In vitro activity and mode of action of phenolic compounds on Leishmania donovani

Abstract

Background Leishmaniasis is a disease caused by the protozoan parasite, Leishmania . The disease remains a global threat to public health requiring effective chemotherapy for control and treatment. In this study, the effect of some selected phenolic compounds on Leishmania donovani was investigated. The compounds were screened for their anti-leishmanial activities against promastigote and intracellular amastigote forms of Leishmania donovani . Methodology/Principal findings The dose dependent effect and cytotoxicity of the compounds were determined by the MTT assay. Flow cytometry was used to determine the effect of the compounds on the cell cycle. Parasite morphological analysis was done by microscopy and growth kinetic studies were conducted by culturing cells and counting at 24 hours intervals over 120 hours. The cellular levels of iron in promastigotes treated with compounds was determined by atomic absorption spectroscopy and the effect of compounds on the expression of iron dependent enzymes was investigated using RT-qPCR. The IC 50 of the compounds ranged from 16.34 μM to 198 μM compared to amphotericin B and deferoxamine controls. Rosmarinic acid and apigenin were the most effective against the promastigote and the intracellular amastigote forms. Selectivity indexes (SI) of rosmarinic acid and apigenin were 15.03 and 10.45 respectively for promastigotes while the SI of 12.70 and 5.21 respectively was obtained for intracellular amastigotes. Morphologically, 70% of rosmarinic acid treated promastigotes showed rounded morphology similar to the deferoxamine control. About 30% of cells treated with apigenin showed distorted cell membrane. Rosmarinic acid and apigenin induced cell arrest in the G0/G1 phase in promastigotes. Elevated intracellular iron levels were observed in promastigotes when parasites were treated with rosmarinic acid and this correlated with the level of expression of iron dependent genes. Conclusions/Significance The data suggests that rosmarinic acid exerts its anti-leishmanial effect via iron chelation resulting in variable morphological changes and cell cycle arrest.

Chlorogenic acid acts upon Leishmania donovani arresting cell cycle and modulating cytokines and nitric oxide in vitro

“…Several studies have shown many bioactivities of CGA, which focussed on its anti‐microbial, antipyretic, anti‐inflammatory, hepatoprotective, cardioprotective, neuroprotective and other activities (reviewed in 21). A recent report to screen the antileishmanial role of several phenolic compounds did not show any significant data on CGA except from IC 50 values 22 …”

In vitro Antileishmanial Activity of Some Ethiopian Medicinal Plants

“…For instance, rosmarinic acid tested against L. donovani promastigotes and intracellular amastigotes resulted in altered membrane integrity of the mitochondria and the cells. 26 Flavonoids were also found to exert significant antileishmanial activity against L. donovani . 27 In an attempt to decipher the mechanism of antileishmanial activity of flavonoids, catechins; type of flavonoid were found to form complexes with the parasite cell wall to influence processes requiring cell linking, and hence inhibit the parasite growth.…”

Evaluation of Modulators of cAMP-Response in Terms of Their Impact on Cell Cycle and Mitochondrial Activity of Leishmania donovani

“…Various methods implicated in determining drug susceptibility for Leishmania promastigotes involve monitoring growth by direct OD 600 measurement ( Bhattacharya et al, 2019 ) or by a more sensitive measurement using constitutively reporter protein expression strains like mcherry expressing promastigotes ( Vacchina and Morales, 2014 ). Alternatively redox indicator like alamer blue ( Mikus and Steverding, 2000 ) or MTT ( Antwi et al, 2019 ) is applied, reduction of which depends on metabolic activity. Often there are differences between the levels of responsiveness determined with these methods.…”