Determination of secondary metabolite in galls of some cynipid wasps (Hymenoptera: Cynipidae) and characterization of the phenolic compound

The galls of cynipid species (Hymenoptera: Cynipidae) have been used since ancient times as an important source of bioactive compounds. Many researchers have evaluated the medicinal potential of some cynipid galls and found that these galls have numerous ethnomedical uses. The aim of this study was to determine the total bioactive (phenolic, flavonoid and tannin) compound amounts of gall extracts, to reveal the phenolic compound contents by HPLC method and to set ground for future pharmaceutical studies. The galls of cynipid wasps (totally 24 taxa) on host plants were collected from the Eastern Black Sea Region of Türkiye. Acetone, ethanol, methanol, and water extracts of these galls were prepared for quantity analysis and HPLC. The phenolic compound amounts (phenolic, flavonoid and tannin) of the cynipid gall extracts were determined, and their phenolic compound contents were also revealed. Some phenolic compounds in ethanol gall extracts were analyzed using HPLC, and some of these compounds were detected for the first time in the cynipid galls. 2,5-dihydroxybenzoic acid, caffeic acid, epicatechin, and ellagic acid are the most abundant in the ethanolic gall extracts. Total phenolic, flavonoid and tannin amounts of the cynipid gall extracts showed high variation. All these studies on quantification and characterization of phenolic compound are the first detailed studies on these taxa of cynipid galls and show that these cynipid galls might pharmaceutically be an important source for human and animal health.