In Silico Investigation of Caged Xanthone Compounds Isolated from Cratoxylum sumatranum Stem Bark Against Entamoeba histolytica Enzymes

Abstract

Amoebiasis is caused by Entamoeba histolytica, a pathogenic species living on human colon tissues. Metronidazole is currently used for the treatment of amoebiasis, but resistance of E. histolytica to the use of such treatment has been reported. Therefore, the development of new anti-amoebic drugs is still very much needed for clinical treatment. Preliminary research on extract and fractions from Cratoxylum sumatranum stem bark has shown their anti-amoebic activity. Two compounds from the cage xanthone groups, cochinchinoxanthone and cochinchinone D, have been isolated from the active fraction of C. sumatranum stem bark. This study aimed to investigate the anti-amoebic activity of the two known compounds against E. histolytica. The in silico method used was molecular docking with several receptors, including thioredoxin reductase, triose phosphate isomerase, pyruvate ferredoxin oxidoreductase, Giardia fructose-1,6-bisphosphate aldolase, serine acetyltransferase, and phosphoserine phosphatase. The prediction of ADMET properties was also carried out for both the compounds. The results showed cochinchinone D to have a higher binding affinity to thioredoxin reductase, pyruvate ferredoxin oxidoreductase, and Giardia fructose-1,6-bisphosphate aldolase receptors than cochinchinoxanthone. In contrast, cochinchinoxanthone bound better to the triose phosphate isomerase and phosphoserine phosphatase receptors, while both exhibited the same affinity for serine acetyltransferase. In general, the two compounds were also found to have similar ADMET profiles. In conclusion, caged xanthone compounds from C. sumatranum have the potential to be developed as anti-amoebic agents against E. histolytica through the mechanism of inhibition of these enzymes.