Abstract
Buckwheat sprouts that are synthesized during the germination process are rich in flavonoids, including orientin, vitexin, rutin, and their isomers (isoorientin, isovitexin, and quercetin-3-O-robinobioside, respectively). The purpose of this study was to optimize and validate an analytical method for separating flavonoid isomers in common buckwheat sprout extract (CSE). Factors, such as range, linearity, precision, accuracy, limit of detection, and limit of quantification, were evaluated for each standard using high-performance liquid chromatography (HPLC). On the basis of resolution and symmetry, a column temperature of 40 °C with 0.1% (v/v) acidic water and acetonitrile as mobile phases, at a flow rate of 1 mL min−1 were determined to be the optimal analytical conditions. Calibration curves for orientin, isoorientin, vitexin, isovitexin, and rutin exhibited good linearity with correlation coefficients of 0.9999 over the 6.25–100.00 μg mL−1 range. Recovery values of 96.67–103.60% confirmed that the method was accurate for all flavonoids. The relative standard deviations of intra-day repeatability and inter-day reproducibility confirmed method preciseness, with values of less than 5.21% and 5.40%, respectively. The developed method was used to analyze flavonoids in CSE, with isomers satisfactorily separated and simultaneously quantified. We demonstrated that the developed HPLC method can be used to monitor flavonoids in buckwheat sprouts.
Highlights
Buckwheat is a pseudocereal belonging to the Polygonaceae family that grows rapidly and is tolerant to cold [1]
The sprout-germination process induces the hydrolysis of triglycerides in the seeds and produces the energy required for various biochemical reactions through the tricarboxylic acid cycle [6], and the content of bioactive compounds in the seeds increases through chemical reactions, for example, the flavone glycoside content is known to increase during the germination of common buckwheat [7,8]
We introduce an high-performance liquid chromatography (HPLC) analysis method that simultaneously quantifies two types of flavone-C-glycoside isomer and flavonol-O-glycoside isomer found in common buckwheat sprout extract (CSE)
Summary
Buckwheat is a pseudocereal belonging to the Polygonaceae family that grows rapidly and is tolerant to cold [1]. Buckwheat is found almost everywhere but is mainly grown in the northern hemisphere [2]. Among the edible parts of common buckwheat, the sprouts have attracted considerable attention in recent years [3] as they are considered to be a popular health food and are widely consumed because of their bioactive compounds [4,5]. The sprout-germination process induces the hydrolysis of triglycerides in the seeds and produces the energy required for various biochemical reactions through the tricarboxylic acid cycle [6], and the content of bioactive compounds in the seeds increases through chemical reactions, for example, the flavone glycoside content is known to increase during the germination of common buckwheat [7,8].
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