Feeding experiments

The reciprocal lattices shown in figure B 1.21.3 and figure B 1.21.4 correspond directly to the diffraction patterns observed in FEED experiments each reciprocal-lattice vector produces one and only one diffraction spot on the FEED display. It is very convenient that the hemispherical geometry of the typical FEED screen images the reciprocal lattice without distortion for instance, for the square lattice one observes a simple square array of spots on the FEED display. 

Feeding experiments utilizing C-, N-, and H-labeled cadaverine (44) and lysine (24) in l upinus augustifolius a source of the lupine alkaloids (—)-sparteine (50, R = H,H) and (+)-lupanine (50, R = O), have been reported which lend dramatic credence to the entire biosynthetic sequence for these and the related compounds discussed above (41). That is, the derivation of these bases is in concert with the expected cyclization from the favored aH-trans stereoisomer of the trimer expected on self-condensation of the 1-dehydropiperidine (45). 

The overall biosynthetic pathway to the tetracychnes has been reviewed (74). Studies (75—78) utilising labeled acetate and malonate and nmr analysis of the isolated oxytetracycline (2), have demonstrated the exclusive malonate origin of the tetracycline carbon skeleton, the carboxamide substituent, and the folding mode of the polyketide chain. Feeding experiments using [1- 02] acetate and analysis of the nmr isotope shift effects, led to the location of... 

Bickel and Wibaut found in feeding experiments with rats and mice that leucenol is probably the toxic constituent of Leuccena glauca seeds, but they did not observe with these animals the loss of hair which seems to occur when these seeds are fed to cattle. ... 

Feeding experiments with horses seemed to indicate that the alkaloid caused toxic symptoms and loss of hair when large doses were administered. 

In Dioscorea hispida, Trigollenine is incorporated into the isoquinuclidine moiety of the alkaloid Dioscorine (208), as proved by a feeding experiment with [TOer/ y/- " C,2- H, H]trigollenine (88P3793). These results are consistent with the hypothesis for the biosynthesis of Dioscorine (208), Dumetorine and Dihydrodioscorine, which is presented in Scheme 68. 

Futterungs-stoff, m. lining material, -versuch, m. feeding experiment. 

Lambert, J.B. and Weydert, J.M. 1993 The fundamental relationship between ancient diet and the inorganic constituents of bone as derived from feeding experiments. Archaeometry 35 279-294. 

The C-NMR spectrum of neosaxitoxin obtained from the feeding experiment showed an enhanced signal for C-4, which was split into a doublet by the spin-spin coupling with the neighboring (J=9.3 Hz) (Scheme 4). The result clearly indicate that the connectivity C-2 - N-2 of arginine was incorporated intact into the toxin molecule, supporting the pathway in Scheme 3. 

Despite our earlier failure in formate feeding experiments, [3- C]serine, [1,2- CJglycine, and [Me- C]methionine were found to enrich C-13 in neosaxitoxin effectively (7). The best incorporation was observed with methionine, indicating it is the direct precursor via S-adenosylmethionine. Glycine C-2 and serine C-3 must have been incorporated through tetrahydrofolate system as methyl donors in methionine biosynthesis. 

We started feeding experiments using C-labeled acetate long before the establishment of the toxin structures with a hope that the analysis of the C-NMR... 

Three other portions of the molecule which do not fit the polyketide combination pattern (Scheme 7B a,f,n) can be also explained by assuming they are derived from a dicarboxylic acid such as 3-hydroxy-3-methylglutaric acid (Scheme 8b). If that is the case, brevetoxins are a new type of mbced polyketides which are formed by condensation on both ends of dicarboxylic acids (Scheme 8c). In order to prove further the hypothesis, feeding experiments with such putative precursors as succinate, acetoacetate, and propionate are in progress. 

Figure 4. Conversion of decane as a function of the reaction temperature on Cu(l)/TiC>2 in absence of 80 2 either in the feed or the solid (Experiment 1), on the same solid but in presence of SO2 in the feed (Experiment 2), and with the same Cu(l)/Ti02 catalyst, presaturated by SC (SO2/CU 3, Experiment...

Figure 7 Proposed biological Favorskii-like reaction involved in DTX-4 biosynthesis. — denotes incorporation of intact units of 13CH3 13C02H in a biosynthetic feeding experiment...

Caffeine contained in tea beverage is absorbed at about the same rate as caffeine in coffee, cola drinks, or in pure water. Data to support this conclusion was obtained in a human feeding experiment.109 The theory that complexation of caffeine with the polyphenolic material in tea retards absorption110-111 is not borne out. 

The 13C spectrum of normal sterigmatocystin can thus be compared with the spectra of the molecules resulting from separate feeding experiments with 13C enriched (o) 13CH3C02H and (b) CH313C02H, respectively. Those carbon atoms, in each case, which now show enhanced 13C signals can thereby be identified ... 

Macrolide aggregation pheromones produced by male cucujid beetles are derived from fatty acids. Feeding experiments with labeled oleic, linoleic, and palmitic acids indicate incorporation into the macrolide pheromone component [ 117 ]. The biosynthesis of another group of beetle pheromones, the lactones, involves fatty acid biosynthetic pathways. Japonilure and buibuilactone biosynthesized by the female scarab, Anomalajaponica, involves A9 desaturation of 16 and 18 carbon fatty acids to produce Z9-16 CoA and Z9-18 CoA,hydroxylation at carbon 8 followed by two rounds of limited chain shortening and cyclization to the lactone [118]. The hydroxylation step appears to be stereospecific [118]. 

Plochberger K (1989) Feeding experiments - a criterion for quality estimation of biologically and conventionally produced foods . Agriculture Ecosystems and Environment, 27, 419 128. 

The relationship between the quality concept and human or animal health needs to be established from a holistic health perspective. The Louis Bolk Instituut has already started animal feeding experiments. Such research can only be done if foodstuffs are available which have been produced using well-balanced processes, in the sense described above, and which have thus achieved an optimum level of quality (defined hereunder). 

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