6 research outputs found
Slight changes in the chemical structure of haemanthamine greatly influence the effect of the derivatives on rumen fermentation in vitro
Abstract Although the potential of plants extracts to improve feed efficiency and animal productivity and decrease methane emissions by enteric fermentation has been shown, the information available is often contradictory which has been attributed to differences in the complex mixture of bioactive compounds and their interactions. Understanding the degree to which structural features in a compound may affect the biological activity of an extract is essential. We hypothesised that relative small variations in the structure of a compound can have a significant influence on the ability of the derivatives to alter fermentation in the rumen. Nine compounds were synthetized from the natural alkaloid haemanthamine and tested in vitro for their effects on rumen protozoa and fermentation parameters. Our results showed that simple esterifications of haemanthamine or its derivative dihydrohaemanthamine with acetate, butyrate, pivalate or hexanoate led to compounds that differed in their effects on rumen fermentation
Sensing magnetic field and intermolecular interactions in diamagnetic solution using residual dipolar couplings of zephycandidine
Abstract: An unusual residual dipolar coupling of methylene protons was recorded in NMR spectra
because aromatic zephycandidine has preferential orientation at the external magnetic field. The
observed splitting contains contribution from the dipole–dipole D-coupling and the anisotropic
component of J-coupling. Absolute values of the anisotropy of magnetic susceptibility |∆χax| are
larger for protic solvents because of the hydrogen-bonding compared to aprotic solvents for which
polar and dispersion forces are more important. The energy barrier for the reorientation due to
hydrogen-bonding is 1.22 kJ/mol in methanol-d4, 0.85 kJ/mol in ethanol-d6 and 0.87 kJ/mol in acetic
acid-d6
. In dimethyl sulfoxide-d6
, 1.08 kJ/mol corresponds to the interaction of solvent lone pair
electrons with π-electrons of zephycandidine. This energy barrier decreases for acetone-d6 which has
smaller electric dipole moment. In acetonitrile-d3
, there is no energy barrier which suggests solvent
ordering around the solute due to the solvent-solvent interactions. The largest absolute values of
the magnetic anisotropy are observed for aromatic benezene-d6 and tolune-d8 which have their own
preferential orientation and enhance the order in the solution. The magnetic anisotropy of “isolated”
zephycandidine, not hindered by intermolecular interaction could be estimated from the correlation
between ∆χax and cohesion energy density