Parasitic helminths continue to pose problems in human and veterinary medicine, as well as in agriculture. Resistance to current anthelmintics has prompted the search for new drugs. Anthelmintic metabolites from medicinal plants could be good anthelmintic drug candidates. However, the compounds active against nematodes have not been identified in most medicinal plants with anthelmintic activity. In this study, we aimed to identify medicinal plants with anthelmintic activity for the subsequent isolation of the compounds.
Materials And Methods:
Six indigenous medicinal plants were chosen based on their ethnopharmacological use in Kenya for the treatment of different infectious diseases. The samples were obtained from the leaves of W. ugandensis , Albizia gummifera , Zanthoxylum chalybeum , Zanthxylum gilleti , Turrea holstii , Toddalia asiatica. 1 mL of extract was re-dissolved in water (for the aqueous extract) or DMSO for the ethanol, hexane and acetone extracts at concentration of 40 mg/mL. The anthelmintic assay was carried out in a 96-well microplate. Freshly cultivated young adult worms were collected in M9 buffer and adjusted to approximately 3000 larvae/mL. Then, 15 μL of this suspension (containing approximately 45 larvae) were added to each well of a 96-well microplate containing 184 μL of E. coli OP50 culture (O.D. 600 = 0.5). Subsequently, 1 μL of test sample (200 μg/ml) was added to each well; DMSO (1 μL) was used in a separate well as a solvent control. After mixing, the 96-well microplate was placed into a WMicrotracker apparatus and incubated for 16 h at 20 °C. The movement of worms in each well was measured every 30 min and the percentage of the average movement over 16 h of test samples, was calculated. The same method was used to test the activity of active compounds on a panel of drug-resistant mutant strains and transient receptor potential (TRP)-channel mutant strains.
Results:
The 24 samples prepared by small-scale extraction of six medicinal plants in four different solvents were tested for anthelmintic activity at the same concentration (200 μg/mL). The results showed that ethanol and acetone extracts of W. ugandensis have quite strong anthelmintic activity in the WMicrotracker assay, with the ethanol extract showing the most potent activity among the four extracts. In addition, ethanol extracts of Z. chalybeum and Z. gilleti showed slight activity. Thus, the ethanol extract of W. ugandensis was selected for subsequent large-scale extraction and bioassay guided isolation of active compounds.
Int J Parasitol. 2018 Jul 18. pii: S0020-7519(18)30151-6. doi: 10.1016/j.ijpara.2017.11.009.
Liu M, Kipanga P, Mai AH, Dhondt I, Braeckman BP, De Borggraeve W, Luyten W.