Fraction Analysis of Flavonoids in Buckwheat (Fagopyrum Esculentum Moench) herb

Object of the research: Six different buckwheat (Fagopyrum esculentum Moench) herb varieties grown in the experimental test fields of Vokė Branch of the Lithuanian Research Centre for Agriculture and Forestry (LRCAF): „Smuglianka“, „Anika“, „Čanita“, „Žaleika“, „Mara“ and „Kvietka“. Tests have been conducted with the raw materials collected in 2014. Standard herb extracts have been made of them. Aim of the research: To evaluate quantitative and qualitative composition of flavonoids in the raw materials subject to research. To identify flavonoids present in (Fagopyrum esculentum Moench) herb. Tasks: 1. To optimize the conditions of ultrasonic extraction (different concentrations of ethanol, durations of ultrasonic extraction, and temperatures) by evaluating total flavonoid quantity in rutin equivalents (RE). 2. To evaluate total flavonoid quantity (RE) in all six samples of buckwheat varieties by using spectrophotometry. 3. To identify flavonoids by applying the selected ESC-MS methodology and to determine their quantities in buckwheat samples. 4. To apply the ESC-MS method for comparison of quantitative changes in flavonoids in the same samples after purification of the samples subject to research by using solid phase extraction. Methods: Evaluation of the extraction conditions and evaluation of the total flavonoid quantity was performed by using the spectrophotometric method by causing reaction with AlCl3. Solid phase extraction was applied for purification of the samples. Analysis of individual flavonoids was made by applying the ESC-MS method. Results: It was found that the most efficient option for production of extracts was using 80% ethanol, to apply ultrasonic extraction for 30 min. at a 60oC temperature. The total flavonoid quantity was evaluated by using spectrophotometry and it ranged from 45.17 ± 2.33 mg RE \g („Mara“) to 81.20 ± 1.27 mg RE/g („Čanita“). Upon conducting analysis by applying the ESC-MS method to samples of all six varieties of buckwheat the following 5 flavonoids were found and identified: rutin, quercitrin, quercetin, isoquercitrin, orientin. The biggest quantity found was rutin