Black tea extract and its thearubigins relieve the sildenafil-induced delayed gut motility in mice: A possible role of nitric oxide

Abstract

In this study we hypothesize that a standardized black tea aqueous extract (BTE) and thearubigins, its main polyphenolic pigments, will improve sildenafil-induced delay in gastric emptying (GE) and small intestinal transit (SIT) in mice. Twenty groups of mice (n = 8) were given a phenol red meal, and three sets of experiments were performed. In the first and second sets, effects of different concentrations of BTE, thearubigins (TRs), and sildenafil (SLD), alone and in combinations, onGE and SITwere measured. In the third set, influence of Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) pretreatment on effects of these treatments was tested. Black tea extract (3% and 4.5%) and thearubigins (50 and 60 mg/kg) dose-dependently increased GE and SIT, whereas BTE 6% and thearubigins 70 mg/kg did not affect them. Sildenafil dose-dependently reduced both GE and SIT. Combination of metoclopramide, BTE 4.5%, thearubigins 60, or L-NAME with sildenafil (5 mg/kg) reversed its motility-delaying effects. P etreatment with L-NAME followed by BTE 4.5%, thearubigins 60, BTE 4.5% + sildenafil 5, or thearubigins 60 + sildenafil 5 only partially affected the accelerating effects of BTE 4.5% and thearubigins 60. In conclusion, a standardized BTE and its thearubigins improve the sildenafil-induced delayed gut motility in mice. This improvement was partially blocked by L-NAME suggesting a possible role of nitric oxide. Thus, BTE 4.5% or TRs 60 mg/kg solution could be considered a reliever therapy for the sildenafil-induced dyspepsia.