Various chemical compounds can inflict developmental toxicity when
sufficiently high concentrations are exposed to embryos at the critical stages
of development. Excipients, such as coloring agents and preservatives, are
pharmacologically inactive ingredients that are included in various medications,
foods, and cosmetics. However, concentrations that may adversely affect embryo
development are largely unknown for most excipients. Here, the lowest observed
adverse effect level (LOAEL) to inflict developmental toxicity was assessed for
three coloring agents (allura red, brilliant blue, and tartrazine) and three
preservatives (butylated hydroxyanisole, metabisulfite, and methylparaben).
Adverse impact of a compound exposure was determined using the stem cell-based
in vitro morphogenesis model, in which three-dimensional
cell aggregates, or embryoid bodies (EBs), recapitulate embryonic processes of
body axis elongation and patterning. LOAEL to impair EB morphogenesis was 200
μM for methylparaben, 400 μM for butylated hydroxyanisole, 600
μM for allura red and brilliant blue, and 1,000 μM for
metabisulfite. Gene expression analyses of excipient-treated EBs revealed that
butylated hydroxyanisole and methylparaben significantly altered profiles of
developmental regulators involved in axial elongation and patterning of the
body. The present study may provide a novel in vitro approach
to investigate potential developmental toxicity of common excipients with
mechanistic insights.