Bidirectional Effects of Mao Jian Green Tea and Its Flavonoid Glycosides on Gastrointestinal Motility

Mao Jian Tea (MJT) has been generally consumed as a digestive aid for more than a hundred years in the Shanxi province of China. However, determination of its efficacy still remains elusive. This study investigated the effect of Mao Jian Green Tea (MJGT) on gastrointestinal motility. The biphasic effects of the hydro extracts of MJGT on gastric emptying and small intestinal propulsion of rats were identified in vivo; namely, the low (MJGT_L) and medium (MJGT_M) concentrations promoted gastrointestinal motility (p < 0.05), whereas the high concentration (MJGT_H) showed the opposite effect (p < 0.01). The expression levels of the gastric hormones, GAS, MTL and VIP (p < 0.05) were consistent with the gastrointestinal motility variation, with the exception of MTL in MJGT_H group (p > 0.01). Two flavonoids, eriodictyol (0.152 mg/mL) and luteolin (0.034 mg/mL), and the corresponding glycosides eriodictyol-7-O-glucoside (0.637 mg/mL) and luteolin-7-O-glucoside (0.216 mg/mL), dominated the hydro extracts identified by HPLC and UPLC-ESI-MS. These compounds can regulate the muscle strip contractions isolated from the gastrointestinal tissues. Additionally, the different concentrations also influenced the gut microbiota accordingly characterized by 16S rDNA gene sequencing. The MJGT_L boosted several probiotic bacteria, such as Muribaculaceae (1.77-fold), Prevotellaceae (1.85-fold) and Lactobacillaceae (2.47-fold), and suppressed the pathogenic species such as Staphylococcaceae (0.03-fold) that, conversely, was enriched in the MJGT_H group (1.92-fold). Therefore, the biphasic effect indicated that the dosage of the herbal tea should not be overlooked.