Remarkable frequency of a history of liver disease in dogs fed homemade diets with buckwheat.

OBJECTIVE: In our nutrition consultation service we observed liver disease in 2 dogs of one owner who was feeding buckwheat. This led to the hypothesis that buckwheat may cause problems. The present retrospective study in a German and a Russian nutrition consultation service was carried out to see whether there is an increased incidence of liver disease in dogs fed buckwheat. MATERIALS AND METHODS: A retrospective study was carried out on the nutrition consultation cases of the Chair of Animal Nutrition and Dietetics, LMU Munich and a Russian nutrition consultant. All cases of dogs with buckwheat in their nutritional history were evaluated and compared with randomly selected dogs that had not been fed buckwheat from the same case set. Two German and 1 Russian buckwheat samples were compared (appearance, nutrient content, starch gelatinization, flavonoids, fagopyrin) as well as cooking methods. RESULTS: In the years 2007-2017, 34 cases of dogs fed buckwheat were identified in Germany and 57 in Russia. Eighty-five control cases in Germany and 48 in Russia were evaluated. In Germany, the incidence of liver disease in dogs fed buckwheat was 32 %, while that of the control group was 3.5 %. However, in Russia there was no significant difference between dogs fed buckwheat and control dogs. The appearance of the German and Russian buckwheat differed, with smaller seeds and more greenish colour in the German specimens while the Russian buckwheat presented larger and more brownish seeds. There was no difference in the analyses of the 3 buckwheat samples in crude nutrient and rutin content. Quercetin, quercitrin and fagopyrin were not detectable in all three samples. The degree of starch gelatinization in the Russian sample was higher than in the German. In Russia it is recommended to remove the reddish scum during boiling whereas this is rarely mentioned in Germany. CONCLUSION AND CLINICAL SIGNIFICANCE: German buckwheat may represent a risk in canine diets. With the difference remaining unclear, it is recommended to refrain from feeding buckwheat to dogs. In dogs fed homemade diets and suffering from liver disease, buckwheat should be considered in the nutrition history.

FT-IR-based method for rutin, quercetin and quercitrin quantification in different buckwheat (Fagopyrum) species.

The present study explores an alternative method for antioxidants determination in buckwheat (Fagopyrum) samples. Buckwheat contains different amounts of the antioxidants rutin, quercetin and quercitrin in different plant parts. Buckwheat seeds are most commonly used as food; however, preparations from the herb can also be used as a rich source of rutin. Infrared spectroscopy was used for individual and sum quantification of rutin, quercetin and quercitrin in whole and ground flowers and leaves of seven different buckwheat species. Correlation coefficients R of calibration and independent validation set for rutin, quercetin and quercitrin were 1.00 and 0.98, 0.94 and 0.99, 0.99 and 0.95, respectively. Some of the developed models had accuracy comparable to the reference HPLC method. Additionally many different parameters that give an important insight into the FTIR technique are discussed (different plant parts, whole and ground untreated samples, 3 different resolutions, 7 spectra pre-treatments, using individual or averaged spectra, reducing spectral data input, considering additional non-spectral data). The implemented technique used no sample preparation, is non-destructive and uses very little amounts of sample. Result show that infrared spectroscopy can be a fast and environmentally friendly alternative technique for routine analysis of main flavonoids in aerial parts of buckwheat.

Isolation, analysis and structures of phototoxic fagopyrins from buckwheat.

Buckwheat products are commonly used in health foods and food supplements. However, public awareness regarding the presence of photodynamic naphthodianthrones fagopyrins that can cause photosensitization is low. At least two additional compounds with structures similar to that of fagopyrin are known to exist; however, the structures of these compounds have never been determined. In this work, we improved the extraction procedure and the chromatographic analysis of fagopyrins by developing a simple, sensitive and high-resolution high performance liquid chromatography (HPLC) analytical method using fluorescence detection. We observed at least six fagopyrin derivatives, which were isolated and characterized via UV-Vis absorption, NMR spectroscopy and mass spectrometry. We determined the structures of two new derivatives (fagopyrin A and fagopyrin E) and proved the existence of protofagopyrins that can transform into fagopyrins upon light exposure. Our methods complement the existing knowledge regarding fagopyrins and will allow for their further analysis, isolation and investigation of their biological activity.