Anti-malarial activity of a polyherbal product (Nefang) during early and established Plasmodium infection in rodent models

Abstract

Background: The emerging resistance of Plasmodium species to currently available anti-malarials remains a public health concern, hence the need for new effective, safe and affordable drugs. Natural products remain a reliable source of drugs. Nefang is a polyherbal anti-malarial of the Cameroonian folklore medicine with demonstrated in vitro antiplasmodial and antioxidant activities. It is composed of Mangifera indica (bark and leaf), Psidium guajava, Carica papaya, Cymbopogon citratus, Citrus sinensis, Ocimum gratissimum (leaves). This study aimed at investigating the suppressive, prophylactic and curative activities of Nefang in Plasmodium infected rodent models.

Methods: Systemic acute oral toxicity of Nefang aqueous and ethanol extracts was assessed in mice up to a dose of 5,000 mgkg(-1) body weight. BALB/c mice and Wistar rats were inoculated with Plasmodium chabaudi chabaudi and Plasmodium berghei, respectively, and treated with Nefang, the Mangifera indica bark/Psidium guajava combination and a Psidium guajava leaf aqueous extracts (75, 150, 300 and 600 mgkg(-1) bwt). Their schizonticidal activity was then evaluated using the Peter's 4-day suppressive test). The prophylactic and curative (Rane's Test) activity of Nefang was also evaluated by determining the parasitaemia, survival time, body weight and temperature in pre-treated rodents.

Results: Acute oral toxicity of the extract did not cause any observed adverse effects. Percent suppressions of parasitaemia at 600 mgkg(-1) bwt were as follows (P. berghei/P. chabaudi): Nefang - 82.9/86.3, Mangifera indica bark/Psidium guajava leaf combination extract - 79.5/81.2 and Psidium guajava leaf - 58.9/67.4. Nefang exhibited a prophylactic activity of 79.5% and its chemotherapeutic effects ranged from 61.2 - 86.1% with maximum effect observed at the highest experimental dose.

Conclusion: These results indicate that Nefang has excellent in vivo anti-malarial activities against P. berghei and P. chabaudi, upholding earlier in vitro antiplasmodial activities against multi-drug resistant P. falciparum parasites as well as its traditional use. Hence, Nefang represents a promising source of new anti-malarial agents.

Figure 1

Suppressive activity of Nefang and active solvent extracts on P. berghei infection in rats. Each bar represents the Mean ± SD for each group of rats, n = 3. Neg Con – negative control; Pos Con – positive control; CQ – chloroquine; PYR – pyrimethamine. *Best chemosuppression compared to control.

Figure 2

Suppressive activity of Nefang and active solvent extracts on P. chabaudi infection in mice. Each bar represents the Mean ± SD for each group of rats, n =3. Neg Con – negative control; Pos Con – positive control; *Best chemosuppression compared to control.

Figure 3

Body temperature (Day 0 and Day 4) of Plasmodium infected animals treated with aqueous extract of Nefang and its active components in the 4-day suppressive test: (A) Plasmodium berghei infected rats (B) Plasmodium chabaudi infected mice. *Compared to negative control (Neg Con); #Compared to positive control (Pos Con); Significant difference: * and #p < 0.05. CQ-chloroquine; PYR-pyrimethamine.

Figure 4

Body weight (Day 0 and Day 4) of Plasmodium infected animals treated with aqueous extract of Nefang and its active components in the 4-day suppressive test: (A) Plasmodium berghei infected rats (B) Plasmodium chabaudi infected mice. *Compared to negative control (Neg Con); #Compared to positive control (Pos Con); Significant difference: * and #p < 0.05. CQ-chloroquine; PYR-pyrimethamine.

Figure 5

Prophylactic activity of Nefang against early P . berghei infection in BALB/c mice. *Compared to negative control (Neg Con); #Compared to positive control (Pos Con); Significant difference: p < 0.05. CQ-chloroquine; PYR-pyrimethamine.

Figure 6

Curative effect of Nefang aqueous extract against established P. berghei infection in Wistar rats. Each data point represents the Mean ± SD for each group of rats, n =3. Neg Con-negative control; Pos Con-positive control; CQ-chloroquine; ART- artesunate.

Figure 7

Mean survival time of Wistar rats treated with Nefang aqueous extract during established P . berghei infection. Each bar represents the Mean ± SD for each group of rats, n =3. Neg Con-negative control; Pos Con-positive control; CQ-chloroquine; ART-artesunate.

Figure 8

Effect of Nefang aqueous extract on the body weight of P. berghei infected rats during established infection (Rane’s Test). *Compared to negative control (Neg Con); #Compared to positive control (Pos Con); Significant difference: p < 0.05). CQ-chloroquine; ART-artesunate.

Figure 9

Effect of Nefang aqueous extract on the body temperature of P. berghei infected rats during established infection (Rane’s Test). Each data point represents the Mean ± SD for each group of rats, n =3. Neg Con-negative control; Pos Con-positive control; CQ-chloroquine; ART-artesunate.