Antiprotozoal Activity Against Entamoeba histolytica of Flavonoids Isolated from Lippia graveolens Kunth

Abstract

Amebiasis caused by Entamoeba histolytica is nowadays a serious public health problem worldwide, especially in developing countries. Annually, up to 100,000 deaths occur across the world. Due to the resistance that pathogenic protozoa exhibit against commercial antiprotozoal drugs, a growing emphasis has been placed on plants used in traditional medicine to discover new antiparasitics. Previously, we reported the in vitro antiamoebic activity of a methanolic extract of Lippia graveolens Kunth (Mexican oregano). In this study, we outline the isolation and structure elucidation of antiamoebic compounds occurring in this plant. The subsequent work-up of this methanol extract by bioguided isolation using several chromatographic techniques yielded the flavonoids pinocembrin (1), sakuranetin (2), cirsimaritin (3), and naringenin (4). Structural elucidation of the isolated compounds was achieved by spectroscopic/spectrometric analyses and comparing literature data. These compounds revealed significant antiprotozoal activity against E. histolytica trophozoites using in vitro tests, showing a 50% inhibitory concentration (IC50) ranging from 28 to 154 µg/mL. Amebicide activity of sakuranetin and cirsimaritin is reported for the first time in this study. These research data may help to corroborate the use of this plant in traditional Mexican medicine for the treatment of dyspepsia.

Stevia Genus: Phytochemistry and Biological Activities Update

“…Sakuranetin showed antiprotozoal activity against Leishmania amazonensis , L. braziliensis , L. major , and L. chagasi , with a range of IC 50 values 43–52 µg/mL, as well as against T. cruzi trypomastigotes, with an IC 50 value of 20.17 µg/mL [ 130 ]. Consistent with Quintanilla-Licea et al [ 131 ], compound 40 also presented antiprotozoal activity against Entamoeba histolytica (IC 50 = 44.51 µg/mL).…”

“…Cirsimaritin showed IC 50 values of 3.9 µg/mL, 3.3 µg/mL, and 19.7 µg/mL for L. donovani , T. brucei rhodesiense , and T. cruzi , respectively. According to Quintanilla-Licea et al [ 131 ], compound 29 also presented antiprotozoal activity against Entamoeba histolytica (IC 50 = 154.26 µg/mL).…”

Furanocoumarins from Ruta chalepensis with Amebicide Activity

“…Next, 2 × 10 5 trophozoites of E. histolytica in 5 mL of the PEHPS medium (with the 10% bovine serum added) were inoculated in 13 mm × 100 mm screw cap test tubes and incubated at 36.5 °C for 120 h to establish the growth curve for E. histolytica . Every 24 h, the number of trophozoites was evaluated to determine the medium’s growth parameters [ 53 ]. The procedure was performed in 3 separate assays per triplicate.…”

“…The negative control was an E. histolytica suspension in the PEHPS medium with no extract added. The percentage of inhibition was determined by evaluating the number of dead trophozoites in the samples and the negative controls [ 53 ].…”

“…The percentage of inhibition was determined by evaluating the number of dead trophozoites in the samples and the negative controls. The 50% inhibitory concentration of each sample was determined using a probit analysis, taking into account a 95% confidence level [ 53 ].…”