Determination of antioxidant and antimicrobial activities of Rumex crispus L. extracts

The antioxidant activities, reducing powers, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging

activities, amount of total phenolic compounds, and antimicrobial activities of ether, ethanol, and

hot water extracts of the leaves and seeds of Rumex crispus L. were studied. The antioxidant activities

of extracts increase with increasing amount of extracts (50-150 íg). However, the water extracts

of both the leaves and seeds have shown the highest antioxidant activities. Thus, addition of 75 íg

of each of the above extracts to the linoleic acid emulsion caused the inhibition of peroxide formation

by 96 and 94%, respectively. Although the antioxidant activity of the ethanol extract of seed was

lower than the water extract, the difference between these was not statistically significant, P >

0.05. Unlike the other extracts, 75 íg of the ether extract of seeds was unable to show statistically

significant antioxidant activity, P > 0.05 (between this extract and control in that there is no extract

in the test sample). Among all of the extracts, the highest amount of total phenolic compound was

found in the ethanol extract of seeds, whereas the lowest amount was found in the ether extract of

seeds. Like phenolic compounds, the highest reducing power and the highest DPPH scavenging

activity were found in the ethanol extract of seeds. However, the reducing activity of the ethanol

extract of seeds was 40% that of ascorbic acid, whereas in the presence of 400 íg of water and

ethanol extracts of seeds scavenging activities were about 85 and 90%, respectively. There were

statistically significant correlations between amount of phenolic compounds and reducing power

and between amount of phenolic compounds and percent DPPH scavenging activities (r ) 0.99, P

< 0.01, and r ) 0.864, P < 0.05, respectively) and also between reducing powers and percent DPPH

scavenging activities (r ) 0.892, P < 0.05). The ether extracts of both the leaves and seeds and

ethanol extract of leaves had shown antimicrobial activities on Staphylococcus aureus and Bacillus

subtilis. However, none of the water extracts showed antimicrobial activity on the studied

microorganisms.