Saponarin, a Di-glycosyl Flavone from Barley (Hordeum vulgare L.): An Effective Compound for Plant Defense and Therapeutic Application

Effect of Abiotic Signals on the Accumulation of Saponarin in Barley Leaves in Hydroponics Under Artificial Lights

Functional flavonoid production is a new agenda in the agricultural industry, and young barley leaves (YBL) are one of the highlighted crops due to their health-beneficial flavonoid, saponarin. For the year-round cultivation of a high saponarin content of YBL, abiotic signal effects on the biosynthesis and metabolism in YBL need to be understood clearly. In this research, the effects of reactive oxygen species (ROS)-related abiotic signals, such as light, potassium, and sodium, were investigated on the biosynthetic metabolism in YBL cultivation under artificial lights. A higher quantity of blue-rich white light (6500 K of light temperature) irradiation enhanced ROS levels and the related enzyme activities (APX and CAT), as well as photosynthesis and saponarin amount, while red-rich white light (3000 K of light temperature) increased the photosynthesis only. In addition, 1.0 g L-1 K+ treatment in water slightly reduced ROS levels and increased saponarin accumulation in YBL. These blue-rich light and K+ supplemental conditions relatively increased OGT expression and reduced 4-coumaric acid and isovitexin as saponarin precursors. Furthermore, the relative ratio of lutonarin as an oxidized product of saponarin increased in increments of light quantity. Finally, the abiotic conditions for saponarin production were optimized with the mixture solution treatment of 1.0 g L-1 Na+ and 1.0 g L-1 K+ under 500 PPFD of 6500 K light, and the saponarin amount per leaf was 219.5 μg plant-1; it was comparable amount with that under sunlight condition.

Enhancement of Growth and Secondary Metabolites by the Combined Treatment of Trace Elements and Hydrogen Water in Wheat Sprouts

This study aimed to evaluate the response of Triticum aestivum to hydrogen water (HW) and trace elements treated with HW. A pot experiment was conducted to assess the growth indices, secondary metabolites, and antioxidant levels. The response surface methodology (RSM) approach was used to ascertain the concentrations and significant interaction between treatments. The outcomes demonstrated that the combined treatment of Se acid and Mo oxide exhibited a notable positive effect on the growth and secondary metabolites, when treated with HW as compared to distilled water (DW). Notably, the interaction between these two treatments is significant, and the higher response was observed at the optimal concentration of 0.000005% for Se acid and 0.06% for Mo oxide. Additionally, an in vitro experiment revealed that the mixture treatment inhibits the accumulation of lipids in HepG2 hepatocytes cells. Moreover, metabolic analysis revealed that upregulated metabolites are linked to the inhibition of lipid accumulation. In addition, the analysis emphasizes that the continued benefits of higher plants as a renewable supply for chemicals compounds, especially therapeutic agents, are being expanded and amplified by these state-of-the-art technologies.

Variation of Saponarin Content in Barley Sprouts (Hordeum vulgare L.) by Natural Light Shielding: Implication of the Importance of Light Intensity

Saponarin is a functional metabolite produced by barley sprouts, and the mass production of saponarin by this crop is attractive for dietary supplement manufacturing. Light is the most important environmental factor determining plant growth, survival, and the production of secondary metabolites including flavonoids. This study was conducted to investigate the importance of light intensity for saponarin production in barley sprouts using a hydroponic growth system. Light intensity was manipulated by using shielding treatments to 100, 80, 70, and 50% natural sunlight (NS), and crop cultivation was performed on a monthly cycle. We found that the growth rate and biomass of barley sprouts did not differ in response to the shield treatments, whereas the saponarin content did. The highest saponarin content (i.e., from 1329 to 1673 mg 100 g-1) was observed in the 100% NS treatment, and it gradually decreased as light intensity also decreased. Statistical analysis revealed a significant polynomial relationship of saponarin content with cumulative PPFD (R2 = 76%), implying that the absolute total amount of light exposure over the growth period has a large effect on saponarin productivity in a hydroponic facility. Taken together, our results showed that shielding conditions, which are often unintentionally created by the design of cultivation facilities, can adversely affect saponarin production in barley sprouts. In addition, it was confirmed through our findings that light conditions with at least 70% NS in the cultivation facility enable the production of an amount corresponding to the saponarin content of the sprouts (>1000 mg 100 g-1) produced in the open field. Further studies are needed to investigate the underlying physiological and molecular mechanisms responsible for the relationship of saponarin content with light quantity and quality in barley sprouts.