Antitumor Activity of the Ethanolic Extract from Syzygium aromaticum in Colorectal Cancer Xenograft Mice

Background/Objectives: Colorectal cancer (CRC) remains a leading cause of cancer-related mortality worldwide, and the development of effective therapies with improved safety profiles is urgently needed. The hydrodistillation residue extract of Syzygium aromaticum (SA) is rich in phenolic compounds, including ellagic acid and gallic acid, which are known for their antioxidant and anticancer properties. This study aimed to evaluate the anticancer efficacy, safety, and metabolic effects of SA extract in CRC models. Methods: The anticancer activity of SA was investigated using in vitro and in vivo approaches. Human colorectal cancer HCT116-Red-FLuc cells were used to assess cytotoxicity, selectivity, and dose- and time-dependent effects. In vivo efficacy was evaluated in a CRC xenograft mouse model using tumor volume measurement, micro-ultrasound imaging, and bioluminescence analysis. Hematological and blood biochemical parameters were analyzed to assess systemic safety. Untargeted metabolomic profiling was performed to explore metabolic alterations associated with SA treatment. Results: SA inhibited HCT116-Red-FLuc cell proliferation in a dose- and time-dependent manner and demonstrated selective cytotoxicity toward cancer cells, with a selectivity index of 4.41 at 24 h, although selectivity declined with prolonged exposure. In xenograft mice, SA significantly suppressed tumor growth and reduced metastatic incidence. The 500 mg/kg dose (SA500) showed the greatest antitumor efficacy while maintaining normal hematological and biochemical profiles, indicating a favorable safety margin compared with 5-fluorouracil (5FU). The 1000 mg/kg dose (SA1000) induced marked suppression of Ki-67, Bcl-2, and CD31 expression and enhanced apoptosis. Metabolomic analysis identified 44 differential metabolites related to fatty acid, amino acid, and nucleotide metabolism. Conclusions: These findings suggest that SA extract exerts significant antitumor activity against CRC with improved tolerability compared with conventional chemotherapy, supporting its potential as a complementary natural therapeutic candidate.