Protus Arrey Tarkang

In Vitro Antiplasmodial Activities and Synergistic Combinations of Differential Solvent Extracts of the Polyherbal Product, Nefang

Nefang, a polyherbal product composed of Mangifera indica (bark and leaf), Psidium guajava, Carica papaya, Cymbopogon citratus, Citrus sinensis, and Ocimum gratissimum (leaves), is a potential therapy against P. falciparum malaria. In vitro antiplasmodial activities of its constituent solvent extracts were analyzed on CQ-sensitive (3D7) and multidrug resistant (Dd2) P. falciparum strains. The interactions involving the differential solvent extracts were further analyzed using a variable potency ratio drug combination approach. Effective concentration 50 (EC50) values were determined by nonlinear regression curve-fitting of the dose-response data and used in calculating the fractional inhibitory concentration 50 (FIC50) and combination indices (CI) for each pair. The derived EC50 values (3D7/Dd2, μg/mL) are Nefang-96.96/55.08, MiB-65.33/34.58, MiL-82.56/40.04, Pg-47.02/25.79, Cp-1188/317.5, Cc-723.3/141, Cs-184.4/105.1, and Og-778.5/118.9. Synergism was obtained with MiB/Pg (CI = 0.351), MiL/Pg (0.358), MiB/Cs (0.366), MiL/Cs (0.482), Pg/Cs (0.483), and Cs/Og (0.414) when analyzed at equipotency ratios. Cytotoxicity testing of Nefang and the solvent extracts on two human cell lines (Hep G2 and U2OS) revealed no significant toxicity relative to their antiplasmodial activities (SI > 20). Taken together, our data confirm the antimalarial activities of Nefang and its constituent plant extracts and identified extract pairs with promising synergistic interactions for exploitation towards a rational phytotherapeutic and evidence-based antimalarial drug discovery.

Evaluation of the antidiarrheal and antioxidant properties of Justicia hypocrateriformis

Abstract 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.

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

BackgroundThe 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.MethodsSystemic 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.ResultsAcute 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.ConclusionThese 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.

Costus afer Possesses Carbohydrate Hydrolyzing Enzymes Inhibitory Activity and Antioxidant Capacity In Vitro

Diabetes mellitus is a metabolic disorder of glucose metabolism which correlates with postprandial hyperglycemia and oxidative stress. Control of blood glucose level is imperative in the management of diabetes. The present study tested the hypothesis that Costus afer, an antihyperglycemic medicinal plant, possesses inhibitory activity against carbohydrate hydrolyzing enzymes. Hexane, ethyl acetate, methanol, and water extracts were prepared from the leaf, stem, and rhizome of C. afer and subjected to phytochemical screening, assayed for α-amylase and α-glucosidase inhibitory activities and antioxidant capacity (determined by total phenolic and total flavonoids contents, ferric reducing antioxidant power (FRAP), and DPPH radical scavenging activity). All extracts inhibited α-amylase and α-glucosidase activities. Ethyl acetate rhizome and methanol leaf extracts exhibited the best inhibitory activity against α-amylase and α-glucosidase (IC50: 0.10 and 5.99 mg/mL), respectively. Kinetic analysis revealed two modes of enzyme inhibition (competitive and mixed). All extracts showed antioxidant capacity, with hexane extracts exhibiting the best activity. DPPH assay revealed that methanol leaf, rhizome, and ethyl acetate stem extracts (IC50 < 5 mg/mL) were the best antioxidants. The presence of bioactive compounds such as flavonoids, alkaloids, phenols, and tannins may account for the antioxidant capacity and carbohydrate hydrolyzing enzyme inhibitory activity of C. afer.

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

BackgroundNefang 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.MethodsAntipyretic 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.ResultsBest 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.ConclusionThe 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.

Antioxidant potential of a polyherbal antimalarial as an indicator of its therapeutic value.

Nefang is a polyherbal product composed of Mangifera indica (bark and leaf), Psidium guajava, Carica papaya, Cymbopogon citratus, Citrus sinensis, and Ocimum gratissimum (leaves), used for the treatment of malaria. Compounds with antioxidant activity are believed to modulate plasmodial infection. Antioxidant activity of the constituent aqueous plants extracts, in vitro, was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH), total phenolic content (TPC), and ferric reducing antioxidant power (FRAP) methods and, in vivo, Nefang (100 and 500 mg kg−1) activity was evaluated in carbon tetrachloride-induced oxidative stressed Wistar rats. Superoxide dismutase, catalase activities, and lipid peroxidation by the malondialdehyde and total proteins assays were carried out. P. guajava, M. indica leaf, and bark extracts had the highest antioxidant properties in all three assays, with no statistically significant difference. Rats treated with the carbon tetrachloride had a statistically significant decrease in levels of triglycerides, superoxide dismutase, and catalase (P < 0.05) and increase in malondialdehyde activity, total protein levels, and liver and renal function markers, whereas rats treated with Nefang showed increased levels in the former and dose-dependent decrease towards normal levels in the later. These results reveal the constituent plants of Nefang that contribute to its in vivo antioxidant potential. This activity is a good indication of the therapeutic potential of Nefang.