Moringa oleifera Lam. Leaf improves constipation of rats induced by low-fiber-diet: A proteomics study

The leaf of Moringa oleifera Lam., a medicinal and edible herb for thousands of years in Ayurveda, is used as Pancha (na) karma (purgative) during and after the body cleansing process, to treat constipation, reduce cholesterol and body weight. The aim was to investigate the diarrhea effects and possible mechanism of M. oleifera leaves in constipation rats. The hot water extract of M. oleifera leaves (WEMOL) was prepared and analyzed using LC-20AT HPLC system. The constipated rat model was induced by feeding with low fiber diet for 21 days. After oral administration of WEMOL for 7 days, the excretion parameter analysis, gastro-intestinal propulsion, histological analysis by HE and Alcian blue staining, and gastrointestinal hormone in rat's digestive tract through ELISA were used to evaluate the laxative effect of WEMOL. Label-free quantitation (LFQ) with LC-MS/MS, bioinformatics and Western blot were used to discover and verify the signal pathways and key proteins of WEMOL related to diarrhea. The contents of isoquercitrin and astragalin were 2.7 mg/g and 1.7 mg/g, respectively in WEMOL. The stool number, weight, and water content of constipation rats were significantly reduced, indicating model had been established successfully. WEMOL (1.25 and 2.5 g/kg) increased water content of feces and the levels of Gas, MTL, NPY in gastric antrum and VIP, SP in colon of constipation rats, improved the muscle layer thickness and mucin secretion of colon. The proteomics revealed a total of 1731 differential proteins and 9 signaling pathways, WEMOL increased the expression of Vamp2, Gnai3, and Prkacb. The laxative mechanism of WEMOL maybe modulate the signaling pathways mediated by 5-HT and Ach receptors, related to gastrointestinal motility and intestinal fluid secretion. It can be considered as the scientific connotation of Pancha (na) karma of M. oleifera leaves in ayurveda.