The Cecal Distribution of Microalgal Pigments in Rats: Do Carotenoids and Chlorophylls Play a Pharmacobiotic Role?

This study investigated the cecal distribution of lipophilic pigments (carotenoids and chlorophylls) from Scenedesmus obliquus and their effects on the activity of the intestinal microbiota in rats. Oleoresins containing different concentrations of microalgal pigments (from 0 to 600 µg·kg^-1bw·d^-1), previously characterized by chromatographic and spectrometric analyses, were administered for four weeks. At the end of the intervention, cecal content samples were collected and analyzed for their pigment composition, short-chain fatty acids (SCFAs), and probiotic microbiota. Nine pigments were identified in the cecal samples, with all-trans-zeaxanthin and pheophytin being the most abundant in all groups. Furthermore, 15-cis-lutein, all-trans-β-cryptoxanthin, and 9-cis-β-carotene-found exclusively in microalgal oleoresin-were detected only in animals receiving doses above 300 µg·kg^-1bw.day^-1, indicating a link with the SCFA modulation. These supplementations significantly increased the levels of acetate (300 and 450 µg·kg^-1bw·d^-1 -13% and 14%), butyrate (300 µg kg^-1bw·d^-1 -19%), and propionate (600 µg·kg^-1bw·d^-1 -16%). Notably, 300 µg·kg^-1bw·d^-1 significantly increased Bifidobacterium and Lactobacillus populations. Overall, the pigment supplementation positively influenced the gut microbiota composition and SCFA production in a dose-dependent manner, particularly at 300 µg·kg^-1bw·d^-1. These results support the potential application of microalgal pigments as functional food ingredients or supplements with gut health benefits.