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 microg). However, the water extracts of both the leaves and seeds have shown the highest antioxidant activities. Thus, addition of 75 microg 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 microg 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 approximately 40% that of ascorbic acid, whereas in the presence of 400 microg 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.

The antioxidant activity of the water extract of Tilia argentea Desf ex DC was determined by the thiocyanate method. The antioxidant activity of the water extract increased with the increasing amount of lyophilized extract (50-400 microg) added into the linoleic acid emulsion. Statistically significant effect was determined in 100 microg and higher amounts. Antioxidant activities of water extracts of tilia (Tilia argentea Desf ex DC), sage (Salvia triloba L.), and two Turkish black teas commercially called Rize tea and young shoot tea (Camellia sinensis) were compared. For comparison studies, 100 microg portions of extracts were added into test samples. All samples were able to show statistically significant antioxidant effect. Both of the tea extracts showed highest antioxidant activities, nevertheless, differences between tilia and sage and tilia and tea were not statistically significant (for both cases p > 0.05). Like antioxidant activity, the reducing power of water extract of Tilia argentea Desf ex DC was also concentration dependent. Even in the presence of 50 microg of extract, the reducing power was significantly higher than that of the control (p < 0.05) in which there was no extract. Unlike antioxidant activity, the highest reducing power activity was shown by sage extract. Among the tea extracts, young shoot extract was the most effective one, however, it had significantly lower activity than sage (p < 0.05). Although tea flower had the lowest reducing power activity, it was higher than that of tilia. But this difference was not statistically significant (p > 0.05). From these results, we could suggest that although the reducing power of a substance may be an indicator of its potential antioxidant activity, there may not always be a linear correlation between these two activities. In addition, antimicrobial activities of each of the above extracts were studied by disk diffusion methods on different test microorganisms. None of the extracts showed antibacterial activity on the studied microorganisms.

The antimicrobial activities of chloroform, acetone, ethanol, and water extracts of 25 plants, mostly used as remedies against various diseases in Turkish traditional medicine, were tested against 10 pathogenic bacteria and one fungus (Candida albicans) using the disk diffusion method. Among the tested plant species, Ziziphora clinopodioides Lam (Labiatae), Thymus fallax Fisch et Mey. (Labiatae), and three Hypericum species [H. heterophyllum Vent., H. hyssopifolium Chaix. subsp. elongatum (Ledeb.) Woron var. elongatum, and H. scabrum L.] (Guttiferae) showed antimicrobial activity at a broader spectrum. In particular, chloroform, acetone, and ethanol extracts of Z. clinopodioides inhibited the growth of all microbial species. Minimal inhibition concentration values of Z. clinopodioides extracts were also found to be low. The antioxidant activity of the acetone, ethanol, and water extracts of 20 plants was also evaluated by lipid peroxidation inhibition and DPPH free radical scavenging methods. It was found that water, ethanol, and acetone extracts of Z. clinopodioides, T. fallax, three Hypericum species, Artemisia santonicum L. (Compositae), and Echinophora tenuifolia L. subsp. sibthorpiena (Umbelliferae) have strong antioxidant activities among the tested plant species. In general, there is a correlation between the antioxidant potential and total phenolic contents of the extracts. In light of the current study, it can be concluded that Z. clinopodioides and T. fallax may have potential use in the food industry as antioxidants and antimicrobial herbs, as well as pharmaceutical interest.

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