Neuronal cell protective effects of phenolic compounds derived from steam exploded nematode-infected pine

Pine wilt disease is one of the most serious forest diseases that kills pine trees. Most of the nematode-infected pines are fumigated or locally incinerated and are thus not appropriately utilized. This study explored methods to utilize abandoned nematode-infected pines. The chemical compositions of healthy and nematode-infected pines were analyzed, and the neuroprotective effects of phenolic compounds extracted after steam explosion treatment were investigated. In terms of chemical composition, the nematode-infected pine chips suffered more damage from the steam explosion treatment than the healthy pine chips. In addition, the total phenolic compound content showed a clear difference depending on the presence of infection and steam explosion conditions. The maximum total phenolic compound content of extracted ethanol was found when the nematode-infected pine chip was subjected to steam explosion with a severity factor (Ro) of 3.82. The steam exploded pine extract of 10 μg/mL inhibited glutamate-induced early apoptotic cell death compared to cells treated with 10 mM glutamate alone. These results suggested that steam-exploded pine can be used as an effective natural material for neuronal cell protection.