Development and Validation of a Spectrophotometric Method for Quantification of Total Glucosinolates in Cruciferous Vegetables

• Published in: Journal of agricultural and food chemistry 2012-02, Vol.60 (6), p.1358-1362
• Main Authors: Gallaher, Cynthia M, Gallaher, Daniel D, Peterson, Sabrina
• Format: Article
• Language: English
• Subjects: absorbance; anion exchange; Biological and medical sciences; boiling; Brassicaceae - chemistry; chemoprevention; chromatography; Colorimetry; dose response; Ferricyanides; Food industries; freeze drying; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Glucose - analogs & derivatives; Glucose - chemistry; Glucosinolates - analysis; Glucosinolates - chemistry; hydrolysis; methanol; sinigrin; sodium hydroxide; spectrophotometers; Spectrophotometry - methods; vegetables; Vegetables - chemistry
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf2041142

Given their putative role in chemoprevention, validated methods are needed for quantification of total glucosinolates. Based on the colorimetric reaction of ferricyanide with 1-thioglucose, released by alkaline hydrolysis of glucosinolates, we developed a simple and sensitive method for spectrophotometric quantification of total glucosinolates in cruciferous vegetables. Lyophilized and ground vegetables are extracted with 80% boiling methanol. Extracted glucosinolates are isolated using a strong anion exchange column and then hydrolyzed with 2 N NaOH to release 1-thioglucose. Ferricyanide is added, and the decrease in absorbance is measured at 420 nm, with final values adjusted for background. Recovery of internal standard (sinigrin) was 107%. Intra- and interassay coefficients of variation were 5.4% and 15.8%, respectively. Dose response was linear with sinigrin and amount of plant material extracted (R 2 ≥ 0.99). Using sinigrin, the lower limit of quantification was 0.6 mg. This straightforward method may be an alternative to time-consuming and costly chromatographic methods.