Evaluation of the antitrypanosomal activity, cytotoxicity and phytochemistry of red Brazilian propolis
by Samyah Alanazi, Naif D. Alenzi
Recently, the growth in the consumption of functional foods with potential nutritional and health benefits revealed rapid progress in phytochemical analysis to assure quality and profile the chemical composition. Bee propolis, a gummy exudate produced in beehives after harvesting from different plant species and showed to contain bioactive secondary metabolites with biological importance. The main goal of the current study is to profile the chemical composition of red propolis samples from the Brazilian stingless bee Tetragonula biroi for the first time using HPLC-UV-ELSD and NMR analysis for assignment of the abundant metabolites’ classes as well as extraction and isolation of the major compounds. Column chromatography and size exclusion chromatography were applied for the purification of the major compounds in red Brazilian propolis. Further, testing the antitrypanosomal and cytotoxic activities against Trypanosoma brucei and human leukemia cell lines (U937) was performed. A total of 29 secondary metabolites were identified as two anthocyanins, 6 flavonoids, 8 isoflavonoids, 10 phenolics, two phenolic acids, and one triterpenoid. Two phenolic compounds were purified and identified using 1D and 2D NMR analysis along with MS analysis as liquiritigenin and calycosin. Red Brazilian propolis FB-3 fraction showed the highest inhibitory activity against T. brucei at 1.6 μg/ml, compared to 12.4 μg/ml of the crude extract. The isolated compounds showed moderate activity with an MIC of 8.5 μg/ml for liquiritigenin and 8.7 μg/ml for calycosin. Moreover, FB-3 fraction and calycosin were showed the potent cytotoxic effect with IC50 = 45.1 and 35.8μg/ml, respectively compared to IC50 = 29.5 μg/ml of the standard diminazen. Hence, red Brazilian propolis is rich source of polyphenols with myriad biological importance. Propolis fractions and purified compounds showed moderate antiprotozoal activity and potent cytotoxic activity against human leukemia cell lines.