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, on GE and SIT were 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. Pretreatment 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.

Mentha longifolia protects against acetic-acid induced colitis in rats

“…Similar results were previously reported with other natural products e.g., lesser H. pylori eradication rate with Nigella sativa 3 g/d than that with 2 g/d (Salem et al, 2010), lesser antibacterial effect of a high concentration of Nigella sativa extract than that with a low concentration (Morsi, 2000), and loss of the prokinetic effects of both black tea extract and thearubigines in high doses (Murad and Abdallah, 2014).…”

Production Mechanisms of Black Tea Polyphenols

“…In considering the biological activities of TRs, the inhibition of digestive enzymes that are related to lifestyle disease, such as lipase and amylase, is an important function of black tea. 96) In addition, protection against acetaminophen-induced hepatic and renal injury, 113) improvement of the sildenafil-induced delayed gut motility, 114) inhibition of benzo[a] pyrene-induced mutagenicity and genotoxicity, 115) counteracting the effects of botulinum neurotoxins, 116) and a protective effect against the neuromuscular blocking action of botulinum neurotoxins 117) have been reported. Furthermore, recent studies have shown that black tea high-molecular-weight polyphenol fraction increases mitochondrial membrane potential and stimulates exercise training-induced improvement of endurance capacity in mice.…”

Effects of polysaccharides and polyphenolics fractions of Zijuan tea (Camellia sinensis var. kitamura) on α‐glucosidase activity and blood glucose level and glucose tolerance of hyperglycaemic mice

“…The theaflavins, thearubigins and theabrownin fractions were extracted by the methods described in previous studies (Gong et al, 2010;Murad & Abdallah, 2014). The supernatant obtained in the above-mentioned previous step was extracted with chloroform (1:1, v/v) to remove caffeine.…”