Extraction of p-hydroxyacetophenone and catechin from Norway spruce needles. Comparison of different extraction solvents

The phenolic compounds p-hydroxyacetophenone and catechin have been extracted from Norway spruce needles with pure methanol, 80 and 50% (v/v) aqueous methanol, pure acetonitrile, 80% (v/v) aqueous acetonitrile, and pure water. Extraction efficiency of the individual solvents was compared. Although 80% aqueous methanol is the solvent most frequently used for extraction of soluble phenolic compounds from needles, it was found that pure methanol is a more suitable extraction solvent. Surprisingly, a two-step procedure based on the extraction of crushed needles with water then re-extraction with methanol proved a good alternative to direct extraction with methanol. Extraction of uncrushed spruce needles might indicate that relatively more p-hydroxyacetophenone than catechin was located in the surface layer of the needle.