Identifying specific plant secondary metabolites that influence feeding behavior can be challenging, but a solid understanding of animal preferences can guide efforts. Common brushtail possums (Trichosurus vulpecula) predominantly eat Eucalyptus species belonging to the subgenus Symphyomyrtus, and avoid eating those belonging to the Monocalyptus subgenus (also called subgenus Eucalyptus). Using an unbiased (1)H NMR metabolomics approach, a previous study identified unsubstituted B ring flavanones in most species of monocalypts examined, whereas these compounds were absent from symphyomyrtles. We hypothesised that unsubstituted B ring flavanones act as feeding deterrents for common brushtail possums. In the current study, we tested this hypothesis by comparing how much possums ate of a basal diet, with diets containing one of four structurally related compounds; pinocembrin, flavanone (unsubstituted B ring flavanones), chrysin (the flavone analogue of pinocembrin), and naringenin (a flavanone with B ring substitution). We found that pinocembrin and flavanone deterred feeding relative to the basal diet, but that chrysin and naringenin did not at equivalent concentrations. Thus, unsubstituted B-ring flavanones may explain why brushtail possums avoid eating monocalypt species. Furthermore, small differences in the structure of secondary compounds can have a large impact on antifeedant properties. These results demonstrate that metabolomics can be a valuable tool for ecologists seeking to understand herbivore feeding preferences.
The
present study investigates the chemical composition governing
the physical properties of mono- and diglycerides (MDGs) at the microstructural
level, as a function of aging and lot-to-lot variability. The physical
structure of the MDG plays a vital role in ameliorating the emulsion
stability and is widely explored in diverse research horizons related
to the pharmaceutical, cosmetic, and food industries. In an effort
to understand the mechanism of emulsion stabilization, physical properties
were extensively evaluated in selective commercial lots to determine
if there is a correlation between the chemical composition of MDG
and physical properties. The solid state of the MDG samples with different
aging profiles was characterized using X-ray scattering, differential
scanning calorimetry, attenuated total reflection-Fourier transform
infrared spectroscopy, and NMR relaxometry. Moreover, the kinetic
aspect of solid-state transformation was also evaluated via treating
MDG samples with a heat–cool cycle. The chemical composition
of MDGs was quantified using a quantitative NMR (qNMR) method. Interestingly,
the X-ray scattering results demonstrated a change in the MDG polymorphic
form and an increase in the %β content as a function of aging.
The increase in the %β content led to the formation of rigid
crystal structures of MDG, as evident from the NMR relaxometry. Chemical
quantification of isomeric composition revealed chemical composition
change as a potentially critical factor responsible for the altered
physical structures of MDG with respect to aging and lot-to-lot variability.
The findings correlated the solid-state transformation with the change
in the chemical composition of the MDG as a combined effect of aging
and lot-to-lot variability. This work serves as a basis to better
understand the interdependency of the physicochemical properties of
MDG. Furthermore, the present work can also be used as guidance for
setting up the specifications of MDG, as per the required polymorphic
form for a multitude of applications.
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