Oral Delivery of Ellagic Acid Encapsulated in Milk Exosomes: Sex-Based Differences in Bioavailability, Urolithin Production, and Gut Microbiota Modulation

Abstract

Milk exosomes (EXOs) enhance polyphenols’ bioavailability, but their potential for oral administration remains underexplored. Ellagic acid (EA) is poorly bioavailable. We investigate whether EA encapsulated in EXOs (EXO-EA) consumed orally improves EA bioavailability and (or) modulates gut microbiota. For 2 weeks, BALB/c mice received EXO, non-encapsulated EA (NEA), or EXO-EA (0.27 mg EA/kg bw) orally. Targeted and untargeted metabolomics (UPLC-qTOF-MS), fecal SCFAs (GC-MS), and gut microbiota (PacBio 16S-sequencing) were performed. Additionally, EA plasma and brain kinetics were evaluated in rats following intravenous administration of EXO-EA and NEA. Unlike NEA, EXO-EA quadrupled EA plasma levels in Sprague-Dawley rats and enabled brain detection. However, oral EXO-EA in mice failed to deliver EA systemically due to gastrointestinal instability, confirmed by in vitro digestion. Sex-dependent EXO-EA metabolomic effects were observed. Also, in males only, EXO-EA increased fecal urolithin A and SCFAs and enriched the microbiota with Christensenellaceae R7, Ruminococcus species, and Clostridium fusiformis, among others. In females, both EXO-EA and NEA enriched the microbiota with bifidobacteria, including Bifidobacterium pseudolongum. Oral EXO-EA impacted plasma metabolome, modulated gut microbiota, and increased urolithin A and SCFA production sex-dependently. However, gastrointestinal instability, limited EA encapsulation, and low dose administered prevented systemic delivery.