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 <i>Scenedesmus obliquus</i> 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-<i>trans</i>-zeaxanthin and pheophytin being the most abundant in all groups. Furthermore, 15-<i>cis</i>-lutein, all-<i>trans</i>-β-cryptoxanthin, and 9-<i>cis</i>-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 <i>Bifidobacterium</i> and <i>Lactobacillus</i> 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.