Isolation and structural elucidation of unique γ-oryzanol species in rice bran oil.

Even though γ-oryzanol (OZ) such as 24-methylenecycloartanyl ferulate (24MCAFA) is abundant in purified rice bran oil, we realized that the oil contained the prospect of two additional novels of OZ species. To identify this, we isolated and analyzed their chemical structures by using HPLC-UV-MS, NMR, and IR. We revealed for the first time that the oil had also contained cyclobranyl ferulate (CBFA) and cyclosadyl ferulate (CSFA) which are likely to be exist due to the isomerism of 24MCAFA under acid condition. OZ profile including CBFA and CSFA was roughly similar between commercial rice bran oils and processed foods containing the oils, suggesting that people might have often consumed CBFA and CSFA from rice bran oils and/or processed foods. Since different OZ species are known to have different functionality, this study opens the chance to explore more the contribution of CBFA and CSFA for human health and wellness.

Cycloartenyl Ferulate and ß-Sitosteryl Ferulate - Steryl Ferulates of γ-Oryzanol - Suppress Intracellular Reactive Oxygen Species in Cell-based System.

γ-Oryzanol is a naturally occurring component of rice bran and consists of various steryl ferulates. The antioxidant activities of γ-oryzanol have mostly been demonstrated in cell-free systems. Therefore, we determined whether steryl ferulate of γ-oryzanol suppress spontaneous intracellular reactive oxygen species (ROS) in cell-based systems. We found that cycloartenyl ferulate and ß-sitosteryl ferulate suppressed spontaneous intracellular ROS in a similar way to N-acetylcysteine and α-tocopherol.

Structural basis of inter-protein electron transfer for nitrite reduction in denitrification.

Recent earth science studies have pointed out that massive acceleration of the global nitrogen cycle by anthropogenic addition of bio-available nitrogen has led to a host of environmental problems. Nitrous oxide (N(2)O) is a greenhouse gas that is an intermediate during the biological process known as denitrification. Copper-containing nitrite reductase (CuNIR) is a key enzyme in the process; it produces a precursor for N(2)O by catalysing the one-electron reduction of nitrite (NO2-) to nitric oxide (NO). The reduction step is performed by an efficient electron-transfer reaction with a redox-partner protein. However, details of the mechanism during the electron-transfer reaction are still unknown. Here we show the high-resolution crystal structure of the electron-transfer complex for CuNIR with its cognate cytochrome c as the electron donor. The hydrophobic electron-transfer path is formed at the docking interface by desolvation owing to close contact between the two proteins. Structural analysis of the interface highlights an essential role for the loop region with a hydrophobic patch for protein-protein recognition; it also shows how interface construction allows the variation in atomic components to achieve diverse biological electron transfers.