Anti-Inflammatory Effects of Hermetia illucens Fermented With Riboflavin-Producing Leuconostoc...

Fermentation is widely used to enhance the nutritional and functional properties of food substrates; however, the biological effects of insect-derived materials fermented with riboflavin-producing lactic acid bacteria remain largely unexplored. This study investigated the anti-inflammatory potential of Hermetia illucens hot-water extract fermented with Leuconostoc mesenteroides KCCM13067P (HeHi_Lm) using LPS-stimulated RAW 264.7 macrophages and a dextran sulfate sodium (DSS)-induced chronic colitis mouse model. Fermentation significantly increased vitamin B₂ derivatives, with riboflavin, flavin adenine dinucleotide (FAD), and flavin mononucleotide (FMN) increasing from 7.82, 10.58, and 2.60 μg/g to 18.53, 29.84, and 9.29 μg/g, respectively, representing an approximately 2.7-fold increase in total vitamin B₂ content. Fermentation also enriched free amino acids and bioactive amines, including glycine, alanine, cystathionine, γ-aminobutyric acid, and ethanolamine. In vitro, HeHi_Lm significantly suppressed LPS-induced nitric oxide production and reduced IL-6 secretion, whereas TNF-α reduction was not statistically significant. In vivo, HeHi_Lm administration alleviated DSS-induced colitis symptoms, as demonstrated by improved body weight recovery, reduced disease activity index scores, and attenuation of colon shortening. Histopathological damage and spleen and liver weight/body weight ratios were also improved. Furthermore, HeHi_Lm significantly reduced colonic expression of inflammatory mediators, including iNOS, COX-2, IL-6, and IL-1β. Gut microbiota analysis revealed compositional shifts characterized by increased Firmicutes and Bacteroidetes and reduced Verrucomicrobia, with enrichment of Lactobacillaceae and Oscillospiraceae. These findings indicate that fermentation of H. illucens with L. mesenteroides enhances functional metabolite profiles and is associated with reduced inflammatory responses and microbiota restructuring in experimental colitis, supporting its potential as a sustainable functional food ingredient.