Subchronic Oral Toxicity and Genotoxicity Assessment of SCFA 455, a Clostridium butyricum S-45-5 Culture Filtrate Powder

Short-chain fatty acids (SCFAs) support intestinal homeostasis and have been explored for applications in functional foods. SCFA 455 is an SCFA-enriched culture filtrate powder produced from Clostridium butyricum S-45-5. This study evaluated the subchronic oral toxicity and genotoxic potential of SCFA 455 in OECD guideline-compliant studies. Acute oral toxicity up to a dose level of 2000 mg/kg (OECD TG 423), and repeat dose oral toxicity for 90 days with a 4-week recovery period (OECD TG 408) at the dose levels of 0, 1000, 2000, and 4000 mg/kg bw/day, were assessed in Sprague–Dawley rats. No mortality or treatment-related clinical signs were observed. Minor changes in urinalysis, hematology, serum biochemistry, and organ weights were sporadic or lacked a consistent adverse pattern and were not supported by histopathology; therefore, these findings were considered non-adverse. The no-observed-adverse-effect level (NOAEL) was 4000 mg/kg bw/day, the highest dose evaluated under the study conditions. Genotoxicity was assessed using a bacterial reverse mutation test (OECD TG 471), an in vitro chromosomal aberration test (OECD TG 473), and an in vivo micronucleus test in male ICR mice (OECD TG 474). SCFA 455 did not induce gene mutations or chromosomal aberrations in vitro , nor did it induce micronuclei in male ICR mice. Overall, SCFA 455 showed low systemic toxicity and no evidence of genotoxicity, supporting further development of SCFA 455 as a postbiotic candidate and potential functional food ingredient.