Augmenting turmeric, galingale, gotu kola extracts, and black sesame as prebiotics by probiotics

Background and Aim: Probiotic products are increasingly utilized in animal feed and the food industry to promote health benefits. Herbs such as turmeric (Curcuma longa L.), galingale (Boesenbergia rotunda (Linn.) Mansf.), gotu kola (Centella asiatica (L.) Urb.), and black sesame (Sesamum indicum L.) are rich in bioactive compounds with potential antioxidant, anti-inflammatory, and antimicrobial properties. However, their bioavailability can be limited, and fermentation with probiotics may enhance these attributes. This study investigated the formulation of a synbiotic product by fermenting aqueous extracts of turmeric, galingale, and gotu kola with multi-strain probiotics, supplemented with prebiotic black sesame extract, to improve probiotic viability and biofunctional activities, including enzyme inhibition and antioxidant effects. Materials and Methods: Seven probiotic strains (Ligilactobacillus salivarius KUKPS6202, Ligilactobacillus paracasei KUKPS6201, Lactobacillus acidophilus KUKPS6107, Ligilactobacillus rhamnosus KUKPS6007, Ligilactobacillus reuteri KUKPS6103, Bacillus coagulans KPS-TF02, and Saccharomyces cerevisiae subsp. boulardii KUKPS6005) were cultivated in a mung bean–soybean medium and used for fermentation of herbal extracts (10% w/v) at 37°C for 24 h. Black sesame extract (1% w/v) was added as a prebiotic. Antimicrobial activity was assessed via agar well diffusion against pathogens like Aeromonas hydrophila and Bacillus cereus. Probiotic viability was measured by plate counts. Bioactivities evaluated included α-amylase and α-glucosidase inhibition (IC50 values), lipase activity (using a commercial kit), and antioxidant potential via 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging and ferric reducing antioxidant power (FRAP) assays. Data were analyzed using one-way analysis of variance and Tukey's test (p < 0.05). Results: All probiotic strains grew effectively in the mung bean–soybean medium, with viable counts reaching 7-8 log CFU/mL. Fermented herbal extracts inhibited A. hydrophila and B. cereus (inhibition zones 7.33-9.00 mm) but showed limited activity against other pathogens. Black sesame extract significantly enhanced probiotic viability (p < 0.05) compared to unsupplemented extracts. Fermentation with L. rhamnosus yielded the lowest IC50 for α-amylase (5.96 mg/mL) and α-glucosidase (3.32 mg/mL). L. reuteri exhibited the highest lipase activity (384.77 mU/L after 24 h). Antioxidant activities were comparable across treatments in DPPH assay, but FRAP values were highest for B. coagulans (0.275 μg Trolox/mL), S. boulardii (0.264 μg Trolox/mL), and L. salivarius (0.252 μg Trolox/mL) (p < 0.05). Conclusion: Synbiotic fermentation with black sesame extract and multi-strain probiotics significantly boosts probiotic survival and biofunctional properties, offering potential as functional foods or animal feed supplements for metabolic health, antimicrobial protection, and antioxidant support. Future in vivo studies could validate these benefits. Keywords: antioxidant activity, black sesame, functional food, gotu kola, prebiotic, probiotic, synbiotic fermentation, turmeric.