Phytochemical Quantification, Antioxidant And Antimicrobial Activities Of Root Extracts Of Dennettia Tripetala And Milicia Excelsa

ABSTRACT

The roots of Dennettia tripetala and Milicia excelsa were analyzed for the presence of

phytochemicals. Five different solvents, which include methanol, ethanol, ethyl acetate, butanol

and water, were used for the extraction of the phytochemicals.The root of Dennettia tripetala

contained alkaloids, terpenoids, flavonoids, saponins, phenols, steroids and glycosides in varying

degrees of abundance in the different solvents with tannins not detected in all the solvents.

Milicia excelsa contained all the phytochemicals in Dennettia tripetala, in addition to tannins, in

different degrees of abundance in the various solvents. The root of Dennettia tripetala contained

1.83 % alkaloids, 3.64 % flavonoids, 1.41 % saponins, 0.67 %phenols, 0.36 % steroids and 0.08

% glycosides whereas that of Milicia excelsa contained 2.19 %alkaloids, 6.40 % flavonoids, 0.87

% saponins, 0.34 % phenols, 0.36 % tannins, 0.15 % steroids and 0.09 % glycosides. Results of

the Principal Component Analysis (PCA) of the phytochemicals revealed that, in Dennettia

tripetala, there was strong positive correlation between alkaloids and glycosides (0.995)and also

phenols and saponins (1.000) while the strong negative correlations were between alkaloids and

flavonoids (-0.980), flavonoids and glycosides (-0.956), phenols and steroids (-1.000) and also

saponins and steroids (-1.000). In Milicia excelsa, the strong positive correlations were between

alkaloids and flavonoids (0.908), phenols and saponins, glycosides (0.866) and also steroids and

tannins (1.000) whereas the strong negative correlations were between phenols and steroids (-

0.866), saponins and tannins, steroids (-1.000) as well as tannins and phenols (-0.866). An assay

of the antioxidant potentials of various extracts of both plants, using 2, 2-diphenyl-1-

picrylhydrazyl (DPPH) radical scavenging method, revealed that the ethanolic extracts of

Dennettia tripetala and Milicia excelsa as well as the methanolic extract of Dennettia tripetala

showed high percent inhibition ranging from 83.34 to 89.75 at 0.01 mg/mL of the extracts;

results which showed to be better than standard ascorbic acid (67.89) at the same concentration.

Other extracts of both plants, at higher concentrations, gave percent inhibitions ranging from

35.80 for the butanolic extract of Milicia excelsa at 0.025 mg/mL to 95.96 for the methanolic

extract of the same plant at 0.5 mg/mL. A comparison of the half maximal inhibitory

concentration (IC50) values of the extracts showed that ethyl acetate extracts of both plants had

the best IC50 values at 0.014 and 0.150 for Dennettia tripetala and Milicia excelsa respectively

which were better than ascorbic acid standard whose IC50 value was 1.060. All the other extracts

of both plants also had IC50 values better than ascorbic acid except for ethanol in both plants and

methanol in Milicia excelsa. The extracts were tested for antimicrobial activity against a gram

positive cocci, staphylococcus aureus, and a gram negative rod, klebsiella sp. The results

revealed that the ethanolic extract of Dennettia tripetala and the butanolic extracts of both plants

showed activity against the test organisms at two concentrations, 400 mg/mL and 200 mg/mL,

with the inhibition zone diameters (IZD) ranging from 8.2 mm to 12.0 mm and 6.5 mm to 14.0

mm for the ethanolic and butanolic extracts respectively. The minimum inhibitory concentration

(MIC) of the extracts ranged from 41.5 mg/mL to 48.3 mg/mL for the ethanolic extracts and 164.8 mg/mL to 111.7 mg/mL for the butanolic extracts. The presence of these secondary metabolites in varying and substantial amounts in the roots of the plants as well as the antioxidant and antimicrobial potentials of the roots of the plants lends scientific credence to the ethnomedicinal use of these plants parts for the treatment of various diseases and ailments