Racemoside A, an anti-leishmanial, water-soluble, natural steroidal saponin, induces programmed cell death in Leishmania donovani

Abstract

Leishmaniasis remains a major health problem of the tropical and subtropical world. The visceral form causes the most fatalities if left untreated. Dramatic increases in the rates of infection and drug resistance and the non-availability of safe vaccines have highlighted the need for identification of novel and inexpensive anti-leishmanial agents. This study reports that racemoside A, a water-soluble steroidal saponin purified from the fruits of Asparagus racemosus, is a potent anti-leishmanial molecule effective against antimonial-sensitive (strain AG83) and -unresponsive (strain GE1F8R) Leishmania donovani promastigotes, with IC 50 values of 1.15 and 1.31 mg ml "1 , respectively. Incubation of promastigotes with racemoside A caused morphological alterations including cell shrinkage, an aflagellated ovoid shape and chromatin condensation. This compound exerts its leishmanicidal effect through the induction of programmed cell death mediated by the loss of plasma membrane integrity as detected by binding of annexin V and propidium iodide, loss of mitochondrial membrane potential culminating in cell-cycle arrest at the sub-G 0 /G 1 phase, and DNA nicking shown by deoxynucleotidyltransferase-mediated dUTP end labelling (TUNEL). Racemoside A also showed significant activity against intracellular amastigotes of AG83 and GE1F8R at a 7-8-fold lower dose, with IC 50 values of 0.17 and 0.16 mg ml "1 , respectively, and was non-toxic to murine peritoneal macrophages up to a concentration of 10 mg ml "1 . Hence, racemoside A is a potent anti-leishmanial agent that merits further pharmacological investigation.

The 8-Aminoquinoline Analogue Sitamaquine Causes Oxidative Stress in Leishmania donovani Promastigotes by Targeting Succinate Dehydrogenase

“…DNA content was analyzed by flow cytometry as described previously (12). Briefly, parasites (1 ϫ 10 7 promastigotes/ml) were incubated with or without 50 and 100 M SQ in culture medium for 24 h at 28°C, washed twice with PBS, fixed with ice-cold methanol by incubation for 3 min on ice, resuspended in 500 l of PBS containing 1 g/ml PI and 100 g/ml RNase A, and incubated for 1 h in the dark at room temperature.…”

In vitro anti-leishmanial activity of Satureja hortensis and Artemisia dracunculus extracts on Leishmania major promastigotes

“…In the present study, the fleawort extract showed no obvious anti-leishmanial activity, while the two others, namely the tarragon and savory extracts, showed a significant anti-leishmanial effect. Studies showed that a number of herbs have moderate to strong anti-leishmanial activity (Dutta et al 2007;Cruz-Ede et al 2013;Rodrigues et al 2014;Azizi et al 2014;Nosratabadi et al 2015). Some authors found that a few plants can be used as an adjuvant in vaccination against Leishmania spp.…”

In Vitro Antileishmanial Activity of Falcaria vulgaris Fractions on Leishmania major

“…At each interval (6,24,48, and 72 hours), 10 µL of each sample was gently mixed with 10 µL of 0.4% trypan blue on a glass slide. The mortality of parasites was determined by counting the number of alive (not stained) and dead (stained) promastigotes according to the following formula (1).…”