Combination and monotherapy of Leishmania major infection in BALB/c mice using plant extracts and herbicides

Background & objectives: Leishmaniasis is a growing health problem in many parts of the world. Efforts to findnew chemotherapeutics for leishmaniasis remain a priority. This study was carried out to determine the effect ofcombination and monotherapies using plant extracts and herbicides on Leishmania major infection in BALB/cmice.Methods: The herbicides and saponin extract were purchased from Sigma. Roots of Plumbago capensis werecollected from Karura forest, Nairobi, Kenya. Plant extractions were done in KEMRI at Center for TraditionalMedicines and Drugs Research.Results: Lesion sizes after infection of BALB/c mice were similar in all the experimental groups till the onset oftherapeutic treatments (p >0.05). At 15 days post-treatment, significant differences (p < 0.05) were discerned inthe lesion sizes of the BALB/c mice in all the mono- and combined-treated groups. However, the combinedtherapies caused total elimination of the parasites from the lesions and significantly reduced parasite burden inliver and spleen compared to the untreated controls at the end of the experiment.Interpretation & conclusion: The results of this study demonstrate that combination therapy using alternativeadministration of saponin, acriflavine, trifluralin and plumbagin is effective in treating L. major infection inmice. In this regard, an investigation into the efficacy of these combined therapies against other Leishmaniastrains should be explored further. Furthermore, studies with these combination therapies should be done onnon-human primates such as the vervet monkey (Cercopithecus aethiops)

Efficacy of combination therapy using extracts of Aloe secundiflora Eng L and Callistemon citrinus William C. in Leishmania major infected BALB/c mice

Background: Leishmania major causes cutaneous leishmaniasis which leads to painful skin sores in humans. In the current study, efficacy of combination therapy of A. secundiflora and C. citrinus against L. major infected mice treated intra-peritoneally and orally was studied. Pentostam administered intra-peritoneally and phosphate buffered saline intra-peritoneally and orally were used as a controls.Objective: To determine the efficacy of combined therapy of C. citrinus and A. secundiflora extracts in Leishmania major infected BALB/c mice.Design: Experimental-Laboratory based studySetting: Kenya Medical Research Institute (Leishmania Department)Subjects: Eight weeks Male BALB/c MiceResults: The minimum inhibitory concentration (MICs) of aqueous extracts of A. secundiflora (A), and C. citrinus (B) were 2 mg/ml and 5 mg/ml respectively while the IC50 for the same extracts were 467.09μg/ml and 457.88μg/ml respectively. The combination of these extracts at ratio (1:1) supported minimal growth of L. major promastigotes and had IC50 of 58.45μg/ml as compared to MICs of 12.50μg/ml for Pentostam. The combination therapy had Infection rate (IR) of 19% and MI of 52.81% compared to Pentostam (IR=21% and MI=11.64%). The combination therapy reduced the footpad lesion size significantly (P &lt; 0.05) just like the Pentostam control drug and no significant nitric oxide was stimulated. The oral and intra-peritoneal combination treatment reduced spleen amastigotes in mice by 73.46% and 78.12% corresponding to total LDUs of 10.87±0.64 and 8.96±0.82 respectively compared to Pentostam at 94.58% and LDU of 2.22±0.13. The difference between efficacy of Pentostam and that of combined extracts was almost significant (t= 2.653, P= 0.057).Conclusion: The combination therapy was active against L. major parasite, reduced lesion size significantly and did not prevent visceralisation but reduced spleen parasite load significantly

Antileishmanial activity of Aloe Secundiflora plant extracts against Leishmania Major (2013).

Human leishmaniases are a spectrum of diseases caused by protozoan parasites of the genus Leishmania. In this study antileishmanial activity of the methanolic and water leaf extracts from Aloe secundiflora plant were analysed by determining the minimum inhibition concentration (MIC), nitric oxide (NO) production stimulation, infection rates (IR) and multiplication index (MI). Cytotoxicity of these plant extracts was also assessed. The MIC levels of water and methanolic plant extracts, amphotericin B and pentostam were 2000 µg/ml, 1000 µg/ml, 125µg/ml and 250 µg/ml respectively against Leishamnia major promastigotes. This study revealed that water and methanolic plant extracts significantly inhibited the growth of Leishmania parasites (P ? 0.05) as compared to amphotericin B with respect to the parasite infection rates and MIC levels. The IC50 for the water and methanolic plant extracts was 279.488 µg/ml and 42.824 µg/ml respectively. The elevated inhibitory activity observed in this study against Leishmania major parasites provides evidence and basis for their potential use as therapeutic agents against leishmaniasis. Key words: Aloe secundiflora, Plant extracts, Leishmania major and Minimum Inhibition Concentrations (MIC

In vitro antileishmanial activity and phytochemical analysis of Carissa edulis against Leishmania major

Background: However, there is need to carry out scientific studies in order to confirm the medicinal properties of many plants used traditionally. Carissa edulis Forskk. (Gentiales: Apocynaceae) used by local communities for the treatment of various diseases has showed antiviral, antibacterial and antiprotozoal properties although there are no studies demonstrating its antileishmanial activity. Objective: To investigate in vitro antileishmanial activity of extracts of Carissa edulis on promastigote and amastigote forms of Leishmania major. Methodology: Solvent extraction of the stem parts of C. edulis was performed using water, methanol, petroleum ether, dichloromethane and ethyl acetate. Minimum inhibitory concentration (MIC), anti-amastigote and nitric oxide production assays were carried out to demonstrate antileishmanial activity of C. edulis extracts against the two forms of L. major parasite species: promastigote and amastigote. The extracts were also screened for phytochemical constituents present. Cytotoxicity assay was then done to assess their safe use as herbal medicinal products. Results: The C. edulis petroleum ether extract showed the strongest antileishmanial activity against L. major promastigotes (MIC=625μg/ml) with the water, dichloromethane and ethyl acetate extracts recording the weakest activity (MIC=2500μg/ml). The successive methanol extract reduced the number L. major amastigotes by 88.29% compared to the negative control (RPMI). The water (13.37μM), petroleum ether (12.93μM) and successive methanol extracts (12.82μM) produced nitrite values lower than the standard drugs Pentostam® (14.35μM) and Amphotericin B (14.13μM). Discussion: All C. edulis extracts have potential antileishmanial activity against L. major. Preliminary phytochemical screening of these extracts showed presence of alkaloids, terpenoids, phenols, anthraquinones and saponins. These phytochemicals were previously reported to have antileishmanial activity. Therefore, the plant extracts could offer an opportunity to develop cheaper antileishmanial alternatives to the more expensive pentavalent antimonials. Key words: C. edulis, L. major, promastigote, amastigot

Skin parasite landscape determines host infectiousness in visceral leishmaniasis

Increasing evidence suggests that the infectiousness of patients for the sand fly vector of visceral leishmaniasis is linked to parasites found in the skin. Using a murine model that supports extensive skin infection with Leishmania donovani, spatial analyses at macro-(quantitative PCR) and micro-(confocal microscopy) scales indicate that parasite distribution is markedly skewed. Mathematical models accounting for this heterogeneity demonstrate that while a patchy distribution reduces the expected number of sand flies acquiring parasites, it increases the infection load for sand flies feeding on a patch, increasing their potential for onward transmission. Models representing patchiness at both macro- and micro-scales provide the best fit with experimental sand fly feeding data, pointing to the importance of the skin parasite landscape as a predictor of host infectiousness. Our analysis highlights the skin as a critical site to consider when assessing treatment efficacy, transmission competence and the impact of visceral leishmaniasis elimination campaigns.Parasitemia has been considered the main determinant of visceral leishmaniasis transmission. By combining imaging, qPCR and experimental xenodiagnoses with mathematical models, Doehl et al. argue that the patchy landscape of parasites in the skin is necessary to explain infectiousness

Immunity to Lutzomyia intermedia Saliva Modulates the Inflammatory Environment Induced by Leishmania braziliensis

Transmission of Leishmania parasites occurs during blood feeding, when infected female sand flies inject humans with parasites and saliva. Chemokines and cytokines are secreted proteins that regulate the initial immune responses and have the potential of attracting and activating cells. Herein, we studied the expression of such molecules and the cellular recruitment induced by salivary proteins of the Lutzomyia intermedia sand fly. Of note, Lutzomyia intermedia is the main vector of Leishmania braziliensis, a parasite species that causes cutaneous leishmaniasis, a disease associated with the development of destructive skin lesions that can be fatal if left untreated. We observed that L. intermedia salivary proteins induce a potent cellular recruitment and modify the expression profile of chemokines and cytokines in mice. More importantly, in mice previously immunized with L. intermedia saliva, the alteration in the initial inflammatory response was even more pronounced, in terms of the number of cells recruited and in terms of gene expression pattern. These findings indicate that an existing immunity to L. intermedia sand fly induces an important modulation in the initial immune response that may, in turn, promote parasite multiplication, leading to the development of cutaneous leishmaniasis

Transmission blocking vaccine studies in leishmaniasis: I Lipophosphogly can is a promising transmission blocking vaccine molecule against cutaneous leishmaniasis

(East African Medical Journal: 2001 78(2): 84-89

Transmission blocking vaccine studies in leishmaniasis: II Effect of immunisation using Leshmania major derived 63 kilodalton on the course of L. major infection in BALB/c mice

(East African Medical Journal: 2001 78(2): 90-92