Isolation and in vitro antiamoebic activity of iridoids isolated from Kigelia pinnata

Serial dilutions of extracts from the stem bark of Kigelia pinnata were tested for their growth inhibitory effects against Entamoeba histolytica. Butanol extract from Kigelia pinnata stem barks exhibited in vitro antiamoebic activity. Three known iridoids specioside, verminoside and minecoside were isolated, purified and identified by comparing their spectral data with the literature values. These compounds were tested against HK-9 strain of Entamoeba histolytica for their in vitro antiamoebic evaluation and metronidazole was used as reference drug in all the biological experiments. It is found that verminoside has two fold antiamoebic activity as compared to the standard drug while specioside showed comparable activity with metronidazole.