# Prunus amygdalus var. amara seed extract enhances the antileishmanial activity of miltefosine

## TL;DR

A seed extract from Prunus amygdalus var. amara boosts the effectiveness of miltefosine against leishmaniasis, a parasitic disease.

## Contribution

The study identifies a new plant-based extract that enhances antileishmanial drug efficacy and reveals novel phytochemicals in the extract.

## Key findings

- The extract inhibits Leishmania donovani proliferation and induces apoptosis in promastigotes and amastigotes.
- Combining the extract with miltefosine significantly enhances antileishmanial activity with reduced IC50 values.
- Phytochemicals like chaulmoogric acid and hydnocarpic acid were identified for the first time in this seed extract.

## Abstract

Leishmaniasis, an infectious disease transmitted via sand flies is caused by the protozoan parasite of Leishmania
spp. The treatment of this disease is quite challenging due to the high cost, resistance, and toxicity of conventional drugs. Various research studies have demonstrated that plant based drug possess least toxicity, anti-inflammatory and anti-oxidant properties. Here, evaluation of anti-leishmanial activity of methanolic Prunus amygdalus var. amara seed extract was conducted and found that it inhibited L. donovani proliferation and cause apoptosis. Moreover, its combinations with miltefosine enhanced antileishmanial effects. GC–MS analysis confirmed the presence of various phytochemicals in the extract that contributed pharmacological efficacy. These findings highlighted the potential of herbal products as a valuable source of new treatments for leishmaniasis.

The antileishmanial effect was determined by promastigote and amastigote assays. Parasite load was evaluated by staining L. donovani-infected macrophages with modified Giemsa stain. Cytotoxicity of seed extract was estimated by MTT (3-(4, 5- dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) assay. In addition, Pro-apoptotic events were inferred using RT-PCR and qRT-PCR. Further characterization of phytoconstituents was evaluated by gas chromatography and mass spectrometry.

The extract promoted a dose-dependent reduction in growth of promastigotes (IC50 = 43.12 ± 3.03 μg/ml) and amastigotes (IC50 = 49.65 ± 3.34 μg/ml). Further, extract in combination with miltefosine showed enhanced antileishmanial activity against both forms of the L. donovani, promastigotes (IC50 = 4.547 ± 1.2 μg/ml) as well as amastigotes (IC50 = 19.54 ± 2.4 μg/ml). Early-stage apoptotic events were also observed in promastigote forms by determining the increased expression of LdMetacaspase and PARP1. The cytotoxic potential on THP-1 differentiated macrophages was assessed and indicated insignificant cytotoxicity of different doses of the extract (CC50 = 799.19 ± 134.59 μg/ml) and in combination with miltefosine (CC50 = 384.16 ± 177.47 μg/ml). Furthermore, the presence of phytocompounds like chaulmoogric acid and hydnocarpic acid was described, for the first time, in Prunus amygdalus var. amara seed extract.

The findings indicated that EPA plays a significant role in combating leishmaniasis and holds promise as a potential treatment for this disease. Moreover, when combined with miltefosine, EPA demonstrated increased effectiveness against leishmaniasis. Therefore, the combination of EPA and miltefosine presents a more promising outlook as a potential therapy for leishmaniasis.

The online version contains supplementary material available at 10.1186/s12906-025-04958-z.