A naturally occurring polyphenol found in rice bran could offer a new route to regulating intestinal motility, according to research from Toho University.
The study, published in the Journal of Pharmacological Sciences, found that ferulic acid (FA) suppressed contractions in guinea pig ileal smooth muscle by inhibiting voltage-dependent calcium channels.
The researchers said the findings could provide a basis for investigating FA in dietary approaches targeting disorders associated with abnormal intestinal movement.
Ferulic acid targets intestinal contractions
Ferulic acid is a phenolic compound found in cereals, fruits and vegetables, with rice bran among its recognised dietary sources.
It is already of interest to the functional food and nutraceutical sectors for its antioxidant and other biological activities.
The Toho University team tested FA using guinea pig ileal longitudinal smooth muscle, with the compound reducing contractions induced by several signalling molecules, including acetylcholine, histamine, prostaglandin F2α and serotonin.
The effect was concentration-dependent and reversible, while experiments indicated that FA acted noncompetitively, suggesting it was affecting a mechanism shared by several contractile pathways rather than blocking an individual receptor.
Calcium channel mechanism could have formulation implications
Further testing found that FA reduced potassium chloride-induced intracellular calcium increases in A7r5 smooth muscle cells.
At 1 mM, FA reduced intestinal contractions by approximately 50% and calcium increases by around 35%, supporting a role for voltage-dependent calcium channel inhibition in the effect.
The mechanism could be relevant to gut health products targeting excessive intestinal motility, including symptoms associated with diarrhoea-predominant IBS (IBS-D).
IBS can involve either accelerated or slowed movement through the digestive tract — thus, an ingredient that suppresses contraction would not necessarily be appropriate for every consumer or IBS subtype.
However, the findings remain preclinical. Additionally, the effective FA concentrations used were higher than typical circulating levels following dietary intake and the study did not demonstrate an effect in humans.
Although local exposure within the gastrointestinal tract could be relevant, human studies will be needed to establish whether supplemental FA can meaningfully influence gut motility, as well as appropriate doses and target populations.
