Hydroalcoholic extract of Tagetes minuta L. inhibits inflammatory bowel disease through the activity of pheophytins on the NF-κB signalling pathway

Abstract

Ethno-pharmacological relevance: Species of the genus Tagetes are well known for their anti-inflammatory properties. Tagetes minuta "Huacatay" is an endemic species of South America that has been used in traditional medicine since ancient times as a remedy for stomach and intestinal discomfort.

Aim of the study: The aim of this study is to investigate the anti-inflammatory activity of the aqueous and hydroalcoholic extracts of the Huacatay, identifying the compounds responsible for this activity.

Materials and methods: Anti-inflammatory activity of the compounds, fractions and extracts was evaluated in Hs 746T (stomach), HIEC-6 (intestine) and THP-1 (monocytes peripheral blood) cells by measuring their inhibitory capacity against the NF-κB production.

Results: Aqueous and hydroalcoholic extracts of Tagetes minuta displayed anti-inflammatory activity in vitro, the hydroalcoholic extract being the most active (IC₅₀ between 59.72 and 66.42 μg/mL) in all cell lines. Bio-guided hydroalcoholic extract fractionation led to the isolation and characterisation of two pheophytins, pheophytin a (1) and 13²-hydroxy pheophytin a (2). Both compounds inhibited the production of NF-κB with IC₅₀ values in the low micromolar range, with an IC₅₀ between 12.32 and 16.01 μM for compound 1 and 7.91-9.87 μM for compound 2.

Conclusions: The two pheophytins isolated in this study inhibit the production of NF-κB, thus showing that the traditional anti-inflammatory use of Tagetes minuta can be proved through pharmacological assays. This contributes to understanding the anti-inflammatory activity of the Huacatay extracts and their use in the treatment of stomach and intestinal discomfort.

Keywords: Anti-inflammatory; NF-κB; Pheophytins; TNF-α; Tagetes minuta.