HPLC-based activity profiling for antiprotozoal compounds in the endemic Iranian medicinal plant Helichrysum oocephalum

In a screening of Iranian plants for antiprotozoal activity a dichlomethane extract from the aerial parts of Helichrysum oocephalum showed in vitro antiprotozoal activity against Plasmodium falciparum and Leishmania donovani, with IC50 values of 4.01 ± 0.50 and 5.08 ± 0.07 μg/mL, respectively. The activity in the extract was tracked by HPLC-based activity profiling, and subsequent targeted preparative isolation afforded 24 compounds, including pyrones 22–24, phloroglucinol derivatives 12–19, and compounds containing both structural motifs (1–11, 20, and 21). Of these, 15 compounds were new natural products. The in vitro antiprotozoal activity of isolates was determined. Compound 3 showed good potency and selectivity in vitro against L. donovani (IC50 1.79 ± 0.17 μM; SI 53).