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Undergraduate Theses

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

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    Development of a high-performance thin layer chromatography (HPTLC)-densitometric method for the estimation of quercetin and kaempferol in Euphorbia hirta (Tawa-tawa) extract
    Baladjay, Diane Monique S. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2017-06)
    A sensitive, fast, efficient, and repeatable high-performance thin-layer chromatographic (HPTLC) method has been developed for simultaneous analysis of quercetin and kaempferol from the extracts of the aerial parts of Euphorbia hirta. In the development of the HPTLC method, different extraction parameters were evaluated and quantification of quercetin and kaempferol in the extract of E.hirta was performed using a densitometric software, Quantiscan™. Among the different combinations of mobile phases used, best separation was achieved in toluene: ethyl acetate: formic acid: methanol (5: 6: 2: 1) solvent system. E.hirta was extracted using the developed extraction method which involves the use of 80% ethanol, 8 minutes of sonication and serial extraction until 3rd extraction. This determined method provides a maximum yield of the compounds at minimum time and cost. The method was also validated for linearity and precision specifically repeatability. The results show that the produced calibration is linear, as supported by the obtained correlation coefficient (r) of > 0.999 and coefficient of determination (R2) of > 0.997. Moreover, the obtained slopes of the calibration curves show that the method is most sensitive towards quercetin and least sensitive to gallic acid. The method was also found out to be repeatable and precise as the %RSD for both the inter-day and intra-day trials obtained a value less than <2%. The present method is being reported for the first time and can be used for routine quality control and quantification of quercetin and kaempferol in various plant samples, extracts, and market formulations.
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    Comparing the quercetin content of different Allium sp. by spectrophotometry
    Asuelo, Allen Daryl F. (Division of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines Visayas, 2007-04)
    Quercetin from two Allium sp. was extracted sequentially with solvents of varying degrees of polarity. The crude quercetin was subjected to chemical tests and the concentration determined by using Shimadzu mini UV-Vis 1240 Spectrophotometer. Results of the study showed that the extraction procedure used was effective in extracting quercetin. This was verified by the identical spectrum obtained with quercetin from the standard (Quercetin Complex) with the IR spectrum of quercetin obtained from the literature. The crude quercetin was positive to the both chemical tests, namely Baeyer's and Ferric chloride tests, subjected to it. Quercetin content in red onions was obtained with mean concentrations of 10.60 mg/kg at 362nm and 7.429 mg/kg at 370nm. Quercetin content in garlic was obtained with mean concentrations of 9.692 mg/kg at 362nm and 5.689 mg/kg at 370nm. The quercetin concentration measured at 370nm was quercetin another wavelength at 362nm measured the concentration of quercetin as flavonols. The result of One-way ANOVA at 0.05a showed that there is a significant difference in the quercetin content between red onions and garlic.