Date of Publication
8-2025
Document Type
Master's Thesis
Degree Name
Master of Science in Chemistry
Subject Categories
Chemistry
College
College of Science
Department/Unit
Chemistry
Thesis Advisor
Drexel H. Camacho
Defense Panel Chair
Vincent Antonio S. Ng
Defense Panel Member
Raymond S. Malabed
Adoracion P. Resurreccion
Abstract/Summary
Balatinao rice is an heirloom black rice variety native to the Cordillera region of the northern Philippines. It is regarded as a healthy rice due to the beneficial pigment components. However, there are no studies available investigating the chemical constituents of its discarded rice bran after milling. This study investigates the chemical constituents and antioxidant potential of the Balatinao rice bran. The bran extract was obtained using ethanol solution. LC-MS analysis of the crude rice bran extract identified 502 detectable compounds, including flavonoid glycosides, organic acids, amino acids, fatty acids, and peptides. In addition, 310 unidentified compounds were detected, absent from the Human Metabolome Database, suggesting the potential for novel bioactive discoveries. The bran extract was subjected to column chromatography fractionation with moderately polar solvents to enhance compound purity. Further purification through semi-preparative liquid chromatography afforded subfractions. Structural elucidation using NMR, FTIR, and UV-vis spectroscopic analysis identified (9Z,12Z)-octadeca-9,12 dienoic acid as the primary component in subfraction 4 (SF4). A variety of sakuranetin related flavonoids, including methylated and glycosylated derivatives, are identified among the minor compounds in subfraction 8 (SF8). The antioxidant activity of SF4 was evaluated using the DPPH radical scavenging assay, revealing a dose-dependent response with an IC₅₀ of 8.908 ppm (95% CI: 8.504–9.341 ppm). This suggests a synergistic effect between the compounds present in SF4, likely enhanced by other bioactive components such as phenolics and tocopherols. These findings highlight the potential of Balatinao rice bran as a natural antioxidant, with possible uses in food preservation, functional foods, and health products.
Abstract Format
html
Language
English
Format
Electronic
Keywords
Rice bran; Rice—Varieties; Antioxidants
Recommended Citation
Dela Cruz, J. D. (2025). Isolation and structural characterization of chemical constituents from black rice bran (Oryza sativa ssp. indica) and evaluation of the antioxidant properties. Retrieved from https://animorepository.dlsu.edu.ph/etdm_chem/28
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Embargo Period
8-12-2028
