Determination And Profiling Of Flavonoids Of Inner Mongolian Buckwheat

Inner Mongolia is the main area of buckwheat production. Buckwheat resources are rich. Buckwheat and its products are exported overseas. However, researches of nutrients and bioactive substances in Inner Mongolian buckwheat are lack. To analyze profile and content of flavonoids in Inner Mongolian buckwheat, a total 80 common buckwheat and tartary buckwheat samples were collected from Inner Mongolia and other provinces. Flavonoids were extracted by 75% hot ethanol reflux extraction, total flavonoids were determined by spectrophotometry, flavonoids profile were analyzed by UPLC-Q-TOF-MS, content of rutin, quercetin and kaempferol-3-O-rutinoside were determined by HPLC method. Chromatographic and mass spectrometric flavonoids profile clustering were analyzed by principal component analysis (PCA).Total flavonoids, rutin and quercetin (X±SD, mg/100g) of common buckwheat were 36.29±17.26,13.66±8.93 and 3.35±0.71 respectively, and were 1418.30±244.23, 1291.36±278.34 and 34.43±13.53 in tartary buckwheat, and kaempferol-3-O-rutinoside in tartary buckwheat was 62.52±16.63. Total flavonoids and rutin in common buckwheats indicated significant differences between Inner Mongolia and Shaanxi provinces, Inner Mongolian samples were higher. Common buckwheat seed had significantly higher total flavonoids, rutin and quercetin than common buckwheat flour and common buckwheat groats; while, samples derived from research institutions were obviously higher in relevant data than sample from countryside farming fields.Rutin was the highest among 15 flavonoids that found in Inner Mongolian common buckwheat, the remaining were quercetin, kaempferol, kaempferol-3-O-rutinoside, catechine, epicatechine, vitexin, isovitexin, orientin, isoorientin, hyperin, luteolin, apigenin, galangin and pinocembrin.12 flavonoids were determined in tartary buckwheats, lacking orientin, isoorientin and luteolin that found in common buckwheat. According to mass spectrum analysis on whole molecule and molecular frangments, (epi)catechin-hexose, (epi)catechin-dimethyl gallate and procyanidin may exist in Inner Mongolian common buckwheats, quercetin-rhamnobiglucoside(galactoside) may exist in Inner Mongolian tartary buckwheats. Generally, similar flavonoid chemicals were found in common and tartary buckwheats from different provinces, however, the detection rates of vitexin, isovitexin, orientin and isoorientin in Inner Mongolian buckwheats were higher than samples of other provinces.PCA profiling on mass spectrum and HPLC profile of flavonoid extracts, both indicated that common buckwheat, tartary buckwheat and wheat samples clusters were obviously separated. PCA on HPLC profile of common buckwheat samples indicated clusters isolation tendency between Inner Mongolia and Shaanxi provinces, and between research institutions breed and countryside derived samples, as well among seed, flour and groats. Clusters separation tendency also observed between tartary buckwheats from research institution seeds and countryside groats. These discrimination tendencies were consistence with significant difference between or among buckwheat categories. The results imply PCA profiling on flavonoids extraction is a promising method that can be applied to identify buckwheat breed, geographical origin and other categorizing. Mass and chromatographic spectrum PCA profiling may get consistent result, or may not as sensitive as each other, thus the two methods are not replaceable sometimes.