Novel flavanones with anti-trypanosomal activity isolated from Zambian and Tanzanian propolis samples. (December 2020)

• Record Type: Journal Article
• Authors: Alenezi, Samya S.; Natto, Manal J.; Igoli, John O.; Gray, Alexander I.; Fearnley, James; Fearnley, Hugo; de Koning, Harry P.; Watson, David G.
• Is Part Of: International journal for parasitology. Volume 14(2020)
• Page Start: 201
• Page End: 207
• Publication Date: 2020-12
• Subjects: Trypanosomiasis -- Flavanones -- Tanzania -- Zambia; Parasitic diseases -- Chemotherapy -- Periodicals; Drug resistance -- Periodicals; 616.96061
• DOI: 10.1016/j.ijpddr.2020.10.011
• Languages: English
• ISSNs: 2211-3207

Abstract

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. Graphical abstract: Image 1 Highlights: Two samples of propolis from East Africa display good activity against Trypanosoma brucei and T. congolense. Activity against both wild type and pentamidine and diminazene resistant forms. Two novel flavonoids and one known flavonoid were isolated from Tanzanian and Zambian propolis samples and characterized. Pure isolated compounds not much more active than crude extracts. Repeated observation of anti-protozoal activity shows the importance of propolis indefending the hive against infections.