Transformation Of Phototoxicants In Buckwheat And Activity Study Of Fagopyrins

Fagopyrins is a naturally occurring substance in the buckwheat plant,which is a kind of phenylpropanone and has a structure similarity with hypericin.Fagopyrins are well documented to be present in common buckwheat,tartary buckwheat and cymosum buckwheat,possessing strong phototoxicity and tyrosine kinase inhibitory activities that can be utilized as photosensitizers in photodynamic therapy against various types of cancer.In the current study,the types of phototoxicants from buckwheat and transformation from protofagopyrin into fagopyrins were studied by darkness and exposure extraction of buckwheat leaves and extracts darkness and exposure placement using UV-visible spectrophotometry,fluorescence spectrometry and electrospray ionization mass spectrometry.We revealed that phototoxicants containing in the buckwheat were primarily present in protofagopyrin form with ionic intensity of about 400 times more when compared to fagopyrins.The protofagopyrin into fagopyrins transformation was observed during the extraction process in the presence of light,and the light placement process.In addition,we further evaluated the effects of fagopyrins and protofagopyrin on the growth and proliferation of human colon cancer cells(HCT-116)and human fetal colon epithelial cells(FHC)by using MTT assay.The results showed that in contrast to the normal FHC cells,200 ?g/m L fagopyrins and protofagopyrin extracts have notable inhibitory activity against HCT-116 cancer cells.The inhibition intensity of fagopyrins extract on HCT-116 cells was found increased in illumination time-dependent and total culture time-dependent manner,where the former showed a greater impact than the latter one.In comparison,hypericin has exerted strong inhibitory effects on FHC rather than on HCT-116 cells,while the fagopyrins extracts did the opposite.Taken together,these results suggested that the fagopyrins extracts are more specific than hypericin in inhibiting the proliferation of colon cancer cells.Next,we carried out a 22-day toxicity test by administering Kunming mice with fagopyrins and protofagopyrin extracts.The general performance of the experimental animals and the skin symptoms of the hair removal area were observed and recorded.Finally,mice were sacrificed and the back-skin tissues were isolated for pathological analysis.The liver,spleen,lungs,kidneys and ears were weighed.Organ coefficient and ear swelling rate were calculated,and blood was tested for blood routine and blood biochemical indicators.It is showed that the light conditions were necessary for the photosensitivity of fagopyrins and protofagopyrin extracts.Mice of 100 g of weight were continuously given 7.05 mg of fagopyrins extract for 15 days to induce photosensitivity in them.Moreover,mice of 100 g of weight were continuously given 27.9 mg of protofagopyrin extracts for 15 days to induce photodermatitis in them.Fagopyrins extracts may also cause inflammation,anemia,and decreased bone marrow hematopoietic function in mice.In summary,this study provides a reference for the potential development of a phototoxic therapeutic drugs from buckwheat as a whole or fagopyrins extracts with minimum toxicity and side effects.