Metabolomics approach to serum biomarker for laxative effects of red Liriope platyphylla in loperamide-induced constipation of SD rats

Abstract

Red Liriope platyphylla (RLP) is a known herbal medicine used in the treatment of some chronic diseases including constipation, neurodegenerative disorders, diabetes and obesity. To determine and characterize putative biomarkers that predict the laxative effects induced by RLP treatment, alteration of endogenous metabolites was measured in the serum of loperamide (Lop)-induced constipation rats after administration of RLP extract (EtRLP) using ¹H nuclear magnetic resonance (¹H NMR) spectral data. The urine volume and amounts, and weights and water contents of stools were significantly recovered in the Lop + EtRLP treated group as compared to the No group, whereas body weight and food intake maintained constant levels. Also, significant recoveries in the thickness of mucosa and muscle were detected in the colon of the Lop + EtRLP treated group. Furthermore, pattern recognition showed absolutely different clustering of the serum analysis parameters when comparing the Lop treated group and Lop + EtRLP treated group. Of the 33 endogenous metabolites, 7 amino acids (alanine, arginine, glutamate, glutamine, glycine, threonine and valine) and 8 endogenous metabolites (betaine, creatine, glucose, taurine, ethanol, lactate, glycerol and succinate) were dramatically increased in the Lop + EtRLP treated SD rats. These results provide the first evidence pertaining to metabolic changes in the constipation rats treated with Lop + EtRLP. Additionally, these findings correlate with changes observed in 15 metabolites during the laxative effects of EtRLP.

Keywords: Constipation; Laxative effects; Metabolomics; Red Liriope platyphylla; Serum.

Fig. 1

Feeding behavior and stool parameters after EtRLP treatment. a-c Three parameters related with the feeding behavior were measured in SD rats of subset groups in duplicate. d-e Three stool parameters were measured in SD rats of subset groups in duplicate. Five to six rats per group were assayed in duplicate by parameter counting. The data are reported as the mean ± SD. * indicates p < 0.05 compared to the NO group. # indicates p < 0.05 compared to the Lop + Veh treated group

Fig. 2

Histological structure of EtRLP treated colon. H&E-stained sections of transverse colons collected from No, EtRLP, Lop + Vehicle, Lop + EtRLP and Lop + BisaC treated rats were observed at two different magnifications (100x and 400x) using a light microscope. Five to six rats per group were assayed in triplicate, after H&E staining. The data are reported as the mean ± SD. * indicates p < 0.05 compared to the NO group. # indicates p < 0.05 compared to the Lop + Veh treated group

Fig. 3

Spectral analysis of metabolomic pattern using PCA and OPLS-DA. a Global profiling of loperamide treatment in serum samples. Targeted profiling of loperamide treatment in serum samples. b The VIP shows the major metabolites contributing to cluster separation. The data are reported as the mean ± SD

Fig. 4

Concentration of 7 amino acids and 8 metabolites after EtRLP administration in SD rats. The pathway relates to the endogenous metabolites that are altered after Lop + EtRLP treatment, while the box shows the altered metabolites. The data are reported as the mean ± SD

Fig. 5

Serum biochemical analysis for glucose a and creatine b concentration. After the collection of serum, their levels were measured using an automatic biochemical analyzer. Five to six rats per group were assayed in duplicate by parameter counting. The data are reported as the mean ± SD. * indicates p < 0.05 compared to the NO group. # indicates p < 0.05 compared to the Lop + Veh treated group