Sword bean (Canavalia gladiata) as a source of antioxidant phenolics

Abstract

Summary Sword beans (Canavalia gladiata) have been used as grain legumes and medicinal plants in China for thousands of years. To explore new natural antioxidant sources, the antioxidant capacity and phenolic composition in the soluble and bound fractions of three sword bean genotypes were evaluated in vitro. The red and black sword beans were found to have antioxidant capacity compared to the white sword bean, and this was attributed to their red and black bean coats, which possessed extremely high phenolic content. Gallic acid and its derivatives, such as methyl gallate, digalloyl hexoside and digallic acid, were the main phenolic compounds in the coats of red and black sword beans. Therefore, the red and black sword beans, especially their bean coats, are good sources of antioxidant phenolics and may have potential health benefits.

Diversity in Antioxidant Capacity, Phenolic Contents, and Flavonoid Contents of 42 Edible Beans from China

“…In addition, beans with pigmented coats such as red sword bean (number 41), big speckled kidney bean (number 14), small rice bean (number 29), and shi-yue bean (number 32), had relatively high antioxidant capacity, whereas beans with nonpigmented coats such as white chickpea (number 5) and white hyacinth bean (number 12) had low antioxidant capacity, in agreement with previous findings about cereal grains (Deng et al 2012). The high antioxidant capacity of red sword bean (number 41) was mainly owing to its red bean coat, because the extracts of its coat had much higher antioxidant capacity than the whole bean, whereas its cotyledon only had weak antioxidant capacity (Gan et al 2016). The high antioxidant capacity of red sword bean (number 41) was mainly owing to its red bean coat, because the extracts of its coat had much higher antioxidant capacity than the whole bean, whereas its cotyledon only had weak antioxidant capacity (Gan et al 2016).…”

“…Two-step extractions were performed to extract the soluble and bound fractions as reported (Gan et al 2016), because the bound fraction could not be directly extracted by common organic solvents and needed to be hydrolyzed by alkaline or acidic solutions. Two-step extractions were performed to extract the soluble and bound fractions as reported (Gan et al 2016), because the bound fraction could not be directly extracted by common organic solvents and needed to be hydrolyzed by alkaline or acidic solutions.…”

Pigmented edible bean coats as natural sources of polyphenols with antioxidant and antibacterial effects

“…Besides, other flavonoids were also detected in bean coats, such as vitexin and isovitexin, which were only found with high level in the coats of mung beans. In addition, consistent with our previous study, gallic acid and its derivatives were the main polyphenols in the coats of red and black sword beans (Gan, Lui, & Corke, 2016). Overall, pigmented bean coats contained a variety of phenolics and could have potential biological functions.…”

Fermentation alters antioxidant capacity and polyphenol distribution in selected edible legumes

“…Soluble and bound fractions of fermented and nonfermented legume powders were extracted as described in our previous report (Gan et al ., ).…”

“…The LC system consisted of a binary pump, an auto‐sampler and a diode‐array detector. The separation was performed according to our previous report (Gan et al ., ) using a SymmetryShield ™ RP18 column (150 × 2.1 mm, 3.5 μm) (Waters, Milford, MA, USA) with the gradient elution solution A (0.1% formic acid – water solution) and solution B (0.1% formic acid – methanol solution) following the program: 0 min, 5% B; 15 min, 20% B; 40 min, 35% B; 60 min, 50% B; 65 min, 55% B; 70 – 75 min, 95% B. The flow rate was 0.2 mL min −1 and injection volume was 5 μL.…”