The main chemical composition, contents of total phenolic (TPh), total flavonoid (TF), and total monomeric anthocyianin (TMA), as well as the antioxidant activity of two raspberry cultivars (Meeker and Willamette), two blackberry cultivars (Čačanska bestrna and Thornfree) and wild bilberry were studied. The raspberry cultivars had the highest total solids among fruits investigated. Bilberry fruits had the highest sugar-to-acid ratio. Blackberry fruits were richer in crude fibers (cellulose) in comparison to raspberry and bilberry fruits. The content of pectic substances was highest in the bilberry. Also, bilberry had a highest content of TPh (808.12 mg GAE/100 g FW), TF (716.31 mg RE/100 g FW) and TMA (447.83 mg CGE/100 g FW). The antioxidant activity was evaluated spectrophotometrically, using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assay. The DPPH free radical scavenging activity, expressed as the EC50 value (in mg of fresh weight of berry fruit per ml of the reaction mixture), of bilberry (0.3157 ± 0.0145 mg/ml) was the highest. These results also showed that the antioxidant value of 100 g FW bilberry, raspberry - Willamette, raspberry - Meeker, blackberry - Čačanska bestrna and blackberry - Thornfree is equivalent to 576.50 mg, 282.74 mg, 191.58 mg, 222.28 mg and 272.01 mg of vitamin C, respectively. There was a significant positive correlation between the antioxidant activities and content of total phenolics (RTPh 2=0.9627), flavonoids (RTF 2=0.9598) and anthocyanins (RTMA 2=0.9496) in berry fruits. [Projekat Ministarstva nauke Republike Srbije, br. TR 31044

Four berry (bilberry, blackberry, strawberry and raspberry) fruits pomace, a waste product coming from juice production, were extracted with 80% methanol containing 0.05% acetic acid. The highest content of antioxidant components, total polyphenols, flavonoids and anthocyanins, was found in the bilberry pomace extract (1116.24, 1047.39 and 1279.49 mg/100g fresh pomace, respectively). The antioxidant activity of the four berry pomace extracts (BPE) was determined using DPPH free radical scavenging assay and reducing power. There was a high linear correlation between the IC50 and content of anthocyanins (r2=0.98) and polyphenols (r2=0.85). Also, a good correlation was found between the IC50 and the content of flavonoids. The strawberry pomace extract showed the highest (RP0.5=0.35 mg/ml), while the blackberry pomace extract showed the lowest (RP0.5=0.57 mg/ml) reducing power. The results showed that BPE can be a valuable source of natural ingrediences of the products in the food, cosmetical and pharmaceutical industry

Mandarin peel, a waste product coming from juice production, was extracted by conventional extraction with 70% acetone. Content of flavonoids in mandarin peel extract (MPE) was determined by HPLC. Hesperidin was the most dominant flavonoid. Free radical scavenging activity of MPE on stable DPPH radicals and reactive hydroxyl radicals was also evaluated. EC50 value determined in spectrophotometrical DPPH radical assay was 0.179 mg/ml, while this value in ESR spin trapping hydroxyl radical assay was 0.415 mg/ml. Also, MPE showed protective effects in stabilising sunflower oil during accelerated storage. The results indicated that mandarin peel can be a valuable source of natural antioxidants

The methanol, petroleum ether, chloroform, ethyl acetate, n-butanol and water extracts were obtained by extraction of marigold flower (Calendula officinalis L). The content of total phenolic compounds, determined by UV spectrophotometric method using the Folin-Ciocalteu reagent, was 15.12 mg/g. The content of total flavonoids, determined by UV spectrophotometric method according to Markham, was 5.13 mg/g. Qualitative determination of phenolic compounds in the extracts was performed by one- and two-dimensional thin-layer chromatography (TLC) procedures. The results of one- and two-dimensional TLC analyses showed that different flavonoids and phenolic acids were present in the investigated extracts. The greatest number of flavonoids (rutin, quercetin and some unidentified flavonoid glycosides) and phenolic acids (chlorogenic, caffeic, coumaric and vanillic acid) were deteminated in methanol extract. The influence of marigold extracts, in concentration range 0.6-1.2 mg/mL, on 2,2’-diphenyl-1-picrylhydrazyl (DPPH) free radicals was investigated by electron spin resonance (ESR) spectroscopy. All extracts showed scavenging activity (SA) in the following order: ethyl acetate > n-butanol > methanol > water > chloroform > petroleum ether. The SA increased with increasing concentration of extracts. The ethyl acetate and n-butanol extracts exibited the most significant SA. These extracts in concentration of 1.2 mg/mL eliminated completely DPPH radicals. The lowest SA had chloroform and petroleum ether extracts (in concentration of 0.6 mg/mL SA=0%). The SA of marigold extracts is attributed to its hydrogen-donating ability and scavenging effect

In this study, three Serbian honey samples (Acacia, Linden and "Homoljski med") were analyzed to determine their total phenolic, flavonoid and antioxidant content, as well as their in vitro antioxidant activity. The antioxidant activity of honeys was examined by different tests, including the reducing power and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay. In addition, correlations between the antioxidant activity and total phenolic, as well as flavonoid content were also sought. The highest content of total phenolics (27.44 mg/100 g), flavonoids (9.78 mg/100 g), reducing power and DPPH free radical scavenging activity were obtained in the case of Linden honey. The EC50 values of the Linden honey, determined based on the reducing power and DPPH radical scavenging activity, were 24.17 mg/ml and 51.34 mg/ml, respectively. Also, the antioxidant content was highest for Linden honey, and it valued 5.45 mg QEAC/100 g (expressed as mg of quercetin equivalent antioxidant content - QEAC per 100 g of honey) and 7.82 mg AEAC/100 g (expressed as mg of ascorbic acid equivalent antioxidant content - AEAC per 100 g of honey). Also, a linear correlation was observed between the antioxidant activity and total phenolics, as well as total flavonoids

This study is concerned with the effects of two extraction procedures (using ultrasonic bath and high performance homogenizer) on the extraction efficiency of polyphenolics present in the tomato waste. The isolation of flavonoid fraction of obtained extracts was performed by solid-phase extraction. The antioxidant activity of flavonoid fractions was determined using different spectrophotometric tests, including reducing power and 2,2- diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays. The content of total polyphenolics and flavonoids in extract obtained employing homogenizer (E2) was higher than in the extract obtained employing ultrasonic bath (E1), and it was 14.33 mg/g and 7.70 mg/g, respectively. The flavonoid fraction (EF2) of extract E2 showed higher antioxidant activity than flavonoid fraction (EF1) of extract E1. The DPPH free radical scavenging activity of fractions EF1 and EF2, expressed as EC50 value, were 0.78 mg/ml and 0.45 mg/ml, respectively. The obtained results show that tomato wastes can be used as an easily accessible source of antioxidant polyphenolics

The methanol, petroleum ether, chloroform, ethyl acetate, 1-butanol and water extracts were obtained by extraction of mountain germander (Teucrium montanum L). The total phenolic content in extracts was measured by Folin-Ciocalteu method. The 1-butanol extract had the highest phenolic content (296.00 mg/g). High performance liquid chromatography (HPLC) was employed to define qualitative and quantitative content of phenolic acids in mountain germander extracts. The largest number of phenolic acids were determined in ethyl acetate and 1-butanol extracts, while these acids were not present in petroleum ether extract. The highest content of phenolic acids (28.619 mg/g) had ethyl acetate extract and gentisic acid (14.432 mg/g) was its major component. Despite of a large number of phenolic acids in 1-butanol extract their content was only 3.740 mg/g

The kinetic behaviour of tomato waste extracts (obtained from six genotypes) and standard antioxidant compounds (ascorbic and caffeic acid) were investigated using 2,2-diphenyl-1-picrylhydrazyl radical test. Based on the time needed for the reaction to reach steady state, the investigated extracts show very slow (steady state ≥ 180 min) antiradical behaviour, ascorbic acid act as rapid antioxidant (steady state < 5min) while caffeic acid is rapidintermediate antioxidant (5 min < steady state < 20 min). The efficient concentrations at different kinetic times EC50,t were determined for all extracts, ascorbic and caffeic acid. EC50,t was used as a parameter to screen and compare antiradical activities of food extracts with slow kinetic action. Irrespective of the time considered, the comparison of the EC50,t for extracts showed that the DPPH radicals scavenging activity of extracts decreased in the order of O2 > Knjaz > Bačka > Saint Pierre > Rutgers > Novosadski niski. Tomato waste extracts showed very slow kinetic action, which is probably result of the different kinetic bevaviour of phenolic compounds, present in tomato waste, as well as other antioxidants (vitamins, carotenoids etc)