Brine shrimp toxicity and antimalarial activity of some plants traditionally used in treatment of malaria in Msambweni district of Kenya

Ethnopharmacological relevance

In Kenya, most people especially in rural areas use traditional medicine and medicinal plants to treat many diseases including malaria. Malaria is of national concern in Kenya, in view of development of resistant strains of Plasmodium falciparum to drugs especially chloroquine, which had been effective and affordable. There is need for alternative and affordable therapy. Many antimalarial drugs have been derived from medicinal plants and this is evident from the reported antiplasmodial activity.

Aim of the study

The present study reports on the in vivo antimalarial activity and brine shrimp lethality of five medicinal plants traditionally used to treat malaria in Msambweni district, Kenya.

Materials and methods

A total of five aqueous crude extracts from different plant parts used in traditional medicine for the treatment of malaria were evaluated for their in vivo antimalarial activity using Plasmodium berghei infected Swiss mice and for their acute toxicity using Brine shrimp lethality test.

Results

The screened crude plant extracts suppressed parasitaemia as follows: Azadirachta indica (L) Burm. (Meliaceae), 3.1%; Dichrostachys cinerea (L) Wight et Arn (Mimosaceae), 6.3%; Tamarindus indica L. (Caesalpiniaceae), 25.1%; Acacia seyal Del. (Mimosaceae) 27.8% and Grewia trichocarpa Hochst ex A.Rich (Tiliaceae) 35.8%. In terms of toxicity, A.indica root bark extract had an LC₅₀ of 285.8 µg/ml and was considered moderately toxic. T.indica stem bark extract and G.trichocarpa root extract had an LC₅₀ of 516.4 and 545.8 µg/ml respectively and were considered to be weakly toxic while A.seyal and D.cinerea root extracts had a LC₅₀>1000 µg/ml and were therefore considered to be non toxic.

Conclusions

The results indicate that the aqueous extracts of the tested plants when used alone as monotherapy had antimalarial activity which was significantly different from that of chloroquine (P≤0.05). The results also suggest that the anecdotal efficacy of the above plants reported by the study community is related to synergism of phytoconstituents since the assayed plant parts are used in combination with others to treat malaria. It is also evident that none of the screened plant extracts is toxic to the arthropod invertebrate, Artemia salina L. (Artemiidae) larvae, justifying the continued use of the plant parts to treat malaria. A.seyal, G.trichocarpa and T.indica have not been reported before for in vivo antimalarial activity and brine shrimp lethality.     

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.     

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.     

Traditional herbal antimalarial therapy in Kilifi district, Kenya

Aim of study

To identify plant species used by the traditional health practitioners (THPs) in treatment of malaria, carry out cytotoxicity and efficacy evaluation of the identified plants and to evaluate combination effects.

Materials and methods

Thirteen plants were selected through interviews with traditional healers. In vitro antiplasmodial testing was done by measuring ability of the test sample to inhibit the incorporation of radio-labelled hypoxanthine into the malaria parasite. The extracts were tested singly and then in combination using the standard fixed ratio analysis to evaluate synergism. In vivo bioassay was done in mice using Peter's 4-days suppressive test and cytotoxicity evaluated in vitro using Vero E6 cells.

Results

Of the plants tested in vitro, 25% were highly active (IC₅₀ < 10 μg/ml), 46% moderately active (IC₅₀ 10-50 μg/ml), 16% had weak activity of 50-100 μg/ml while 13% were not active IC₅₀ >100 μg/ml. Methanolic extracts of Azadirachta indica, Premna chrysoclada and Uvaria acuminata were the most active (IC₅₀ < 10 μg/ml) against both the chloroquine (CQ) sensitive (D6) and the CQ resistant (W2) Plasmodium falciparum clones. When tested in vivo in a mouse model, Azadirachta indica, Rhus natalensis and Grewia plagiophylla depicted the highest percent parasite clearance and chemo suppression of 89%, 82% and 78%, respectively. Evaluating effect of combining some of these extracts with one another against a multi-drug resistant Plasmodium falciparum (W2) clone revealed synergism among some combinations. The highest synergy was between Uvaria acuminata and Premna chrysoclada. The interaction between Grewia plagiophylla and Combretum illairii was largely antagonistic. Impressive cytotoxicity results were obtained with most of the plants tested revealing high selectivity indices an indication of enabling achievement of therapeutic doses at safe concentrations. Uvaria acuminata was, however, toxic to the cultured cells. Mild cytotoxicity was also observed in Hoslundia opposita and Lannea schweinfurthii (CC₅₀ 37 and 76 μg/ml, respectively).

Conclusions

This study identified plants with low IC₅₀ values, high percent chemo suppression and low cytotoxicity thus potential sources for novel antiplasmodial agents. The findings remotely justify use of combined medicinal plants in traditional medicine practices as synergy among some plant species was demonstrated.     

In vivo antimalarial activity,toxicity and phytochemical screening of selected antimalarial plants

Ethnopharmacological relevance

Malaria continues to kill over a million people each year and in many populations affected by malaria, conventional drugs are often unaffordable or inaccessible. Historically, plants have been a prominent source of antimalarial drugs. Those plants currently used by indigenous people to treat malaria should be documented and investigated as potential sources of new antimalarial drugs.

Aim of the study

To investigate in vivo antimalarial activity, toxicity and carry out phytochemical screening of selected plants which have been used in traditional medicine for the treatment of malaria.

Materials and methods

Organic and water extracts of four medicinal plants used for the treatment of malaria in traditional health systems of Msambweni people in Kenya were tested for antimalarial activity against Plasmodium berghei and brine shrimp lethality. They were also screened for their major phytochemical constituents.

Results

Aqueous extract of the stem bark of Adansonia digitata exhibited highest chemosuppression of parasitaemia, >60% in a murine model of Plasmodium berghei infected mice. Aqueous and organic extracts of Launaea cornuta and Zanthoxylum chalybeum were toxic to the brine shrimp (LD₅₀<1000 μg/ml) while aqueous and organic extracts of Adansonia digitata and aqueous extracts of Canthium glaucum were not toxic to brine shrimp (LD₅₀>1000 μg/ml). Phytochemical screening revealed the presence of alkaloids and flavonoids in all the crude extracts of the selected plant species studied. Sesquiterpene lactones and saponis were present in organic extracts but absent in the aqueous extracts of Adansonia digitata, Canthium glaucum, Launaea cornuta and Zanthoxylum chalybeum.

Conclusion

The results showed that the crude extracts of Adansonia digitata and Canthium glaucum demonstrated promising antimalarial activity and there is potential for isolation of lead compounds from their extracts.     

Antimalarial plant remedies from Burkina Faso: their potential for prophylactic use

Ethnopharmacological relevance

Saye, a combination remedy prepared from Cochlospermum planchonii Hook.f. (Cochlospermaceae), Cassia alata L. (Fabaceae) and Phyllanthus amarus Schumach. et Thonn. (Euphorbiaceae), N’Dribala, a Cochlospermum planchonii root decoction, and a fruit preparation of Azadirachta indica A. Juss. (Meliaceae) are plant remedies of the folk medicine in Burkina Faso and are commonly used by traditional healers for the treatment of malaria.

Aim of the study

This study aimed at validating the antiplasmodial activity of the preparations and at estimating their potential for prophylaxis, using the murine malaria system Plasmodium berghei/Anopheles stephensi.

Materials and methods

Aqueous extracts were orally administered to mice (6 animals per treatment group) at a daily dose of 200 mg/kg body weight for nine days, applying protocols that mimic as much as possible traditional recipes and treatment schemes.

Results

Saye, N’Dribala and Azadirachta indica preparations revealed prophylactic activity, reducing parasitaemia in treated mice, with respect to controls, by 52.0% (CI₉₅ 46.1–57.9), 45.5% (CI₉₅ 44.5–46.5) and 45.0% (CI₉₅ 41.1–48.9), respectively. No evidence of transmission blocking effects was detected with any of the tested remedies.

Conclusions

This study confirms, in the murine malaria system, the antiplasmodial properties of the examined remedies on the Plasmodium stages developing in the vertebrate host, thus encouraging studies aiming at identifying the active fractions and compounds responsible for the described activity and to develop standardized prophylactic remedies.     

Evaluation of the use of Cocos nucifera as antimalarial remedy in Malaysian folk medicine

Ethnopharmacological relevance

White flesh extract of Cocos nucifera (coconut) was studied to ascertain the ethnopharmacological standing of its antimalarial usage in Malaysian folk medicine.

Materials and methods

The crude methanol extract was investigated for phytochemical constituents and acute oral toxicity. Antimalarial activity of different extract doses of 50, 100, 200 and 400 mg/kg were investigated in vivo against Plasmodium berghei (NK65) infections in mice during early, established and residual infections. Chloroquine (20 mg/kg) and pyrimethamine (1.2 mg/kg) were used as reference drugs.

Results

The results revealed that the extract contained some phytochemical constituents and is toxicologically safe by oral administration. The extract significantly reduced the parasitaemia by the 200 and 400 mg/kg doses in the all three in vivo assessment assays. However, the extract did not significantly increase the survival time of the infected mice.

Conclusions

The observed pharmacological activities suggest that the Malaysian folkloric medicinal application of Cocos nucifera has a pharmacological basis.     

In vivo antimalarial evaluation of Gomphostenins

Aim of the study

The present study aims to evaluate the in vivo antimalarial potential of the leaf extract of Gomphostemma niveum and two new compounds; named as Gomphostenin (GN–6) and acetyl Gomphostenin (GN–10) isolated and purified from this plant against Plasmodium berghei in mice.

Materials and methods

The blood schizontocidal activity was performed in early infection of Plasmodium berghei and also in established infection of Plasmodium berghei. The mice were orally administrated with various doses of water and chloroform extracts of leaves of Gomphostemma niveum (GN–W and GN–C, 300, 400 and 500 mg/kg/day), GN–6 and GN–10 (50, 100, 150 and 200 mg/kg/day). Chloroquine (8 mg/kg) used as a positive control, while an equal volume of saline plus 0.5% tween-80 was used as a negative control.

Results

GN–W, GN–C and pure compounds (GN–6 and GN–10) produced a dose dependent chemosuppression effect at various dose levels. GN–10 exhibited highest percent of chemosuppression i.e. 92.65% at a dose level of 200 mg/kg/day. In case of curative test, the survival period of the parasitized infected mice was significantly prolonged at 200 mg/kg dose of GN–10.

Conclusions

The studies have indicated that clerodane class of diterpenes GN–6 and GN–10 certainly holds great promise for malaria control and will be useful in antimalarial chemotherapy.     

Antimalarial and safety evaluation of Pluchea lanceolata (DC.) Oliv. & Hiern: In-vitro and in-vivo study

Ethnopharmacological relevance

Many of the effective therapeutic strategies have been derived from ethnopharmacologically used natural products. Pluchea lanceolata is an herb employed in Indian folk medicine for malaria like fever but it lacks proper pharmacological intervention.

Aim of the study

To evaluate antimalarial and safety profile of Pluchea lanceolata: an in-vitro, in-vivo for its ethnopharmacological validation.

Materials and methods

Methanol, butanol, ethyl acetate, chloroform, hexane extracts and its isolate, taraxasterol acetate (TxAc) were obtained from air dried aerial part of Pluchea lanceolata. These were tested in-vitro against chloroquine-sensitive strain of Plasmodium falciparum NF54 by measuring the parasite specific lactate dehydrogenase activity. The most potent hexane extract and TxAc were further validated for in-vivo antimalarial and safety evaluation. TxAc, a pentacyclic-triterpene isolated from the most active fraction was further evaluated with special emphasis on inflammatory mediators involved in malaria pathogenesis. Murine malaria was induced by intra-peritoneal injection of Plasmodium berghei infected red blood cells to the male Swiss inbred mice. Mice were orally treated following Peters 4-Day suppression test. In-vivo antimalarial efficacy was examined by evaluating the parasitaemia, percent survival, mean survival time, blood glucose, haemoglobin and pro-inflammatory mediators involved in malaria pathogenesis.

Results

Hexane extract and TxAc showed promising antimalarial activity in-vitro and in-vivo condition. TxAc attributed in inhibition of the pro-inflammatory cytokines as well as afford to significant increase in the blood glucose and haemoglobin level when compared with vehicle treated infected mice. We have not observed the synergistic action of combinations of chloroquine and TxAc from our experimental results. In-vitro and in-vivo safety evaluation study revealed that hexane extract is non toxic at higher concentration.

Conclusion

Present study further validates the ancient Indian traditional knowledge and use of Pluchea lanceolata as an antimalarial agent. Study confirms the suitability of Pluchea lanceolata as a candidate for further studies to obtain a prototype for antimalarial medicine.     

Toxicity and potential anti-trypanosomal activity of ethanolic extract of Azadirachta indica (Maliacea) stem bark: An in vivo and in vitro approach using Trypanosoma brucei

Aim of the study

To determine the toxicity and anti-trypanosomal activity of the ethanolic extract of Azadirachta indica (Maliacea) stem bark, through in vivo and in vitro approach using Trypanosoma brucei brucei.

Materials and methods

Graded concentrations (100, 200, 400, 800, 1600 and 3200 mg/kg) of the crude stem bark ethanolic extract of Azadirachta indica, Hochst ex. A. Dc. (Maliacea) was tested for acute toxicity in 35 out bred Swiss (Wister) adult albino rats of both sexes. Secondly, the in vitro activity in test tubes and in vivo activity of the extract in 30 out bred Swiss (Wister) adult albino rats against Trypanosoma brucei brucei strain NITR/14 (Federe) was evaluated in a graded dose manner.

Results

The calculated intra-peritoneal LD₅₀ of the extract was 870 mg/kg and produced toxicity at high doses (>800 mg/kg). Graded concentrations of the ethanolic extract produced remarkable in vitro activity against Trypanosoma brucei brucei within seconds of inoculation. It also suppressed the establishment of parasitaemia at 100 mg/kg when administered simultaneously with infection in vivo. Similarly, at 200 and 400 mg/kg, the extract administered at the onset of parasitaemia for 4 consecutive days reduced parasitaemia, modulated declined packed volume (PCV) changes by day 48 post-infection in vivo.

Conclusion

The results confirm that the folkloric medicinal application of the extract of Azadirachta indica (Maliacea) has a pharmacological basis. Further investigation is however, needed to optimize the effectiveness of the extract.     

Prophylactic and curative activities of extracts from Warburgia ugandensis Sprague (Canellaceae) and Zanthoxylum usambarense (Engl.) Kokwaro (Rutaceae) against Plasmodium knowlesi and Plasmodium berghei

Ethnopharmacological relevance

This work reports the anti-plasmodial activities of Warburgia ugandensis and Zanthoxylum usambarense commonly used as phytomedicines against malaria by some Kenyan communities.

Aim of study

To determine the anti-plasmodial activities of extracts from Warburgia ugandensis and Zanthoxylum usambarense against Plasmodium knowlesi and Plasmodium berghei.

Materials and methods

Eight plant extracts were screened for in vitro anti-plasmodial activity against Plasmodium knowlesi, in a 96-well plate incubated at 37 °C on a RPMI culture medium supplemented with baboon serum. Of the eight, three were investigated for prophylactic and curative activities in BALB/c mice against drug-sensitive Plasmodium berghei in a 4-day test at a dose rate of 200 mg/kg/day.

Results

Inhibitory concentrations (IC₅₀) values of between 3.14 and 75 μg/ml, up to 69% chemosuppression of parasites growth and over 80% survivorship of treated mice were observed.

Conclusion

The two medicinal plants, Warburgia ugandensis and Zanthoxylum usambarense possess bioactive compounds against malaria parasites and could be exploited for further development into malaria therapy.     

In vivo antiplasmodial potential of three herbal methanolic extracts in mice infected with Plasmodium berghei NK65

Objective: The present study deals with the investigation of antiplasmodial potential of leaf methanolic extract of Aegle marmelos, Aristolochia indica and Cassia auriculata against Plasmodium berghei(NK65)infected mice.Methods: The chloroquine-sensitive parasites P. berghei(1 × 106) were inoculated into Swiss albino mice intraperitoneally. The methanol extracts of three herbal plants were orally administered in P. berghei infected mice which were further assessed using the four-day suppressive test at different doses of 150, 300 and 600 mg/kg per day. Chloroquine(CQ) was used as the standard drug with of 1.25, 2.5 and 5 mg/kg concentrations and was orally administered.Results: The leaves of A. marmelos, A. indica, and C. auriculata were found to suppress P. berghei parasitaemia in Swiss albino mice by(67.0 ± 4.02)%,(72.0 ± 8.44)% and(52.7 ± 2.06)% at 600 mg/kg/d with ED50 values of 284.73, 233.77 and 562.48 mg/kg, respectively. These herbal plants increased the mean survival time of infected mice and prevented body weight loss. GC-MS analysis revealed the presence of hentriacontan-16-one(C31 H62 O) in A. indica extract. The histopathology study showed non-toxic to kidney and liver at 600 mg/kg/body weight.Conclusions: Overall results revealed that herbal plants may be active in the development of novel and cheap antimalarial compounds.     

Potential of a Khaya ivorensis -Alstonia boonei extract combination as antimalarial prophylactic remedy

Ethnopharmacological relevance

The decoction of the combined stem barks of Khaya ivorensis A. Chev. (Meliaceae) and Alstonia boonei De Wild (Apocynaceae) has a history of use in traditional medicine of central Cameroon for malaria treatment but also for the prevention of the disease.

Aim of the study

The purpose of this investigation was to determine the antiplasmodial activity of Khaya ivorensis (K) and Alstonia boonei (A) preparations in the murine malaria model Plasmodium berghei/Anopheles stephensi, to estimate their prophylactic potential and to assess acute and sub-acute toxicity of the formulations prepared according to the traditional recipes.

Materials and methods

Aqueous extracts from the stem-bark of the two plants were prepared and tested separately and in combination. BALB/c mice were treated for 9 days and challenged on day 3 by exposure to mosquitoes infected with Plasmodium berghei. Treatment doses ranged between 200 and 400 mg/kg/day, corresponding approximately to the dosage applied by traditional healers to cure malaria patients or prevent the disease. Parasitemia reduction in treated animals was calculated from Giemsa smear counts, of two replicate experiments. To estimate acute toxicity in terms of median lethal dose (LD50), geometrically increasing doses were administered to mice. Sub-acute toxicity of the herbal combination (KA) was investigated by administering the same doses as in the antiplasmodial activity test for a period of 14 days, followed by 14 days of recovery observation. Locomotor activity (Open Field Test), body weight, liver and kidney morphology were monitored.

Results

The combination KA was found to exhibit antiplasmodial activity in the murine malaria model. In mice treated with the combination remedy at a dosage of 200 mg/kg/day, parasitemia values of 6.2% ± 1.7 and 6.5% ± 0.8 were recorded, compared to 10.8% ± 1.3 and 12.0% ± 4.0 in controls (p < 0.01). Doubling the dosage of the extracts did not significantly increase parasite suppression. When extracts of K and A were administered separately at a dosage of 400 mg/kg, a reduction in parasitemia was still obtained, but it did not reach statistical significance. Toxicity studies yielded comforting results: the LD50 was estimated to be greater than 2779.5 mg/kg. Moreover, mice exposed to the fourteen-day repeated-dose toxicity test (sub-acute toxicity test) did not display weight loss, liver or kidney morphological modifications, significant alterations in locomotor activity or any other sign of illness.

Conclusion

The antiplasmodial activity and the wide dose interval between the therapeutic dosage and the toxic dosage exhibited by the KA herbal combination in the murine malaria model argue in favor of its use as an antimalarial prophylactic remedy. It remains to be demonstrated by human clinical trials whether the combination remedy, when taken by inhabitants during malaria transmission season, can reduce parasite density and lead to a reduction of malaria episodes in the community.     

Substantiation of the ethnopharmacological use of Conyza sumatrensis (Retz.) E.H.Walker in the treatment of malaria through in-vivo evaluation in Plasmodium berghei infected mice

Ethnopharmacological relevance

Scientific validation of ethnopharmacologically used plants and their utilization for therapeutic interventions can be a source of affordable treatment especially for neglected diseases in endemic areas. Conyza sumatrensis is a plant which finds its use in treating malaria like fevers but lacks proper scientific validation. Our study has tried to address this gap by authenticating its traditional use for the treatment of malaria.

Aim of the study

Evaluate the antimalarial activity of extracts derived from Conyza sumatrensis for its ethnopharmacological validation.

Materials and methods

Shade dried leaves were extracted with varying concentrations of ethanol and concentrated for bio-evaluation. Swiss albino mice infected with 1×10⁶ parasitized red blood cells, were orally administered with test extracts for 7 days in two sets of experiments. The first set was used to evaluate alcoholic, hydroalcoholic and aqueous extracts while the second set was used to evaluate the dose response of alcoholic extract ranging from 500–1600 mg/kg. Mean survival time, parasitaemia and haemoglobin levels were considered to interpret the antimalarial potential. Phytochemical analysis for the presence of flavonoids, alkaloids tannins, total phenolics, riboflavin and thiamine was also carried out.

Results

Among the three extracts administered at 1000 mg/kg, chemo suppression was significantly (p<0.001) observed in the alcoholic extract (62.59±12.52%) followed by hydroalcoholic (41.81±19.04%, p<0.01) and aqueous (32.04±19.04%, P<0.05) indicating that the active constituents leach out in ethanol. The dose response study involving the ethanol extract concluded the optimum dose to be 1000 mg/kg, as also evidenced by the haemoglobin levels.

Conclusion

The plant exhibits moderate antimalarial activity which can be further prospected for active fractions or pure molecules for adjunctive therapy.     

Screening of antiplasmodial properties among some traditionally used Iranian plants

Ethnopharmacological relevance

An investigation of plants was undertaken through interviews and literature surveys on plants used to treat malaria or cancer or microbial diseases in Iran.

Aim of study

In vitro and in vivo antiplasmodial tests were carried out on selected plants traditionally used in Iran.

Materials and methods

Thirty-two plants were extracted with methanol and tested for their in vitro (pLDH assay) activity against Plasmodium falciparum, in vivo activity against Plasmodium berghei and assessed for any cytotoxicity against the human cancer cell line MCF7 and the normal cell MDBK.

Results

Extracts from four plants, Buxus hyrcana Pojark. (Buxaceae), Erodium oxyrrhnchum M. Bieb. (Geraniaceae), Glycyrrhiza glabra L. (Fabaceae) and Ferula oopoda (Boiss and Bushe) Boiss. (Apiaceae) were found to have significant antiplasmodial activity (IC₅₀ ranging from 4.7 to 26.6 μg/ml). These findings lend support to the use of Buxus hyrcana and Glycyrrhiza glabra in traditional medicine. The chloroformic fraction also was active against K1 and 3D7 strains. The chloroformic fraction was studied at 10 mg per kg body weight mouse per day. This fraction reduced parasitaemia by 86.1% compared to untreated control mice.

Conclusion

Glycyrrhiza glabra showed antiplasmodial activity and has selectivity for Plasmodium falciparum and Plasmodium berghei when tested on mammalian cells. This is the first report that mentioned in vitro and in vivo antiplasmodial activity of Glycyrrhiza glabra.     

Plants used by native Amazonian groups from the Nanay River (Peru) for the treatment of malaria

Aim of the study

In order to evaluate the antimalarial potential of traditional remedies used in Peru, Indigenous and Mestizo populations from the river Nanay in Loreto were interviewed about traditional medication for the treatment of malaria.

Materials and methods

The survey took place on six villages and led to the collection of 59 plants. 35 hydro-alcoholic extractions were performed on the 21 most cited plants. The extracts were then tested for antiplasmodial activity in vitro on Plasmodium falciparum chloroquine resistant strain (FCR-3), and ferriprotoporphyrin inhibition test was also performed in order to assume pharmacological properties.

Results

Extracts from 9 plants on twenty-one tested (Abuta rufescens, Ayapana lanceolata, Capsiandra angustifolia, Citrus limon, Citrus paradise, Minquartia guianensis, Potalia resinífera, Scoparia dulcis, and Physalis angulata) displayed an interesting antiplasmodial activity (IC₅₀ < 10 μg/ml) and 16 remedies were active on the ferriprotoporphyrin inhibition test.

Conclusions

The results give scientific validation to the traditional medical knowledge of the Amerindian and Mestizo populations from Loreto and exhibit a source of potentially active plants.     

Renaissance remedies: Antiplasmodial protostane triterpenoids from Alisma plantago-aquatica L. (Alismataceae)

Aim of the study

In a preliminary screen of extracts from plants used as antimalarial remedies used in Europe in the 16th and 17th, the ethyl acetate extract of Alisma plantago-aquatica L. (Alismataceae) was active against Plasmodium falciparum K1 strain with 77% growth inhibition at 4.9 μg/ml. The aim of this study was to isolate and identify the substances responsible for this antiplasmodial activity.

Materials and methods

With HPLC-based activity profiling in combination with HPLC hyphenated methods (HPLC-PDA, -MSn, HR-MS, and off-line microprobe NMR) the activity was assigned to time windows, and the substances contained therein were characterised chemically. The active compounds were isolated with semi-preparative HPLC and structures were elucidated with high resolution mass spectrometry, and 1D and 2D NMR spectroscopy.

Results

Four compounds were isolated and identified as protostane triterpenoids alisol A, alisol B 11-monoacetate, alisol B 23-monoacetate, and alisol G. Their IC₅₀s against Plasmodium falciparum ranged from 5.4 to 13.8 μM.

Conclusions

This is the first report of antiplasmodial activity from protostanes triterpenoids, and the first result of our ongoing project of screening for antiprotozoal natural products from remedies used in European renaissance medicine.     

Antiplasmodial activity of extracts from seven medicinal plants used in malaria treatment in Cameroon

Aim of the study

In a search for new plant-derived biologically active compounds against malaria parasites, we have carried out an ethnopharmacological study to evaluate the susceptibility of cultured Plasmodium falciparum to extracts and fractions from seven Cameroonian medicinal plants used in malaria treatment. We have also explored the inhibition of the Plasmodium falciparum cysteine protease Falcipain-2.

Materials and methods

Plant materials were extracted by maceration in organic solvents, and subsequently partitioned or fractionated to afford test fractions. The susceptibility of erythrocytes and the W2 strain of Plasmodium falciparum to plant extracts was evaluated in culture. In addition, the ability of annonaceous extracts to inhibit recombinant cysteine protease Falcipain-2 was also assessed.

Results and discussion

The extracts showed no toxicity against erythrocytes. The majority of plant extracts were highly active against Plasmodium falciparumin vitro, with IC₅₀ values lower than 5 μg/ml. Annonaceous extracts (acetogenin-rich fractions and interface precipitates) exhibited the highest potency. Some of these extracts exhibited modest inhibition of Falcipain-2.

Conclusion

These results support continued investigation of components of traditional medicines as potential new antimalarial agents.     

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.     

Potent antiplasmodial extracts from Cameroonian Annonaceae

Aim of the study

In a search for new antimalarial leads, we have carried out a preliminary ethnopharmacological study with the aim of evaluating the in vitro antiplasmodial activity of extracts from thirteen Annonaceae species growing in Cameroon, and of assessing the acute toxicity of promising fractions in Swiss albino mice.

Materials and methods

Plants were selected on the basis of an ethnobotanical survey carried out in four sites in centre and south regions of Cameroon (Yaoundé neighbourhoods, Kon-Yambetta, Ngobayang and Mbalmayo) on Annonaceae plants locally used to treat malaria and related symptoms. The choice of the sites was mainly based on environmental factors enabling mosquito breeding, cosmopolitan areas regrouping people from different cultural origins, areas with limited access to health centers, and areas with people relying exclusively on traditional medical practices. Collected materials were extracted by maceration in 95% ethanol. The crude extract was partitioned using organic solvents and the fractions afforded were evaluated for antiplasmodial activity in culture against the W2 strain of Plasmodium falciparum. Promising fractions (methanol fractions) were assessed for their acute toxicity in Swiss albino mice.

Results

From the results achieved, 37 (31.3%) out of 118 extracts tested exhibited antiplasmodial activity, with IC₅₀ values ranging from 1.07 μg/ml to 9.03 μg/ml. Of the active extracts, 29 (78.4%) were methanol fractions, 21 (72.4%) of which inhibited the parasites with IC₅₀ < 5 μg/ml. The promising fractions proved to be safe through oral administration in mice.

Conclusions

The activities and toxicity profiles of methanol fractions indicate that they deserve to be further investigated in detail for antimalarial lead discovery.