Vitamin C or ascorbic acid content has been determinated by spectrophotometric method and titrimetric method in flowers of some Bosnian hawthorns (Crataegus L). species. Spectrophotometric method used in this study was based on the kinetic reaction between Vitamin C and methylene blue. Measurements were carried out at absorption maximum, λmax= 665 nm. We found that the lowest content of vitamin C was 617.07 mg/100 g of dry sample in flowers of the C. microphylla, and the highest level of Vitamin C was found in the C. monogyna (1104 mg/100 g of dry sample) flowers. Recoveries of the results obtained by the spectrophotometric method were 94 % 100% with relative standard deviation (RSD) values from 4.5% – 6.7 %. Obtained results shown that flowers of investigated Crataegus L. species are good source of vitamin C.

The aim of this work was the qualitative and quantitative determination of selected phenolic compounds in three Crataegus species grown in Bosnia. Crataegus plants are consumed for medicinal purposes and as foodstuff in the form of canned fruit, jam, jelly, tea, and wine. Two samples of plant material, dry leaves with flowers, and berries of three Crataegus species—Crataegus rhipidophylla Gand., Crataegus x subsphaericea Gand., and Crataegus x macrocarpa Hegetschw.—were analyzed. Twelve ethanolic extracts were isolated from the selected plant material using Soxhlet and ultrasound extraction, respectively. Soxhlet extraction proved to be more effective than ultrasound extraction. A simple and sensitive method, high-performance liquid chromatography with electrochemical detection, HPLC-ED, was used for the simultaneous determination of phenolic acids and flavonoids in Crataegus species. The content of gallic acid in the extracts ranged from 0.001 to 0.082 mg/g dry weight (DW), chlorogenic acid from 0.19 to 8.70 mg/g DW, and rutin from 0.03 to 13.49 mg/g DW. Two flavonoids, vitexin and hyperoside, commonly found in chemotaxonomic investigations of Crataegus species, were not detected in the examined extracts. In general, leaves with flowers samples are richer in gallic acid and rutin, whereas the berries samples are richer in chlorogenic acid. Distinct similarities were found in the relative distribution of gallic acid among the three species. Extracts of C. x macrocarpa had the highest content of all detected compounds, while significant differences were found in rutin content, depending on the plant organ. To the best of our knowledge, this is the first study reporting content of phenolic compounds in Crataegus rhipidophylla Gand., Crataegus x subsphaericea, and Crataegus x macrocarpa from Bosnia.

UDK: 547.56:582.728.4 Phenolic compounds content and antioxidant capacity from Viscum album ssp. album Beck. leaves and twigs extracts were determined. Common mistletoe was collected from four hosts (Crataegus monogyna, Malus domestica, Prunus cerasifera, and Populus x canadensis.). Folin-Ciocalteu method, AlCl3 method, method with Arnow reagent, and acid-butanol assay were applied for determination of total phenols, flavonoids, phenolic acids and proanthocyanidins respectively. DPPH, ABTS and FRAP methods were applied in the determination of antioxidant capacity of the extracts. Total phenols were in the range 7.16-11.70 mg GAE/g DW, flavonoids 2.115-4.668 mg RE/g DW, phenolic acids 0.811-1.789 mg caffeic CAE/g DW, and proanthocyanidins 0.71-2.62 mg LCE/g DW. Content of phenols and flavonoids was higher in the leaves than the twigs. The highest antioxidant capacity in leaves (50.86-65.93 µmol Trolox equivalents/g DW) was determined for mistletoe collected from Crataegus monogyna while the highest capacity in twigs had mistletoe collected from Malus domestica (67.28-81.72 µmol Trolox equivalents/g DW). Also, high correlation has been noticed between total phenols, flavonoids, phenolic acids and antioxidant capacity for V. album leaves. For twigs, high correlation was obtained between phenols and antioxidant capacity, and in some moderate extends for proanthocyanidins.  

UDK: 582.711.71:547.56 Phenolic content and antioxidant activity of Rosa canina fruit extracts obtained with five different extraction systems were investigated. Extractions were done with water, and aqueous 50% methanol, 50% ethanol, 80% methanol and 80% ethanol. Antioxidant activity was investigated with DPPH, ABTS and FRAP methods using Trolox as a standard. The highest level of phenols (78.83 mg GAE/g), phenolic acids (11.21 mg CAE/g), and proanthocyanidins (29.12 mg CE/g) were found for 50% methanol extract. The highest flavonoid content (1.163 mg RE/g and 0.675 mg QE/g) was determined for 50% ethanol extracts and antocyanin content (0.139 mg CGE/g) for 80% methanol extract. The lowest level of phenols (35.89 mg GAE/g), phenolic acids (4.55 mg CAE/g) and proanthocyanidins (11.93 mg CE/g) had 80% ethanol extract. Flavonoid content (0.341 mg RE/g and 0.214 mg QE/g) was the lowest in water extract and anthocyanidin content (11.93 mg CE/g) in 50% ethanol extract. Antioxidant activity for DPPH was in a range 255.62-407.82 µmol TE/g, for ABTS 312.06-616.10 µmol TE/g and for FRAP 349.33-690.37 µmol TE/g with lowest values for 80% ethanol extract and highest values for 50% methanol extract. Phenols and proanthocyanidins showed high positive correlation with antioxidant activity for DPPH (r2 =0.927-0.9621), ABTS (r2 =0.980-0.9935) and FRAP (r2 =0.9352-0.9633). No correlation was observed for flavonoid and anthocyanidin content with antioxidant activity.

UDK: 582.916.16:547.56             547.56:543.42 Total contents of phenols, flavonoids, phenolic acids and proanthocyanidins have been determined in methanolic extracts of Fraxinus ornus L. and Fraxinus pennsylvanica Marsch. leaves and branches bark.  DPPH and FRAP assay were used in the determination of antioxidant capacity. F. ornus leaves had higher contents of flavonoids (13.08 mg RE g-1 DW) and proanthocyanidins (7.29 mg LCE g-1 DW) while the bark had higher contents of phenols (56.47 mg GAE g-1 DW), phenolic acids (14.32 mg CAE g-1 DW) and coumarins (94.81 mg CE g-1 DW). F. pennsylvanica leaves were richer in contents of phenols (25.73 mg GQE g-1 DW), flavonoids (2.87 mg CE g-1 DW and 5.13 mg RE g-1 DW), phenolic acids (14.60 mg CAE g-1 DW) and coumarins (20.01 mg CE g-1 DW) while the bark had more proanthocyanidins (6.88 mg CE g-1 DW). F. ornus leaves had lower contents of phenolic acids (11.09 mg CAE g-1 DW) than F. pennsylvanica leaves. Also, F. pennsylvanica bark had higher contents of flavonoids (1.25 mg RE g-1 DW) and proanthocyanidins (6.88 mg CE g-1 DW) than F. ornus bark. Antioxidant capacity for both species was higher for the leaves than the bark. Generally, F. ornus had better antioxidant capacity than F. pennsylvanica. Very high correlations were found between antioxidant capacity and phenols (r2= 0.9361-0.9805), flavonoids (r2= 0.9358-0.9876) and coumarins (r2= 0.9661-0.9938) in leaves. In bark, correlations were found for phenols (r2= 0.9744-0.9796) and coumarins (r2= 0.9757-0.9911).

In this work, Fraxinus excelsior L. and Fraxinus angustifolia Vahl. leaves and branches bark extracts have been estimated for their phenolic content and antioxidant capacity. The antioxidant capacity was examined by DPPH and FRAP methods. Higher contents of total phenols (23.9446.98 mg GAE g) and flavonoids (6.30 – 9.14 mg RE g and 3.67 – 5.34 mg QE g) have been determined in leaves than in the bark for both species. The bark contained higher amounts of total phenolic acids (17.79 – 36.67 mg CAE g), coumarins (27.91 – 70.98 mg CE g) than the leaves. F. excelsior bark had higher content of proanthocyanidins (4.14 – 7.95 mg LCE g) while F. angustifolia leaves were richer in proanthocyanidins (5.76 – 11.16 mg LCE g). Generally, higher amounts of bioactive compounds and better antioxidant capacity was found for F. angustifolia. Also, extracts of F. excelsior bark and F. angustifolia leaves displayed higher antioxidant activities. Established correlations between phenols (r = 0.8381 – 0.9228), phenolic acids (r = 0.8799 – 0.9843), coumarins (r = 0.9223 – 0.9716) and antioxidant capacity determined by DPPH and FRAP shown these compounds are the main contributors to the antioxidant capacity in leaves and bark of investigated species.

UDK: 581.19:547.56]:582.916.16   In this work, Fraxinus excelsior L. and Fraxinus angustifolia Vahl. leaves and branches bark extracts have been estimated for their phenolic content and antioxidant capacity. The antioxidant capacity was examined by DPPH and FRAP methods.  Higher contents of total phenols (23.94- 46.98 mg GAE g-1) and flavonoids (6.30 – 9.14 mg RE g-1 and 3.67 – 5.34 mg QE g-1) have been determined in leaves than in the bark for both species. The bark contained higher amounts of total phenolic acids (17.79 – 36.67 mg CAE g-1), coumarins (27.91 – 70.98 mg CE g-1) than the leaves. F. excelsior bark had higher content of proanthocyanidins (4.14 – 7.95 mg LCE g-1) while F. angustifolia leaves were richer in proanthocyanidins (5.76 – 11.16 mg LCE g-1). Generally, higher amounts of bioactive compounds and better antioxidant capacity was found for F. angustifolia. Also, extracts of F. excelsior bark and F. angustifolia leaves displayed higher antioxidant activities. Established correlations between phenols (r2 = 0.8381 – 0.9228), phenolic acids (r2 = 0.8799 – 0.9843), coumarins (r2 = 0.9223 – 0.9716) and antioxidant capacity determined by DPPH and FRAP shown these compounds are the main contributors to the antioxidant capacity in leaves and bark of investigated species.

Phenolic contents of methanolic extracts prepared from leaves and fruits of Crataegus monogyna Jacq. and Crataegus macrocarpa Hegetschw. were determined. The antioxidant capacity was assessed by DPPH, ABTS and FRAP assay. The results showed that leaves were richer in the content of phenols (59.23 91.91 GAE g-1), flavonoids (2.38 4.08 mg QE g-1 and 5.24 8.9 mg RE g-1) , phenolic acids (33.40 68.98 CAE g-1) and proanthocyanidins (26.15 48.60 CE g-1) while in fruits anthocyanins dominateted (0.43 0.80 CG g-1). Leaves also had higher antioxidant capacity than fruits for both species. Generelly, C. monogyna fruits had higher content of anthocyanins. Total phenols, phenolic acids and proanthocyanidins were highly corelated with DPPH (r2 = 0.8703 0.9618), ABTS (r2 = 0.7833 0.9443) and FRAP (r2 = 0.903 0.9695) assay. The results suggests that these compounds were the major contributors to the antioxidant capacity in leaves and fruits extracts of both species. Higher contents of bioactive compounds and higher antioxidant capacity were determined for C. x macrocarpa samples. Therefore, C. x macrocarpa leaves and fruits are valuble source of antioxidant polyphenols with high potential for use in preparation of different natural health products.

UDK: 547.56:582.711.714           582.711.714:581.45/.47 Phenolic contents of methanolic extracts prepared from leaves and fruits of Crataegus monogyna Jacq. and Crataegus macrocarpa Hegetschw. were determined. The antioxidant capacity was assessed by DPPH, ABTS and FRAP assay. The results showed that leaves were richer in the content of phenols (59.23 - 91.91 GAE g-1), flavonoids (2.38 - 4.08 mg QE g-1 and 5.24 - 8.9 mg RE g-1) , phenolic acids (33.40 - 68.98 CAE g-1) and proanthocyanidins (26.15 - 48.60 CE g-1) while in fruits anthocyanins dominateted (0.43 - 0.80 CG g-1). Leaves also had higher antioxidant capacity than fruits for both species. Generelly, C. monogyna fruits had higher content of anthocyanins. Total phenols, phenolic acids and proanthocyanidins were highly corelated with DPPH (r2 = 0.8703 - 0.9618), ABTS (r2 = 0.7833 - 0.9443) and FRAP (r2 = 0.903 - 0.9695) assay. The results suggests that these compounds were the major contributors to the antioxidant capacity in leaves and fruits extracts of both species. Higher contents of bioactive compounds and higher antioxidant capacity were determined for C. x macrocarpa samples. Therefore, C. x macrocarpa leaves and fruits are valuble source of antioxidant polyphenols with high potential for use in preparation of different natural health products.

UDK: 547.56:582.711.714(234.422 Trebević) Methanolic and acidified methanolic extracts of C. monogyna and C. rhipidophylla dried fruits were used in estimation of total phenolic contents and antioxidant activities. The extracts of fruit were examined for their antioxidant activity by DPPH method. Antioxidant activity of the extracts varied from 17.65 to 22.05 mg ascorbic acid equivalents per g-1 dry weight. Total phenols, flavonoids, monomeric anthocyanins and proanthocyanidins in fruits ranged from 21.53 to 34.72 mg gallic acid equivalents per g-1 dry weight, 0.75 to 1.92 mg rutin equivalents and 0.13-0.93 mg quercetin equivalents per g-1 dry weight, 0.51 to 0.82 mg cyanidin-3- glucoside equivalents per g-1 dry weight, 11.27-18.77 mg cyanidin chloride equivalents per g-1 dry weight respectively. The higher values of total flavonoids generally are obtained with 80% methanol extracts for both species. The amounts of all investigated compounds and antioxidant activity were significantly higher in C. monogyna fruits which were confirmed by one-way ANOVA analysis.  Correlations between antioxidant activity and total phenols and proanthocyanidin contents were found as the main compounds influencing the antioxidant capacity of the samples. Obtained results suggest that both species represent valuable source of antioxidant compounds.

UDK: 547.56:582.711.714           582.711.714:581.47 The aim of this work was to determine the content of total polyphenols, total flavonoids, total monomeric anthocyanins, total proanthocyanidins, and antioxidant activity of Crataegus monogyna L. fruit in water, hydroalcohol and alcohol extracts. Phenolic content and antioxidant assay of the different fruit extracts was determined using spectrophotometric methods. Obtained results indicated that the content of total polyphenols in the investigated extracts varied from 2.01 to 4.60 mg GAE g-1 of fresh hawthorn fruit. The content of flavonoids ranged from 0.254 to 0.595 mg RUE g-1 fresh fruit extracts. Total monomeric anthocyanins varied from 0.004 to 0.132 mg cyanidin-3-glucoside g-1 of fresh fruit and total proanthocyanidins varied from 0.187 to 1.168 mg cyanidin chloride g-1 fresh fruit. The best antioxidant activity was obtained for hawthorn extract with 80% methanol. A good correlation between antioxidant activity and total polyphenols (R² = 0.9473) and proanthocyanidins (R² = 0.7469) was observed.

UDK 582.711.714:577.164.2           543.42:577.164.2 Vitamin C or ascorbic acid content has been determinated by spectrophotometric method and titrimetric method in flowers of some Bosnian hawthorns (Crataegus L). species. Spectrophotometric method used in this study was based on the kinetic reaction between Vitamin C and methylene blue. Measurements were carried out at absorption maximum, λmax= 665 nm. We found that the lowest content of vitamin C was 617.07 mg/100 g of dry sample in flowers of the C. microphylla, and the highest level of Vitamin C was found in the C. monogyna (1104 mg/100 g of dry sample) flowers. Recoveries of the results obtained by the spectrophotometric method were 94 % - 100% with relative standard deviation (RSD) values from 4.5% – 6.7 %. Obtained results shown that flowers of investigated Crataegus L. species are good source of vitamin C.

UDK 577.164.2:582.711.714           535.234:577.164.2 Vitamin C or ascorbic acid content has been determined by spectrophotometric method in fruits of some Bosnian hawthorns (Crataegus L). species. Spectrophotometric method used in this study is based on the kinetic reaction between Vitamin C and methylene blue. Measurements were carried out at absorption maximum, λmax= 665 nm. Titrimetric method was used as the reference method for comparison of the obtained results. We found that the lowest content of vitamin C was 106.12 mg/100 g of a dry sample in fruits of the C. monogyna, and the highest level of Vitamin C was found in the C. microphylla (231.96 mg/100 g of a dry sample) fruits. Recoveries of the results obtained by the spectrophotometric method were 101.4% - 108.0% with relative standard deviation (RSD) values ranging between 0.40% - 3.37%. Obtained results showed that fruits of studied Crataegus L. species are a good source of vitamin C with its potential to be used in food industry as the natural antioxidant.

UDK 546.215:546.4/.8 Stability of hydrogen peroxide in time was investigated in the presence of various metal ions and a complexing agent ethylenediaminetetraacetic acid (EDTA). Metal ions: Fe(III), Mn(II), Co(II), Cu(II), Ni(II), Zn(II) and Pb(II) were applied at different concentrations with a chelator in a concentration of 1 ·10-5 mol/dm3, and the solutions were kept at 4oC between the measurements. Obtained data indicate the existence of pronounced catalytic effect for Fe(III), Mn(II), Co(II) ions on stability of hydrogen peroxide. Cu(II) ions showed significant catalytic influence only when applied at high concentration. Ni(II), Pb(II) and Zn(II) did not show significant catalytic effect on the decay of hydrogen peroxide at applied concentrations.