Phenylpropanoid-conjugated iridoid glucosides from leaves of Morinda morindoides

Three phenylpropanoid-conjugated iridoid glucosides, acetylgaertneric acid (1), acetyldehydrogaertneroside (2), and dehydrogaertneric acid (10), together with nine known related iridoid glucosides (3–9, 11, and 12), two coumaroyl alkaloids, one benzenoid, and three flavonoid glucosides were isolated from leaves of Morinda morindoides (Rubiaceae). Structures of these isolated compounds were determined using spectroscopic analysis. Compounds 1–18 and previously isolated compounds (19–29) were evaluated for anti-trypanosomal activity against Trypanosoma cruzi Tulahuen strain (trypomastigote and amastigote) together with cytotoxicity against host cells, new-born mouse heart cells. Among them, molucidin (21) and prismatomerin (22) exhibited good anti-trypanosomal activity (IC₅₀ of 4.67 and 5.70 µM, respectively), together with cytotoxicity (CC₅₀ of 2.76 and 3.22 μM, respectively). Compounds 1–18 did not show anti-malarial activity against a chloroquine/mefloquine-sensitive strain of Plasmodium falciparum.