5-Keto-D-Fructose Did Not Induce Structural Chromosomal Aberrations in an In Vitro Mammalian Chromosomal Aberration Test Conducted According to OECD TG 473 Principles

Background: Sweetening ingredients may be consumed broadly across populations; therefore, comprehensive genotoxicity assessment is foundational for safety evaluation. Objective: To evaluate the clastogenic potential of crystalline 5-keto-D-fructose (5-KDF) in cultured human peripheral blood lymphocytes (HPBL) under exposure conditions consistent with OECD Test Guideline 473 principles. Methods: Duplicate HPBL cultures were treated with 5-KDF at 100, 500, and 1,000 μg/mL under three conditions: short exposure (3 h) without metabolic activation (−S9), short exposure (3 h) with metabolic activation (+S9), and continuous exposure (24 h) without metabolic activation (−S9). Vehicle control was dimethyl sulfoxide (DMSO, ≤1% v/v). Positive controls were mitomycin C (MMC, 0.1 μg/mL; −S9) and cyclophosphamide (CP, 10 μg/mL; +S9). Structural chromosomal aberrations were scored in 400 metaphases per treatment group (200 per duplicate culture), and mitotic index (MI) was determined to monitor cytotoxicity. Results: Across all exposure conditions, 5-KDF did not produce statistically significant or biologically relevant increases in the frequency of cells with structural chromosomal aberrations compared with vehicle controls. Aberrant cell frequencies ranged from 0.5% to 0.8% for all 5-KDF treatment groups, comparable to vehicle control values (0.5%). No biologically meaningful MI reductions were observed at concentrations up to 1,000 μg/mL. Positive controls produced strong, expected increases in aberrant cells (17.5–22.0%, p