Fecal fermentation and gut microbiota modulation of dietary fibre and polyphenols from Gnetum gnemon Linn. leaves

Abstract

The purpose of this study was to analyze the effects of Gnetum gnemon var. tenerum leaf powder, dried using a vacuum microwave, on gut health properties. The two alternative drying conditions were 3600 Watts for 12 min (G1) and 2400 Watts for 15 min (G2) compared to the commercial Japanese green tea matcha powder (M) and the gut health effects were assessed by human fecal fermentation in a one-stage colon system. The enumeration of gut microbiota at 24 h of fermentation by next generation sequencing (NGS) confirmed elevated Bacteroides levels and significantly (P < 0.05) higher numbers of Bifidobacterium with G1 (33%) and G2 (37%) compared to M (31%). Additionally, short-chain fatty acid (SCFA) profile for acetic, propionic and butyric acids was analysed using gas chromatography-flame ionization detector (GC-FID), and especially butyric acids was significantly (P < 0.05) higher with G1 (4.698 ± 0.61 mM) and G2 (2.768 ± 0.10 mM) compared to M, 1.805 ± 0.01 mM at 24 h. The Gnetum leaf powders G1 and G2 were investigated for promoting γ-aminobutyric acid (GABA) microbial metabolite, which was detected using liquid chromatography-mass/mass spectrometry (LC-MS/MS). Thus, Gnetum gnemon var. tenerum leaf powder could provide gut health benefits with good potential for use as a functional food ingredient in the future.