Selective activity of extracts of Margaritaria discoidea and Homalium africanum on Onchocerca ochengi

Abstract

BackgroundThe current treatment of onchocerciasis relies on the use of ivermectin which is only microfilaricidal and for which resistant parasite strains of veterinary importance are increasingly being detected. In the search for novel filaricides and alternative medicines, we investigated the selective activity of crude extracts of Margaritaria discoidea and Homalium africanum on Onchocerca ochengi, a model parasite for O. volvulus. These plants are used to treat the disease in North West Cameroon.MethodsSixteen crude extracts were prepared from various parts of M. discoidea and H. africanum using different organic solvents. The filaricidal activities were determined in vitro. Cytotoxicity of the active extracts was assessed on monkey kidney epithelial cells in vitro and the selectivity indices (SI) of the extracts determined. Acute toxicity of the promising extracts was investigated in mice.ResultsFour out of the 16 extracts showed microfilaricidal activity based on motility reduction, whereas, none showed macrofilaricidal activity based on the MTT/formazan assay. The methylene chloride extract of H. africanum leaves (HLC) recorded the lowest IC50 of 31.25 μg/mL and an IC100 of 62.5 μg/mL. The SI for the active extracts ranged from 0.5 - 2.63. No form of acute toxicity was observed in mice. Phytochemical analysis revealed the presence of anthraquinones, sterols and terpenoids in the promising extracts.ConclusionsThe non-polar extracts of M. discoidea and H. africanum are potential sources of new microfilaricidal lead compounds, and the results support their use in traditional medicine.

Antimycobacterial activity against different pathogens and selectivity index of fourteen medicinal plants used in southern Africa to treat tuberculosis and respiratory ailments

“…A good selectivity index is an indication of a large safety margin between the concentration of the extract that is able to kill the mycobacteria and the concentration that is toxic to mammalian Vero cells in this case. Therefore, the higher the selectivity index is for a crude extract, the more likely it is that the activity is not due to a general metabolic toxin (Cho-Ngwa et al, 2010). Although the elimination of toxic components by manipulation of the extract may yield more suitable antibacterial extracts (Eloff et al, 2005), the selection of an extract with a high selectivity index increases the potential that a useful herbal medicine can be produced.…”

Antimycobacterial, antioxidant and cytotoxic activities of essential oil of gall of <i>Pistacia atlantica</i> Desf. From Algeria

“…The FRAP of essential oil samples was determined by direct reduction of potassium ferricyanide (K 3 Fe(CN) 6 ) to potassium ferrocyanide (K 4 Fe(CN) 6 ) (electron transfer process from the antioxidant). The increase in absorbance from the formation of Pearl's Prussian blue complex following the addition of excess ferric ion was measured as described by Berker et al (2007) with some modification.…”

Anti-inflammatory and antinociceptive activities ofHomalium letestui

“…However, other members of the genus Homalium have been reported to possess various biological activities; Homalium deplanchei Warburg (Flacourtiaceae) has antileishmanial, antitrypanosomal and antitrichomonal activities (Desrivot et al, 2007), Homalium panayanum F. Villar (Flacourtiaceae) has been reported to exert antibacterial activity against some Gram-positive and Gram-negative bacteria (Chung et al, 2004), Homalium cochinchinensis (Lour) Druce (Salicaceae) has antiviral activity (Ishikawa et al, 2004), Homalium africanum (Hook. F) (Flacourtiaceae) has filaricidal activity (Cho-Ngwa et al, 2010) and anthelmintic activity has been reported on Homalium zeylanicum (Gardner) Benth (Flacourtiaceae) (Gnananath et al, 2012). Information on the pharmacology and phytochemistry of H. letestui is scarce.…”