In vitro assessment of the impact of astragalus, pineapple stem 2 and bergamot extracts on the human fecal bacteria

Botanical extracts are increasingly included in functional foods and supplements, yet their impact on the gut microbiota remains underexplored. In this study, we investi-gated the effects of Astragalus membranaceus root extract, pineapple stem extract, and bergamot extract—both in native and digested forms (simulated via the INFOGEST protocol)—on human gut bacteria. Antimicrobial activity was first assessed in mono-cultures of nine commensal strains, including Lactobacillus acidophilus LA14, Lactica-seibacillus paracasei DG, Hafnia alvei HA4597, Bifidobacterium longum BB536, and B. an-imalis BL-04. Only minimal, strain-specific inhibition was observed at a supraphysio-logical concentration (100 mg/mL), mainly affecting Akkermansia muciniphila, Bac-teroides fragilis, and Collinsella aerofaciens. The botanical extracts were then tested on a complex bacterial consortium derived from human fecal microbes, anaerobically in-cubated for 48 h. 16S rRNA gene profiling showed no significant changes in α- or β-diversity, regardless of botanical type or digestion status. Minor compositional shifts were observed, notably a reduction in Collinsella spp. with digested Astragalus extract, while key taxa such as Faecalibacterium prausnitzii and A. muciniphila remained stable. These results suggest that, at physiologically relevant concentrations, the tested botan-icals do not disrupt core gut microbiota members, supporting their classification as microbiome-compatible functional ingredients.