Ameliorative effects of a Lactobacillus paracasei and Puerariae Radix extract complex on hydrogen peroxide-induced oxidative damage in zebrafish

Objective This study aimed to investigate the protective effects of a novel composite comprising Lactobacillus paracasei and Puerariae Radix extract (Lac_PRE) against hydrogen peroxide (H 2 O 2 )-induced multi-organ oxidative damage in a zebrafish model. Methods An acute toxicity test was conducted to determine the optimal subacute H 2 O 2 exposure concentration in wild-type AB strain zebrafish. Subsequently, zebrafish were divided into four groups: control, H 2 O 2 exposure (2.0 mmol/L), H 2 O 2 exposure with Lac_PRE treatment, and Lac_PRE control. After 14 days, we assessed hepatic and cardiac function markers, inflammatory gene expression (cyclooxygenase, cox; tumor necrosis factor-alpha, tnf-α; interleukin-6, il-6), oxidative stress indicators (malondialdehyde, MDA), and the intestinal Firmicutes/Bacteroidetes (F/B) ratio. Results H 2 O 2 exposure induced significant oxidative and inflammatory damage in zebrafish, Kruskal-Wallis tests revealed significant overall differences among groups for hepatic ALT, hepatic MDA, cardiac cTnI, cardiac MDA, cardiac COX, cardiac TNF-α, cardiac IL-6, and the intestinal F/B ratio (all p < 0.05). Two a priori planned comparisons were tested using Dunn’s post hoc test with Bonferroni ×2 correction. H 2 O 2 exposure significantly elevated cardiac cTnI (adjusted p = 0.002), cardiac MDA (adjusted p = 0.015), cardiac COX (adjusted p = 0.029), TNF-α (adjusted p = 0.023), IL-6 (adjusted p = 0.005), and significantly disrupted the F/B ratio (adjusted p = 0.012) compared to control. The Lac_PRE composite significantly reduced hepatic ALT (adjusted p < 0.001) and cardiac COX expression (adjusted p = 0.023). For the remaining indicators, the H 2 O 2 _Lac_PRE group showed consistent numerical improvements, but these differences did not reach statistical significance after Bonferroni correction. Conclusion The L. paracasei and Puerariae Radix extract composite effectively alleviates H 2 O 2 -induced oxidative inflammatory damage in zebrafish by enhancing antioxidant defenses, suppressing inflammation, and modulating gut microbiota. These preliminary findings suggest that this probiotic-botanical combination may exert synergistic protective effects against oxidative damage. However, given the methodological limitations including small effective sample sizes, these results should be interpreted as exploratory and hypothesis-generating. Further validation in studies with larger sample sizes and individual-level analyses is warranted before translational applications can be considered.