Optaining of stilbens with deep eutectic solvents (DES) from knot of Pinus nigra

In this study, Black pine (Pinus nigra) stem wood and knots with a diameter of 32 cm and age range of 25-30, obtained from Abdipaşa- Ulus Forestry Management Directory, were used. Holocellulose, alpha-cellulose, lignin and sequential extraction (n-hexane, acetone:water) was applied to stem wood and knots. In addition, pinoslyvin and pinosylvinmonomethylether were determined in the knotwood using deep eutechic solvents (DES) using ultrason bath and hot-water bath. In DES experiments, 1 gram of knotwood was used with two different temperatures (600C – 70 0C), two different time (30 – 60 min.), three different solid:liquid ratio (10 – 20 – 40 g/ml), three different water content (10 – 20 – 30 %) and choline-chloride based three different DES mixture (ChCl: formic acit, ChCl: Urea, ChCl: Et-gly). Chemical composition of stem wood and knot wood of Black-pine were found similar to each other. Stem and knot wood values are 76,4–75,6 % for holocellulose, 48,9–47,9 % for α-cellulose and 27,5 – 25,8 % for lignin respectively. However, extraction results are quite different between stem (3,5 – 4,5 %) and knot wood (14- 25 %). In the recovery of stilbenes (pinoslyvin -PS and pinosylvinmonomethylether –PSMME) with DES applications solid:liquid ratio, extraction method, DES type, extraction time are effective respectively. Optimum conditions for recovering of PS and PSMME were determined as applying ChCl: Et-gly (1:2) in ultrason bath for 60 min at 70 0C, 10 % solid:liquid ratio with 30 % water content. According to the conditions mentioned above, PS was found 230 ppm and PSMME as 489 ppm. In the sequential extraction these values were measured as 0-195 ppm and 46,3-75,3 ppm for acetone:water (95:5 v/v) respectively. With deep eutectic solvents, stilbenes in knot woods can be recovered 5 times more for PS and 2,5-6,5 times for PSMME compared to conventional extraction method and solvents. In addition, only 1 gram sample was used with DES. The amount of used DES solvent was only 7 mL and extraction time 1 hour. Considering all these conditions, it was concluded that it would be more appropriate to obtained stilbenes with environmentally friendly green chemicals.