Antiprotozoal activity of the constituents of Teloxys graveolens.

Antiprotozoal activity-guided fractionation of a methanol extract of the aerial parts of Teloxys graveolens led to the isolation of one coumarinic acid derivative, melilotoside, and five flavonoids, pinocembrine, pinostrobin, chrysin, narcissin and rutin. Among them, melilotoside exhibited the most potent activity toward Entamoeba histolytica and Giardia lamblia (IC(50) 12.5 and 16.8 micro g/mL, respectively). Narcissin showed selectivity against E. histolytlica (IC(50) 17.2 micro g/mL). The results support data for the traditional use of T. graveolens in some gastrointestinal diseases.