Probiotic Potential of <i>Lacticaseibacillus casei</i> Isolated From Traditional Dairy Products and Its Hepatoprotective Effects in <scp>STZ</scp> ‐Induced Diabetic Rats

Type 2 diabetes mellitus is linked to liver dysfunction and gut dysbiosis, and probiotics, especially Lactobacillus strains, are considered potential biotherapeutics for improving metabolic health. In this study, 15 lactic acid bacteria were isolated from traditional dairy products in Northwestern Iran and assessed for probiotic properties, including acid and bile tolerance, aggregation, hydrophobicity, antibacterial activity, and safety. Strain ad1 exhibited high acid (71.13% ± 0.62% at pH 2.5, 3 h) and bile tolerance (74.31% ± 0.65% at 0.3% oxgall, 4 h), strong autoaggregation (69.61%), and broad antibacterial activity, notably against Staphylococcus aureus (21.4 mm inhibition zone). Additionally, it was non-hemolytic and sensitive to all eight tested antibiotics. To evaluate its antidiabetic potential, ad1 was administered to streptozotocin-induced diabetic rats for 4 weeks. Results showed significant reductions in ALT (60.6 ± 1.3 to 45.5 ± 0.8 U/L), AST (93.5 ± 1.0 to 60.1 ± 1.2 U/L), ALP (264.1 ± 34.2 to 191.3 ± 28.2 U/L), and blood glucose (311.9 ± 37.2 to 153.1 ± 36.9 mg/dL, p < 0.05). Histopathological analysis confirmed reduced hepatic damage and steatosis. In conclusion, Lacticaseibacillus casei strain ad1 shows strong probiotic potential, along with hepatoprotective and antihyperglycemic effects, making it a promising candidate for T2DM management.