In Vitro Antileishmanial and Antitrypanosomal Activities of Plicataloside Isolated from the Leaf Latex of Aloe rugosifolia Gilbert & Sebsebe (Asphodelaceae)

Abstract

Trypanosomiasis and leishmaniasis are among the major neglected diseases that affect poor people, mainly in developing countries. In Ethiopia, the latex of Aloe rugosifolia Gilbert & Sebsebe is traditionally used for the treatment of protozoal diseases, among others. In this study, the in vitro antitrypanosomal activity of the leaf latex of A. rugosifolia was evaluated against Trypanosoma congolense field isolate using in vitro motility and in vivo infectivity tests. The latex was also tested against the promastigotes of Leishmania aethiopica and L. donovani clinical isolates using alamar blue assay. Preparative thin-layer chromatography of the latex afforded a naphthalene derivative identified as plicataloside (2,8-O,O-di-(β-D-glucopyranosyl)-1,2,8-trihydroxy-3-methyl-naphthalene) by means of spectroscopic techniques (HRESI-MS, 1H, 13C-NMR). Results of the study demonstrated that at 4.0 mg/mL concentration plicataloside arrested mobility of trypanosomes within 30 min of incubation period. Furthermore, plicataloside completely eliminated subsequent infectivity in mice for 30 days at concentrations of 4.0 and 2.0 mg/mL. Plicataloside also displayed antileishmanial activity against the promastigotes of L. aethopica and L. donovani with IC50 values 14.22 ± 0.41 µg/mL (27.66 ± 0.80 µM) and 18.86 ± 0.03 µg/mL (36.69 ± 0.06 µM), respectively. Thus, plicataloside may be used as a scaffold for the development of novel drugs effective against trypanosomiasis and leishmaniasis.

In vitro antileishmanial evaluation of Vernonia Brachycalyx leaf latex extract against two leishmania species

“…The results obtained in this study are much higher than the results of other similar studies conducted with the same genus of Vernonia on Leishmania aethiopica (Azeb T. et al, 1993). Furthermore, it was higher than that reported for latex extracts of A. rugosifolia (IC50 = 31.21 ± 0.01 µg/ml and IC 50 = 24.5 ± 0.24 µg/ml) (Chemeda et al, 2022) on the promastigote and amastigote stages of the parasite.Although the potency of the tested substances against intracellular amastigotes was lower than that of the reference drug, their low toxicity to THP-1 cells and their high SI represent a great advantage over the reference drug. Compounds with SI values above 20 are ideal candidates for further development of antileishmanial agents (Nwaka S. and Hudson A., 2006).For axenically cultured amastigotes in the present work, the latex extract exhibited a significantly greater SI value than 20.…”

“…Therefore, in this study, the in vitro antileishmanial activity, phytochemical analysis, and in vitro cytotoxicity studies of the 80% methanolic Vernonia brachycalyx latex extract were investigated. [1][2][3]…”

Medicinal plants with promising antileishmanial activity in Ethiopia: A systematic review and meta-analysis

“…1). [38][39][40][41][42][43] Table 1 Summary of included studies in this systematic review and meta-analysis.…”

In vitro antileishmanial activities of hydro-methanolic crude extracts and solvent fractions of Clematis simensis fresen leaf, and Euphorbia abyssinica latex

“…The total amount of live cells correlated with the fluorescence intensities. [ 45 , 46 ] In this study, the level of in vitro activity of reference remedies, the crude extract and its solvent fractions were accepted according to the next criteria: half maximal inhibitory concentration (IC 50 ) < 10 µg/mL, good activity; IC 50 10 to 50 µg/mL, moderate activity; IC 50 50 to 100 µg/mL, low activity; and IC 50 > 100 µg/mL, inactive. [ 47 ] Accordingly, the crude extract and solvent fractions were exposed to antileishmanial activity tests using the promastigote stages of L aethiopica and L donovani .…”