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Undergraduate Theses

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14583/13

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Committee Chair: search.filters.chair.Janagap, Steve P.SDG: search.filters.sdg.SDG 3 - Good health and well-being

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    Phytochemical, antioxidant, and antibacterial analysis of essential oils from Zingiber officinale Roscoe(Ginger) and Curcuma long Linn.(Turmeric)
    Alviar, Joseph Noel G. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2015-06)
    This study was conducted to characterize and compare the phytochemistry, antibacterial and antioxidant activities of essential oils extracted from the rhizomes of Zingiber officinale Roscoe (ginger) and Curcuma longa Linn. (turmeric). Percent yields in the steam distillation of ginger and turmeric were 0.42±0.02% and 0.43± 0.02%, respectively. Qualitative phytochemical screening showed that both essential oils are positive for flavonoids, phenols, saponins, terpenoids, tannins, and quinones. Antibacterial activity was tested against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli using 100%, 75%, 50%, and 25% (v/v) essential oil in ethanol with positive control tetracycline and negative control ethanol. It was determined that C. longa did not have antibacterial activity against both bacteria while Z. officinale had “moderately inhibitory” to “strongly inhibitory” activity against S. aureus with zone of inhibition (ZOI) from 17.67±1.53 mm to 23.67±0.58 mm and “weakly inhibitory” to “moderately inhibitory” activity against E. coli (ZOI from 12.33±1.15 mm to 15.67±2.08 mm). The standard antibiotic tetracycline also showed “moderately inhibitory” activity against both S. aureus (ZOl = 19.00±0.89 mm) and E. coli (ZOI = 17.33±1.21 mm). Antioxidant activity was determined by DPPH free radical inhibition. Highest % DPPH free radical inhibition was exhibited by the standard antioxidant ascorbic acid (92.98%), followed by C. longa essential oil (88.74%), and Z. officinale (76.30%).
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    Antibacterial activity, antioxidant property and photochemical analysis of crude ethanolic extract from Dalanghita (Citrus nobilis) peels
    Aglobo, Jastine S. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2015-05)
    The crude ethanolic extract of Dalanghita (Citrus nobilis) was studied for their antibacterial activity, antioxidant and phytochemical properties. The DPPH free radical scavenging assay of extracts with varying concentrations showed strong antioxidant activity with a maximum % inhibition of 92.30 at 80.70 ug/mL concentration. The IC50 was calculated to be 26.26 pg/mL against 12.48 ug/mL for Ascorbic acid, the positive control. The antibacterial activity of the extract was determined against Escherichia coli and Staphylococcus aureus by measuring the mean zones of inhibition using the paper disc diffusion assay at different concentration of crude ethanolic extract. The crude ethanol extract at 100% concentration yielded the highest inhibition for E. coli at 21.50±0.50 mm which is comparable to tetracycline, the positive control. The presence of phytochemicals in the extract were evaluated and the phytochemicals identified were: alkaloids, flavonoids, saponins, steroids, tannins, and terpenes.
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    Optimization of extraction Conditions of water-soluble phenolics from tawa-tawa (Euphorbia hirta L.) based on Densitometric TLC using gallic acid as marker compound
    Aborka, Ma. Ayanne B. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2015-06)
    The present study aimed to optimize the extraction conditions of water-soluble phenolics for tawa-tawa (Euphorbia hirta L.) with gallic acid as the compound of interest. Water was used as extraction solvent. The effect of the interactions of different extraction temperature (50°C, 60°C and 70°C) and extraction time (20 min, 40 min and 60 min) were investigated. To evaluate the importance of the parameters on the extraction efficiency of gallic acid, a factorial design was used. The normal probability plot and estimates of standard error showed that time and temperature were both significant parameters. It further showed that time was a more significant contributor than temperature to the extraction efficiency of gallic acid. The results revealed that interaction of time and temperature did not have significant effects. The ANOVA results showed that only extraction parameter with significant effect was time (p < 0.05). Temperature and its interaction with time did not have significant effects. Based on the desirability values generated by Design-Expert 9.0.4, the optimal conditions in extracting gallic acid were the following: extraction time of 60 minutes and extraction temperature of 70°C. Results of FTIR analysis confirmed the presence of the following functional groups: O-H, C=O, C-O, C-H (aromatic), C=C (benzene) and out-of-plane bending or oops. Gallic acid in tawa-tawa is present in esterified form and exists as part of hydrolysable tannins.
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    Antioxidant and antibacterial activities of bika (Ampelocissus martini panch) seed oil
    Angot, Rose Imee Lyn N. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2016-06)
    Ampelocissus martini Planch, locally known as Bika, is a native tropical plant generally found in Southeast Asia. It is abundant in Panay Island, particularly in the provinces of Antique and Iloilo. Despite that the fruit is being consumed as food, used as medicine, and made into wine, very few scientific studies pertaining to Bika grape exist. Hence, this study focused on its antioxidant and antibacterial activities. The antioxidant activities were carried out through the % DPPH radical scavenging activity and reducing power method. Results show that the Bika seed oil has antioxidant activity. Its IC50 using DPPH assay is 23.63 ppm. Moreover, it also showed a significant antioxidant activity based on the results from the reducing power assay. Both results demonstrated that Bika grape seed oil have antioxidant activity. On the other hand, the mean zones of inhibition using disk diffusion assay was used to assess the antibacterial activity of Bika seed oil against Escherichia coh and Staphylococcus aureus. Only the antibiotic Gentamicin showed active antibacterial property, whereas the Bika seed oil showed little zone of inhibition, only goes to show that it has an inactive antibacterial property.