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Undergraduate Theses

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    Antioxidative properties of the fruits of selected tomato (Lycopersicon esculentum Mill.) varieties
    Baltazar, Gleza Wae D. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2016-05)
    This study was conducted to compare the antioxidative properties of greenstage fruits of selected Lycopersicon esculentum Miller varieties (Diamante, Diamante Max, and Pidada) from Barangay Durog, Miagao, Iloilo. The fresh fruit samples were extracted with 95% ethanol. The crude extracts were concentrated using rotary evaporator. The antioxidant activity of the ethanolic fruit extracts was assayed for DPPH radical scavenging activity and the IC50 values were determined. The determination of the phenolic and flavonoid contents was done employing Folin- Ciocalteu method and aluminum chloride spectrophotometric method, respectively. The results show that the fruits of the studied L. esculentum varieties exhibit DPPH radical scavenging activity. The IC50 values, however, differ significantly among the varieties. The IC50 values for Diamante (24.22 ± 1.41 g/L) and Diamante Max (25.08 ± 0.45 g/L) are comparable but are significantly lower than Pidada (29.47 ± 1.33 g/L). These findings imply that Diamante and Diamante Max varieties have stronger antioxidative capacity than the Pidada variety. Moreover, the results indicate that the antioxidative property of L. esculentum is variety-dependent. The results of the determination of the total phenolic content, expressed in mg gallic acid equivalent (GAE) per g fresh sample, are in the order of 0.16 ± 0.02 mg GAE/g for Diamante > 0.15 ± 0.02 mg GAE/g for Diamante Max and Pidada. On the other hand, the results of the determination of the flavonoid content, expressed in μg quercetin equivalent (QE) per g fresh sample, are in the order of 6.31 ± 1.27 μg QE/g for Diamante >6.21 ± 0.88 μg QE/g for Diamante Max > 5.63 ± 0.94 pg QE/g for Pidada. No significant difference in the total phenolic and flavonoid contents was found among varieties. Nonetheless, the detection of phenolics and flavonoids, known antioxidants, supports the present results on the antioxidative property of the fruits of the L. esculentum varieties studied.
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    Antioxidant property of anthocyanin from malatinta (Phyllanthus reticulatus Poir.) fruits obtained by static and microwave-assisted extraction
    Baldonasa, RB Hera Angelica R. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2015-06)
    Fresh fruits of Phyllanthus reticulatus Poir. were analyzed for anthocyanin by spectrophotometric method. The antioxidant activity using 1,1 -diphenyl-2-picrylhydrazyl (DPPH ) free radical scavenging activity (FRSA) and reducing power (RP) through FeCl3 assay were determined. The use of two extraction processes, namely, the static method and microwave-assisted extraction, using two extraction solvents, acidified methanol and aqueous ethanol (1:1) were compared. The total anthocyanin content (TAC) of P. reticulatus fruit was highest in extract using static method of extraction in acidified methanol solvent (279.94 ±17.31 mg/lOOg), comparable to levels found in plants rich in anthocyanins, (e.g., berries genotypes, grapes and red cabbages). In microwave-assisted extraction, TAC using acidified methanol was higher (278.01 ± 18.76 mg/lOOg) compared to using aqueous ethanol (210.96 ± 2.02 mg/100g). P. reticulatus fruits exhibited high antioxidant activity as revealed by its RP and DPPH FRSA results when compared to ascorbic acid. These findings highlight the usefulness of P. reticulatus as a source of anthocyanins with good antioxidant properties, which, in turn, gives importance to the undervalued and underutilized plant.