acid) and four lactones (3,4-O-dicaffeoyl-1,5-c-quinide, 3-O-[3,4-
(dimethoxy)cinnamoyl]-1,5-c-quinide, 3,4-O-bis[3,4-(dimethoxy)cinnamoyl]-1,5-c-quinide, and 1,3,
4-O-tris[3,4-(dimethoxy)cinnamoyl]-1,5-c-quinide), finding dissociation constants of the albumin–chlorogenic
acids and albumin–quinides complexes in the micromolar range, between 2 and 30 lM. Such values
are comparable with those of the most powerful binders of albumin, and more favourable than the
values obtained for the majority of drugs. Interestingly in the case of 3,4-O-dicaffeoyl-1,5-c-quinide,
we have observed the entrance of two ligand molecules in the same binding site, leading up to a first dissociation
constant even in the hundred nanomolar range, which is to our knowledge the highest affinity
ever observed for HSA and its ligands. The displacement of warfarin, a reference drug binding to HSA, by
the quinide has also been demonstrated
BAKER'S YEAST REDUCTION OF CYCLIC DELTA-KETOESTERS.SYNTHESIS AND CHIROPTICAL PROPERTIES OF CONDENSED DELTA-LACTONES
No full textEnantiomerically pure condensed delta-lactones have been prepared from the corresponding delta-ketoesters by the use of Saccharomyces cerevisiae. The reactions were not only highly enantioselective but also highly diastereoselective, provided the baker's yeast was preincubated at 50 degrees C for 30 min. Interestingly, and contrary to what is usually found, the use of nutrients inhibited the bioreductions. The relative configurational assignments have been made by means of NMR, while the absolute configurations and conformations of the lactone rings were attributed by means of CD studies
Chemoenzymatic synthesis of enantioenriched 5-oxo-tetrahydro-3-furancarboxylic acid derivatives
No full text(R)-(+)-Paraconic acid 4, (S)-(-)-terebic acid 6 and their corresponding methyl and ethyl esters having ee's ranging from 60% to 92% were obtained by enzymatic resolution of their racemates. The enzymatic resolution of racemic ethyl gamma-methylparaconates 14a and 14b allowed the isolation of the unreacted ester (2R,3R)-(+)-14a and that of the lactonic acid (2S,3R)-(-)-5b with 80% and 93% ee, respectively, the former by the use of Horse liver acetone powder (HLAP), the latter using a-chymotrypsin (a-CT). The enantiomeric ethyl (2S,3S)-(-)-14a and (2S,3R)-(-)-14b, both with >99% ee, were obtained by baker's yeast reduction of diethyl acetylsuccinate
Synthesis and CD study of optically active bicyclic gamma-lactones belonging to the m-menthane series
No full textA series of γ-lactones possessing the m-menthane skeleton has been prepared from optically active cyclohexanols obtained by reduction with baker's yeast of γ-keto esters, the latter compounds deriving from 4-methylcyclohexanone via enamine formation and Stork alkylation. CD spectra are also reported
Baker's Yeast reduction of 4-hetero-2-(2-nitroethyl)cyclohexanones
No full textBaker's yeast reduction of 3-(2-nitroethyl)-tetrahydro-4H-pyran-4-one 10 and 3-(2-nitroethyl)-tetrahydro-4H-thiopyran-4-one 11 gave the corresponding optically active cis alcohols with good diastereo- and enantioselectivity. The unreacted optically active ketones were also isolated
Recent Aspects of the Synthesis of Enantiopure 5-oxo-tetrahydro-3-furan carboxylic acids
No full textRecent advances in enantioselective synthesis of 5-oxo-tetrahydro-3-furancarboxylic acids are surveye
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