Anthelmintic Activity of Ethanolic and Aqueous Extracts of Khaya grandifoliola Stem Bark against Heligmosomoides polygyrus: In Vitro and In Silico Approaches.

Background: Parasitic infection remains a serious health trade for humans and livestock. The purpose of this study was to present scientific proof of the anthelmintic properties of Khaya grandifoliola, which the native population uses to cure helminthiasis.

Method: Fresh Heligmosomoides polygyrus eggs were isolated from faecal samples of experimentally infected mice. The faecal material was cultured, and L1 and L2 larval stages were recovered after 48 and 120 hours, respectively. Using the worm microtracker, the anthelminthic efficacy of the extracts against H. polygyrus was assessed. Two different extracts (aqueous and ethanol extracts) were prepared. For the ovicidal and larvicidal activities, 100 µL of various concentrations of plant extracts, levamisole and 1.5% dimethyl sulfoxide (DMSO), were introduced into a 96-well microplate titer followed by the addition of 100 µL of embryonated eggs (60 eggs) for the ovicidal activity and 100 µL of L ₁ or L ₂ larvae (50 larvae) for the larvicidal activity. The movement of the worm was monitored for 24 hours in the worm microtracker at 27°C. The Glide module of the Schrodinger Maestro software was used to perform docking studies.

Results: For the aqueous extracts, the highest percentage of inhibition of hatching was 42.77 ± 12% at 7.5 mg/mL. The IC₅₀ values for the ethanol (0.36 mg/mL) extract showed that the ethanol extract had a good inhibitory effect on the ability of parasites to hatch from eggs. The inhibition percentage of L1 larvae motility at 7.5 mg/mL was 98.0 ± 1.66% and 83.33 ± 1.66% for ethanol and aqueous extracts, respectively. The negative controls, distilled water and 1.5% DMSO, had no inhibitory impact on larvae. On L1-larvae, the drug of choice levamisole (positive control) had the highest percentage effect (100.0%). Six compounds had the highest docking score and their interactions with the receptor as well. Grandiamide A interacts most with tyrosine, glycine, phenylalanine, asparagine, and serine, and its benzene ring and oxygens inhibit these receptors. Carbonyl and hydroxyl (OH) groups connect grandiamide D to asparagine, isoleucine, and phenylalanine, respectively. By donating hydrogen to the receptor through OH groups, D-glucopyranose-6-phosphate also forms relatively strong hydrogen bonds with its oxygen-bound phosphorus and the receptor. 1-O-deacetylkhayanolide E interacts most with serine and glutamic acid. The carbamic acid benzyl ester of carbamic acid [(1S)-1-phenyl-2-[(4-methylphenyl) sulfinyl] ethyl] interacts most with the receptor with carbonyl groups and with asparagine and serine. With its abundant hydroxide, D-mannitol acts as a hydrogen donor and acceptor and interacts most strongly with amino acids such as glycine, asparagine, aspartic acid, alanine, and glutamic acid.

Conclusions: K. grandifoliola extracts possess anthelminthic properties. However, in vivo studies are still necessary to demonstrate the effectiveness of this plant for the treatment of helminthiasis.