Bioassay-based Corchorus capsularis L. leaf-derived ß-sitosterol exerts antileishmanial effects against Leishmania donovani by targeting trypanothione reductase.

Leishmaniasis, a major neglected tropical disease, affects millions of individuals worldwide. Among the various clinical forms, visceral leishmaniasis (VL) is the deadliest. Current antileishmanial drugs exhibit toxicity- and resistance-related issues. Therefore, advanced chemotherapeutic alternatives are in demand, and currently, plant sources are considered preferable choices. Our previous report has shown that the chloroform extract of Corchorus capsularis L. leaves exhibits a significant effect against Leishmania donovani promastigotes. In the current study, bioassay-guided fractionation results for Corchorus capsularis L. leaf-derived ß-sitosterol (ß-sitosterolCCL) were observed by spectroscopic analysis (FTIR, 1H NMR, 13C NMR and GC-MS). The inhibitory efficacy of this ß-sitosterolCCL against L. donovani promastigotes was measured (IC50 = 17.7 ± 0.43 µg/ml). ß-SitosterolCCL significantly disrupts the redox balance via intracellular ROS production, which triggers various apoptotic events, such as structural alteration, increased storage of lipid bodies, mitochondrial membrane depolarization, externalization of phosphatidylserine and non-protein thiol depletion, in promastigotes. Additionally, the antileishmanial activity of ß-sitosterolCCL was validated by enzyme inhibition and an in silico study in which ß-sitosterolCCL was found to inhibit Leishmania donovani trypanothione reductase (LdTryR). Overall, ß-sitosterolCCL appears to be a novel inhibitor of LdTryR and might represent a successful approach for treatment of VL in the future.

Curative efficacy of purified serine protease inhibitor PTF3 from potato tuber in experimental visceral leishmaniasis.

To overcome the drug toxicity and frequent resistance of parasites against the conventional drugs for the healing of human visceral leishmaniasis, innovative plant derived antileishmanial components are very imperative. Fuelled by the complications of clinically available antileishmanial drugs, a novel potato serine protease inhibitor was identified with its efficacy on experimental visceral leishmaniasis (VL). The serine protease inhibitors from potato tuber extract (PTEx) bearing molecular mass of 39 kDa (PTF1), 23 kDa (PTF2) and 17 kDa (PTF3) were purified and identified. Among them, PTF3 was selected as the most active inhibitor (IC50 143.5 ± 2.4 µg/ml) regarding its antileishmanial property. Again, intracellular amastigote load was reduced upto 83.1 ± 1.7% in pre-treated parasite and 88.5 ± 0.5% in in vivo model with effective dose of PTF3. Protective immune response by PTF3 was noted with increased production of antimicrobial substances and up-regulation of pro-inflammatory cytokines. Therapeutic potency of PTF3 is also followed by 80% survival in infected hamster. The peptide mass fingerprint (MALDI-TOF) results showed similarity of PTF3 with serine protease inhibitors database. Altogether, these results strongly propose the effectiveness of PTF3 as potent immunomodulatory therapeutics for controlling VL.

White jute (Corchorus capsularis L.) leaf extract has potent leishmanicidal activity against Leishmania donovani.

In pursuit of effective, safe and affordable antileishmanial drugs, the current study was designed to explore Corchorus capsularis L. leaf extract (CCEx) as an effective leishmanicidal substitute against Leishmania donovani. The leaf extract displays potent antileishmanial activity against L. donovani promastigotes with an IC50 value of 79.00 ±â€¯0.3 µg/ml. CCEx also significantly induces intracellular reactive oxygen species (ROS) with a concomitant decrease in the level of non-protein thiols in virulent parasites. Additionally, CCEx treatment induces substantial morphological alterations in parasites. Moreover, reagent-based phytochemical analysis of the extract revealed the presence of various phytochemical constituents. Further study is underway to identify the bioactive component(s) or fraction(s) of CCEx through bioassay-guided fractionation.

Serine protease inhibitors rich Coccinia grandis (L.) Voigt leaf extract induces protective immune responses in murine visceral leishmaniasis.

Leishmaniasis is a parasite-mediated tropical disease affecting millions of individuals worldwide. The available antileishmanial chemotherapeutic modalities exhibit adverse toxicity, exorbitant price and advent of drug-resistant parasites. Hence, plant-derived products are an alternative preference for the emergence of novel and effective antileishmanial agents that rejuvenate the host immunity with limited toxicity. The present work is complementary to our previous report that revealed the in vitro antileishmanial and immunomodulatory activity of Coccinia grandis (L.) Voigt leaf extract (Cg-Ex) rich in serine protease inhibitors. Thus, preliminary objectives of the study were to elucidate the leishmanicidal activity and host effector mechanism in Leishmania donovani infected BALB/c mice treated with Cg-Ex. Oral administration of Cg-Ex significantly reduced the spleen and liver parasite burden at dose-dependently. The parasite elimination was associated with generation of ROS and NO that are interrelated with up-regulation of disease-suppressing Th1 cytokines and down-regulation of disease-promoting Th2 cytokines at both protein and mRNA level. Moreover, Cg-Ex augmented the delayed-type hypersensitivity (DTH) response and serum IgG2a level which are correlated with the diminution of parasite burden with no hepatic and renal toxicity. Additionally, histological analysis of spleen depicted the improvement of structural disorganization of white and red pulp after Cg-Ex treatment. Therefore, our intriguing findings have presented the first indication of in vivo antileishmanial efficacy through activation of pro-inflammatory immune responses of the host by a natural plant leaf extract (Cg-Ex) containing serine protease inhibitors which could have a role as a potential immunomodulator against visceral leishmaniasis.

Protective inflammatory response against visceral leishmaniasis with potato tuber extract: A new approach of successful therapy.

The increasing number of drug resistance issue of Leishmania donovani strain to common drugs compels to develop new therapeutics against leishmaniasis with minimal toxicity. In this regard, bioactive phytocomponents may lead to the discovery of new medicines with appropriate efficiency. The important roles of Leishmania proteases in the virulence of Leishmania parasite make them very hopeful targets for the improvement of current remedial of leishmaniasis. As part of a hunt for new drugs, we have evaluated in vivo anti-leishmanial activity of serine protease inhibitor rich fraction (PTEx), isolated by sodium bisulfite extraction from potato tuber. The amastigote load of 25mg/kg body weight/day treated BALB/c mice showed 86.9% decrease in liver and 88.7% in case of spleen. This anti-leishmanial effect was also supported by PTEx induced immunomodulatory activity like acute formation of ROS and prolonged NO generation. The Th1/Th2 cytokine balance in splenocytes of PTEx treated animals was estimated and evaluated by ELISA assay as well as by mRNA expression using RT-PCR. Furthermore, significant survival rate (80%) was observed in PTEx treated hamsters. Thus, from the present observations we could accentuate the potential of PTEx to be employed as a new therapeutics from natural source against L. donovani. This might also provide a novel perception of natural serine protease inhibitor from potato tuber as an alternate approach for the treatment of visceral leishmaniasis.