A novel galacto-glycerolipid from Oxalis corniculata kills Entamoeba histolytica and Giardia lamblia

Abstract

Oxalis corniculata is a naturally occurring weed that has been used in traditional medicine for the cure of dysentery and diarrhoea in India. One of the common causes of dysentery is due to infection by the protist pathogen Entamoeba histolytica. Bioactivity profiling of extracts from O. corniculata identified several compounds that showed anti-amoebic activity in axenic cultures of E. histolytica. These were characterized by NMR, IR and mass spectrometry as -i) Oc-1: a mixture of saturated fatty acids C₂₄-C₂₈, ii) Oc-2: a mixture of long chain alcohols C₁₈-C₂₈ and iii) Oc-3: a single compound which was a galacto-glycerolipid (GGL). Of the different compounds that were obtained, the strongest anti-amoebic activity was found in GGL. Addition of GGL to E. histolytica xenic cultures containing other microbial flora from the large intestine did not affect its anti-amoebic activity. Amoebicidal concentrations of GGL had no effect on intestinal microbial flora or on the mammalian cell line HEK-293. GGL was also found to be equally effective in killing another protist pathogen- Giardia lamblia - that causes diarrhea in humans. The importance of this study is based on the identification of novel natural products and the possibility of developing these compounds as active agents to treat at least two pathogenic parasitic intestinal infections endemic to tropical regions.