Antiprotozoal activity of compounds isolated from Psychotria leiocarpa

Abstract

With an estimated amount of 241 million cases of malaria and 627,000 deaths from it in 2021, malaria remains one of the most important infectious parasitic diseases worldwide [1]. Due to increasing resistance against the drugs currently used to treat this illness, there is an urgent need to find new and more effective antimalarial therapies [2]. Over the years, medicinal plants have been an inspiring source for antimalarial compounds, such as quinine and artemisinin. Our approach to discover new drugs was to explore South American plants used in traditional medicine. The genus Psychotria is one of the most important within the Rubiaceae family and includes about 1200 species. This genus is reported as a source of alkaloids and iridoids, which exhibited psychotropic, anti-inflammatory, antioxidant, antimutagenic, antimicrobial and antiprotozoal activities [3]. The present study focused on the isolation and identification of bioactive compounds from the methanolic extract of the leaves of Psychotria leiocarpa (SisGen Brazil A9C0F2F), and the evaluation of their antiprotozoal activity towards Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum, as well as of their cytotoxicity against rat skeletal myoblast L6 cells. The extract demonstrated an activity against the NF54 strain of P. falciparum (IC50 value of 8.8 µg/mL). Fractionation and isolation combined to LC-HRMS/MS-based dereplication provided 10 compounds including alkaloids, iridoids and phenolic acids. The isolated compounds were tested for their antiprotozoal activity and cytotoxicity to determine their selectivity index and potential for future studies.