Novel flavanones with anti-trypanosomal activity isolated from Zambian and Tanzanian propolis samples

Samya S Alenezi; Manal J Natto; John O Igoli; Alexander I Gray; James Fearnley; Hugo Fearnley; Harry P de Koning; David G Watson

doi:10.1016/j.ijpddr.2020.10.011

Novel flavanones with anti-trypanosomal activity isolated from Zambian and Tanzanian propolis samples

Int J Parasitol Drugs Drug Resist. 2020 Dec:14:201-207. doi: 10.1016/j.ijpddr.2020.10.011. Epub 2020 Oct 31.

Authors

Samya S Alenezi¹, Manal J Natto², John O Igoli³, Alexander I Gray¹, James Fearnley⁴, Hugo Fearnley⁴, Harry P de Koning⁵, David G Watson⁶

Affiliations

¹ Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, G40RE, Glasgow, UK.
² Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences University of Glasgow, Sir Graeme Davies Building 120 University Place, G12 8TA, Glasgow, Scotland, UK.
³ Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, G40RE, Glasgow, UK; Phytochemistry Research Group, Department of Chemistry, University of Agriculture, PMB 2373, Makurdi, Nigeria.
⁴ BeeVital, Whitby, North Yorkshire, YO22 5JR, UK.
⁵ Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences University of Glasgow, Sir Graeme Davies Building 120 University Place, G12 8TA, Glasgow, Scotland, UK. Electronic address: harry.de-koning@glasgow.ac.uk.
⁶ Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, G40RE, Glasgow, UK. Electronic address: d.g.watson@strath.ac.uk.

Abstract

A bioassay-guided phytochemical investigation of propolis samples from Tanzania and Zambia that screened for activity against Trypanosoma brucei has led to the isolation of two novel flavanones with promising antitrypanosomal activity. The compounds were characterized based on their spectral and physical data and identified as 6-(1,1-dimethylallyl) pinocembrin and 5-hydroxy-4″,4″-dimethyl-5″-methyl-5″-H-dihydrofuranol [2″,3″,6,7] flavanone. The two compounds, together with the propolis extracts and fractions, were assayed against a standard drug-sensitive strain of T. b. brucei (s427 wild-type), multi-drug resistant-resistant T. b. brucei (B48), drug-sensitive T. congolense (1L300) and a derived diminazene-resistant T. congolense strain (6C3), and for toxicity against U947 human cells and RAW 246.7 murine cells. Activity against T. b. brucei was higher than against T. congolense. Interestingly, the Tanzanian propolis extract was found to be more active than its fractions and purified compounds in these assays, with an IC₅₀ of 1.20 μg/mL against T. b. brucei. The results of a cytotoxicity assay showed that the propolis extracts were less toxic than the purified compounds with mean IC₅₀ values > 165.0 μg/mL.

Keywords: Flavanones; Tanzania; Trypanosomiasis; Zambia.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Antiprotozoal Agents*
Flavanones
Humans
Mice
Propolis*
Trypanocidal Agents*
Trypanosoma brucei brucei
Trypanosoma*

Substances

Antiprotozoal Agents
Flavanones
Trypanocidal Agents
Propolis