PHENOLIC CONTENT AND ANTIOXIDANT CAPACITIES OF PARINARI CURATELIFOLIA, STRYCHNOS SPINOSA AND ADANSONIA DIGITATA
ABSTRACT The phenolic content and antioxidant capacities of Parinari curatelifolia, Strychnos spinosa and Adansonia digitata were determined and compared to orange juice and baobab nectar, a commercial beverage. Methanolic extracts were investigated for their ability to scavenge free radicals by the 1, 1-diphenyl-2 picrylhydrazyl radical and superoxide radical scavenging assays whilst the β-Carotene Linoleic Acid Model System and inhibition of phosholipid peroxidation were used as model systems. The reducing power assay was used to determine the reducing potential of the extracts.Results showed that the beverages in this investigation were capable of acting as antioxidant sources as they displayed significant radical scavenging properties. Adansonia digitata had the highest and comparable antioxidant activities to Citrus sinensis (orange). The total phenolic, ascorbic acid, proantocyanidin and flavonoid contents ranged between 12 and 58 mg GAE/100 mL, 0.00 to 51.26 mg/100 mL, 0.35–1.071% and 18.3–124 mg/100 mL, respectively. There was a positive correlation between antioxidant activities and phenolic compounds content but there was no clear relationship between proanthocyanidin content and antioxidant activity.PRACTICAL APPLICATIONSFruits contribute significantly to the diets of many rural families in times of famine and they also provide some essential micronutrients. The results obtained in this study showed that fruits are valuable sources of antioxidants and if their consumption is promoted they will go a long way in addressing some problems of malnutrition bedeviling rural communities in Africa.
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ABSTRACT: Sixteen red grape cultivars (Md. Jean Matthias, Öküzgözü, Muscat Hamburg, Cabarnet Sauvignon, Tekirdağ Çekirdeksizi, Gewürztraminer, 2B/56, Kalecik karası, Carignan, Kokulu Siyah, Alfonse Lavallée, Boğazkere, Adakarası, Papazkarası, Mourvedre and Cinsaut) which are grown in Tekirdağ Viticulture Research Institute were analyzed for determination of antioxidant activities, total phenolics, anthocyanins, external colour, polyphenoloxidase activities, sugar and acidity. The lowest antioxidant activity (percentage of inhibition on peroxidation in linoleic acid system; AA) was determined in Tekirdağ çekirdeksiz extracts as 87.58% and the highest AA was in Mourvedre (93.78%). Total phenolic content (TP) varied from 817 to 3062 μg/ml GAE in the same varieties, respectively. The total anthocyanin (TA) content ranged from 40.3 to 990.8 mg/l fresh weight. The lowest PPO activity was found in Boğazkere and the highest was in Kalecik karası. The total sugar content in the analyzed varieties varied between 13.29 and 24.46%. There was stronger correlation between AA and TP than AA and TA.Scientia Horticulturae. 01/2007;
Article: Antioxidant activity of sesame coat[show abstract] [hide abstract]
ABSTRACT: The antioxidant activity of ethanolic extracts of sesame coat (EESC) was investigated. The antioxidant activity (91.4%) of 1.0 mg EESC was equal to 1.0 mg tocopherol (90.5%) but was weaker than 1.0 mg butylated hydroxyanisole (98.6%) on peroxidation of linoleic acid. EESC showed an inhibitory effect against the formation of thiobarbituric acid reactive substances (TBARS) in a liposome model system. EESC at 10.0 mg exhibited a 94.9% scavenging effect on α,α-diphenyl-β-picrylhydrazyl radicals and marked reducing power, indicating that EESC acts as a primary antioxidant. The extracts, at a dose of 1.0 mg, showed a 50.0% scavenging effect on the hydroxyl radical. EESC also exhibited a metal-binding ability. Sesamin and sesamolin, the lignan substances, were found in EESC, by HPLC analysis. In addition, chromatographic analysis demonstrated that phenolic compounds and tetranortriterpenoids, which had positive reactions with β-carotene, indicating antioxidant activity, are present in EESC. According to these results, termination of free radical reaction, metal-binding ability and quenching of reactive oxygen are suggested to be, in part, responsible for the antioxidant activity of EESC.Food Chemistry. 01/2002;
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ABSTRACT: Methanolic extracts of three different Tanacetum subspecies [Tanacetum densum (Lab.) Schultz Bip. subsp. sivasicum Hub-Mor and Grierson, Tanacetum densum (Lab.) Schultz Bip. subsp. eginense Heywood and Tanacetum densum (Lab.) Schultz Bip. subsp. amani Heywood] which are endemic to Turkish flora were screened for their possible antioxidant activities by two complementary test systems namely DPPH free radical scavenging and beta-carotene/linoleic acid. In DPPH system, the most active plant was T. densum subsp. amani with an IC(50) value of 69.30+/-0.37 microg/ml. On the other hand, T. densum subsp. sivasicum exerted greater antioxidant activity than those of other subspecies in beta-carotene/linoleic acid system (79.10%+/-1.83). Antioxidant activities of BHT, curcumine and ascorbic acid were also determined as positive controls in parallel experiments. Total phenolic constituents of the extracts of Tanacetum subspecies were performed employing the literature methods involving Folin-Ciocalteu reagent and gallic acid as standard. The amount of total phenolics was highest in subsp. sivasicum (162.33+/-3.57 microg/mg), followed by subsp. amani (158.44+/-2.17 microg/mg). Especially, a positive correlation was observed between total phenolic content and antioxidant activity of the extracts.Bioresource Technology 12/2007; 98(16):3076-9. · 4.75 Impact Factor