Chemosuppressive Activities Research Articles

Evaluation of the combination of Uvaria chamae (P. Beauv.) and amodiaquine in murine malaria

Ethnopharmacological relevanceThe leaf and fruit of Uvaria chamae P. Beauv (Annonaceae) are used in antimalarial ethnomedical preparations. Therefore, they were investigated for antimalarial activities as well as possible herb-drug interaction with amodiaquine (AQ). Materials and methodsThe methanol extracts of the leaf (UCL) and fruit (UCF) were administered orally at 100–800mg/kg/day in mice infected with chloroquine (CQ)-sensitive Plasmodium berghei NK65 using the four-day, curative and prophylactic antimalarial test models. The UCL was further evaluated at 100–800mg/kg as twice-daily doses and combinations of UCL+AQ using the four-day test. Mice infected with CQ-resistant P. berghei ANKA were treated with UCL at 400mg/kg and AQ at 10mg/kg – [UCL400+AQ10]mg/kg – in the four-day and curative test models. ResultAt 800mg/kg/day, UCL, UCF gave chemosuppression of 42, 28% (four-day test), parasite clearance of 36.3, 49.5% on day 5 (curative test) and 64.3, 82.6% (prophylactic test), respectively. The twice-daily dose of UCL at 800mg/kg showed activity of 51.50% while the combination of [UCL200+AQ5]mg/kg exhibited chemosuppression of 91.66%, which was not significantly different (p>0.05) from AQ at 10mg/kg (85.41%). In the CQ-resistant P. berghei experiment, the combination gave a chemosuppression of 45.80%, significantly lower (p<0.05) than AQ (78.40%) while the parasite clearance was not significantly different from AQ (curative test). ConclusionThe leaf extract showed moderate chemosuppressive activity. The lower-dose combination of the leaf extract and amodiaquine had better antimalarial activity in CQ-sensitive murine malaria. However, the tested combination had no beneficial antimalarial effect in CQ-resistant murine malaria.

Anti-malarial Activities of Two Soil Actinomycete Isolates from Sabah via Inhibition of Glycogen Synthase Kinase 3β.

Exploiting natural resources for bioactive compounds is an attractive drug discovery strategy in search for new anti-malarial drugs with novel modes of action. Initial screening efforts in our laboratory revealed two preparations of soil-derived actinomycetes (H11809 and FH025) with potent anti-malarial activities. Both crude extracts showed glycogen synthase kinase 3β (GSK3β)-inhibitory activities in a yeast-based kinase assay. We have previously shown that the GSK3 inhibitor, lithium chloride (LiCl), was able to suppress parasitaemia development in a rodent model of malarial infection. The present study aims to evaluate whether anti-malarial activities of H11809 and FH025 involve the inhibition of GSK3β. The acetone crude extracts of H11809 and FH025 each exerted strong inhibition on the growth of Plasmodium falciparum 3D7 in vitro with 50% inhibitory concentration (IC50) values of 0.57 ± 0.09 and 1.28 ± 0.11 µg/mL, respectively. The tested extracts exhibited Selectivity Index (SI) values exceeding 10 for the 3D7 strain. Both H11809 and FH025 showed dosage-dependent chemo-suppressive activities in vivo and improved animal survivability compared to non-treated infected mice. Western analysis revealed increased phosphorylation of serine (Ser 9) GSK3β (by 6.79 to 6.83-fold) in liver samples from infected mice treated with H11809 or FH025 compared to samples from non-infected or non-treated infected mice. A compound already identified in H11809 (data not shown), dibutyl phthalate (DBP) showed active anti-plasmodial activity against 3D7 (IC50 4.87 ± 1.26 µg/mL which is equivalent to 17.50 µM) and good chemo-suppressive activity in vivo (60.80% chemo-suppression at 300 mg/kg body weight [bw] dosage). DBP administration also resulted in increased phosphorylation of Ser 9 GSK3β compared to controls. Findings from the present study demonstrate that the potent anti-malarial activities of H11809 and FH025 were mediated via inhibition of host GSK3β. In addition, our study suggests that DBP is in part the bioactive component contributing to the anti-malarial activity displayed by H11809 acting through the inhibition of GSK3β.

Evaluation of the use of Ocimum suave Willd. (Lamiaceae), Plectranthus barbatus Andrews (Lamiaceae) and Zanthoxylum chalybeum Engl. (Rutaceae) as antimalarial remedies in Kenyan folk medicine

Ethnopharmacological relevanceCrude extracts from the leaves of Ocimum suave Willd (Lamiaceae) and the root barks of Plectranthus barbatus Andrews (Lamiaceae) and Zanthoxylum chalybeum Engl. (Rutaceae) were studied to ascertain the ethnopharmacological standing of their antimalarial usage in Kenyan folk medicine. Materials and methodsAqueous and Chloroform: Methanol (1:1) extracts of the plants were used in this study. Toxicity of the extracts was investigated by using brine shrimp lethality test and acute oral toxicity in mice. The antimalarial activity at a dose of 100mg/kg was screened in Swiss albino mice against chloroquine sensitive Plasmodium berghei (D6) using Peters 4-day suppressive test. Chloroquine, at a dosage rate of 20mg/kg was used as a reference drug. ResultsThe extracts showed some signs of acute toxicity in the brine shrimp lethality test. However, no signs of toxicity were observed in the mice at a dose of 2000mg/kg of the crude extracts. The results revealed that all the tested crude extracts were safe. Z. chalybeum aqueous extract and P. barbatus organic extract showed chemosuppressive activities of 81.45% and 78.69%, respectively. This antimalarial activity was not significantly different from that of chloroquine (P<0.05). ConclusionThe findings suggest that the Kenyan folkloric medicinal application of these plants has a pharmacological basis. Bioactivity guided fractionation and isolation of bioactive molecules from the two species could lead to new hits against Plasmodiumfalciparum malaria.

Antimalarial activity of 80 % methanolic extract of Brassica nigra (L.) Koch. (Brassicaceae) seeds against Plasmodium berghei infection in mice.

BackgroundResistances to currently available drugs and insecticides, significant drug toxicities and costs and lack of vaccines currently complicated the treatment of malaria. A continued search for safe, effective and affordable plant-based antimalarial agents thus becomes crucial and vital in the face of these difficulties. The aim of the study was to evaluate the antimalarial activity of 80 % methanolic extract of the seeds of Brassica nigra against Plasmodium berghei infection in mice.MethodChloroquine sensitive Plasmodium berghei (ANKA strain) was used to test the antimalarial activity of the extract. In suppressive and prophylactic models, Swiss albino male mice were randomly grouped into five groups of five mice each. Group I mice were treated with the vehicle, group II, III and IV were treated with 100, 200, and 400 mg/kg of the extract, respectively and the last group (V) mice were treated with chloroquine (10 mg/kg). The level of parasitemia, survival time and variation in weight of mice were used to determine the antimalarial activity of the extract.ResultsChemosuppressive activities produced by the extract of the seeds of Brassica nigra were 21.88, 50.00 (P < 0.01) and 53.13 % (P < 0.01), while the chemoprophylactic activities were 17.42, 21.21 and 53.79 % (P < 0.05) at 100, 200 and 400 mg/kg of the extract, respectively as compared to the negative control. Mice treated with 200 and 400 mg/kg extract were significantly (P < 0.05) lived longer and gained weight as compared to negative control in 4-day suppressive test.ConclusionFrom this study, it can be concluded that the seed extract of Brassica nigra showed good chemosuppressive and moderate chemoprophylactic activities and the plant may contain biologically active principles which are relevant in the treatment and prophylaxis of malaria, thus supporting further studies of the plant for its active components.

Antiplasmodial Properties of Alstonia boonei Stem-Bark and Picralima nitida Seed in Different Combinations

The use of mixtures of plants in form of decoctions is common practice in African ethnomedicine.The study evaluated the antiplasmodial activities of the freeze-dried decoctions of different combination ratios of the stem-bark of Alstonia boonei De Wild (Apocynaceae) and dry seed of Picralima nitida (Stapf) T.&amp;H.Dur. (Apocynaceae) against chloroquine-sensitive Plasmodium bergheiberghei NK65 strain.Thus, the decoctions of the mixtures of A. boonei stem-bark (A) and P. nitida seed (P) were prepared in three different ratios 1:1 (AP1), 1:2 (AP2) and 2:1 (AP3), were separately filtered, concentrated in vacuo and freeze-dried to obtain the corresponding extractive for each ratio. The acute toxicity test was carried out on each of the ratios using Lorke’s method. The antiplasmodial activity of each ratio was assessed using 4-day test at 1.5-100 mg/kg. The ratio with the best chemosuppressive activity was subjected to prophylactic and established malaria infection tests at 6.25–50 mg/kg, with pyrimethamine (1.25 mg/kg) and chloroquine (5 mg/kg) as positive controls, respectively. The LD50 of each extractive was greater than 5000 mg/kg. The chemosuppressions of AP1, AP2 and AP3 at 12.5 mg/kg were 55.7%, 64.4% and 57.2%, respectively, with AP2 being comparable to chloroquine. The ED50 for AP1, AP2 and AP3 were 27.8, 26.0 and 29.7 mg/ kg, respectively.Furthermore, AP2 exhibited curative activity with parasite clearance between 82.6% and 84% at 12.5 - 50 mg/kg while it showed prophylactic activities between 46.5% and 55.3% at the same doses. The observed antiplasmodial activities of the freeze-dried extractive (AP2) from the decoction of A. boonei stem-bark and P. nitida seed in ratio 1:2 can therefore be exploited for herbal antimalarial drug development.Keywords: Antimalarial, Parasitaemia, Pyrimethamine, Chemosuppression

Antiplasmodial activity of solvent fractions of methanolic root extract of Dodonaea angustifolia in Plasmodium berghei infected mice.

BackgroundMalaria is one of the most important infectious diseases in the World. The choice for the treatment is highly limited, and several of these may eventually be lost or compromised due to drug resistance. The use of plant medicine in the treatment of malaria and its various presentations is a common practice in many countries of Africa where the disease is mostly endemic. Dodonaea angustifolia is traditionally used in Ethiopia for prophylaxis against malaria. The present study is attempted to evaluate the antimalarial activity of the solvent fractions of root extracts of D. angustifolia in P. berghei infected mice.MethodsIn this study, 4-days Peter’s suppressive test was used to determine parasite inhibition. Acute toxicity test was also conducted on the most active fraction according to Organization for Economic Cooperation and Development (OECD) guidelines 425. Data was analyzed by using Windows SPSS version 16 and expressed as mean ± SD for each dose level. ANOVA followed by Post Hoc Tukey’s HSD was used to compare result between treatment and control groups. Students paired t-test was employed to test significance for the difference between initial and final results within the same group.ResultsAll three fractions showed varying degrees of antiplasmodial activity. The n-butanol fraction displayed a relatively highest suppression of parasitaemia (67.51%) at an oral dose of 600 mg/kg. Lower doses, 200 mg/kg and 400 mg/kg, of the fraction also resulted in parasitaemia suppression of 38.02% and 55.85%, respectively. Chemosuppressive activity of chloroform and aqueous fractions was less compared to that of n-butanol fraction. All the three fractions displayed dose dependent significant (P < 0.001) antiplasmodial activity as compared to the control. Survival time was prolonged in case of n-butanol and chloroform fractions. No lethality to mice was seen with n-butanol fraction up to a dose of 2000 mg/kg.ConclusionAll the three fractions possessed significant antiplasmodial activity as compared with the control group. n-butanol fraction was found to be the most active fraction with minimal toxicity and might contain potential lead molecule for the development of a new drug for treatment of malaria.

In vivo antiplasmodial activities of four Nigerian medicinal plants

Infusions and decoctions of Nauclea latifolia, Artocarpus altilis, Murraya koenigii and Enantia chlorantha are used ethnomedicinally as antimalarial and febrifuge in West and South Africa, especially Nigeria and Cameroon (Madubunyi, 1995; Adjanohoun et al., 1996; Betti, 2002; Ogbonna et al., 2008; Adebayo and Krettli, 2012). Therefore, aqueous-ethanolic extracts of N. latifolia root and A. altilis stem bark were investigated for prophylactic, chemosuppressive and curative antiplasmodial activities using Plasmodium berghei berghei infected mice (Peters, 1967; Ryley and Peters, 1970). The curative activity of E. chlorantha was also studied. Using the three models, the activities of all the extracts were significantly (p < 0.05) less than those of the positive controls. The standard drug chloroquine gave ED50,ED90 of 2.19 ± 0.10; 4.29 ± 0.1 and 2.16 ± 0.02; 4.14 ± 0.02 mg/kg for the chemosuppressive and the curative test respectively, while Pyrimethamine gave 0.45 ± 0.11 and 0.91 ± 0.11 mg/kg for the prophylactic test. The order of curative activities was E. chlorantha = N. latifolia > A. altilis. The chemosuppressive ED50 235.5 and 279.3 mg/kg and prophylactic ED90 values of 455.7 and 356.0 mg/kg for A. altilis and N. latifolia, respectively differed significantly (p < 0.05). Hence, the extract of A. altilis had a higher chemosuppressive activity while N. latifolia stem and root had higher prophylactic and curative activities. Therefore, the combinations of A. altilis and N. latifolia, and A. altilis, E. chlorantha and N. latifolia, as used in herbal decoctions, were evaluated for their antiplasmodial activities in order to have a scientific justification for the ethnomedicinal antimalarial use of these plants. The results may also suggest that their combinations in an herbal potion may be beneficial in preventing, suppressing and curing malaria infection, as is currently obtained in Artemisinin Combination Therapy drugs.

Pharmacokinetics and in vivo chemosuppressive activity studies on cryptolepine hydrochloride and cryptolepine hydrochloride-loaded gelatine nanoformulation designed for parenteral administration for the treatment of malaria

The main objective of this investigation was to establish the pharmacokinetics profile and in vivo chemosuppressive activities of cryptolepine hydrochloride-loaded gelatine nanoparticles (CHN) designed for parenteral administration for the treatment of malaria in comparison to the drug free in solution (CHS). Single-dose pharmacokinetics was investigated in Wistar rats by administering CHN or CHS (equivalent to 10mg/kg of drug) by IV bolus injection via the lateral tail vein. The drug concentration in plasma was monitored over a 24-h period following administration. Chemosuppressive activity was investigated in Wistar rats challenged with P berghei parasites. Animals were given a daily dose of either CHN or CHS, equivalent to 2.5–100mg/kg by intraperitoneal injection. The level of parasitaemia was determined by light microscopy by examining Giemsa-stained thin blood smears prepared from the tail end on day four of infection. It was found that CHN attained a higher (4.5-folds) area under the curve (AUC (0–24)) compared to CHS. CHS however produced a higher volume of distribution (4-folds). Distribution and elimination rates were higher with CHS which resulted in a lower (11.7h) elimination half-life compared to that of CHN (21.85h). The superior pharmacokinetic profile of CHN translated into superior chemosuppressive activity at all dose levels relative to CHS. As a conclusion, loading cryptolepine hydrochloride into gelatine nanoparticles improved both pharmacokinetics and in vivo antiplasmodial activity of the compound with the highest chemosuppression (97.89±3.10) produced by 100mg/kg of CHN.

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.

Gongronema latifolium Benth. Leaves (Uteze) Ameliorate Malaria Infection in Plasmodium berghei-Infected Mice

Herbs are vital sources of bioactive compounds. This study evaluates the antimalarial, antioxidant, phytochemical and nutritional properties of Gongronema latifolium Benth. (Uteze) leaves. Pulverized dry leaves sample were macerated in hexane, methanol, ethanol and distilled water to obtain their respective extracts. The antimalarial efficacy of these extracts was assessed in male Swiss albino mice infected intraperitoneally with chloroquine-sensitive Plasmodium berghei NK65, using the chemo-suppressive, prophylactic and mean survival time (MST) assays. Phytochemical and proximate analyses were assessed by standard protocols. The antioxidant capacity of the extracts was analyzed using DPPH radical scavenging and ferrous ion chelating assays. From the results, the plant had significant (p &lt; 0.05) antimalarial activity compared to the infected untreated control. The chemo-suppressive activity of the extracts declined accordingly; ethanol (46.34%) &gt; methanol (43.16%) &gt; aqueous (32.24%), while their prophylactic activity declined in the order of aqueous (40.25%) &gt; ethanol (38.99%) &gt; methanol (26.94%). Only MST in the four-day chemo-suppressive assay was significant (p &lt; 0.05) compared to the infected untreated control. Tannins, alkaloids, flavonoids, saponins, phenolics, cardiac glycosides and proanthocyanidins were detected in reasonable quantities in the plant. The plant also had antioxidant activity as the aqueous extract (IC50 48.50 ± 0.42) scavenged DPPH radicals better, while methanol extract (IC50 21.15 ± 0.33) chelated ferrous ion radicals more compared to other extracts. Meanwhile, the percentage nutritional composition of the plant was moisture (6.23 ± 0.01), total ash (2.22 ± 0.02), crude fat (16.32 ± 0.04), crude fibre (1.04 ± 0.01), crude protein (9.33 ± 0.58) and nitrogen free extract (64.85 ± 0.63). In conclusion, the antimalarial activity of Gongronema latifolium Benth. (Uteze) leaves could be due to its rich phytochemical and nutritional properties.