Quantitative differentiation of phenolic compounds in different varieties of buckwheat cultivars from China, Japan and Korea

Jeong Min Seo,Mariadhas Valan Arasu,Da Bin Lee,Tatsuro Suzuki,Sang-Won Lee,Sun-Ju Kim,Qi Wu,Young-Ho Yoon,Sang Un Park

doi:10.4236/jacen.2013.24016

Abstract

The aim of this study was to determine the variation of phenolic compounds in common and tartary buckwheats collected from China, Japan and Korea. Two buckwheat varieties of each country were cultivated using nutrient solution and vermiculite in the greenhouse from February to May, 2012 and harvested at two-week intervals. Phenolics such as chlorogenic acid, C-glycosylflavones (orientin, isoorientin, vitexin, and isovitexin), rutin, and quercetin were quantified using high performance liquid chroma-tography (HPLC). At 17, 29, 44, 58, and 72 days after sowing (DAS), before harvesting each organs, rutin content of cultivars from China and Korea at 17 DAS was the highest (mean 43.63 and 39.95 mg?g–1 DW, respectively) than that of 29 and 44 DAS. However, two varieties from Japan at 44 DAS were documented maximum; whereas, the amount of rutin in “Hokkai T10” harvested at 44 DAS (58.36 mg?g–1 DW) was the highest of all cultivars. Rutin level in the leaves and stems at 72 DAS were comparatively higher than at 58 DAS. The highest of rutin content was found at 72 DAS (73.33 mg?g–1 DW) in “Hokkai T10” leaves followed by “Daegwan No.3-3” (61.13 mg?g–1 DW), “rice tartary” (53.89 mg?g–1 DW). Rutin content of flowers was presented as the highest amount in “Hokkai T10” at 72 DAS (88.3 mg?g–1 DW) was approximately 14-fold higher than that of 58 DAS (6.44 mg?g–1 DW). However, rutin content of flower in “Xiqiao No.2” was 3-fold higher at 72 DAS than at 58 DAS. Rutin and total phenolic compounds content in flowers, leaves, and stems were higher in the order. The content of four C-glycosylflavones in common buckwheat was higher than those in tartary buckwheat, but rutin content which accounted >90% of the total phenolic compounds was higher in tartary buckwheat. The highest amounts of chlorogenic acid and quercetin were measured in the flower of “Xiqiao No.2” (6.85 and 11.69 mg?g–1 DW, respectively). Based on these results, the presence of different phenolic compounds in all the varieties of buckwheat confirmed that it can be regarded as a potent source of functional foods.

Highlights

Buckwheat (Fagopyrum esculentum) belonging to the family Polygonaceae which is originated from China, Korea, and Japan, has been commonly used as a vegetable in arid and cold regions in the world
The protein present in the buckwheat improves human health in various ways, notably reducing serum cholesterol [2] and suppressing gallstones and tumors [3]. Buckwheat possesses both antioxidant and antidiabetic activities which is attributed to its phenolic contents like rutin and quercetin [4]. This plant is considered as a functional food because of its high contents of phenolic compounds including rutin, quercetin, orientin, vitexin, isovitexein, and isoorientin [5]
The other flavonoids like vitexin, isovitexin, orientin, and isoorientin are considered as good anti-oxidant compounds present in buckwheat and have been reported to exhibit 4% - 40% of anti-oxidant activities [11,12]

Summary

Introduction

Buckwheat (Fagopyrum esculentum) belonging to the family Polygonaceae which is originated from China, Korea, and Japan, has been commonly used as a vegetable in arid and cold regions in the world. The protein present in the buckwheat improves human health in various ways, notably reducing serum cholesterol [2] and suppressing gallstones and tumors [3] Buckwheat possesses both antioxidant and antidiabetic activities which is attributed to its phenolic contents like rutin and quercetin [4]. This plant is considered as a functional food because of its high contents of phenolic compounds including rutin, quercetin, orientin, vitexin, isovitexein, and isoorientin [5] Among these compounds, rutin, a flavonol glycoside, has been considered as a major antioxidant component that accounts 85% - 90% of the total anti-oxidant activity [6]. Orientin has the ability to protect liver from carcinogens and radiations and isoorientin is known to scavenge free radicals and prevent human LDL (low density lipoprotein) against oxidation [14]

Objectives

Methods

Results