Exploring the antimalarial potential of whole Cymbopogon citratus plant therapy

Abstract

Ethnopharmacological relevance

Cymbopogon citratus (lemon grass) has been used in traditional medicine as an herbal infusion to treat fever and malaria. Generally, whole plant extracts possess higher biological activity than purified compounds. However, the antimalarial activity of the whole C. citratus plant has not been experimentally tested.

Aim of the study

To evaluate the antimalarial activity of an herbal infusion and the whole Cymbopogon citratus plant in two experimental models of malaria.

Material and methods

The plant was dried for 10 days at room temperature and was then milled and passed through brass sieves to obtain a powder, which was administered to CBA/Ca mice with a patent Plasmodium chabaudi AS or P. berghei ANKA infection. We analysed the effects of two different doses (1600 and 3200 mg/kg) compared with those of the herbal infusion and chloroquine, used as a positive control. We also assessed the prophylactic antimalarial activities of the whole C. citratus plant and the combination of the whole plant and chloroquine.

Results

The C. citratus whole plant exhibited prolonged antimalarial activity against both P. chabaudi AS and P. berghei ANKA. The low dose of the whole C. citratus plant displayed higher antimalarial activity than the high dose against P. berghei ANKA. As a prophylactic treatment, the whole plant exhibited higher antimalarial activity than either the herbal infusion or chloroquine. In addition, the combination of the whole C. citratus plant and chloroquine displayed higher activity than chloroquine alone against P. berghei ANKA patent infection.

Conclusions

We demonstrated the antimalarial activity of the whole C. citratus plant in two experimental models. The whole C. citratus plant elicited higher anti-malarial activity than the herbal infusion or chloroquine when used as a prophylactic treatment. The antimalarial activity of the whole C. citratus plant supports continued efforts towards developing whole plant therapies for the management of malaria and other infectious diseases prevalent in resource-poor communities.

Introduction

Malaria is a devastating infectious disease that is concentrated in low-income Sub-Saharan African countries where it mainly affects marginalised communities (Omumbo et al., 2013). The high cost of and poor access to antimalarial drugs and the development of drug resistance has increased the problems associated with malaria (Chukwuocha and Dozie, 2011, Onwujekwe and Uzochukwu, 2005). Plants play a noteworthy role in therapeutics and have been the principal source of drugs for many centuries (Phillipson and Wright, 1991b, Zirihi et al., 2005). In malaria-endemic areas, accessible malaria treatments are primarily based on the use of traditional herbal remedies. In fact, most antimalarial drugs, such as quinine, atovaquone, chloroquine (CLQ) and primaquine, are either obtained directly from plants or developed using the chemical structures of plant-derived compounds as templates (Gomez Castellanos et al., 2009, Willcox and Bodeker, 2004). Artemisinin is another antimalarial drug isolated from Artemisia annua, a plant that has been traditionally used for the treatment of malaria in China for over 1000 years. Artemisinin represents a new class of highly effective antimalarial drugs that have positively influenced malaria therapy (de Ridder et al., 2008, Hsu, 2006, Phillipson and Wright, 1991a). However the high demand of artemisinin and the high cost of its chemical synthesis make this drug unaffordable for most individuals in malaria-endemic areas (Barbacka and Baer-Dubowska, 2011, Ro et al., 2006). Emerging resistance to artemisinin, particularly in association with its use in combined therapies, has been reported in Asia and is of major concern (Amaratunga et al., 2014, Fairhurst, 2015). Interestingly, treatment with the whole plant has been shown to overcome parasite resistance and to be even more resilient to the evolution of this resistance than the pure drug in mice (Elfawal et al., 2015). These results demonstrate the need to identify other plants with antimalarial activity, preferably those growing locally in endemic areas, as additional options for effective and sustainable malaria control. Notably, Cymbopogon citratus, a tropical plant belonging to the Poaceae (Gramineae) family, has been used in traditional medicine as an anti-inflammatory, antipyretic, antiprotozoal and particularly antimalarial agent (Adebayo and Krettli, 2011, Avoseh et al., 2015, Ginsburg and Deharo, 2011, Santoro et al., 2007). In fact, the essential oils isolated from C. citratus have been reported to exhibit antimalarial activity in mice in vivo (Akono Ntonga et al., 2014, Tchoumbougnang et al., 2005). C. citratus has been classified as a safe herb for human consumption (Ekpenyong et al., 2015, Koh et al., 2012); however, the antimalarial activity of the whole C. citratus plant has not been experimentally assessed. Thus, we evaluated the antimalarial activity of the whole C. citratus plant compared with that of and herbal infusion. We also tested the whole C. citratus plant antimalarial activity using two different Plasmodium species, P. chabaudi AS and P. berghei ANKA. The whole plant was administered either as a single dose after establishment of parasitaemia or as a prophylactic treatment prior to infection.