Stool-softening effect and action mechanism of free anthraquinones extracted from Rheum palmatum L. on water deficit-induced constipation in rats

Huijuan Lv; Jingjing Niu; Wenhao Pan; Yudong Wang; Lifang Wang; Meng Wang; Yali Shi; Guifang Zhang; Bandar Al Hamyari; Shaohua Wang; Xuefeng Li; Yanbin Shi

doi:10.1016/j.jep.2023.117336

Stool-softening effect and action mechanism of free anthraquinones extracted from Rheum palmatum L. on water deficit-induced constipation in rats

J Ethnopharmacol. 2024 Jan 30;319(Pt 3):117336. doi: 10.1016/j.jep.2023.117336. Epub 2023 Oct 30.

Authors

Huijuan Lv¹, Jingjing Niu², Wenhao Pan³, Yudong Wang⁴, Lifang Wang⁵, Meng Wang⁶, Yali Shi⁷, Guifang Zhang⁸, Bandar Al Hamyari⁹, Shaohua Wang¹⁰, Xuefeng Li¹¹, Yanbin Shi¹²

Affiliations

¹ School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 730000, China. Electronic address: lvhj20@lzu.edu.cn.
² School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 730000, China. Electronic address: 220220944140@lzu.edu.cn.
³ School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 730000, China. Electronic address: Panwh21@lzu.edu.cn.
⁴ School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 730000, China. Electronic address: ydwang21@lzu.edu.cn.
⁵ School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 730000, China. Electronic address: wanglf21@lzu.edu.cn.
⁶ School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 730000, China. Electronic address: 220220944320@lzu.edu.cn.
⁷ School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 730000, China. Electronic address: shiyl2019@lzu.edu.cn.
⁸ School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 730000, China. Electronic address: zhangguifang97@qq.com.
⁹ School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 730000, China. Electronic address: bandarhmed@gmail.com.
¹⁰ School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 730000, China; Collaborative Innovation Center for Northwestern Chinese Medicine, Lanzhou University, Lanzhou, 730000, China. Electronic address: wangshh@lzu.edu.cn.
¹¹ School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China. Electronic address: lixuefeng@lzu.edu.cn.
¹² School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 730000, China; Collaborative Innovation Center for Northwestern Chinese Medicine, Lanzhou University, Lanzhou, 730000, China. Electronic address: shiyb@lzu.edu.cn.

PMID: 37907143
DOI: 10.1016/j.jep.2023.117336

Abstract

Ethnopharmacological relevance: In traditional Chinese herbal medicine, rhubarb is said to remove accumulation with purgation, clearing heat, and discharging fire. Modern pharmacology has shown that rhubarb extract has a purgative effect when given to experimental animals in an appropriate dose. However, the active components and their mechanism of action are still not clearly defined.

Aim of the study: The current research aimed to evaluate the synergistic stool-softening effects and explore the action mechanism of rhubarb free anthraquinones (RhA) and their monomers on constipation in rats.

Materials and methods: A rat model of water deficit-induced constipation was established to induce constipation, and these rats were treated with RhA and its monomers. ELISA, histopathology, immunohistochemistry, qPCR and Western blotting based on network pharmacology and molecular docking were conducted to explore the possible mechanism of action of RhA and its monomers.

Results: RhA, aloe-emodin, rhein, and chrysophanol showed stool-softening activity, and the combination of aloe-emodin and rhein had the strongest softening effect on faecal pellets. Aloe-emodin, rhein, and chrysophanol significantly increased the serum levels of vasoactive intestinal peptide (VIP), motilin (MTL), and substance P (SP), upregulated the expression of VIP, cyclase-associated protein 1 (CAP1), protein kinase A (PKA), cystic fibrosis transmembrane conductance regulator (CFTR), aquaporin 3 (AQP3), aquaporin 4 (AQP4), and aquaporin 8 (AQP8), decreased the expression of epithelial sodium channel (ENaC) and Na⁺/H⁺ exchanger 3 (NHE3), and reduced the colonic tissue concentration of Na⁺-K⁺-ATPase in the constipated rats. Osmolality of colonic fluid in model rats treated by RhA, aloe-emodin, rhein, and chrysophanol was increased.

Conclusion: Aloe-emodin, rhein, and chrysophanol were the stool-softening components of the RhA extract, and there were certain drug-interactions between the components. RhA upregulated VIP expression, activated the cyclic adenosine monophosphate protein kinase A (cAMP/PKA) pathway, and further stimulated CFTR expression while inhibiting NHE3 and ENaC expression, resulting in a hypertonic state in the colonic lumen. Water transport could then be driven by an osmotic gradient, which in turn led to the upregulation of AQP3, AQP4, and AQP8 expression. In addition, RhA likely improved gastrointestinal motility by increasing serum VIP, SP, and MTL concentrations, thus promoting faecal excretion.

Keywords: AQPs; Rhubarb free anthraquinones; Stool-softening effect; VIP-cAMP/PKA pathway; water deficit-induced constipation.

MeSH terms

Animals
Anthraquinones / pharmacology
Anthraquinones / therapeutic use
Aquaporin 3
Constipation / chemically induced
Constipation / drug therapy
Cyclic AMP-Dependent Protein Kinases
Cystic Fibrosis Transmembrane Conductance Regulator
Emodin*
Molecular Docking Simulation
Plant Extracts / pharmacology
Plant Extracts / therapeutic use
Rats
Rheum*
Sodium-Hydrogen Exchanger 3

Substances

rhein
chrysophanic acid
Cystic Fibrosis Transmembrane Conductance Regulator
Emodin
Sodium-Hydrogen Exchanger 3
Anthraquinones
aloe emodin
Aquaporin 3
Cyclic AMP-Dependent Protein Kinases
Plant Extracts