Phenolic characterization and bioactivity of microwave-assisted extracts from edible house crickets (Acheta domesticus)

Entomophagy, which is the habit of eating insects, has become relevant in the past few years as it could potentially help reduce current and future food insecurity, due to the highly nutritious and sustainable characteristics of edible insects. In addition to the nutritional content of insects, research on the potential bioactive components of insect extracts has also gained popularity. In this study, extracts from house cricket (Acheta domesticus) from two farms and their corresponding feeds were obtained using a microwave-assisted extraction. Further phenolic characterization led to the identification and quantification of 4-hydroxybenzoic acid, p-coumaric acid, ferulic acid and syringic acid as major phenolic compounds in both A. domesticus extracts as well as both feed extracts. Additionally, 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. In both in vitro assays, A. domesticus extracts showed higher antioxidant activity compared to the feeds. Antibacterial activity against E. coli and L. innocua was also evaluated using the microwell method. The A. domesticus extracts showed a selective inhibition (p<0.05) towards the gram-positive bacteria L. innocua between a period of 4 to 8 h. This inhibition is thought to have occurred as a result of the presence of phenolic acids and antimicrobial peptides, while the feed extracts did not exhibit any inhibitory activity towards any of the bacteria. The finding of the same phenolic acids in A. domesticus and their corresponding feed could imply the capacity of A. domesticus to absorb and sequester dietary phenolics that may provide additional health benefits when the insect is consumed, unveiling new benefits of entomophagy.