Antitrypanosomal and Antileishmanial Activities of Tacca leontopetaloides Tubers and Zanthoxylum zanthoxyloides Stem Bark

Phytochemical screening of extracts of Tacca leontopetaloides tubers, has afforded the isolation of two novel chalcones, tarkalynins A and B, along with taccalonolide A and its 12-propanoate. Screening of Zanthoxylum zanthoxyloides stem bark yielded taraxerol acetate, dihydrochelerythrin and fagaramide. These compounds were obtained through column and thin-layer chromatography and identified using NMR and LC-HRMS. The compounds were tested against Trypanosoma brucei brucei s427 and its multi-drug-resistant clone B48, against T. evansi, T. equiperdum, T. congolense, and against L. mexicana. Cytotoxicity was tested against the human HEK293 cell line. The highest activities were observed with dihydrochelerythrin and fagaramide against T. b. brucei s427 and B48, T. evansi, and L. mexicana with EC50 values of 0.5, 0.9, 0.4, and 1.9 µg/mL and of 4.4, 2.7, 2.7, and 3.3 µg/mL, respectively. In addition, tarkalynin A and taraxerol acetate displayed promising activity against T. equiperdum (EC50 = 7.1 and 9.98 µg/mL, respectively). None of these compounds showed significant cross-resistance with existing trypanocides (RF ≈ 1; P>0.05). The compounds displayed low toxicity to human cells, with most exhibiting no growth inhibition at concentrations of 100 or 200 µg/mL. This report provides further evidence of the potential of natural products for combating parasitic diseases.