Bioaccessibility and Absorption of Flavonoid C-glycosides from Abrus mollis Using Simulated Digestion, Caco-2 Cell, and In Situ Single-pass Perfusion Models

Abrus mollis is commonly used as a traditional Chinese medicine for the treatment of liver diseases due to its hepatoprotection and anti-inflammation, but the absorption properties of its main bioactive ingredients remain unclear. Our previous studies verified that the flavonoid C-glycosides, including vicenin-2 (1: ), isoschaftoside (2: ), and schaftoside (3: ), were the major active components in A. mollis for hepatic protection against nonalcoholic fatty liver disease, hepatitis, and hepatic fibrosis. This study investigated the bioaccessibility and transport mechanisms of total flavonoid C-glycoside, as well as vicenin-2 (1: ), isoschaftoside (2: ), and schaftoside (3: ), in A. mollis by simulated digestion and use of the Caco-2 cell model. Moreover, this study attempted to verify their absorption properties by in situ gastrointestinal perfusion in rats. Total flavonoid C-glycoside and 1, 2: , and 3: exhibited similar bioaccessibility of 84.58%, 85.13%, 83.05%, and 81.65% respectively after simulated digestion. The transport of total flavonoid C-glycoside in the Caco-2 cell model increased with the concentration, and the transport showed saturation characteristics with the time and concentration of total flavonoid C-glycoside to a certain degree. The Papp values of total flavonoid C-glycoside and the 3 flavonoid C-glycosides were significantly improved by verapamil, probenecid, and EDTA-Na₂. Their absorption properties in the gastrointestinal tract were consistent with that found in Caco-2 cells, and superior absorption rates were observed in the duodenum and jejunum. The absorption pattern of total flavonoid C-glycoside may involve multiple transport pathways, including active transport, passive diffusion, and the paracellular pathway. TFC was actively pumped out by P-glycoprotein and multidrug resistance-associated protein. These results revealed that the bioaccessibility and intestinal absorption characteristic of total flavonoid C-glycoside were consistent with the 3 major flavonoids.

Modulation of methotrexate-induced intestinal mucosal injury by dietary factors

Methotrexate (MTX)-induced intestinal mucosal injury in animals has been studied to understand how MTX can cause gastrointestinal disorders, but the pathogenesis of gastrointestinal disorders is still uncertain. We have attempted to reveal how dietary factors influence intestinal toxicity due to MTX. Mice were fed normal chow (NC) or a high-fat high-sucrose diet (HFHSD) before oral administration of MTX. While MTX significantly decreased the survival rates of mice fed HFHSD, the intestinal epithelial injury was detected. MTX excretion in the feces of mice fed HFHSD was reduced. Change of diets between NC and HFHSD influences the survival. The survival rates of the mice fed a high-sucrose diet or control diet were higher than those fed HFHSD. Higher survival rates were observed in mice fed a high-fat high-sucrose diet modified (HFHSD-M) in which casein was replaced by soybean-derived proteins. The survival rates of mice treated with vancomycin were lower than those administered neomycin. Microbiome and metabolome analyses on feces suggest a similarity of the intestinal environments of mice fed NC and HFHSD-M. HFHSD may modify MTX-induced toxicity in intestinal epithelia on account of an altered MTX distribution as a result of change in the intestinal environment.

Licorice root extract and magnesium isoglycyrrhizinate protect against triptolide-induced hepatotoxicity via up-regulation of the Nrf2 pathway

Triptolide, the predominant biologically active component of the Chinese herb Tripterygium wilfordii Hook f., possesses numerous pharmacological activities, including anti-inflammatory, anti-fertility, anti-neoplastic, and immunosuppressive effects. However, toxicity and severe adverse effects, particularly hepatotoxicity, limit the clinical application of triptolide. Licorice root extract contains various bioactive compounds and is potent hepatoprotective. Magnesium isoglycyrrhizinate, a magnesium salt of the 18α-glycyrrhizic acid stereoisomer of glycyrrhizic acid, is used clinically in China to treat chronic viral hepatitis and acute drug-induced liver injury. The aim of this study was to investigate the role of the factor erythroid 2-related factor 2 pathway in the protective effects of LE and MIG against triptolide-induced hepatotoxicity. Hepatotoxicity models were established in L-02 cells and rats using triptolide, and the protective effects of LE and MIG were investigated in vitro and in vivo, respectively. LE and MIG significantly protected against triptolide-induced cytotoxicity. Additionally, triptolide decreased the mRNA and protein levels of Nrf2 and down-regulated Nrf2 target genes, including UGT1A, BSEP, and MRP2, while pretreatment with LE and MIG reversed these effects. Finally, Nrf2-involved antioxidant responses were activated in the presence of LE and MIG.

Dipeptide prodrug approach to evade efflux pumps and CYP3A4 metabolism of lopinavir

Oral absorption of lopinavir (LPV) is limited due to P-glycoprotein (P-gp) and multidrug resistance-associated protein2 (MRP2) mediated efflux by intestinal epithelial cells. Moreover, LPV is extensively metabolized by CYP3A4 enzymes. In the present study, dipeptide prodrug approach was employed to circumvent efflux pumps (P-gp and MRP2) and CYP3A4 mediated metabolism of LPV. Valine-isoleucine-LPV (Val-Ile-LPV) was synthesized and identified by LCMS and NMR techniques. The extent of LPV and Val-Ile-LPV interactions with P-gp and MRP2 was studied by uptake and transport studies across MDCK-MDR1 and MDCK-MRP2 cells. To determine the metabolic stability, time and concentration dependent degradation study was performed in liver microsomes. Val-Ile-LPV exhibited significantly higher aqueous solubility relative to LPV. This prodrug generated higher stability under acidic pH. Val-Ile-LPV demonstrated significantly lower affinity toward P-gp and MRP2 relative to LPV. Transepithelial transport of Val-Ile-LPV was significantly higher in the absorptive direction (apical to basolateral) relative to LPV. Importantly, Val-Ile-LPV was recognized as an excellent substrate by peptide transporter. Moreover, Val-Ile-LPV displayed significantly higher metabolic stability relative to LPV. Results obtained from this study suggested that dipeptide prodrug approach is a viable option to elevate systemic levels of LPV following oral administration.