Quinoa seeds leach phytoecdysteroids and other compounds with anti-diabetic properties

Abstract

Quinoa (Chenopodium quinoa Willd.) contains high levels of biologically active phytoecdysteroids, which have been implicated in plant defense from insects, and have shown a range of beneficial pharmacological effects in mammals. We demonstrated that the most prevalent phytoecdysteroid, 20-hydroxyecdysone (20HE), was secreted (leached) from intact quinoa seeds into water during the initial stages of seed germination. Leaching efficiency was optimized by ethanol concentration (70% ethanol), temperature (80°C), time (4h), and solvent ratio (5 ml/g seed). When compared to extraction of macerated seeds, the leaching procedure released essentially all the 20HE available in the seeds (491 μg/g seed). The optimized quinoa leachate (QL), containing 0.86% 20HE, 1.00% total phytoecdysteroids, 2.59% flavonoid glycosides, 11.9% oil, and 20.4% protein, significantly lowered fasting blood glucose in obese, hyperglycemic mice. Leaching effectively releases and concentrates bioactive phytochemicals from quinoa seeds, providing an efficient means to produce a food-grade mixture that may be useful for anti-diabetic applications.

Keywords: Ecdysterone; Flavonoids; Metabolic syndrome; Nutraceutical; Phytoecdysteroids.

Conflict of interest statement

Conflict of interest

IR and MAL have equity in Nutrasorb LLC, which is involved in quinoa R&D.

Copyright © 2014 Elsevier Ltd. All rights reserved.

Figures

Figure 1. 20-Hydroxyecdysone (20HE) leaches from quinoa seeds into water cumulatively over time

AlterEco Red quinoa seeds were surface sterilized and immersed into sterile water for 24–144 h under light or dark conditions at 25 or 37°C. 20HE content was determined in dried leachates by LC-UV-MS. Data are the mean ± SEM (n=3).

Figure 2. Leaching versus extraction of 20-hydroxyecdysone (20HE) from quinoa seeds into varying concentrations of ethanol

Intact quinoa seeds were incubated in ethanol (0–95%) at 25°C for 24 h to produce leachates, or macerated seed material was extracted in ethanol (0–95%) at 25°C for 4 h. The 20HE content was determined in dried leachates and extracts by LC-UV-MS. Three parameters were measured, shown from top to bottom: (A) amount 20HE released from seeds (μg 20HE/g seed), (B) 20HE concentration in the final dry leachate or extract (μg 20HE/mg), and (C) yield of dry leachate or extract (mg/g seed). Data are the mean ± SEM (n=3).

Figure 3. Molecular structures and LC-UV chromatogram at 247 nm of phytochemicals putatively identified in QL

QL was dissolved in 30% acetonitrile (20 mg/ml) and 3 μl was injected for chemical characterization alongside standards of 20HE, makisterone A and quercetin trisaccharide I via LC-UV using a C8 column with a gradient of 7 to 27% acetonitrile over 40 min. Compounds were putatively identified by UV retention time, MS m/z and fragmentation pattern, and based on quinoa compounds reported in the literature. Numbers indicate peaks corresponding with the compounds listed in Table 2.

Figure 4. Quinoa leachate (QL) lowers fasting blood glucose (FBG) in obese, hyperglycemic C57BL/6J mice

QL was dissolved in 70% Labrasol (vehicle). FBG was determined via tail-nick before and 4 h after administration of vehicle (Ctl), 300 mg/kg Metformin® (Met, positive control), or QL (250 and 500 mg/kg). Data are the mean ± SEM (n=7). Values reported below the x-axis are the results of mean final % FBG for each group. Final % FBG was calculated for individual mice as post-treatment FBG/ pre-treatment FBG x 100. *P < 0.05 and ***P < 0.001 (1-way ANOVA followed by Dunnett’s post hoc test compared to control).