Activity of Compounds from Temperate Propolis against Trypanosoma brucei and Leishmania mexicana

Ethanolic extracts of samples of temperate zone propolis, four from the UK and one from Poland, were tested against three Trypanosoma brucei strains and displayed EC50 values < 20 mu g/mL. The extracts were fractionated, from which 12 compounds and one two-component mixture were isolated, and characterized by NMR and high-resolution mass spectrometry, as 3-acetoxypinobanksin, tectochrysin, kaempferol, pinocembrin, 4 '-methoxykaempferol, galangin, chrysin, apigenin, pinostrobin, cinnamic acid, coumaric acid, cinnamyl ester/coumaric acid benzyl ester (mixture), 4 ',7-dimethoxykaempferol, and naringenin 4 ',7-dimethyl ether. The isolated compounds were tested against drug-sensitive and drug-resistant strains of T. brucei and Leishmania mexicana, with the highest activities <= 15 mu M. The most active compounds against T. brucei were naringenin 4 ',7 dimethyl ether and 4 ' methoxy kaempferol with activity of 15-20 mu M against the three T. brucei strains. The most active compounds against L. mexicana were 4 ',7-dimethoxykaempferol and the coumaric acid ester mixture, with EC50 values of 12.9 +/- 3.7 mu M and 13.1 +/- 1.0 mu M. No loss of activity was found with the diamidine- and arsenical-resistant or phenanthridine-resistant T. brucei strains, or the miltefosine-resistant L. mexicana strain; no clear structure activity relationship was observed for the isolated compounds. Temperate propolis yields multiple compounds with anti-kinetoplastid activity.

Automated summary

Ethanolic extracts of temperate zone propolis from the UK and Poland exhibited anti-trypanosomal activity, with compounds like naringenin 4 ',7-dimethyl ether and 4 '-methoxykaempferol showing the highest activity. Different compounds were isolated and characterized, showing varying levels of activity against drug-resistant strains of T. brucei and L. mexicana, without a clear structure-activity relationship observed. Multiple compounds from temperate propolis have anti-kinetoplastid activity.