UDK: 577.13:582  Plants produce a numerous and diverse secondary metabolites, organic compounds which are not essential and do not participate directly in the growth and development, but may have very important role in their adaptation and adjustment to particular environmental conditions. For humans, secondary metabolites are very important in medicine, pharmacology, food and cosmetics industries. The presence of eight types of secondary metabolites (anthocyanins, coumarins, emodins, fatty acids, phenols, saponins, steroids and tannins) in water extracts of leaves and barks of 25 broadleaf deciduous species from 15 families was qualitatively investigated by rapid phytochemical screening methods. According to literature data, in this study for the first time is determined the presence of six types of secondary metabolites in analyzed dendro species: anthocyanins in one species; both coumarins and phenols in five species; emodins in six species; saponins in eight species; and tannins in four species. Particular attention in further research should be given to Fagus sylvatica L., Populus tremula L., Quercus petraea (Matt.) Liebl., Robinia pseudoacacia L. and Sorbus aria (L.) Crantz. Since preliminary results of this study are promising it would be desirable both to identify active compounds and assess their potential antimicrobial and antioxidant activities.

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.