Free Water-Soluble Phenolics Profiling in Barley (Hordeum vulgare L.)

Abstract

The phenolic profile of barley ( Hordeum vulgare L.) leaves, seeds, awns, and stems, collected in two different locations from Portugal, was determined by a high-performance liquid chromatography/diode array detector (HPLC/DAD). A total of 28 compounds were identified and quantified, which included 4 phenolic acids, 6 C-glycosylflavones, and 18 O-glycosyl-C-glycosyl flavones, with some of them acylated. Distinct profiles were noticed among the analyzed materials. The greatest diversity of compounds was found in barley leaves (26 flavonoids and 2 phenolic acid derivatives), which also exhibited the highest concentration of phenolics. Isoorientin-7-O-glucoside (lutonarin) was the major compound in leaves, while, in general, the pair isovitexin-7-O-rutinoside plus isoscoparin-7-O-glucoside were the main phenolics in the other materials. Thus, barley leaves may constitute an important dietary source of protective compounds, which could be used, for example, to take profit from the wastes resulting from alcoholic drink obtainment.

The Occurrence, Fate and Biological Activities ofC-glycosyl Flavonoids in the Human Diet

“…-D-glucoside and isoscoparin-7-O-rutinoside (Ferreres et al, 2009). It is worth noting that this complex form of glycosylation differs to those equally complex but structurally divergent compounds containing an O-glycosidic linkage between the two hexose sugars of a C-linked disaccharide flavonoid sub-species that are present in the inedible leaves of plants such as barley (Ferreres et al, 2007).…”

“…Significant quantities of vitexin have also been found in the flour of millet seeds (Pennisetum americanum), with reported amounts ranging between 77 and 275 mg g -1 (Akinbala, 1991), whilst isovitexin is also present in rice hulls (Ramarathnam et al, 1989). Barley grains contain nine Oglycosylated C-glycosyl flavonoids, in which both pathways of glycosylation are followed by the same compound during in planta biosynthesis, resulting in at least one of each O-and Cglycosyl substituent groups being present at separate positions on the aglycone flavonoid backbone (Ferreres et al, 2009). In barley grain, these are isoorientin…”

“…It is worth noting that this complex form of glycosylation differs to those equally complex but structurally divergent compounds containing an O-glycosidic linkage between the two hexose sugars of a C-linked disaccharide flavonoid sub-species that are present in the inedible leaves of plants such as barley (Ferreres et al, 2007). Isoorientin is the only additionally identified mono-C-glycosyl flavonoid in barley seed (Ferreres et al, 2009). …”

Effects of Elicitors on Seedling Growth, Total Polyphenol and Chlorophyll Content and Antioxidant Activity of Barley (Hordeum vulgare L.)

“…It is one of the widely consumed cereals (Ferreres et al, 2009) and has become main cereal grains since ancient time. It has long been cultivated and particularly used for feeding livestocks (Kamiyama et al, 2012).…”

“…The young barley leaf extract contains phenolic and isoflavonoid compounds which have been shown to exhibit antioxidative activity in the lipid peroxidation system and is well-known for being good natural source of various vitamins and minerals (Yu et al, 2003). Since the benefits of barley leaves have been discovered and identified, barley meals and fractions are increasingly used as functional food, baked product ingredient (Kamiyama et al, 2012;Ferreres et al, 2009). In Japan, young barley leaves are prepared as material of green-colored drink named: 'Aojiru' (Ikeguchi et al, 2014), and 'Barley sprouts' in Korea (Na, 2014;Seo, 2015).…”