The abusive consumption of thermogenic supplements occurs worldwide and deserves special attention due to their use to stimulate weight loss and prevent obesity. Thermogenic formulations usually contain Synephrine (SN) and Caffeine (CAF), stimulating compounds extracted from natural sources, but no genetic toxicology studies have predicted this hazardous combination potential. This study examined the toxicogenomic responses induced by SN and CAF, either alone or in combination, in the human hepatic cell line HepG2 in vitro. SN (0.03–30 μM) and CAF (0.6–600 μM) alone did neither decrease cell viability nor induce DNA damage, as assessed using the MTT and comet assays, respectively. SN (3 μM) and CAF (30–600 μM) were combined at concentrations similar to those found in commercial dietary supplements. SN/CAF at 3:90 and 3:600 μM ratios significantly decreased cell viability and increased DNA damage levels in HepG2 cells. CAF (600 μM) and the SN/CAF association at 3:60, 3:90, and 3:600 μM ratios promoted cell death by apoptosis, as demonstrated by flow cytometry. Similar results were observed in gene expression (RT-qPCR): SN/CAF up-regulated the expression of apoptosis- (BCL-2 and CASP9) and DNA repair-related (XPC) genes. SN/CAF at 3:90 μM also downregulated the expression of cell cycle control (CDKN1A) genes. In conclusion, the SN/CAF combination reduces cell viability by inducing apoptosis, damages DNA, and modulates the transcriptional expression of apoptosis-, cell cycle-, and DNA repair-related genes in human hepatic (HepG2) cells in vitro. These effects can be worrisome to consumers of thermogenic supplements.

生热补充剂的滥用在世界范围内发生，由于它们用于刺激减肥和预防肥胖，因此值得特别关注。生热制剂通常含有辛弗林 (SN) 和咖啡因 (CAF)，它们是从天然来源提取的刺激性化合物，但没有遗传毒理学研究预测这种危险的组合潜力。本研究在体外研究了 SN 和 CAF 在人肝细胞系 HepG2中单独或联合诱导的毒基因组学反应. 单独使用 SN (0.03–30 μM) 和 CAF (0.6–600 μM) 既不会降低细胞活力，也不会诱导 DNA 损伤，分别使用 MTT 和彗星试验进行评估。SN (3 μM) 和 CAF (30–600 μM) 的组合浓度与商业膳食补充剂中的浓度相似。3:90 和 3:600 μM 比率的 SN/CAF 显着降低了 HepG2 细胞中的细胞活力并增加了 DNA 损伤水平。CAF (600 μM) 和 3:60、3:90 和 3:600 μM 比率的 SN/CAF 结合促进了细胞凋亡导致的细胞死亡，如流式细胞术所示。在基因表达（RT-qPCR）中观察到类似的结果：SN/CAF 上调细胞凋亡（BCL-2和CASP9）和 DNA 修复相关（XPC) 基因。3:90 μM 的 SN/CAF 也下调细胞周期控制 ( CDKN1A ) 基因的表达。总之，SN/CAF 组合通过诱导细胞凋亡、损伤 DNA 和调节体外人肝 (HepG2) 细胞中细胞凋亡、细胞周期和 DNA 修复相关基因的转录表达来降低细胞活力。这些影响可能会让产热补充剂的消费者感到担忧。