Antimalarial drug interactions of compounds isolated from Kigelia africana (Bignoniaceae) and their synergism with artemether, against the multidrug-resistant W2mef Plasmodium falciparum strain
ABSTRACT For decades, drug resistance has been the major obstacle in the fight against malaria, and the search for new drugs together with the combination therapy constitutes the major approach in responding to this situation. The present study aims at assessing the in vitro antimalarial activity of four compounds isolated from Kigelia africana stem bark (atranorin - KAE1, specicoside - KAE7, 2β,3β,19α-trihydroxy-urs-12-20-en-28-oic acid - KAE3, and p-hydroxy-cinnamic acid - KAE10) and their drug interactions among themselves and their combination effects with quinine and artemether. The antiplasmodial activity and drug interactions were evaluated against the multidrug-resistant W2mef strain of Plasmodium falciparum using the parasite lactate dehydrogenase assay. Three of the four compounds tested were significantly active against W2mef: specicoside (IC(50) = 1.02 ± 0.17 μM), 2β,3β,19α-trihydroxy-urs-12-en-28-oic acid (IC(50) = 1.86 ± 0.15 μM) and atranorin (IC(50) = 1.78 ± 0.18 μM), whereas p-hydroxy-cinnamic acid showed a weak activity (IC(50) = 12.89 ± 0.87 μM). A slight synergistic effect was observed between atranorin and 2β,3β,19α-trihydroxy-urs-12-en-28-oic acid (Combination index, CI = 0.82) whereas the interaction between specicoside and p-hydroxy-cinnamic acid were instead antagonistic (CI = 2.67). All the three compounds showed synergistic effects with artemether, unlike the slight antagonistic interactions of atranorin and 2β,3β,19α-trihydroxy-urs-12-en-28-oic acid in combination with quinine. K. africana compounds are therefore likely to serve as leads in the development of new partner drugs in artemether-based combination therapy.
- SourceAvailable from: Vishnu Kirthi[Show abstract] [Hide abstract]
ABSTRACT: Malaria is an overwhelming impact in the poorest countries in the world due to their prevalence, virulence and drug resistance ability. Currently, there is inadequate armoury of drugs for the treatment of malaria. This underscores the continuing need for the discovery and development of new effective and safe antimalarial drugs. To evaluate the in vitro and in vivo antimalarial activity of the leaf ethyl acetate extract of Murraya koenigii, bioassay-guided chromatographic fractionation was employed for the isolation and purification of antimalarial compounds. The in vitro antimalarial activity was assayed by the erythrocytic stages of chloroquine-sensitive strain of Plasmodium falciparum (3D7) in culture using the fluorescence-based SYBR Green I assay. The in vivo assay was done by administering mice infected with Plasmodium berghei (NK65) four consecutive daily doses of the extracts through oral route following Peter's 4-day curative standard test. The percentage suppression of parasitaemia was calculated for each dose level by comparing the parasitaemia in untreated control with those of treated mice. Cytotoxicity was determined against HeLa cells using MTT assay. Histopathology was studied in kidney, liver and spleen of isolated compound-treated Swiss albino mice. The leaf crude ethyl acetate extract of M. koenigii showed good in vitro antiplasmodial activity against P. falciparum. The in vivo test of the leaf crude ethyl acetate extract (600 mg/kg) showed reduced malaria parasitaemia by 86.6 % against P. berghei in mice. Bioassay-guided fractionation of the leaf ethyl acetate extract of M. koenigii led to the isolation of two purified fractions C3B2 (2.84 g) and C3B4 (1.97 g). The purified fractions C3B2 and C3B4 were found to be active with IC50 values of 10.5 ± 0.8 and 8.25 ± 0.2 μg/mL against P. falciparum, and in vivo activity significantly reduced parasitaemia by 82.6 and 88.2 % at 100 mg/kg/body weight on day 4 against P. berghei, respectively. The isolated fractions C3B2 and C3B4 were monitored by thin-layer chromatography until a single spot was obtained with R f values of 0.36 and 0.52, respectively. The pure compounds obtained in the present investigation were subjected to UV-visible spectroscopy, Fourier transformer infrared spectroscopy, 1D and 2D (1)H-Nuclear magnetic resonance (NMR), (13)C NMR, DEPT, COSY and Mass spectral analysis. Based on the spectral analysis, it is concluded that the isolated compounds were myristic acid (C3B2) and β-caryophyllene (C3B4). The cytotoxic effect of myristic acid and β-caryophyllene showed the TC50 values of >100 and 80.5 μg/mL, respectively against HeLa cell line. The histopathology study showed that protection against nephrotoxicity of kidney, hepatic damage of liver and splenocytes protection in spleen was achieved with the highest dose tested at 100 mg/kg/body weight. The present study provides evidence of antiplasmodial compounds from M. koenigii and is reported for the first time.Parasitology Research 03/2014; 113(5). DOI:10.1007/s00436-014-3810-3 · 2.33 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: To validate scientifically the traditional use of Salacia leptoclada Tul. (Celastraceae) (S. leptoclada) and to isolate and elucidate the structure of the biologically active compound. Bioassay-guided fractionation of the acetonic extract of the stem barks of S. leptoclada was carried out by a combination of chromatography technique and biological experiments in viro using Plasmodium falciparum and P388 leukemia cell lines as models. The structure of the biologically active pure compound was elucidated by 1D and 2D NMR spectroscopy and mass spectrometry. Biological screening of S. leptoclada extracts resulted in the isolation of a pentacyclic triterpenic quinone methide. The pure compound exhibited both in vitro a cytotoxic effect on murine P388 leukemia cells with IC50 value of (0.041±0.020) μg/mL and an antiplasmodial activity against the chloroquine-resistant strain FC29 of Plasmodium falciparum with an IC50 value of (0.052±0.030) μg/mL. Despite this interesting anti-malarial property of the lead compound, the therapeutic index was weak (0.788). In the best of our knowledge, the quinone methide pentacyclic triterpenoid derivative compound is reported for the first time in S. leptoclada. The results suggest that furthers studies involving antineoplastic activity is needed for the development of this lead compound as anticancer drug.Asian Pacific Journal of Tropical Biomedicine 10/2013; 3(10):780-4. DOI:10.1016/S2221-1691(13)60155-0
- [Show abstract] [Hide abstract]
ABSTRACT: The crude methanol extracts of leaf, stem bark, root bark and stem bark fractions of Trichilia megalantha (Meliaceae) were screened for in vivo antimalarial activities in mice against a chloroquine resistant Plasmodium berghei berghei ANKA clone using the 4-day suppressive test procedure. Chloroquine diphosphate was used as the positive control. The extracts demonstrated intrinsic antimalarial property. Of all the seven extracts studied, the stem bark gave the highest activity. At 200 mg/kg of mouse, the stem bark extract had complete suppression of parasite growth (100 %). Least activity was observed for the leaf extract, while the root bark had a parasite suppression of 98.4 % at 800 mg/kg comparable to that of Chloroquine. Percentage suppression of parasite growth on day 4 post-infection ranged from 3.1 to 96.1 % in mice infected with P. berghei and treated with extracts and fractions of T. megalantha when compared with chloroquine diphosphate, the standard reference drug which had a chemosuppression of 96.2 %. At 400 mg/kg, the stem bark chloroform fraction was the most active fraction with 89.1 % parasite growth suppression followed by the ethyl acetate fraction (76.4 %), hexane soluble fraction (54.8 %) and methanol fraction (20.5 %). The mean survival time of mice that received extract ranged from 8.75 ± 0.65 to 26.0 ± 1.2 days (increased as the dose increases to 800 mg/kg), which was statistically significant, except the lowest dose (100 mg/kg) compared to the negative control group mice (9.45 ± 0.6 days). The animals that were treated with Chloroquine had mean survival time of 23.5 ± 1.2 days.Parasitology Research 06/2013; DOI:10.1007/s00436-013-3471-7 · 2.33 Impact Factor