Antileishmanial and immunomodulatory potential of Ocimum sanctum Linn. and Cocos nucifera Linn. in murine visceral leishmaniasis

The role of immunomodulation in the therapeutic treatment of visceral leishmaniasis has gained eminence in view of moderate to severe drawbacks of the currently available drugs like toxicity, drug resistance and prohibitive costs. The potential for modulation of the immune system of many herbal plants can be tapped to address these problems. We conducted the present research study to investigate the antileishmanial and immunomodulatory effects of Ocimum sanctum Linn. and Cocos nucifera Linn. during the progression of visceral leishmaniasis in BALB/c mouse model. The IC₅₀ values of the ethanolic leaf extract of O. sanctum and that of the aqueous husk-fibre extract of C. nucifera against the sodium stibogluconate (SSG) susceptible strain (MHOM/IN/80/Dd8) were found to be 73.3 and 62 µg/ml respectively. On treatment of infected BALB/c mice with the extracts, we observed a reduction in hepatic parasite load by 43.63 % (O. sanctum), 65.42 % (C. nucifera) and 75.61 % (O. sanctum + C. nucifera) at 1st post treatment day (p.t.d.), while at 15th p.t.d., the reduction was 73.61 % (O. sanctum), 76.59 % (C. nucifera) and 94.12 % (O. sanctum + C. nucifera). This was accompanied by an up-scaling of the DTH response, skewing of the humoral response towards Th1 type and hepatoprotection in the form of normalization of liver function tests. Overall, administration of the extracts of these two plants in combination as compared to their administration alone rescued the affected mice from the disease greatly, which can be attributed to their antileishmanial and immunomodulatory activities.