Abstract / Summary
Leishmaniasis is a widespread parasitic disease with cutaneous, mucocutaneous, and visceral forms. Despite longstanding recognition, effective treatment remains a challenge due to limitations of current chemotherapies, including toxicity and resistance. Natural toxins, particularly those from venomous organisms, have emerged as promising alternatives. This study investigated anti-leishmanial effect of crude honey bee venom ( Apis mellifera ) and its phospholipase A2 fraction (bvPLA2) against Leishmania major promastigotes and amastigotes. Crude bee venom, purified bvPLA2, Glucantim® were tested on L. major promastigotes, intracellular amastigotes, and macrophages (RAW 264.7). Cytotoxicity and anti-parasitic activity were evaluated by MTT assay at different time and amount intervals. The CC 50 and IC 50 values were calculated using GraphPad Prism. Crude bee venom exhibited high toxicity towards macrophages, with a CC 50 of 2.17 µg/mL and complete mortality at later time points (48 and 72 h). In contrast, bvPLA2 showed lower cytotoxicity (CC 50 = 45.89, 36.22 & 86.01 µg/mL at 24, 48, and 72 h, respectively). Notably, increased MTT absorbance values were recorded at the first four bvPLA2 concentrations after 48 h. Anti-leishmanial activity of both compounds seems dose-dependent. The inhibitory effect on the promastigote stage was observed from the lowest concentration at two tested time points. In case of amastigote stage, crude bee venom showed non-significant inhibitory effect at lower concentrations, whereas bvPLA2 exhibited significant inhibitory activity at both incubation times. At higher concentrations, viability percentage decreased more in bee venom treatment. Furthermore, when the inhibitory effects at constant concentrations were compared between 24 and 48 h, it either decreased or remained non-significant after 48 h. At 48 h, IC 50 values (µg/mL) for crude venom were 4.89 (promastigotes) and 6.07 (amastigotes), while bvPLA2 showed IC 50 values of 5.76 and 9.03, respectively. The IC 50 values for both treatments were significantly lower than Glucantim® ( P < 0.0001). Results demonstrate the ability of both compounds to inhibit the growth of L. major promastigote and amastigote forms. To the best of our knowledge, this is the first report of anti-leishmanial activity of bvPLA2, which may open new insights for future studies on the pharmacological and biotechnological potential of the compound.