AbstraktBuřičová L., Andjelkovic M., Čermáková A., Réblová Z., Jurček O., Kolehmainen E., Verhé R., Kvasnička F. (2011): Antioxidant capacity and antioxidants of strawberry, blackberry, and raspberry leaves. Czech J. Food Sci., 29: 181-189.The total phenolic content (Folin-Ciocalteu method), free radical scavenging ability expressed as DPPH value, ferric reducing antioxidant capacity (FRAP), and oxygen radical absorbance capacity (ORAC) were determined in water extracts of leaves from rosaceae family plants (Fragaria vesca L., rubus fructicosus L., and rubus idaeus L.). The antioxidant capacities of the extracts (in the order of the above mentioned methods) were 73.6-88.9%, 60.1-71.4%, 49.7-78.0% respectively, and 45.3-66.5% of that of green tea water extract. Further, the presence of 15 compounds (gallic acid, rutin, ellagic acid, caffeic acid, p-coumaric acid, quercetin, kaempferol, myricetin, quercetin-3-d-glucoside, ascorbic acid, (+)-catechin, (-)-epicatechin, epicatechingallate, epigallocatechin, procyanidin B1) was studied by HPLC-ECD and their antioxidant capacities were compared to the antioxidant capacity of the extracts. Out of the compounds studied, mostly (+)-catechin, ellagic acid, and (-)-epicatechin participated in the antioxidant capacities of the studied plant leaves water extracts. The antioxidant capacity of leaves infusions (determined by DPPH method) was lower than those of red wines and tea infusions, but comparable to the antioxidant capacities of white wines and fruit beverages. In the screening study comparing the antioxidant capacities (AC) (measured by DPPH method) of seventeen Czech medicinal plants, the leaves of strawberry (Fragaria vesca L.), blackberry (rubus fructicosus L.) and raspberry (rubus idaeus L.) belonged to the most efficient plants tested (Buři-čová & Réblová 2008). The AC of their extracts were comparable to and in some cases even higher than AC of the studied plants from the family Lamiaceae (oregano, sweet balm, thyme, dead-

The antioxidant activity of 17 Czech medicinal plants was studied and compared with the antioxidant activity of green tea. The antioxidant activities of water and ethanol extracts of the plants tested were determined by a spectrophotometric method using the stable free radical DPPH (2,2-diphenyl-1-picrylhydrazyl), and further the contents of the compounds with reducing properties in water extracts were determined by flow injection analysis with amperometric detection (using a detection potential +0.7 V). Considerable antioxidant activities were found in the extracts of plants from the Rosaceae family (rosehips and leaves of raspberry, blackberry, and strawberry), the Lamiaceae family (oregano, sweet balm, thyme, dead-nettle, and mint), and flowers of linden and elder. Many human diseases are caused or negatively affected by free radicals. The natural defense of the human organism againts free radicals is not always sufficient mainly due to the significant exposition to free radicals from external sources in the modern world. The dietary intake of antioxidants plays an important role in the protection of the human organism againts free radicals. Many clinical and epidemiological studies show a connection between the antioxidant activity of the substances present in the diet and the prevention from such diseases as cardiovascular diseases or carcinogenesis (Hughes 2000; Kris-Etherton et al. 2002;Lindsay & Astley 2002).Fruits, vegetables, grains, teas, wines, and some kinds of spices are natural sources of antioxidants (Rice-Evans et al. 1996). The intake of these food comodities is not always satisfactory. Therefore, the studies of possible new sources of antioxidants have become important in the last few years. The new sources of the antioxidants could be used for direct consumption or for the production of food supplements which could be used for enriching foods with the aim of increasing their nutritional value. Medicinal plants used in the traditional medicine and healing are one of these sources of antioxidants. In many countries, screening studies were carried out for the comparison of antioxidant activities of medicinal plants typical for the respective country (Chanwitheesuk et al. 2005;Ivanova et al. 2005;Katalinic et al. 2006;Proestos et al. 2006;Wong et al. 2006). There is no study of this kind in the available literature concerning the Czech medicinal plants.The aim of this work was to compare the Czech medicinal plants in view of their antioxidant activ- 133Czech J. Food Sci. Vol. 26, ity. Seventeen plants resp. parts of plants were selected with respect to: popularity, the conventional use, and the recommendation for use (they can be taken for a long time) in the traditional medicine and healing, their use for beverage preparation, as well as legislation regulating the use of these plants in food industry. The antioxidant activity of water and ethanol extracts of the dry medicinal plants was estimated using the free radical DPPH, usually used in this type of screening study. To confirm the plants an...

Synthesis, detailed structural characterization (X-ray, NMR, MS, IR, elemental analysis), and studies of toxicity, antioxidant activity and bioavailability of unique potent anti-atherosclerotic succinobucol-steroid conjugates are reported. The conjugates consist of, on one side, the therapeutically important drug succinobucol (4-{2,6-di-tert-butyl-4-[(1-{3-tert-butyl-4-hydroxy-5-(propan-2-yl)phenyl]sulfanyl}ethyl)sulfanyl]phenoxy}-4-oxo-butanoic acid]) possessing an antioxidant and anti-inflammatory activity, and on the other side, plant stanol/sterols (stigmastanol, β-sitosterol and stigmasterol) possessing an ability to lower the blood cholesterol level. A cholesterol-succinobucol prodrug was also prepared in order to enhance the absorption of succinobucol through the intestinal membrane into the organism and to target the drug into the place of lipid metabolism—The enterohepatic circulation system. Their low toxicity towards mice fibroblasts at maximal concentrations, their antioxidant activity, comparable or even higher than that of ascorbic acid as determined by direct quenching of the DPPH radical, and their potential for significantly altering total and LDL cholesterol levels, suggest that these conjugates merit further studies in the treatment of cardiovascular or other related diseases. A brief discussion of succinobucol’s ability to quench the radicals, supported with a computational model of the electrostatic potential mapped on the electron density surface of the drug, is also presented.