Investigation Of The Efficacy And Chemistry Of Selected Traditional Medicines Used In The Treatment Of Schistosomiasis And Their Antitrypanosomal Potential

ABSTRACT This research investigated the efficacy and chemistry of selected traditional medicines (TM) used in the treatment of schistosomiasis and also explored their antitrypanosomal potential. Crude extracts were obtained by successive extraction of dried herbs with dichloromethane and methanol while aqueous herbal preparations were extracted with dichloromethane and butanol. Biological activity was conducted by screening the crude extracts against the schistosomula (NTS) and adult worms of Schistosoma mansoni and bloodstream forms of Trypanosoma brucei brucei. At 100 μM, two crude extracts, NTD_B4 DCM and NTD_B7 DCM completely killed the NTS and demonstrated greater than 70% effect against adult worms of S. mansoni. Furthermore, all crude extracts exhibited antitrypanosomal activity with IC50 ranging from 6 – 19 μg/mL, with NTD_B4 DCM recording the highest IC50 of 6 μg/mL as compared to the 0.54 μg/mL of the standard, diminazene aceturate. Since NTD_B4 DCM displayed the highest antischistosomal and antitrypanosomal activities, it was selected for fractionation, chromatographic separations and further biological activity testing. Fractionation of NTD_B4 DCM yielded 6 fractions of which F5 (100% ethyl acetate) and F1 (100% petroleum ether + PE:EtOAc/9:1) displayed the highest antitrypanosomal activity with IC50 values of 7.4 and 8.5 μg/mL, respectively. Antischistosomal assay on the fractions is currently ongoing. Chromatographic separations of the two fractions led to the isolation of 4 solid compounds and 4 oils from F1 and 2 solid compounds from F5. Spectroscopic (IR and NMR) and spectrometric (MS) data led to the identification of 5,7-dihydroxy-6-methyl-2-tricosyl-4Hchromen-4-one and a fatty acid from F1, and β-sitosterol-3-O-glucoside and ethyl 4- hydroxybenzoate from F5. The structure elucidation of the remaining compounds was inconclusive due to the paucity of material. All the isolated compounds, apart from 5,7-dihydroxy-6-methyl-2-tricosyl-4H-chromen-4-one (81 μg/mL), were not active against T. brucei brucei. The oily compounds, however, demonstrated profound antitrypanosomal activity with IC50 ˂ 32.2 μg/mL, with one oil (F1/HML) exhibiting 1.3-fold activity (IC50 ˂0.0977 μg/mL) as compared to the positive standard diminazene aceturate (IC50 = 0.13 μg/mL). Initial cytotoxicity tests against RAW murine macrophage cells indicated that F1/HML was not cytotoxic and was selective in killing trypanosomes. The GC-MS analysis of F1/HML led to the identification of phytane (6.31%) 1,4,5,8-tetrahydro-4a,8a- v naphthalenedicarboximide (10.30%), 2-butylbenzothiazole (4.26%), 4α-Methyl-24-ethyl-5αcholest-8(9)-en-3β-ol (4.61%), and 11-(2,5-dimethylphenyl)-10-heneicosene (2.49%) as the major constituents. This research confirmed the efficacy of 2 of the schistosomiasis remedies, NTD_B4 and NTD_B7, and provided scientific justification for their use. In addition, NTD_B4 and NTD_2 exhibited remarkable antitrypanosomal potential confirming these traditional medicines have activity against Trypanosoma brucei brucei.