In Vivo Antiplasmodial Activity of Terminalia mantaly Stem Bark Aqueous Extract in Mice Infected by Plasmodium berghei.

BACKGROUND: Terminalia mantaly is used in Cameroon traditional medicine to treat malaria and related symptoms. However, its antiplasmodial efficacy is still to be established. OBJECTIVES: The present study is aimed at evaluating the in vitro and in vivo antiplasmodial activity and the oral acute toxicity of the Terminalia mantaly extracts. MATERIALS AND METHODS: Extracts were prepared from leaves and stem bark of T. mantaly, by maceration in distilled water, methanol, ethanol, dichloromethane (DCM), and hexane. All extracts were initially screened in vitro against the chloroquine-resistant strain W2 of P. falciparum to confirm its in vitro activity, and the most potent one was assessed in malaria mouse model at three concentrations (100, 200, and 400 mg/kg/bw). Biochemical, hematological, and histological parameters were also determined. RESULTS: Overall, 7 extracts showed in vitro antiplasmodial activity with IC50 ranging from 0.809 µg/mL to 5.886 µg/mL. The aqueous extract from the stem bark of T. mantaly (Tmsbw) was the most potent (IC50 = 0.809 µg/mL) and was further assessed for acute toxicity and efficacy in Plasmodium berghei-infected mice. Tmsbw was safe in mice with a median lethal dose (LD50) higher than 2000 mg/kg of body weight. It also exerted a good antimalarial efficacy in vivo with ED50 of 69.50 mg/kg and had no significant effect on biochemical, hematological, and histological parameters. CONCLUSION: The results suggest that the stem bark extract of T. mantaly possesses antimalarial activity.

Uvaria angolensis as a promising source of inhibitors of HIV-1 RT-associated RNA-dependent DNA polymerase and RNase H functions.

Reverse transcriptase (RT)-associated DNA polymerase (RDDP) and ribonucleaser H (RNase H) functions are both essential for HIV-1 genome replication, and the identification of new inhibitors to block both of them is a goal actively pursued by the scientific community. In this field, natural extracts have shown a great potential as source of new antivirals. In the present work, we investigated the effect of Uvaria angolensis extracts on the HIV-1 reverse transcriptase-associated DNA polymerase and ribonuclease H activities. The U. angolensis stem bark methanol extract inhibit both HIV-1 RNase H function and RDDP activity with IC50 values of 1.0 ± 0.2 and 0.62 ± 0.15 µg/mL, respectively and, after been fractionated with different solvents, its solid residue showed an IC50 of 0.10 ± 0.03 and of 0.23 ± 0.04 µg/mL against RNase H and RDDP, respectively, hence laying the bases for further studies for identification of single active components.

In Vitro Activity of Selected West African Medicinal Plants against Mycobacterium ulcerans Disease.

Buruli ulcer (BU) is the third most prevalent mycobacteriosis, after tuberculosis and leprosy. The currently recommended combination of rifampicin-streptomycin suffers from side effects and poor compliance, which leads to reliance on local herbal remedies. The objective of this study was to investigate the antimycobacterial properties and toxicity of selected medicinal plants. Sixty-five extracts from 27 plant species were screened against Mycobacterium ulcerans and Mycobacterium smegmatis, using the Resazurin Microtiter Assay (REMA). The cytotoxicity of promising extracts was assayed on normal Chang liver cells by an MTT assay. Twenty five extracts showed activity with minimal inhibitory concentration (MIC) values ranging from 16 µg/mL to 250 µg/mL against M. smegmatis, while 17 showed activity against M. ulcerans with MIC values ranging from 125 µg/mL to 250 µg/mL. In most of the cases, plant extracts with antimycobacterial activity showed no cytotoxicity on normal human liver cells. Exception were Carica papaya, Cleistopholis patens, and Polyalthia suaveolens with 50% cell cytotoxic concentrations (CC50) ranging from 3.8 to 223 µg/mL. These preliminary results support the use of some West African plants in the treatment of Buruli ulcer. Meanwhile, further studies are required to isolate and characterize the active ingredients in the extracts.

In vitro nematicidal activity of aryl hydrazones and comparative GC-MS metabolomics analysis.

A series of aryl hydrazones were synthesized and in vitro assayed for their activity on the root-knot nematode Meloidogyne incognita. The phenylhydrazones of thiophene-2-carboxyaldehyde 5, 3-methyl-2-thiophenecarboxyaldehyde, 6, and salicylaldehyde, 2, were the most potent with EC50/48h values of 16.6 ± 2.2, 23.2 ± 2.7, and 24.3 ± 1.4 mg/L, respectively. A GC-MS metabolomics analysis, after in vitro nematode treatment with hydrazone 6 at 100 mg/L for 12 h, revealed elevated levels of fatty acids such as lauric acid, stearic acid, 2-octenoic acid, and palmitic acid. Whereas control samples showed the highest levels of monoacylglycerols such as monostearin and 2-monostearin, surprisingly, 2 h after treatment with hydrazone 6, nematodes excreted 3 times the levels of ammonia eliminated in the same conditions by controls. Thus, phenylhydrazones may represent a good scaffold in the discovery and synthesis of new nematicidal compounds, and a metabolomics approach may be helpful in understanding their mechanisms of toxicity and mode of action.