Anti-amoebic Activity of Leaf Extracts and Aporphine Alkaloids Obtained from Annona purpurea

Abstract

Annona purpurea has been traditionally used by indigenous and socioeconomically disadvantaged people to treat infectious and parasitic diseases, including amoebiasis. The goal of this study was to assess the effect of a crude methanolic extract, an alkaloid extract, and aporphine alkaloids from leaves of A. purpurea on the viability of Entamoeba histolytica trophozoite cultures and to identify the mechanism of action. Different concentrations of the extracts and alkaloids purpureine (1), 3-hydroxyglaucine (2), norpurpureine (3) glaziovine (4), and oxopurpureine (5) were added to the cultures, and dead parasites were counted after 24 h using a tetrazolium dye reduction assay and analyzed by flow cytometry. The crude extract did not affect the viability of amoebae, but the alkaloid extract and the derived alkaloid glaziovine (4) had important anti-amoebic activity with an IC50 of 33.5 µM compared to that shown by metronidazole (6.8 µM). The treatments induced significant morphological changes in the trophozoites, and most parasites killed by the alkaloid extract were positive for Annexin V, suggesting that apoptosis was the main mechanism of action. In contrast, glaziovine (4) induced less apoptosis with more amoebic lysis. This study supports the idea that aporphine alkaloids from A. purpurea, mainly (+)-(R)-glaziovine (4), could contribute to the development of new formulations for the treatment of amoebiasis. In addition, X-ray diffraction structural analysis and complete 1H and 13C NMR assignments of (+)-(R)-glaziovine (4) were performed and reported for the first time.

Potent Anti-amoebic Effects of Ibogaine, Voacangine and the Root Bark Alkaloid Fraction of Tabernaemontana arborea

“…In agreement, the half-maximal inhibitory concentration (IC 50 ) values for the alkaloid fraction and both alkaloids were quite similar over cultures treated for 24 h, ranging between 1.4 µg/mL (4.5 µM) for ibogaine and 3.0 µg/mL (8.1 µM) for voacangine ( Table 1 ). IC 50 median values obtained were very close to the metronidazole IC 50 of 1.17 µg/mL (6.8 µM) previously reported by us 30 . Considering the CC 50 values on VERO cells previously reported by our group 21 , the SI obtained for the alkaloid fraction of T. arborea root bark and the isolated alkaloids ibogaine and voacangine were of 10.14, 252.8 and 13.6, respectively ( Table 1 ).…”

“…Studies in India [33] demonstrated that Tabernaemontana spp. roots have also been reported to be anti-amoebic, although * Cytotoxic Concentration 50 previously reported in [21], except for metronidazole, which was previously reported by us in [30]; SI: Selectivity Index (CC 50 / IC 50 ); ND: Not determine no information was provided on effective concentrations for the extracts. In a unique experimental antique report on the effect of ethanolic extracts from 15 Tabernaemontana species from Africa, Asia, and Guyana, on E. histolytica DU strain, it was found that extracts from leaves and root and stem barks of all species showed significant activity killing most amoebae at 4.5 mg/mL, whereas extracts from only three species, stem barks of T. contorta, stem barks of T. penduliflora, and leaves of T. psorocarpa, showed some activity at 0.45 mg/mL [34].…”

“…Viability of E. histolytica trophozoites was performed, as previously described [30]. In brief, trophozoites were seeded in 96-well culture plates at 10 4 cells/100 µL of fresh TYI-S-33 medium.…”

Linearolactone and Kaempferol Disrupt the Actin Cytoskeleton in Entamoeba histolytica: Inhibition of Amoebic Liver Abscess Development

“…Subsequently, an analysis of DNA fragmentation (Figure B) showed 100% and 78% of cells with DNA fragmentation with H 2 O 2 (positive control) and using the IC 50 concentration of 1 , respectively. Similar apoptosis-like processes on E. histolytica have been reported for resveratrol and leaf alkaloid extracts from Annona purpurea . In addition, the giardicidal effect of curcumin was observed through the activation of an apoptotic-like effect .…”

“…Similar apoptosis-like processes on E. histolytica have been reported for resveratrol 18 and leaf alkaloid extracts from Annona purpurea. 19 In addition, the giardicidal effect of curcumin was observed through the activation of an apoptotic-like effect. 20 Apoptosis in Af rican trypanosomes has also been reported as a consequence of the treatment with methanol, butanol, and dichloromethane extracts of the leaves and roots from Zanthoxylum zanthoxyloides 21 and for withanolides derived from Withania aristata.…”