In vitro activities of plant extracts on human Loa loa isolates and cytotoxicity for eukaryotic cells

Abstract

Loa loa, a filarial worm, can cause fatal encephalitis in humans. In an attempt to find alternatives to the standard treatments (ivermectin and diethylcarbamazine citrate), we tested 12 methanolic extracts of nine traditional plant remedies. The extracts (100-0.09 microg/ml) were incubated with 20 Loa loa microfilariae isolated from patients at 37 degrees C with 5% CO(2) in modified Eagle's medium supplemented with 10% fetal serum and antibiotics. Activity was evaluated 120 h later by counting live microfilariae under a microscope. Cytotoxicity for eukaryotic cells was estimated by measuring 3-[4,5-dimethylthiazol-2-yl]-2-5 diphenyl tetrazolium bromide transformation to formazan at 450 nM in a spectrophotometer. The plants tested were Lophira alata, Greenwayodendron suaveolens, Uapaca togoensis, Zanthoxylum heitzii, Peperomia pellucida, Piptadeniastrum africanum, Petersianthus macrocarpus, Vernonia conferta, and Vernonia hymenolepis. Chemical screening showed that most of the extracts contained reducing sugars, tannin or polyphenols, sterols or triterpenes, saponosides, and alkaloids. None contained carotinoids and few contained flavonoids. The 50% lethal concentration ranged from 0.22 to 70.28 microg/ml, while the 50% inhibitory concentration for eukaryotic cells (IC(50)) ranged from 8.52 to 119.52 microg/ml. Extracts of P. macrocarpus (selectivity index = 72.16), P. africanum (13.69), Z. heitzii (12.11), and L. alata (9.26) were highly selective for L. loa.

Evaluation of Pharmacological and Phytochemical Profiles of Piptadeniastrum africanum (Hook.f.) Brenan Stem Bark Extracts

“…In the MTT test, HypoE22 cells were stimulated with the extracts in the range 0.1-10 μg/mL and a null effect on cell viability was observed (Figure 2). This is consistent, at least in part, with previous studies suggesting anti-proliferative effects induced by P. africanum extracts at higher concentrations [37,38]. Based on results gathered from the MTT test, a concentration of 10 μg/mL was chosen for evaluating protective and neuromodulatory effects.…”

Potential of Central, Eastern and Western Africa Medicinal Plants for Cancer Therapy: Spotlight on Resistant Cells and Molecular Targets

“…The plant grows in tropical Africa, from Senegal to southern Chad and Central African Republic and from Gabon to DR Congo and northern Angola. In traditional medicine, the plant is used as antiemetic, lotion for skin disorders (Mengome et al, 2010), remedy for pneumonia, cough, fever, rheumatism, vomiting, epilepsy (Kone et al, 2006) and bacterial diseases (Kone et al, 2004). The cytotoxicity of the methanol extract from fruit was reported toward CCRF-CEM cells (IC 50 : 4.23 μg/mL), CEM/ADR5000 cells (IC 50 : 4.44 μg/mL), MDA-MB-231- pcDNA cells (IC 50 : 25.85 μg/mL), MDA-MB-231- BCRP cells (IC 50 : 4.17 μg/mL), HCT116 ( p53 +/+ ) cells (IC 50 : 3,69 μg/mL), HCT116 ( p53 −/− ) cells (IC 50 : 3.09 μg/mL), U87MG cells (IC 50 : 8.01 μg/mL), U87MG.Δ EGFR cells (IC 50 : 8.68 μg/mL), and HepG2 cells (IC 50 : 19.90 μg/mL) (Kuete et al, 2015e).…”

In vitro evaluation of the schistosomicidal effect of the extracts, fractions and major 3-hydroxy-2,6-dialkyl-substituted piperidine alkaloids from the flowers of Senna spectabilis (Fabaceae)

“…they do not show high safety indices. An example of this toxic profile can be seen in the work of Mengome and co-workers 54 in which monkey kidney cells were used for the cytotoxicity evaluation. In this same context, another recent study showed that 3alkylpyridine marine alkaloid analogues showed significant toxicity against murine peritoneal macrophages.…”