Application of multi-target phytotherapeutic concept in malaria drug discovery: a systems biology approach in biomarker identification.

There is an urgent need for new anti-malaria drugs with broad therapeutic potential and novel mode of action, for effective treatment and to overcome emerging drug resistance. Plant-derived anti-malarials remain a significant source of bioactive molecules in this regard. The multicomponent formulation forms the basis of phytotherapy. Mechanistic reasons for the poly-pharmacological effects of plants constitute increased bioavailability, interference with cellular transport processes, activation of pro-drugs/deactivation of active compounds to inactive metabolites and action of synergistic partners at different points of the same signaling cascade. These effects are known as the multi-target concept. However, due to the intrinsic complexity of natural products-based drug discovery, there is need to rethink the approaches toward understanding their therapeutic effect. This review discusses the multi-target phytotherapeutic concept and its application in biomarker identification using the modified reverse pharmacology - systems biology approach. Considerations include the generation of a product library, high throughput screening (HTS) techniques for efficacy and interaction assessment, High Performance Liquid Chromatography (HPLC)-based anti-malarial profiling and animal pharmacology. This approach is an integrated interdisciplinary implementation of tailored technology platforms coupled to miniaturized biological assays, to track and characterize the multi-target bioactive components of botanicals as well as identify potential biomarkers. While preserving biodiversity, this will serve as a primary step towards the development of standardized phytomedicines, as well as facilitate lead discovery for chemical prioritization and downstream clinical development.

Pharmacological evidence for the folk use of Nefang: antipyretic, anti-inflammatory and antinociceptive activities of its constituent plants.

BACKGROUND: Nefang is a polyherbal anti-malarial composed of Mangifera indica ( MiB and MiL; bark and leaf), Psidium guajava ( Pg ), Carica papaya ( Cp ), Cymbopogon citratus ( Cc ), Citrus sinensis ( Cs ) and Ocimum gratissimum ( Og ) (leaves). Previous studies have demonstrated its in vitro and in vivo antiplasmodial activities, antioxidant properties and safety profile. This study aimed at evaluating the antipyretic, anti-inflammatory and antinociceptive activities of the constituent plants of Nefang which are relevant to the symptomatic treatment of malaria fever. METHODS: Antipyretic activities were determined by the D-Amphetamine induced pyrexia and Brewer's Yeast induced hyperpyrexia methods. Anti-inflammatory activities were investigated using the carrageenan-induced rat paw edema method. Antinociceptive activities were determined by mechanical nociception in the tail pressure and thermal nociception in the radiant heat tail flick and hot plate methods. Data was analysed using the one way ANOVA followed by Neuman-Keuls multiple comparison test. RESULTS: Best percentage inhibition of induced pyrexia (amphetamine/brewer's yeast; p < 0.05) was exhibited by Cc (95/97) followed by Og (85/94), MiL (90/89), MiB (88/84) and Cs (82/89). Cc and Og exhibited comparable activities to paracetamol (100/95). Anti-inflammatory studies revealed paw edema inhibition (%) as follows (p < 0.05): Indomethacin (47), MiL (40), Cp (30), MiB (28) and Og (22), suggesting best activity by MiL. Antinociceptive studies revealed significant (p < 0.01) pain inhibition (%) as follows: Paracetamol (97), Og (113), MiL (108), Pg (84) and MiB (88). Og and MiL exhibited the best activities. CONCLUSION: The results obtained suggest that the constituent plants possess biologically active compounds with antipyretic, anti-inflammatory and antinociceptive activities. These activities are essential in the symptomatic treatment of malaria fever, thereby justifying the folk use of Nefang. This would be useful in its subsequent development for clinical application.

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

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.

Evaluation of the antidiarrheal and antioxidant properties of Justicia hypocrateriformis.

CONTENT: Justicia hypocrateriformis Vahl (Acanthaceae) is used as an herbal remedy for diarrhea in Cameroon folk medicine. OBJECTIVE: This study evaluates the antidiarrheal and antioxidant properties of the aqueous extract of J. hypocrateriformis (JH). MATERIALS AND METHODS: Preliminary phytochemical screening and an acute toxicity testing of the extract were carried out. The antidiarrheal activity of JH extract (100, 250, and 500 mg/kg) was assessed at curative and preventive levels in castor oil-induced diarrhea in mice. The antioxidant activity was measured by ferric reducing antioxidant power (FRAP), total phenolic content, and radical scavenging activity. RESULTS: A high lethal dose (LD50) of 14.35 g/kg obtained in acute toxicity implies the extract is not toxic. Phytochemical screening revealed the presence of phenols, tannins, flavonoids, saponins, anthraquinones, and anthocyanins. JH showed a significant protection against castor oil-induced diarrhea as evidenced by a decrease in the number of defecation and wet stool. JH (100-500 mg/kg, p.o.) produced a non-significant dose-dependent decrease in castor oil-induced intestinal transit in the preventive study. In the curative and in healthy mice study, the decrease was only significant at 500 mg/kg. JH possessed a radical scavenging activity with an IC50 of 9.93 mg/ml compared to 4.90 mg/ml for catechin. JH FRAP of 2703.77 ± 0 mg/g (catechin equiv) and phenolic concentration of 14 169.99 ± 612.39 mg/g (catechin equiv) were also obtained. CONCLUSION: Justicia hypocrateriformis extract possesses antidiarrheal activity supported by its antioxidant potential and phytochemical constituents.