Effect of the growth stage and cultivar on policosanol profiles of barley sprouts and their adenosine 5'-monophosphate-activated protein kinase activation.

Adenosine 5'-monophosphate-activated protein kinase (AMPK) is an intracellular sensor that can regulate glucose levels within the cell. For this reason, it is well-known to be a target for drugs against diabetes and obesity. AMPK was activated significantly by the hexane extract of barley sprouts. This AMPK activation emerges across the growth stages of the sprout, becoming most significant (3 times above the initial stages) 10 days after sprouting. After this time, the activation decreased between 13 and 20 days post-sprouting. Analysis of the hexane extracts by gas chromatography-mass spectrometry showed that the amounts of policosanols (PCs, which are linear, primary aliphatic alcohols with 20-30 carbons) in the plant dramatically increased between 5 days (109.7 mg/100 g) and 10 days (343.7 mg/100 g) post-sprouting and then levels fell back down, reaching 76.4 mg/100 g at 20 days post-sprouting. This trend is consistent with PCs being the active ingredient in the barley plants. We validate this by showing that hexacosanol is an activator of AMPK. The richest cultivar for PCs was found to be the Daejin cultivar. Cultivars had a significant effect on the total PC content (113.2-183.5 mg/100 g) within the plant up to 5 days post-sprouting. However this dependence upon the cultivar was not so apparent at peak stages of PC production (10 days post-sprouting). The most abundant PC in barley sprout, hexacosanol, contributed 62-80% of the total PC content at every stage. These results are valuable to determine the optimal times of harvest to obtain the highest yield of PCs.

Structural and quantitative analysis of antioxidant and low-density lipoprotein-antioxidant flavonoids from the grains of sugary rice.

Grains of sugary rice were extracted with 80% aqueous methanol, and the concentrated extracts were successively partitioned using ethyl acetate, n-butanol, and water. From the n-butanol fractions, four flavonoid glycosides were isolated through repeated silica gel, octadecyl silica gel, and Sephadex LH-20 column chromatographies. Based on the nuclear magnetic resonance, mass spectrometry, and infrared spectroscopic data, the chemical structures of the compounds were determined to be taxifolin-7-O-ß-d-glucopyranoside (1), hyperin (2), isoquercitrin (3), and quercetin gentiobioside (4). These compounds were isolated from the grains of sugary rice for the first time. All isolated compounds were tested for antioxidant activity and low-density lipoprotein (LDL)-antioxidative activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and LDL assays. Compound 1 exhibited a strong scavenging effect on DPPH, with a 50% inhibition concentration (IC(50)) value of 8.1 µM, and also inhibited LDL oxidation with an IC(50) value of 40.0±20 µM. A simple and efficient high-performance liquid chromatography/diode array detection method for the simultaneous determination of the four bioactive flavonoids (1-4) has been developed and applied to their content determination in the sugary rice. The grains were extracted by 80% methanol, and the contents of 1, 2, 3, and 4 were determined to be 1.12±0.045, 0.65±0.011, 0.68±0.032, and 0.89±0.021 mg/g, respectively.