Determination of the Bioactive Components and Antitrypanosome Activity of the Leaves and Stem Barks Extract of Olea Hochstetteri Bak (Oleaceae)

Abstract

Trypanosomiasis is one of the most infectious diseases caused by Trypnosomas parasites. 
With the raising resistance to conventional antitrypanosomal drugs, increasing resistance 
of vector to insecticides, lack of effective vaccines and adverse effects of the existing 
antitrypanosomal drugs justify the urgent need for affordable, tolerable and effective 
drug. The method of cold marceration was used in the extraction. Phytochemical analysis 
of ethanolic extract of Olea hochstetteri leaves EEOHL, ethanolic extract of Olea 
hochstetteri stem bark EEOHSB, aqueous extract of Olea hochstetteri leaves AEOHL and 
aqueous extract of Olea hochstetteri stem bark AEOHSB showed the presence of 
flavonoids, glycosides, saponins, terpenoids, steroids, reducing sugar, alkaloids, tannins, and 
phenol at various concentration,  quantitative determination of some secondary metabolites 
indicates that extracts  contained  flavonoids saponnins and phenol and alkaloid .Two 
compounds AEOHL and EEOHSB were tested for antitrypanosomal activities against 
Trypanosoma evansi field isolate using in vitro and in vivo techniques. Parasite load, packed 
cell volume (PVC) and body weight in Mice were evaluated. In vitro test was performed in 
triplicates to detect any motile trypanosomes in a 96 well microplates. Twenty microliters 
of blood containing about 16 – 32 organisms per field were mixed with 5µL of the test 
substance at concentration of 2.5, 5, 10 and 20 mg/mL to produce test concentration of 
0.5, 1, 2 and 4 mg/mL, respectively.  AEOHL inhibited parasite motility and eliminated the 
organism within 60 min at 4mg/mL concentration and within 80 min at 2mg/mL, the EEOHSB 
inhibited parasite motility within 80 min at 4 and 2mg/mL concentration respectively. The 
extracts also reduces parasitemia and prevented drop in Packed Cell Volume and body 
weight significantly (p<0.05) at 400 and 200 mg/kg dose, as compared to control. Fourier 
Transform Infrared (FTIR) analysis of isolated compound  revealed the presence of 
characteristic functional group of esters (1729 cm-1), ethers (1077 cm-1) absorption band 
at, 1259 cm-1 (C-O), 2922 cm-1. GC-MS of the methanol extract of leaves of O. hochstetteri 
showed an active compound ethyl octadecanoate ethyl ester as one most abundance 
constituent with peak areas 12351016.76, height 3966129.27 and retention time 16.3 and 
base peak 88.1.