706 č č Free radical-scavenging activities of Crataegus monogyna extracts Jurga Bernatonienė, Rūta Masteikova 1 , Daiva Majienė, Arūnas Savickas, Egidijus Kėvelaitis 2 , Rūta Bernatonienė 3 , Katerina Dvoráčková 1 , Genuvaitė Civinskienė 2 , Raimundas Lekas 2 , Konradas Vitkevičius 4 , Rimantas Pečiūra Department of Drug Technology and Social Pharmacy, Kaunas University of Medicine, Lithuania, 1 University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic, 2 Department of Physiology, 3 Department of Pharmaceutical Chemistry and Pharmacognosy, 4 Department of Analytical and Toxicological Chemistry, Kaunas University of Medicine, Lithuania Key words: free radicals; antioxidant activity. Summary. The aim of this study was to investigate antiradical activity of aqueous and ethanolic hawthorn fruit extracts, their flavonoids, and flavonoid combinations. Material and methods. Total amount of phenolic compounds and the constituents of flavonoids were determined using a high-performance liquid chromatography. The antioxidant activity of Crataegus monogyna extracts and flavonoids (chlorogenic acid, hyperoside, rutin, quercetin, vitexin-2O-rhamnoside, epicatechin, catechin, and procyanidin B 2 ) quantitatively was determined using the method of spectrophotometry (diphenyl-1-picrylhydrazyl (DPPH·) radical scavenging assay and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid)(ABTS·+) radical cation decolorization assay). The level of tyrosine nitration inhibition was determined using a high- performance liquid chromatography. Results. Ethanolic hawthorn fruit extract contained 182±4 mg/100 mL phenolic compounds, i.e. threefold more, as compared to aqueous extract. The antioxidant activity according to DPPH· reduction in the ethanolic extracts was higher 2.3 times (P<0.05). The ABTS·+ technique showed that the effect of ethanolic extracts was by 2.5 times stronger than that of aqueous extracts. Tyrosine nitration inhibition test showed that the effect of ethanolic extracts was by 1.4 times stronger than that of aqueous extracts. The investigation of the antiradical activity of the active constituents in aqueous and ethanolic extracts revealed that epicatechin and catechin contribute to radical-scavenging properties more than other components. Procyanidin B 2 only insignificantly influenced the antiradical activity of the extracts. Conclusion. Both aqueous and ethanolic hawthorn extracts had antiradical activity, but ethanolic extract had stronger free radical-scavenging properties, compared to the aqueous extract. The antioxidant activity of the studied preparations was mostly conditioned by epicatechin and catechin. The individual constituents of both extracts had weaker free radical-scavenging properties than the combination of these substances did. Medicina (Kaunas) 2008; 44(9) Correspondence to J. Bernatonienė, Department of Drug Technology and Social Pharmacy, Kaunas University of Medicine, A. Mickevičiaus 9, 44307 Kaunas, Lithuania. E-mail: jurgabernatoniene@yahoo.com Introduction Despite the possibilities of modern scientifically oriented cardiologic diagnostics and treatment, morta- lity from cardiovascular diseases remains high, and cardiovascular diseases rank first among the causes of death (1). It is stated that one of the causes of heart failure is free radicals formed during metabolic pro- cesses in the body – organic substances with one or more unpaired electrons, such as hydroxyl (OH·), peroxyl (ROO – ), alkoxy (RO – ), and peroxonitrite (ONOO – ) (2). For this reason, it is important to neut- ralize these free radicals. Neutralization of free radi- cals may be affected not only by the enzymes of the antioxidant protection system (catalase, superoxide dismutase, etc.), but also possessing antiradical acti- vity in phyto preparations. Preparations from hawthorn fruits have a cardio- stimulating effect and are used for teas, dry and liquid extracts, tinctures, and juice. The main biologically active substances detected in the medicinal vegetal raw material of monogynous hawthorn are flavonoids and their glycosides: hyperoside (quercetin-3-galacto- side), quercetin, vitexin, vitexin-O-rhamnoside, isovi- texin-O-rhamnoside, acetylvitexin-O-rhamnoside, ru- tin, quercitrin (quercetin-3-rhamnoside), orientin, kaempferol, spireoside, saponaretin, oligomeric pro- cyanidins, catechins, and phenolic acids (chlorogenic acid, caffeic acid, triterpene saponins, etc.) (3, 4). Literature provides abundant data proving that various biologically active compounds posses differ-