Objective Novel self-assembled nanoparticles (RMN-SAN) of Dahuang (Rhei Radix et Rhizoma) and Mudanpi (Moutan Cortex) were prepared by the micro-precipitation method, and their characterization, formation mechanism and anti-colorectal cancer (CRC) efficacy were investigated. Methods The process parameters were optimized through single-factor experiments, and characterization methods such as dynamic light scattering, ζ potential and transmission electron microscopy were performed. The core active components were identified by UPLC-Q-TOF-MS, and the self-assembly mechanism of RMN-SAN was revealed by FTIR and UV spectroscopy. The in vitro CT26 cell experiments and in vivo tumor-bearing mouse models were used to verify its anti-CRC efficacy. Results The optimized preparation method for RMN-SAN involves taking 10 g each of Rhei Radix et Rhizoma and Moutan Cortex, adding 10 times their volume of water, soaking for 30 min, and refluxing for 0.5 h, followed by filtration. The residue is then refluxed with 8 times its volume of 70% ethanol for 0.5 h and filtered again. The two extracts are combined, magnetically stirred at 600 r/min and 25 ℃ for 30 min, and the alcohol is removed by rotary evaporation at 60 ℃, concentrating to a final concentration of 0.2 g/mL. The solution is subjected to gradient centrifugation (4 ℃, 6 000, 8 000, and 10 000 r/min, each for 10 min), followed by dialysis (cut-off molecular weight 3 500) for 12 h, yielding the final product. The results showed that the average particle size of the optimized RMN-SAN was (109.30 ± 4.20) nm, the PDI was 0.353 ± 0.009, and the ζ potential was (-24.5 ± 1.3) mV, presenting a uniform spherical structure. Five core components such as rhein, aloe-emodin, sennoside B, paeonol, and paeoniflorin were identified, and their self-assembly was driven by hydrogen bonds and π-π stacking interactions, which was verified by molecular docking. The in vitro experiments confirmed that RMN-SAN could inhibit the proliferation of CT26 cells in a concentration-dependent manner, induce apoptosis and block the cell cycle at the G₁ phase. In the in vivo experiments, the tumor suppression effect of the high-dose RMN-SAN group (6.0 g/kg) was significantly higher than that of the traditional decoction group, and it could regulate the levels of immune and inflammatory factors more efficiently. Conclusion This study enabled the utilization of the therapeutic advantages of traditional Chinese medicine through modern processing, providing new ideas for the optimization of the preparation of self-assembled nanoparticles of traditional Chinese medicine, and also providing an efficient and stable new formulation for the treatment of CRC with traditional Chinese medicine.

Rhei Radix et Rhizoma  /  Moutan Cortex  /  herb pair  /  novel self-assembled nanoparticles  /  microprecipitates  /  anti-colorectal cancer  /  UPLC-Q-TOF-MS  /  rhein  /  aloe-emodin  /  sennoside B  /  paeonol  /  paeoniflorin  /  π-π stacking