Anti‐inflammatory and anti‐hyperalgesic effects induced by an aqueous aged black garlic extract in rodent models of ulcerative colitis and colitis‐associated visceral pain

Abstract

Inflammatory bowel disease (IBD) is a morbid condition characterized by relapsing–remitting inflammation of the colon, accompanied by persistent gut dysmotility and abdominal pain. Different reports demonstrated biological activities of aged black garlic (ABG), including anti‐inflammatory and antioxidant effects. We aimed to investigate beneficial effects exerted by ABGE on colon inflammation by using ex vivo and in vivo experimental models. We investigated the anti‐inflammatory effects of an ABG water extract (ABGE) on rat colon specimens exposed to E. coli lipopolysaccharide (LPS), a known ex vivo experimental model of ulcerative colitis. We determined gene expression of various biomarkers involved in inflammation, including interleukin (IL)‐1β, IL‐6, nuclear factor‐kB (NF‐kB), tumor necrosis factor (TNF)‐α. Moreover, we studied the acute effects of ABGE on visceral pain associated with colitis induced by 2,4‐di‐nitrobenzene sulfonic acid (DNBS) injection in rats. ABGE suppressed LPS‐induced gene expression of IL‐1β, IL‐6, NF‐kB, and TNF‐α. In addition, the acute administration of ABGE (0.03–1 g kg−1) dose‐dependently relieved post‐inflammatory visceral pain, with the higher dose (1 g kg−1) able to significantly reduce both the behavioral nociceptive response and the entity of abdominal contraction (assessed by electromyography) in response to colorectal distension after the acute administration in DNBS‐treated rats. Present findings showed that ABGE could represent a potential strategy for treatment of colitis‐associated inflammatory process and visceral pain. The beneficial effects induced by the extract could be related to the pattern of polyphenolic composition, with particular regard to gallic acid and catechin.