New triterpenoidal saponins from Koelreuteria paniculata

Bioassay guided fractionation and chemical investigation of the ethanolic extract of the aerial parts of Koelreuteria paniculata Laxm. (Sapindaceae), resulted in the isolation and identification of three new triterpenoid saponins 1-3 named Paniculatosoid A-C, along with eleven known compounds. The structures of the isolated compounds were elucidated using 1D and 2D NMR experiments, HRESIMS, and comparison with literature data. The occurrence of tridesmosidic saponin is reported for the first time from family Sapindaceae, as well as it is rarely found in natural saponins. Compounds 4-13 were evaluated for their antibacterial, antifungal, antimalarial and antileishmanial activities. Compound 12 showed weak antibacterial activity against Escherichia coli with an IC₅₀ value of 101 μM. Compounds 12 and 13 showed antimalarial activity against chloroquine-sensitive (D6) Plasmodium falciparum protozoan with IC₅₀ values of 6.46 and 6.95 μM, and against chloroquine-resistant (W2) Plasmodium falciparum protozoan with IC₅₀ values of 9.34 and 4.18 μM.