Stimulation of Phenolics, Antioxidant and α-Glucosidase Inhibitory Activities During Barley (Hordeum vulgare L.) Seed Germination

Abstract

The rationale of this study was to enhance the nutritional quality of dry barley seeds. In this study we are evaluating the effect of germination on barley seeds relevant to total phenolic contents, antioxidant activity (in terms of DPPH free-radical scavenging) and the in vitro α-glucosidase inhibitory activities. Barley seeds were germinated for 18.5, 24, 30, 48, and 67 h and then extracted in water. The total phenolic contents, antioxidant activities and α-glucosidase inhibitory activities changed with germination time. More specifically, within the first 48 h of germination the total phenolic content increased from 1.1 mg/g fresh weight (0 h) to 3.4 mg/g fresh weight (48 h) and then slightly reduced by 67 h. Similarly, α-glucosidase inhibitory activity was significantly increased from an IC50 128.82 mg/mL (0 h) to an IC50 18.88 mg/mL (48 h) and then slightly reduced by 67 h. Significant maltase inhibitory activity was observed only with 48 h-germinated extract. Antioxidant activities increased continuously from an IC50 15.72 mg/mL at 0 h to and IC50 5.72 mg/mL after 48 h of germination. Based on our observations, barley seed germination was over after 48 h. During the progress of germination phenolic compounds are becoming available and are more easily extracted. After 48 h, lignification is initiated resulting to the decreased total phenolic content and observed antioxidant and carbohydrate hydrolyzing enzyme inhibition activities. The above results indicate the positive effect of germination in barley seeds for enhanced antioxidant and α-glucosidase inhibitory activities.

Impact of Cereal Seed Sprouting on Its Nutritional and Technological Properties: A Critical Review

“…A 1.2‐ to 3.6‐fold increase in total polyphenol content has been measured in wheat (Alvarez‐Jubete et al., ; Hithamani & Srinivasan, ; Swieca & Dziki, ), barley (Ha et al., ; J. Lu et al., ), sorghum (Hithamani & Srinivasan, ), rye (Katina, Laitila, Juvonen, et al., ; Liukkonen et al., ), oats (Tian et al., ; J.G. Xu et al., ), and brown rice (Cáceres et al., ; Cornejo et al., ; Pal et al., ) when sprouted for 2 to 6 days at 15 to 28 °C.…”

“…A 1.2-to 3.6-fold increase in total polyphenol content has been measured in wheat (Alvarez-Jubete et al, 2010;Hithamani & Srinivasan, 2014;Swieca & Dziki, 2015), barley (Ha et al, 2016;J. Lu et al, 2007), sorghum (Hithamani & Srinivasan, 2014), rye (Katina, Laitila, Juvonen, et al, 2007;Liukkonen et al, 2003), oats (Tian et al, 2010;J.G.…”

“…In general, sprouting increases the antioxidant activity of cereals. Various researchers have shown a 1.2‐ to 2.9‐fold increase in antioxidant activity in wheat (Alvarez‐Jubete, Wijngaard, Arendt, & Gallagher, ; Zilic et al., ), barley (Ha, Jo, Mannam, Kwon, & Apostolidis, ), brown rice (Cáceres et al., ; Cornejo et al., ; Ti et al., ), and oats (J.G. Xu et al., ) when sprouted for 2 to 5 days at 15 to 28 °C.…”

“…The higher antioxidant activity in sprouted grains is mainly attributed to accumulations of vitamin E (see section “Impact of sprouting on the vitamin content in cereals”) and polyphenols (Ahmad et al., ; Kim et al., ). The latter secondary plant metabolites play a role in the protection of plants against environmental stresses (Alvarez‐Jubete et al., ; Ha et al., ; Pal et al., ). Their antioxidant activity is associated with their ability to scavenge free radicals, break radical chain reactions, and chelate metals (Fardet et al., ; Ha et al., ; J. Lu et al., ).…”

“…The latter secondary plant metabolites play a role in the protection of plants against environmental stresses (Alvarez‐Jubete et al., ; Ha et al., ; Pal et al., ). Their antioxidant activity is associated with their ability to scavenge free radicals, break radical chain reactions, and chelate metals (Fardet et al., ; Ha et al., ; J. Lu et al., ). The main (poly‐)phenols in cereal grains are p‐hydroxybenzoic, ferulic, sinapic, vanillic, and p‐coumaric acids, and in oats also avenanthramides (Cáceres et al., ; Fardet et al., ; Hithamani & Srinivasan, ; Kim et al., ; J. Lu et al., ; Skoglund, Peterson, Andersson, Nilsson, & Dimberg, ; J.G.…”