Aqueous cinnamon extract ameliorates bowel dysfunction and enteric 5-HT synthesis in IBS rats

Abstract

Cinnamon protects against irritable bowel syndrome with diarrhea (IBS-D) in humans, but its efficacy and underlying mechanism of action remain poorly understood. Maternally separated (MS) IBS-D rat model and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced post-inflammatory IBS-D rat model are characterized by visceral hyperalgesia and diarrhea. This study used the two models to evaluate the effect of cinnamon extract (CE) on bowel symptoms. The MS rat model was also used to explore its underlying anti-IBS mechanism. cinnamon extract reduced defecation frequency and visceral hyperalgesia in MS rats in a dose-dependent manner and effectively improved visceral hyperalgesia in TNBS rats. The efficacy of cinnamon extract was comparable to the positive drug serotonin receptor 3 (5-HT3) selective antagonist, Ramosetron. Excessive 5-HT, a well-known pathogenic factor for IBS, in the colon and circulation of IBS rats was reduced after cinnamon extract intervention. Both, gene and protein levels of the colonic 5-HT synthetase, Tryptophan Hydroxylase 1 (Tph1), were also decreased in CE-treated IBS rats. In addition, a luciferase assay revealed that cinnamon extract and its major components, catechin, procyanidin B1/2, cinnamic acid, and cinnamyl alcohol, significantly inhibited Tph1 transcription activity in vitro. These findings illustrated that aqueous cinnamon extract partially attenuated bowel symptoms in IBS models by directly inhibiting Tph1 expression and controlling 5-HT synthesis. This provides a scientific viewpoint for the use of cinnamon as a folk medication to treat IBS.

An in vitro study elucidating the synergistic effects of aqueous cinnamon extract and an anti-TNF-α biotherapeutic: implications for a complementary and alternative therapy for non-responders

“…Similar results have been observed for curcumin and many other natural products [21]. In another study, aqueous cinnamon extract (aCE) partially controlled bowel Khedkar and Khan BMC Complementary Medicine and Therapies (2024) 24:131 symptoms by downregulating tryptophan hydroxylase 1 in a model of irritable bowel syndrome [22]. It has also been reported that cinnamon extract acts as a proapoptotic agent, downregulating BCL2, BcL-xL and Survivin [15].…”

Electroacupuncture protects the intestinal mucosal barrier in diarrhea-predominant Irritable Bowel Syndrome rats by regulating the MCs/Tryptase/PAR-2/MLCK pathway

“…The current treatment cannot meet the needs of IBS-D patients, so complementary and alternative medicine (CAM) provides pa-Am J Transl Res 2024; 16(3):781-793 tients with options [9]. Acupuncture, as a complementary and alternative therapy [10], has been practiced in China for thousands of years [11], and is becoming more popular and accepted among the public and health care professionals in the west. IBS is among 63 kinds of common diseases for which acupuncture was recommended by the World Health Organization (WHO) in 1996 [12].…”