Synergistic Fat-Reducing Effect of Deoxycholic Acid and Rhein in Lipid-Based Nanoparticles with Reduced Toxicity for Obesity Treatment.

Purpose: Injectable deoxycholic acid (DA) has been approved for removing excess submental fat and is off-label for local adipose tissue reduction. Conventional DA injections fail to control fat reduction and generate severe adverse effects in adjacent non-adipose tissues. We designed squarticles as lipid-based nanoparticles for DA delivery to reduce fat accumulation. Methods: The liquid lipid phase of the squarticles was composed of squalene, which was previously reported to sequester the toxicity of overdosed drugs. Rhein, a natural anti-adipogenic compound, was incorporated into the squarticles for combined fat-lowering. Results: The squarticles had an average diameter of 93 nm and high rhein encapsulation (96%). The nanoparticles were easily internalized into mature adipocytes and were located in the lysosomes. DA induces adipocyte death via apoptosis and necrosis; however, nanoencapsulation can decrease cell death. Compared to free DA, squarticles showed superior mitigation of cytotoxicity against non-targeted cells (skin fibroblasts). Oil Red O staining indicated that squarticles loaded with DA or rhein alone inhibited lipid droplets by 42% and 17%, respectively. DA and rhein worked together in squarticles to further suppress fat accumulation by 50%. Dual administration of DA and rhein to the nanocarriers downregulated adipokines. The intraperitoneal administration of squarticles loaded with DA and rhein significantly decreased body weight, total cholesterol, and adipokine release. Histological analysis revealed that squarticles reduced adipocyte hypertrophy in the groin and epididymis by 11% and 53%, respectively. We examined the toxicity of the combination of DA+rhein in healthy rats that received a dose three-fold higher than that used in the pharmacological assessment. The survival rate of the overdosed DA+rhein increased from 50% to 100% after nanoencapsulation. Free compounds induce ascites, liver size reduction, AST/ALT elevation (1.5-fold), and potassium imbalance in rats. Nanoencapsulation significantly reduced these adverse effects. Conclusion: Our findings highlight the potential of squarticles for treating obesity.