The use of insects in traditional medicine and unveiling the chemical structure of the bright pigments in butterfly wings led to the discovery of bioactive phenolic compounds in the insect bodies. These metabolites have been found not only due to the insect absorption and metabolisation of the plant-derived phenolic present in their diet, but also from the ability of insects to synthesise phenolic compounds de novo through the sclerotisation process. Plant phenolics are secondary metabolites involved in the protection of tissues against UV radiation, herbivores, and pathogens, as well as pigmentation of fruits and flowers. These bioactive compounds exhibit antioxidant, anti-inflammatory, anticancer, and antimicrobial activities, demonstrated through in vitro and in vivo studies. This bioactive potential is thought to occur due to their chemical characteristics that allow them to stabilise reactive oxygen species (ROS), chelate prooxidant metal ions, interact with key enzymes and signal cascades involved in biological pathways. Bioactivity of plant phenolics and both in vitro, in vivo studies, suggest that the dietary compounds absorbed by the insect maintain their chemical and bioactive properties. Further characterisation of the phenolic composition in edible insects and evaluation of their bioactive capacity as well as their bioavailability, could result in discovering additional health benefits of entomophagy apart from macro-nutritional (e.g. protein) content.

With entomophagy gaining popularity in the Western hemisphere as a solution for future food insecurity, research on alternative protein sources, such as edible insects, has become relevant. Most of the research performed on insects has been on their nutritional qualities; however, little is known regarding bioactive compounds, such as polyphenols, that, if present in the insect, could provide additional benefits when the insect is consumed. In this study, methanolic extracts of Acheta domesticus from two farms and their corresponding feeds were obtained using a microwave-assisted extraction. Targeted phenolic characterization was accomplished through LC-MS/MS leading to the identification of 4-hydroxybenzoic acid, p-coumaric acid, ferulic acid, and syringic acid as major phenolic compounds in both A. domesticus extracts. Furthermore, the in vitro antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl radical cation (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical assays demonstrating the superior quenching activity of the A. domesticus extracts compared to the feeds. The discovery of phenolic compounds in A. domesticus implies the ability of this insect species to sequester and absorb dietary phenolics leading to possible added health benefits when consumed.