Formation mechanism, prevention of malignant ascites effusion and reduction of intestinal mucosal irritation of natural microemulsion from Euphorbia lathyris Pulveratum.

Malignant ascites effusion (MAE) is a common complication of advanced malignant tumors with limited treatments. Euphorbia lathyris (EL) has a long history of application in patients with edema and ascites. Herein, we reported for the first time a mode in which EL and EL Pulveratum (PEL) spontaneously formed natural microemulsions (ELM and PELM) without the addition of any carriers and excipients, and found that the protein and phospholipid contained in them encapsulated fatty oil and diterpenoid esters through non-covalent interactions. The denaturation and degradation of protein in PELM resulted in stronger binding of diterpenoid esters to the hydrophobic region of protein, which facilitated the sustained and slow release of diterpenoid esters and improved their bioavailability in vivo, thereby retaining the efficacy of preventing MAE while alleviating the irritation of intestinal mucosa. The mechanism by which PELM retained efficacy might be related to increased feces moisture and urine volume, and decreased expression of AVPR2, cAMP, PKA and AQP3 in MAE mice. And its mechanism of reducing intestinal mucosal irritation was related to decreased cell apoptosis, amelioration of oxidative stress, elevation of mitochondrial membrane potential, and up-regulation of Occludin and Claudin-1 expression in IEC-6 cells. This nano-adjuvant-free natural microemulsions may be a promising therapeutic strategy in the field of phytochemistry for promoting the application of natural and efficient nano-aggregates spontaneously formed by medicinal plants in MAE, and provide a new perspective for advancing the development of the fusion of Chinese herbal medicine and nanomedicine and its clinical translation.