In vitro activities of plant extracts on human Loa loa isolates and cytotoxicity for eukaryotic cells.
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.
Mengome
Line-Edwige
LE
Institut de Pharmacopée et de Médecine Traditionnelle (IPHAMETRA), Libreville, Gabon.
Akue
Jean Paul
JP
Souza
Alain
A
Feuya Tchoua
Guy Raymond
GR
Nsi Emvo
Edouard
E
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002522:Chlorocebus aethiops; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D020128:Inhibitory Concentration 50; D007668:Kidney / Q000166:cytology / Q000187:drug effects*; D008117:Loa / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D008118:Loiasis / Q000469:parasitology; D008842:Microfilariae / Q000187:drug effects; D021261:Parasitic Sensitivity Tests; D010636:Phenols / Q000494:pharmacology; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity*; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*; D059808:Polyphenols; D014315:Triterpenes / Q000494:pharmacology; D014709:Vero Cells / Q000187:drug effects
D000470:Alkaloids; D005419:Flavonoids; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; D014315:Triterpenes