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Undergraduate Theses

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

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Degree: search.filters.degree.Bachelor of Science in ChemistrySDG: search.filters.sdg.SDG 13 - Climate action

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    Antifungal activities of lemongrass (Cymbopogon citratus) essential oil -B-cyclodextrin inclusion complex incorporated in commercial fish feeds
    Baure, Jiaren G. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2019-06)
    During the wet season in the Philippines, fish feeds can be contaminated with mycotoxins, affecting fish production. The addition of essential oil (EO) is one of the ways to prevent this, but it is prone to physical and chemical reactions. Thus, this study aims to encapsulate lemongrass essential oil (LGEO) in B-cyclodextrin (B-CD) to produce an inclusion complex (IC) that can be used as an additive in commercial tilapia feeds to prevent or minimize fungal contamination. The inclusion complex was made using the co-precipitation method and was characterized by Fourier Transform Infrared (FTIR) Spectroscopy. The spectrum was similar to that of citral, a major component of lemongrass essential oil that is responsible for inhibiting fungi. The antifungal activities of pure and encapsulated LGEO at varying concentrations against Aspergillus species were carried out by the Agar Well Diffusion assay. Results showed that A. flavus was more susceptible in LGEO and IC compared with A. fumigatus. The tested concentration of EO could inhibit both fungi. However, it would take 50% IC to effectively inhibit the growth of both fungi. The stability of the inclusion complex in commercial fish feeds was also evaluated. The feeds were stored in an area with the appropriate conditions that could promote the growth of molds, such as temperature (>27°C), moisture levels (14%), and relative humidity levels (>70%). The results showed that the encapsulated LGEO was effective in extending the shelf life of the feeds and was best observed at a concentration of 5 g kg-1 IC. The oil remained active for nine days, wherein about 10- 40% of the feeds with 5 g kg-1 IC were covered with molds. On the other hand, about 70-100% of the surface of the feeds with essential oil was contaminated with molds after nine days, which indicated that encapsulation of EO was needed to maintain its effectiveness as an antifungal agent.
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    Treatment of Vibrio harveyi-infected Penaeus monodon using Alibutbut (Tabernaemontana pandacaqui Poir.) plant powder
    Bacaling, Marivic T. (Division of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines Visayas, 2005-04)
    The cytotoxicity test of crude methanolic leaf extract using Brine Shrimp Lethality Assay revealed that Alibutbut (Tabernaemontana pandacaqui Poir.) is safe to use in treating vibrio-infected penaeid shrimps. The effectiveness of the alibutbut powder against vibriosis was examined through the determination of the post-larvae 20 (PL 20) penaeid shrimp mortality and the water microbial assay after 48 hours. Percent penaied shrimp mortality (0-6.67%) and microbial count (2.91 x 10^4- 3.26 x 104 cfu/mL) of the plant treatments were significantly lower compared to the negative control (no treatment) that exhibited 50% penaeid shrimp mortality and a microbial count greater than 6.00 x 10^4 cfu/mL. The results of the experiment showed that Alibutbut plant powder is indeed effective in controlling Vibrio harveyi bacteria.
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    Cytotoxicity and anti-vibriotic activity of Noni as an ethnobotanical
    Arrojo, Marley C. (Division of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines Visayas, 2005-12)
    The crude methanolic extract of Acacia, Alibutbut, Bayabas, Biab, Botolan, Bulobitu-un, Buyo, Kamunsil, Kasla, Kayos, Langka-langka, Noni, Pasaw, Sampaguita, Tabong, Talisay, Yellow bell, were bioassayed for their cytotoxicity using brine shrimp nauplii assay. Among the plant extracts, Noni gave the highest LCso equal to 943.329 pg/mL. Noni was the least toxic among the plants tested and its crude methanolic extract was found to have activity against V. harveyi with an anti-vibriotic index of 0.256. Sequential extraction using solvents with increasing polarity gave fractions that exhibited anti-vibriotic property but the more polar ethyl acetate fraction gave the highest anti-vibriotic index of 0.513. It appears that the anti-vibrio constituent is polar. Using VLC, the ethyl acetate fraction was further separated into eighteen fractions which were in turn pooled into five fractions, Fa, Fb, Fc, Fd, and Fe based on their TLC profile. Anti-vibriotic activity of each fraction was determined. Fraction Fa has the highest anti-vibriotic index (0.192) but this is much lower than 0.513. There must be some synergy among the polar constituents that exhibited a higher anti-vibriotic index in the ethyl acetate fraction compared to fraction Fa. Based on several color reactions, ethyl acetate fraction may contain any of the following plant metabolites such as tannins, saponins, phenolic groups, conjugated double bonds, flavonoids, sterols, terpenes, except alkaloids.
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    Heavy metal concentrations in sediments from Batan Bay and its tributaries
    Andrada, Mary Royce D. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2014-04)
    The concentration of three heavy metals (Cd, Pb, Cu) in sediments from Batan Bay and its tributaries were determined in order to assess the degree of contamination of sediments in the said area. The samples were digested following the Method 3050B of US Environmental Protection Program (EPA, 1996). The heavy metal concentrations were determined using Flame Atomic Absorption Spectrometer (FAAS). Results show that the heavy metal concentrations ranged from n.d. - 2.57 mg/kg dry weight (dw) for Cd; 16.44-143.02 mg/kg dw for Cu; and 3.18-28.53 mg/kg dw for Pb. Sediment sample collected from BTN #10 has the highest Cd concentration while sediment sample collected from BTN 052 which is a rice field in Batan, Aklan registered the highest Pb and Cu concentrations. Three sediment quality guidelines (National Oceanic and Atmospheric Administration, Canadian Sediment Quality Guideline and Hong Kong Sediment Quality Guideline) were employed to assess the metal contamination in sediments. The concentrations of Cd and Pb in all sites did not exceed the maximum permissible limits set by the three guidelines. As for Cu, BTN 052 exceeded the Upper Chemical Exceedance Level set by Hong Kong SQG. Correlation analysis showed that there is a significant correlation (p <0.01) between Pb and Cu indicating possible similar source input. Special attention must be given to BTN 052 since the levels of the studied heavy metals are high in this area. The results can be used as basis for the pollution level of sediments from Batan Bay and its tributaries. Special consideration should be given to BTN 052 since all of the test metals are significantly high in this area. It is also suggested to in identify the primary sources of metal contamination in this area.