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Undergraduate Theses

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Department: search.filters.department.College of Arts and SciencesKeyword: search.filters.keyword.Bioactivity

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    Chromatographic analysis and antibacterial assay of Avicennia officinalis bark extracts
    Janagap, Steve P. (Division of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines Visayas, 2003-04)
    In this study, the antibacterial activity and the chemical constituents of Avicennia officinalis bark were determined. The antibacterial assay showed that the dichloromethane (DCM) fraction at 1000 ug/mL was most effective against the tested bacteria especially to Staphylococcus aureus. It had a microbial index of 0.97 while the positive control, amoxicillin had 1.00. The aqueous fraction did not show antibacterial activity to the organisms tested. A number of chemical constituents were found to be present in the different fractions obtained from Avicennia officinalis bark: alkaloids, cardiac glycosides, flavonoids, phenolic compounds, saponins and terpenes. These constituents were determined using thin layer chromatography. The DCM fraction which showed the highest bioactivity, had the most number of components while the aqueous fraction had the least number of components. The DCM fraction was subjected to two-dimensional thin layer chromatography. Nine spots were observed with the first solvent system (ethyl acetate-DCM; 5:3) while eleven spots were observed with the second solvent system (ethyl acetate-n-hexane-DCM; 2:1:1).
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    Bioactivity-guided screening of selected plants from UPV Miag-ao campus
    Arceo, Ma. Ofelia H. (Division of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines Visayas, 1998-05)
    Twelve selected ethnomedically-used plants were screened for alkaloids, saponins, and flavonoids. Nine out of twelve plants contained at most two of the phytochemicals tested, and three showed the absence of these phytochemicals. Methanolic extracts of three selected plants (Stachy/arpheta /amaicensis, Hyptis suaveo/ens, Semecarpus philippinensis) were examined for antibacterial activity against Staphylococcus aureus. Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. All extracts were found to be active at least against two of the microorganisms tested. The extract of Siachytarphe/a jamaicensis was found to be active against three out of four microorganisms and found to be the most bioactive. Stachyiarpheta jamaicensis was subjected to bioactivity-guided fractionation using solvents of increasing polarity - hexane, ethyl acetate, and n-butanol. The hexane extract was considered as the most bioactive fraction. Its chromatogram contained seven spots in which four turned blue violet after spraying with vanillin-H2SO4. The color change exhibited suggests the possible presence of saponins.