Integrated Analysis of Microbiome and Serum Metabolomics to Understand How Rauvolfia vomitoria Alkaloids Inhibit Colorectal Cancer Growth

Background/Objectives: Rauvolfia vomitoria alkaloids (RVA) exhibited excellent activity against colorectal cancer (CRC) growth in the heterotopic model. However, their antitumor effects in the orthotopic models, as well as the underlying mechanisms related to gut microbiota and serum metabolomics, remain poorly understood. Methods: We performed 16S rRNA sequencing and serum metabolomics analysis in orthotopic CRC-bearing mice following different treatments. Univariate and multivariate logistic regression analyses were used to screen key gut microbes and metabolites associated with RVA treatments. KEGG enrichment analysis was conducted to identify the metabolic pathways modulated by RVAs in vivo. Results: RVA, either alone or in combination with 5-Fluorouracil (5-FU), exhibited a potent inhibitory effect on CRC growth, comparable to intraperitoneally administered 5-FU. In terms of body weight and organ indices, RVA showed lower toxicity compared to 5-FU. Both treatments induced measurable shifts in the gut microbial profiles of CRC mice. Increased abundance of Akkermansia and Lactobacillus and decreased abundance of Enterococcus were found to be associated with RVA monotherapy. The enrichment of Acinetobacter and Mucispirillum in CRC mice was suppressed by the combination treatment. A serum metabolomics study revealed that linoleic acid metabolism and β-oxidation of long-chain fatty acids were modulated by both RVA-containing regimens. Conclusions: These findings demonstrate that oral administration of RVA, either alone or combined with current clinical therapeutic methods, may represent a promising strategy for CRC treatment. Targeted modulation of gut microbiota and fatty acid metabolism may provide promising approaches to hinder CRC progression.