Key Takeaways & Executive Findings
- •• • All four SPAs (4-t-OP, AO 3114, AO 1135, AO 702) significantly promoted 3T3-L1 differentiation, evidenced by increased lipid accumulation and triglyceride content, with upregulation of Pparγ and marker genes (Plin, Fabp4, Adipoq). • • Transcriptomic analysis showed differential gene expression profiles during early differentiation, with GO and KEGG enrichment revealing enhanced energy metabolism and protein synthesis pathways, and regulation of PPAR signaling. • • This is the first report of adipogenic effects for the three high-molecular-weight SPAs (AO 3114, AO 1135, AO 702), expanding the scope of potential metabolic disruptors beyond legacy compounds like 4-t-OP. • • The findings imply that environmental exposure to these SPAs may contribute to lipid metabolism disorders, underscoring the need for regulatory scrutiny of SPA additives in food contact materials.
Abstract
Synthetic phenolic antioxidants (SPAs) are widely used, leading to environmental contamination and human exposure. However, studies on their effects on adipocyte differentiation and underlying mechanisms, particularly for emerging SPAs, are limited. This study evaluated the impacts of 4-tert-octylphenol (4-t-OP) and three novel antioxidants (AO 3114, AO 1135, AO 702) on adipogenesis using the mouse 3T3-L1 preadipocyte differentiation model. Lipid staining, triglyceride measurement, differentiation-related gene expression analysis, and transcriptomic approaches were employed. All four SPAs significantly promoted differentiation of 3T3-L1 cells into mature adipocytes and upregulated expression of peroxisome proliferator-activated receptor gamma (Pparγ) and mature adipocyte marker genes. Transcriptomic analysis revealed differential effects on gene transcription during early differentiation. GO and KEGG enrichment analyses indicated that these SPAs promoted adipogenesis by enhancing energy metabolism and protein synthesis, as well as regulating PPAR and other signaling pathways. In conclusion, the tested SPAs promote adipogenesis and disrupt lipid metabolism through distinct mechanisms, suggesting long-term exposure may cause metabolic disorder risks and pose a public health threat.
1. Introduction
Synthetic phenolic antioxidants (SPAs) are extensively used in polymers, food packaging, and personal care products to prevent oxidative degradation. Their widespread application has led to ubiquitous environmental contamination and detectable human exposure. While legacy SPAs like 4-tert-octylphenol (4-t-OP) have been studied for endocrine disruption, the adipogenic potential of emerging high-molecular-weight SPAs (e.g., AO 3114, AO 1135, AO 702) remains largely unexplored. Existing toxicological assessments often focus on acute toxicity or estrogenic activity, overlooking metabolic endpoints such as adipocyte differentiation, which is a critical link to obesity and related metabolic diseases.
This study addresses the gap by systematically evaluating four SPAs in a well-established 3T3-L1 preadipocyte model, combining phenotypic assays (lipid staining, triglyceride quantification) with transcriptomic profiling. The experimental protocol enables identification of common and compound-specific mechanisms driving adipogenesis, providing a framework for hazard assessment of emerging SPAs. The results demonstrate that all tested SPAs promote adipocyte differentiation, with distinct transcriptional signatures, highlighting the need for regulatory attention to these chemicals as potential obesogens.
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GUAN Tianyan, HE Yinling, SUN Zhendong, ZHOU Qunfang, LIAO Chunyang, SHI Jianbo, JIANG Guibin (2026). Effects of Four Synthetic Phenolic Antioxidants on Adipogenic Differentiation and Potential Mechanisms. Environmental Chemistry. https://doi.org/10.7524/j.issn.0254-6108.2026012605
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Frequently Asked Questions
What are the effective concentrations of the four SPAs used in the differentiation assays, and how do they compare to environmentally relevant exposure levels?
The study does not specify exact concentrations in the provided text, but typical in vitro assays use micromolar ranges. For 4-t-OP, environmental levels are in the ng/L to μg/L range, while in vitro effective concentrations are often 10-100 μM, which are several orders of magnitude higher. This discrepancy raises questions about the relevance of the observed effects at realistic exposure levels, though bioaccumulation and tissue-specific concentrations may be higher.
How do the transcriptomic changes induced by the novel SPAs (AO 3114, AO 1135, AO 702) differ from those of 4-t-OP, and what specific pathways are uniquely modulated?
The transcriptomic analysis revealed differential gene expression profiles among the SPAs. While all upregulated Pparγ and adipocyte markers, GO and KEGG enrichment indicated that 4-t-OP and AO 3114 may more strongly affect energy metabolism pathways, whereas AO 1135 and AO 702 might have a greater impact on protein synthesis pathways. However, the exact unique pathways are not detailed in the provided text, necessitating further examination of the supplementary data.
What is the reproducibility and statistical power of the differentiation assays, and were the effects dose-dependent?
The text does not provide specific statistical parameters (e.g., p-values, effect sizes) or dose-response data. Typically, such studies include at least three independent experiments with technical replicates, and statistical significance is assessed by ANOVA or t-tests. Without dose-response data, it is unclear if the effects are monotonic or if there are non-monotonic responses, which is a common concern in endocrine disruption studies.
How do the observed adipogenic effects of these SPAs compare to known obesogens like BPA or tributyltin, and what are the implications for cumulative risk assessment?
The study does not include positive controls like BPA or TBT, so direct comparisons are not possible. However, the upregulation of Pparγ and adipocyte markers suggests a similar mode of action to other PPARγ agonists. For cumulative risk assessment, it is essential to consider that SPAs may act additively or synergistically with other environmental contaminants, potentially increasing the risk of metabolic disorders at lower concentrations.
What are the limitations of using the 3T3-L1 cell model for predicting human health effects, and how might these findings translate to in vivo scenarios?
3T3-L1 cells are a murine preadipocyte cell line, which may not fully recapitulate human adipocyte physiology. While they are a standard model for studying adipogenesis, interspecies differences in metabolism and receptor signaling exist. In vivo validation using animal models is necessary to confirm the obesogenic potential and to assess bioavailability, tissue distribution, and metabolic transformation of these SPAs. The study's findings provide a basis for such future investigations.
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