Antiplasmodial activity of root extract and fractions of Croton zambesicus

Aim of the study

Antiplasmodial activity of root extract and fractions of Croton zambesicus were evaluated to ascertain the folkloric claim of its antimalarial activity and elucidate its antiplasmodial mechanism of action.

Material and method

The crude ethanolic root extract (27–81 mg/kg) and gradient fractions ( n- hexane, chloroform, ethyl acetate and methanol; 54 mg/kg) of Croton zambesicus were investigated for antiplasmodial activity against chloroquine - sensitive Plasmodium berghei infections in mice. The antiplasmodial activity during early and established infections as well as the prophylactic activity were investigated. Chloroquine (5 mg/kg) and pyrimethamine (1.2 mg/kg) were used as positive controls. Thin films made from tail blood of each mouse were used to assess the level of parasitaemia of the mice. Oxidant generation potentials of the crude extract and fractions was also evaluated to elucidate their mechanism of action.

Results

The crude root extract (27 – 81 mg/kg) demonstrated significant (P < 0.01–0.001) schizonticidal activity during early and established infections and also had prophylactic activity. The activity was comparable to that of the standard drug used (chloroquine 5 mg/kg, pyrimethamine 1.2 mg/kg). Methanol, ethyl acetate and chloroform fractions had comparative in vivo antiplasmodial activity and oxidant generation potentials.

Conclusion

The antiplasmodial activity of this root extract and fractions which is likely to be through peroxidation confirms the folkloric use of this plant.     

Antimalarial and safety evaluation of extracts from Toddalia asiatica (L) Lam. (Rutaceae)

Ethnopharmacological relevance

Toddalia asiatica (L) Lam. (Rutaceae) is a medicinal plant traditionally used in Kenya by many communities for the treatment of malaria and other ailments. All parts of the plant are claimed to have medicinal value, but the root bark in particular is believed to be more potent. Decoctions or infusions of the roots are taken orally to treat malaria, fever and stomach ache.

Aim of the study

To evaluate antimalarial activity of aqueous and organic extracts prepared from Toddalia asiatica and determine in vitro and in vivo safety of the extracts.

Materials and methods

Aqueous, ethyl acetate, hexane and methanol extracts were obtained from Toddalia asiatica root bark, fruits and leaves. In vitro antiplasmodial activity was done using chloroquine-sensitive (D6) and chloroquine-resistant (W2) Plasmodium falciparum strains and the concentration causing 50% inhibition of radioisotope incorporation (IC₅₀) was determined. In vivo assay was done by administering mice infected with Plasmodium berghei four consecutive daily doses of the extracts through oral route following Peters 4-Day suppressive test. The percentage suppression of parasitaemia was calculated for each dose level by comparing the parasitaemia in untreated control with those of treated mice. Quinine hydrochloride was used as positive control while double distilled water or 20% Tween-80 was used as a negative control. In vivo acute toxicity was determined in mice using standard procedures. In vitro cytotoxicity assay was carried out using actively dividing sub-confluent Vero cells.

Results

Inhibitory concentrations of ethyl acetate extract of Toddalia asiatica fruits showed high activity against chloroquine resistant (W2) strains of Plasmodium falciparum (IC₅₀=1.87 μg/ml), followed by root bark aqueous extract (IC₅₀=2.43 μg/ml). Tested in vivo against Plasmodium berghei, the fruit ethyl acetate extract (500 mg/kg) and root bark aqueous extract (250 mg/kg) reduced malaria parasitaemia by 81.34% and 56.8% respectively. Higher doses were found to be less effective in vivo. Acute toxicity and cytotoxictiy of the tested extracts, with the exception of hexane extract from the roots, showed LD₅₀>1000 mg/kg and CC₅₀>100 μg/ml respectively.

Conclusions

The results obtained contribute to the validation of traditional use of Toddalia asiatica and provides in vivo and safety data of the plant extracts tested for the first time. Ethyl acetate extract of the fruits was active against chloroquine resistant Plasmodium falciparum as well as against Plasmodium berghei. These findings confirm the suitability of Toddalia asiatica as a good candidate for further tests to obtain a prototype for antimalarial medicine.     

Antiplasmodial activity of Homalium letestui

The in vivo antiplasmodial activity of the ethanol root extract of Homalium letestui used as a malaria remedy in Southern Nigeria was evaluated in Plasmodium berghei berghei infected mice. Homalium letestui root extract (500-1000 mg/kg/day) exhibited significant (p < 0.05) blood schizontocidal activities both in a 4-day early infection test and in an established infection with a considerable mean survival time comparable to that of the standard drug, chloroquine, 5 mg/kg/day. The root extract possesses significant (p < 0.05) antiplasmodial activity, which can be exploited in malaria therapy.     

In vitro and in vivo evaluation of betulinic acid as an antimalarial

The lupane-type triterpene betulinic acid was isolated from an ethanol extract of the root bark of the Tanzanian tree Uapaca nitida Müll-Arg. (Euphorbiaceae). The in vitro antiplasmodial IC50 values of betulinic acid against chloroquine resistant (K1) and sensitive (T9-96) Plasmodium falciparum were found to be 19.6 micrograms/mL and 25.9 micrograms/mL, respectively. The in vitro activities of several related triterpenes were also evaluated. Betulin was found to be inactive at 500 micrograms/mL for both K1 and T9-96. Ursolic acid exhibited IC50 values of 36.5 micrograms/mL and 28 micrograms/mL, and oleanolic acid exhibited IC50 values of 88.8 micrograms/mL and 70.6 micrograms/mL against K1 and T9-96, respectively. When betulinic acid was tested for in vivo activity in a murine malaria model (P. berghei) the top dosage employed of 250 mg/kg/day was ineffective at reducing parasitaemia and exhibited some toxicity. Betulinic acid has not previously been evaluated for in vivo activity. This is believed to be the first compound to be isolated from U. nitida.     

Antimalarial activities of Tithonia diversifolia (Asteraceae) and Crossopteryx febrifuga (Rubiaceae) on mice in vivo

Ethanolic extracts of the aerial part of Tithonia diversifolia and the stem bark of Crossopteryx febrifuga were investigated against early, residual (repository) and established malaria infections in vivo using Swiss albino mice at a dose range of 50-400 mg/kg per day. Chloroquine at 5 mg/kg per day was used as the positive control for the early and established infections while Pyrimethamine at 1.2 3/kg per day was used as the positive control for the residual infection test. Dose dependent chemo suppressive activities were obtained at the different levels of the infection tested. Tithonia diversifolia and Crossopteryx febrifuga gave some level of suppression of parasitaemia in the early and established infection stages. Tithonia diversifolia was active at 200 mg/kg per day in the repository test. The mean survival period of the mice treated with the extract in the established infection test was low, a possible indication of toxicity as a result of sub chronic administration of the extract. Crossopteryx febrifuga was inactive in the repository test. Beside the above limitations, the suppression of parasitaemia by the extracts at the highest dose was similar to chloroquine and pyrimathamine.     

Antimalarial activity of alkaloids isolated from Stephania rotunda

Stephania rotunda (Menispermaceae) is used in traditional medicine for the treatment of fever. Four major alkaloids: dehydroroemerine, tetrahydropalmatine, xylopinine, cepharanthine as well as aqueous extract (SA), dichloromethane extracts (SD1 and SD2) from this plant were tested against Plasmodium falciparum W2 in vitro. Dehydroroemerine, cepharanthine and SD1 were the most active against W2 with IC(50) of 0.36, 0.61microM and 0.7microg/mL, respectively. Their IC(50) on human monocytic THP1 cells were 10.8, 10.3microM and >250microg/mL, respectively. Cepharanthine, SD1 and SA were selected for in vivo antimalarial test against Plasmodium berghei in mice. The results of SD1 and SA at dose of 150mg/kg showed a decrease of 89 and 74% of parasitaemia by intra-peritoneal injection and 62.5 and 46.5% of parasitaemia by oral administration, respectively. The result of cepharanthine at dose of 10mg/kg showed a decrease of 47% of parasitaemia by intra-peritoneal injection and 50% of parasitaemia by oral administration. Drug interaction of chloroquine and major alkaloids indicates that cepharanthine-chloroquine and tetrahydropalmatine-xylopinine associations are synergistic. These results are in agreement with the use of this plant in the treatment of malaria. This is the first report on in vivo antimalarial investigation for Stephania rotunda.     

Evaluation of antiplasmodial activity of ethanolic seed extract of Picralima nitida

The in vivo antiplasmodial activity of the ethanol seed extract of Picralima nitida grown particularly for the leaf and seed in Niger Delta region of Nigeria was evaluated in Plasmodium berghei berghei infected mice. Picralima nitida (35-115 mg/kg day) exhibited significant (P<0.05) blood schizonticidal activity both in 4-day early infection test and in established infection with a considerable mean survival time though not comparable to that of the standard drug, chloroquine, 5 mg/kg day. The seed extract possesses significant (P<0.05) antiplasmodial activity which correlate with it reported in vitro activity.     

In vivo antimalarial activities of Enantia polycarpa stem bark against Plasmodium berghei berghei in mice

Ethnopharmacological relevance

Enantia polycarpa (PC) Engl. Et Diels (Annonaceae) is used in traditional medicine as an antimalarial remedy in Southern Nigeria.

Aim of the study

The antimalarial activities of ethanolic stem bark extracts of Enantia polycarpa was studied in vivo, in mice infected with Plasmodium berghei berghei.

Materials and methods

The ethanolic stem bark extract of Enantia polycarpa was administered at doses ranging from 200 to 600 mg/kg/day to Plasmodium berghei infected mice in both early and established models of antiplasmodial studies.

Results

The extract of Enantia polycarpa exhibited promising antimalarial activity against both early and established infections. At a dose of 600 mg/kg the extract achieved a 75.8% and 72% chemosuppression of parasitaemia in the study of acute and established infections, respectively. The extract also prolonged mean survival time of Plasmodium berghei infected mice during the study of established infection. The mean survival time of mice administered Enantia polycarpa extract at 600 mg/kg/day (27 days) was significantly longer than infected/untreated control (12 days). For the acute toxicity study the extract had an intraperitoneal LD₅₀ of 186 mg/kg but caused no mortality when administered orally at doses as high as 2,000 and 4,000 mg/kg.

Conclusions

Collectively, the results indicate that Enantia polycarpa is safe when administered orally and possesses promising antimalarial activity, thus supporting its use in traditional medicine for the treatment of malaria.     

Analgesic and antimalarial activities of crude leaf extract and fractions of Acalypha wilkensiana

Aim of the study

Antiplasmodial and analgesic activities of leaf extract and fractions of Acalypha wilkensiana were evaluated to ascertain the folkloric claim of its antimalarial and analgesic activities.

Materials and methods

The crude leaf extract (220–659 mg/kg) and fractions (chloroform and aqueous; 440 mg/kg) of Acalypha wilkensiana were investigated for antiplasmodial activity against chloroquine sensitive Plasmodium berghei infections in mice and for analgesic activity against chemical and heat-induced pains. The antiplasmodial activity during early and established infections as well as prophylactic activity were investigated. Chloroquine (5 mg/kg) and pyrimethamine (1.2 mg/kg) were used as positive controls. Thin films made from tail blood of each mouse were used to assess the level of parasitaemia of the mice. Analgesic activity of the crude extract was also evaluated against acetic acid, formalin and heat-induced pains.

Results

The extract and its fractions dose-dependently reduced parasitaemia induced by chloroquine sensitive Plasmodium berghei infection in prophylactic, suppressive and curative models in mice. These reductions were statistically significant (p < 0.001). They also improved the mean survival time (MST) from 16 to 22 days relative to control (p < 0.01–0.001). The activities of extract/fractions were incomparable to that of the standard drugs used (chloroquine and pyrimethamine). On chemically and thermally induced pains, the extract inhibited acetic acid and formalin-induced inflammation as well as hot plate-induced pain in mice. These inhibitions were statistically significant (p < 0.001) and in a dose-dependent fashion.

Conclusion

The antiparasitaemic and analgesic effects may in part be mediated through the chemical constituents of the plant.     

Antiplasmodial activity of Cylicodiscus gabunensis

The antimalarial activity of ethanolic stembark extract of Cylicodiscus gabunensis was studied in vivo in mice infected with Plasmodium berghei berghei during early and established infections as well as for repository activity. The LD(50) of the extract was determined to be 223.6 mg/kg, while doses of 250 mg/kg and above were found to be lethal to mice. Cylicodiscus gabunensis extract (20-60 mg/kg/day) exhibited a significant (P<0.05) blood schizontocidal activity in 4-day early infection, repository evaluation and in established infection with a significant mean survival time comparable to that of the standard drug, chloroquine, 5 mg/kg/day. The stembark extract possesses a promising antiplasmodial activity, which can be exploited in malaria therapy.     

Antiplasmodial activity of Setaria megaphylla

The antimalarial activity of an ethanol leaf extract of Setaria megaphylla was studied in vivo in mice infected with Plasmodium berghei berghei during early and established infections. Setaria megaphylla (100-300 mg/kg/day) exhibited a significant (p < 0.05) blood schizonticidal activity in 4-day early infection and in established infection with a significant (p < 0.05) mean survival time comparable to that of the standard drug, chloroquine, 5 mg/kg/day. The leaf extract possesses a promising antiplasmodial activity in vivo which can be exploited in malaria therapy.     

Antimalaria activity of ethanolic extract of Tetrapleura tetraptera fruit

The in vivo antiplasmodial activity of the ethanol fruit extract of Tetrapleura tetraptera used as spice and in the treatment of various ailment in Niger Delta region of Nigeria was evaluated in Plasmodium berghei infected mice. Tetrapleura tetraptera (300-900 mg/kg day) exhibited significant (P < 0.05) blood schizonticidal activity both in 4-day early infection test and in established infection with a considerable mean survival time comparable to that of the standard drug, chloroquine, 5 mg/kg day. The fruit extract possesses significant (P < 0.05) antiplasmodial activity with may have contributed to the immune status of the Nigerians against malaria in addition to its nutritive value.     

Assessment of the phytochemical and antitrypanosomal properties of some extracts of leaves, stem and root bark of Landolphia sp., P. Beauv

INTRODUCTION/JUSTIFICATION: There is urgent need to source for alternative chemotherapy against trypanosmosis, a disease of major importance in human and economic animals. MATERIALS AND METHODS: Therefore, petroleum ether, chloroform, methanol and aqueous extracts sequentially obtained from the leaves, stem and root barks of Landolphia uniflora were evaluated for their in vitro and in vivo antitrypanosomal activities against Trypanosoma brucei brucei, as well as their phytochemical constituents. RESULTS: Steroids and triterpenes, resins, tannins, saponins and flavonosides were detected in almost all the extracts, but alkaloid was absent in methanol extract of the stem and stem, as well as the chloroform extract of the root bark. In vitro, all extracts of the roots displayed significant antitrypanosomal activity, while only the chloroform extracts of the leaves and stem bark showed activity at both test concentrations (4 and 2 mg/ml). However, under in vivo condition, the methanol extracts showed the greatest activity, eliminating parasitaemia within the 10 days treatment period and prolonging survival period at 200 and 300 mg/kg body weight intramuscular doses. CONCLUSION: These results suggest that Landolphia uniflora could be useful in the management of trypanosomiasis.     

Antiplasmodial, analgesic, and anti-inflammatory activities of the aqueous extract of the stem bark of Erythrina senegalensis

The in vivo antiplasmodial, analgesic and anti-inflammatory properties of Erythrina senegalensis, an ornamental plant commonly used in Northern Nigeria for the treatment of fevers, was evaluated. Aqueous extracts of the stem bark of the plant was used for the study. The in vivo antiplasmodial activity of the aqueous extract against Plasmodium berghei was assessed using the suppressive and curative test procedures. Analgesic activity was assessed using the acetic acid (0.75%v/v) induced abdominal constriction, while the anti-inflammatory activity was evaluated on egg-albumin induced paw oedema in rats as a model of acute inflammation. The stem bark extract of E. senegalensis exhibited only slight antiplasmodial activity while significant (P<0.05) analgesic and anti-inflammatory effects were observed. Preliminary phytochemical analysis of the extract indicates the presence of alkaloids and glycosides.     

Acute and sub-chronic oral toxicity studies of an aqueous stem bark extract of Pterocarpus soyauxii Taub (Papilionaceae) in rodents

Pterocarpus soyauxii Taub (Papilionaceae) is used in Cameroonian traditional medicine and pharmacopoeia to treat hypertension, diabetes, gastrointestinal parasitizes and cutaneous diseases.

Aim of the study

The present investigation was carried out to evaluate the safety of an aqueous stem bark extract of Pterocarpus soyauxii by determining toxicity after acute and sub-chronic oral administration in male and female rodents.

Materials and methods

The acute toxicity test was conducted in mice. An aqueous extract of barks was administrated by gavage in single doses of 2.5-12.5 g/kg. General behaviour and mortality were examined for up to 7 days. The sub-chronic toxicity test was performed in rats. The plant extract was administered by daily gavage of 150-600 mg/kg for 42 days. Body weight, food and water intakes were followed weekly. Haematological, biochemical and organ parameters were determined at the end of the 42-day administration.

Results

In the acute study in mice, oral administration of the aqueous extract of Pterocarpus soyauxii caused dose-dependent general behaviour adverse effects and mortality. The no-observed adverse effect level (NOAEL) of the extract was 5.0 g/kg. The lowest-observed adverse effect level (LOAEL) was 7.5 mg/kg. Mortality increased with the dose, LD₅₀ was > 10.75 g/kg for the mouse. In the sub-chronic study in rats, daily oral administration of the aqueous extract of Pterocarpus soyauxii did not result in death or significant changes in haematological or biochemical parameters, excepted increased hepatic catalase activity (P < 0.05) at the dose of 600 mg/kg. No alteration was observed in body weight, food and water intake. Liver, kidney, lung and pancreas histopathology did not reveal morphological alteration.

Conclusions

The results showed that the aqueous stem bark extract of Pterocarpus soyauxii Taub had very low toxicity in oral acute high dose administration and no toxicity in oral sub-chronic low dose administration and indicate that the plant could be considered safe for oral medication.     

Antimalarial activity of some plants traditionally used in Meru district of Kenya

Ten plant extracts commonly used by the Meru community of Kenya were evaluated for the in vitro antiplasmodial, in vivo antimalarial, cytotoxicity and animal toxicity activities. The water and methanol extracts of Ludwigia erecta and the methanol extracts of Fuerstia africana and Schkuhria pinnata exhibited high antiplasmodial activity (IC(50) < 5 microg/mL) against chloroquine sensitive (D6) and resistant (W2) Plasmodium falciparum clones. The cytotoxicity of these highly active extracts on Vero E6 cells were in the range 161.5-4650.0 microg/mL with a selectivity index (SI) of 124.2-3530.7. In vivo studies of these extracts showed less activity with chemosuppression of parasitaemia in Plasmodium berghei infected mice of 49.64-65.28%. The methanol extract of Clerodendrum eriophyllum with a lower in vitro activity (IC(50) 9.51-10.56 microg/mL) exhibited the highest chemosuppression of 90.13%. The methanol and water extracts of Pittosporum viridiflorum were toxic to mice but at a lower dose prolonged survival of P. berghei infected mice (p < 0.05) with no overt signs of toxicity. However, the extracts were cytotoxic (SI, 0.96-2.51) on Vero E6 cells. These results suggest that there is potential to isolate active non-toxic antimalarial principles from these plants.     

Antimalarial activity and toxicity evaluation of a quantified Nauclea pobeguinii extract

Aim of the study

To evaluate the in vitro and in vivo antiplasmodial activity and toxicity of the aqueous and 80% EtOH extract of the stem bark of Nauclea pobeguinii (Pob. Ex. Pell.) Petit (Rubiaceae), a plant used in traditional medicine in DR Congo against malaria.

Materials and methods

The aqueous and 80% EtOH extract from N. pobeguinii stem bark, and its constituents (5S)-5-carboxystrictosidine, 19-O-methylangustoline, 3-O-β-fucosylquinovic acid, 3-ketoquinovic acid and strictosamide, were evaluated for their in vitro activity against Plasmodium falciparum (chloroquine-sensitive Ghana-strain). The 80% EtOH extract, containing 5.6% strictosamide, was evaluated in vivo in the 4-day P. berghei mouse model, and in the P. yoelii N67 model.

Results

All compounds were inactive or only moderately active in vitro. The aqueous and 80% EtOH extract displayed moderate in vitro activity with IC₅₀ values of 44 and 32 μg/mL, respectively, without apparent cytotoxicity on MRC-5 cells (CC50 > 64 μg/mL). Daily oral dosing of the 80% EtOH extract, at 300 mg/kg, resulted in 86% reduction of parasitaemia in the 4-day P. berghei mouse model, and 75% reduction in the P. yoelii N67 model. Prolonging oral dosing to 2 × 5 days, with an interval of 2 days, and oral administration of the 80% EtOH extract at 300 mg/kg induced 92% reduction of parasitaemia, and a mean survival time of 17 days. Strictosamide, the putative active constituent, may be metabolically activated in the gastrointestinal tract after oral administration. Levels of creatinin, urea, ALAT and ASAT remained unchanged after treatment. No acute toxicity was observed in mice after a single 2 g/kg oral dose, nor after 4 weekly doses. No significant macroscopic or microscopic lesions were observed in heart, lung, spleen, kidney, liver, large intestine and brain.

Conclusions

These results can partly support and justify the use of N. pobeguinii in traditional medicine in the DR Congo for the treatment of uncomplicated malaria.     

Antidiarrhoeal activity of the methanol stem-bark extract of Annona senegalensis Pers. (Annonaceae)

AIM OF THE STUDY: To investigate the antidiarrhoeal properties of the stem-bark extract of Annona senegalensis, using both in vivo and in vitro models. MATERIALS AND METHODS: Swiss albino mice were used to investigate the acute oral toxicity of the extract. The extract was administered orally to mice fed with charcoal meal in order to investigate intestinal transit time. The effect of the extract on contraction of isolated rabbit jejunum and the responses of the tissue to acetylcholine and histamine were also investigated. RESULTS: The extract was safe at doses up to 5000 mg/kg. The extract at the dose of 10mg/kg significantly (p<0.05) decreased intestinal transit time at concentrations of 0.2-3.2 mg/ml, the extract attenuated spontaneous contractions of the isolated rabbit jejunum, and those induced by acetylcholine in a concentration-dependent fashion. CONCLUSION: The extract decreased intestinal transit time by attenuating the spontaneous contractions of the intestine, thus the study provided a scientific basis for the use of Annona senegalensis stem bark extract in the treatment of diarrhoea.     

In Vivo antimalarial activity of aqueous extracts from Kenyan medicinal plants and their chloroquine (CQ) potentiation effects against a blood-induced CQ-resistant rodent parasite in mice

Hot water extracts from eight medicinal plants representing five families, used for malaria treatment in Kenya were screened for their in vivo antimalarial activity in mice against a chloroquine (CQ) resistant Plasmodium berghei NK65, either alone or in combination with CQ. Extracts of three plants, Toddalia asiatica (root bark), Rhamnus prinoides (leaves and root bark) and Vernonia lasiopus (root bark) showed high chemosuppression in the range 51%-75%. Maytenus acuminata, M. heterophylla, M. senegalensis and Rhamnus staddo had moderate activities of 33%-49% parasitaemia suppression in the root bark and/or leaf extracts, while Withania somnifera (root bark) had a non-significant suppression (21%). In combination with CQ, extracts of V. lasiopus (all parts), leaf extracts of M. senegalensis, R. prinoides and T. asiatica as well as root barks of M. heterophylla, R. staddo and T. asiatica had improved parasitaemia suppression in the range 38%-66%, indicating synergistic interactions. Remarkable parasitaemia suppression by the extracts, either alone or in combination with CQ resulted into longer survival of mice relative to the controls, in some cases by more than 2 weeks. Plants, which showed significant antimalarial activity including V. lasiopus, T. asiatica and R. prinoides, should further be evaluated in the search for novel agents against drug-resistant malaria.     

Evaluation of the antimalarial properties and standardization of tablets of Azadirachta indica (Meliaceae) in mice

The antimalarial activities of the tablet suspension of the bark and leaf of Azadirachta indica were evaluated on Plasmodium yoelli nigeriensis infected mice. The tablet suspensions exhibited high prophylactic, mode-rate suppressive and a very minimal curative schizonticidal effect. No animal was cured of the infection in the curative test and there was not much increase in the survival time of the animals compared with the control. The tablet suspensions from the leaf and bark at a concentration of 800 mg/kg and chloroquine at a concentration of 62.5 mg/kg body weight produced average percentage (%) parasitaemia of 79.6%, 68.2% and 99.5% for leaf, bark and chloroquine, respectively, in chemosuppression. Also in the prophylactic treatment, the tablet suspensions at 800 mg/kg and pyrimethamine at a concentration of 0.35 mg/kg gave an average parasitaemia reduction of 75.3%, 65.6% and 98.3% for the leaf, bark and pyrimethamine, respectively. There was a clear indication that both tablet suspensions from the leaf and bark possess antimalarial activity and a suspension from the former is relatively more effective than the bark. Extrapolation of the results from the antimalarial activity of the tablet suspension of the crude plant parts showed that an adult human would need to ingest a minimum of 48 g of the powdered plant material per day, an amount that is impracticable. A survival index value of 0.33 was obtained with the 800 mg/kg dose level, indicating that the tablet suspension has some moderate beneficial effect.