Toxicity reduction and water expelling effect preservation of Shizaotang after its toxic members processing with vinegar on rats with malignant pleural effusions

Shizaotang (SZT), consisted of Euphorbia kansui S.L.Liou ex S.B.Ho (EK), Euphorbia pekinensis Rupr. (EP), Daphne genkwa Sieb. et Zucc. (DG，fried) and Ziziphus jujuba Mill. (ZJ), is usually used for treating malignant pleural effusions (MPE), but the toxicity of EK and EP limits its clinical safe application. It was reported that vinegar processing can reduce the toxicity of EK and EP. Whether EK and EP processing with vinegar can cause the reduced toxicity and retained pharmacological effects of SZT, it still remains unknown. Aim of the study: We aimed to evaluate whether using vinegar processed EK and EP would reduce toxicity and preserve water expelling effect of SZT. Network pharmacology and qualitative analysis of SZT/VSZT were used to construct compound-target-pathway network of their effects and toxicity. Pleural fluid weight, urine volume, uric electrolyte, pH, pro-inflammatory cytokines in pleural fluid, serum Renin-Angiotensin-Aldosterone System (RAAS), anti-diuretic hormone (ADH) and intestinal aquaporin 8 (AQP8) protein were used to evaluate the effect mechanisms involved in rats experiments. And liver damage, oxidative damage and HE staining (liver, stomach, and intestine) were used to determine the toxicity. Network pharmacology analysis reviewed inflammation-related pathways of the effect and toxicity of SZT/VSZT: VEGF-PI3K-AKT pathway inhibited MPE by changing the vasopermeability; PI3K-Akt/Mitogen-activated protein kinase (MAPK)/TNF-NF-κB signaling pathway inhibited MPE by up-regulating expression of AQP8 protein. In vivo experiments displayed that SZT/VSZT could reduce pleural fluid, increase urine volume, lower pro-inflammatory cytokines levels and up-regulate AQP8 protein expression significantly (P < 0.05, P < 0.01). In addition, disorders on electrolyte (Na+, K+ and Cl−) and pH were ameliorated (P < 0.05, P < 0.01). The levels of RAAS and ADH were significantly dose-dependently called back (P < 0.01). These findings were partly consistent with the results of network pharmacology analysis. Results of toxicity experiments demonstrated that SZT and VSZT exhibited certain toxicity on normal rats, and VSZT had lower toxicity than that of SZT. Interestingly, SZT and VSZT exerted alleviation effect to the liver damage and oxidative damage on model rats. SZT/VSZT improved MPE by regulating associated inflammation pathways. Besides, compared to SZT, VSZT showed lower toxicity and equivalent expelling MPE effect. This study may provide scientific basis for guiding the clinical application of SZT.