Physicochemical characteristics of dietary fiber polysaccharides extracted from Murraya koenigii leaves and their functional role on gut homeostasis

Dietary fiber (DF) is an indigestible carbohydrate in plant foods that supports various physiological functions. This study aimed to extract the soluble and insoluble dietary fiber (DF) from the curry leaves and investigate their physicochemical properties as well as their functional role in the homeostasis of the gut microbiome. The study observed that insoluble-DF (IDF) yielded higher amounts than soluble-DF (SDF) across alkali, acid, and water extraction methods. Acid-extracted SDF showed the highest polysaccharide content (91.58 ± 1.53 %). Among IDFs, alkali-extracted IDF showed the highest polysaccharide content (81.93 ± 1.94 %). Glucose, arabinose, and xylose were identified as major monosaccharides. IDF had a larger particle size (463.5 ± 14.2 μm) compared to SDF (1.23 ± 15.55 μm), which influenced its physicochemical properties. IDF displayed better oil-holding capacity, while SDF showed superior water-holding capacity, potentially impacting glucose diffusion and cholesterol micelle formation. Furthermore, SDF and IDF promoted the growth of beneficial gut bacteria and increased production of short-chain fatty acids, which play critical roles in physiological regulation. Acid-extracted SDF restored gut homeostasis by increasing species richness and diversity, predominantly increasing beneficial bacteria and reducing pathogenic bacteria in LPS-induced dysbiotic mice. This study reveals the impact of extraction methods on the physicochemical and functional properties of curry leaves-DF, underscoring its promise as a functional food for gut health.