Reduction of Inflammation and Colon Injury by a Spearmint Phenolic Extract

What is it about?

Inflammatory Bowel Diseases (IBD) encompasses both Crohn’s Disease and Ulcerative Colitis, known to be connected to an enlarged risk for developing colorectal cancer (CRC). Spearmint (Mentha spicata L.) is a Mediterranean plant used as an aromatic agent, and studies have mainly focused on the essential oil suggesting anti-inflammatory activity. This work aimed to perform a preliminary screening of the in vivo anti-inflammatory effects of a spearmint phenolic extract in an acute inflammation model, in a chronic inflammation model of colitis, and also study the effects in vitro on a colon cancer model. Spearmint extract was administered to rats of a paw oedema model (induced by carrageenan) and to mice from a TNBS-induced colitis model in parallel with studies using HT-29 CRC cells. Administration of the extract led to reduced paw inflammation, reduction of colon injury and inflammation, with attenuation of histological markers, and reduction of iNOS expression. It repressed the in vitro movement of HT-29 cells in a wound healing assay. Conclusions: These findings suggest that spearmint extract exhibits acute and chronic anti-inflammatory activity and is able to inhibit migration of cancer cells, suggesting a potential role in the supplementary therapy of IBD patients.

Featured Image

Photo by Alexander Schimmeck on Unsplash

Photo by Alexander Schimmeck on Unsplash

Why is it important?

Spearmint is frequently ingested as an aromatic herb in food and tea infusions. Phenolic compounds are the major components of spearmint extract and given the relevance of RA in inflammatory processes, its high concentration in the extract might be one of the main reasons for the beneficial effects observed. Preliminary screening of the extracts’ antioxidant and anti-inflammatory properties suggested that it might be beneficial in an experimental model of IBD. Indeed, findings showed that the administration of a spearmint phenolic extract attenuated the severity of inflammation associated with experimental colitis, including a decrease of the mortality rate of 15.3%. The inhibition of iNOS expression appears to be relevant for the effects observed with the spearmint extract, which may reduce the inflammation associated to colitis along with a possible pleiotropic effect in other inflammatory and oxidative pathways. The mechanisms involved in the impairment of the inflammatory process in this experimental model of colitis may also be responsible for the inhibitory effects exhibited by the extract in the migration/invasion properties of HT-29 colorectal cancer cells. Studies focusing on the characterization of the chemical composition of several spearmint infusions obtained by different methods and spearmint strains have shown that the intake of RA by this route (equivalent to three cups/300 mL every day) would range between 50 and 560 mg/day, which is half of the dose obtained with a single administration (980 mg) of the extract when translated to a 70 kg adult. Therefore, this extract yielded a high concentration of RA, thus being a good candidate for further research and development of formulations intended to provide a dose of RA and other phenolic compounds with potential complementary therapeutic effects. Given the role of inflammatory processes in the progression of colorectal cancer and the important link between inflammation and cancer, spearmint extract might be a useful pharmacological tool for the adjuvant management of IBD patients and may open up new research opportunities in the impairment of colon cancer progression.

Perspectives