Intracellular anti-leishmanial effect of Spergulin-A, a triterpenoid saponin of Glinus oppositifolius

Saswati Banerjee,1,* Niladri Mukherjee,1,* Rahul L Gajbhiye,2 Snehasis Mishra,1 Parasuraman Jaisankar,2 Sriparna Datta,3 Krishna Das Saha1 1Cancer Biology and Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India; 2Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India; 3Department of Chemical Technology, University of Calcutta, Kolkata 700009, India*These authors contributed equally to this workCorrespondence: Krishna Das SahaCancer Biology and Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700032, IndiaTel +91 0 332 499 5810Email krishna@iicb.res.inBackground: Many of present chemotherapeutics are inadequate and also resistant against visceral leishmaniasis (VL), an immunosuppressive ailment caused by Leishmania donovani. Despite the interest in plant-based drug development, no antileishmanial drugs from plant source are currently available. Glinus oppositifolius had been reported in favor of being immune modulators along with other traditional uses. Novel anti-VL therapies can rely on host immune-modulation with associated leishmanicidal action.Objective: Discovery of novel plant-based antileishmanial compound from G. oppositifolius having permissible side effects.Methods: With this rationale, an n-BuOH fraction of the methanolic extract of the plant and obtained triterpenoid saponin Spergulin-A were evaluated against acellular and intracellular L. donovani. Immunostimulatory activity of them was confirmed by elevated TNF-α and extracellular NO production from treated MФs and was found nontoxic to the host cells. Identification and structure confirmation for isolated Spergulin-A was performed by ESI-MS,13C, and 1H NMR.Results: Spergulin-A was found ineffective against the acellular forms while, against the intracellular parasites at 30 μg/mL, the reduction was 92.6% after 72 hrs. Spergulin-A enhanced ROS and nitric oxide (NO) release and changes in Gp91-phox, i-NOS, and pro and anti-inflammatory cytokines elaborated its intracellular anti-leishmanial activity.Conclusion: The results supported that G. oppositifolius and Spergulin-A can potentiate new lead molecules for the development of alternative drugs against VL.Keywords: visceral leishmaniasis, Glinus oppositifolius, spergulin-A, macrophage, immunostimulation, anti-amastigote