Osmoprotectant and antioxidant effects of new synthesized 6-(2-hydroxyethyl)cyclohex-3-enol on barley under drought stress

The aim of present study was synthesize 6-(2-hydroxyethyl)cyclohex-3-enol (11) and investigate its antioxidant properties in barley plants under drought stress. For this aim, 1,4-cyclohexadiene (7) was subjected to [2 + 2] ketene addition reaction with dichloro ketene and the chlorine atoms were reduced. After that, the cyclobutanone ring was converted to a lactone ring and the lactone ring was reduced with LiAlH4. Subsequently, 6-(2-hydroxyethyl)cyclohex-3-enol (13) was obtained with high yield. The structures of the synthesized molecules were clarified by NMR, FTIR, GCMS spectroscopic methods. Two different methods were used to evaluate antioxidant activity of cyclohexenediol 11. One of them was DPPH radical scavenging activity which was used extensively. Also, osmoprotectant and antioxidant effects of 6-(2-hydroxyethyl)cyclohex-3-enol (13) were investigated in barley under drought stress. Drought decreased the relative water content (RWC) and water potential (WP) in barley leaves. Cyclohexenediol 11 treatment remarkably increased RWC and WP in leaves under drought conditions. Superoxide $$(O_{2}^{ - } )$$ and nitric oxide (NO) accumulated under drought. In cyclohexenediol 11 treated-plants, the accumulation $$O_{2}^{ - }$$ and NO were strongly reduced under drought conditions. Our results showed that cyclohexenediol 11 helped barley plants for maintaining water under drought stress; this makes synthetic cyclitol cyclohexenediol 11 as a good osmoprotectant candidate. Another important result in this study was the strong radical scavenging potential of cyclohexenediol 11. We think that much more comprehensive biochemical studies should be conducted to determine how cyclohexenediol 11 performs the radical scavenge role.