Phenolic compounds in spring onion (Allium fistulosom, Linn): profile, angiogenic potential and antioxidant activity on DNA and lipid oxidation

Date

10-2005

Degree

Bachelor of Science in Agricultural Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Evelyn B. Rodriguez

Co-adviser

Maxima E. Flavier

Committee Member

Norma N. Fajardo

Abstract

The phenolic compounds in spring onion (Allium fistulosum, Linn) in three ways: extraction by methanol-acetone-water (MAW 7:7:6); extraction by 60% methanol followed by hydrolysis with 1 N 'ICI, and saponification of the MAW extract with 4 N Na011. A descending two-dimensional paper chromatography technique was employed to obtain the phenolic profile of the extracts. The phenolics present were identified or classified into compound types according to their chromatographic mobility and color under visible and UV light, both in the presence and absence of ammonia. The major phenolics were eluted from paper using methanol, rechromatographed (one-dimensional) with 1-butanol-acetic acid-water (BAW 6:1:2) together with some standards and subjected to UV spectral analysis. The major phenolics of the MAW extract were quercetin-3-0-glucoside and a flavonol glycoside suspected to he that of kaempferol. The major phenolic of the acid-hydrolyzed extract was quercetin. No spots were detected in the chromatogram of the base-hydrolyzed extract. The total phenolic contents of the extracts were determined using the Folio Ciocalteu reagent. The acid-hydrolyzed extract had the highest phenolic content (2076.00 mg GAE / kg fresh sample and 3624.00 mg CE / kg fresh sample), followed by the MAW extract (378.00 mg GAE / kg fresh sample and 665.87 nig CE / kg fresh sample) and the base-hydrolyzed extract (122.88 mg GAE / kg fresh sample and 216.96 mg CE • kg fresh sample). The MAW extract was evaluated for its antioxidant activity on metal-catalyzed oxidation of lecithin liposomes and Fenton-induced oxidation of calf th∎mus DNA by measuring percentage inhibition of TEARS formation. Highest inhibition of TEARS formation for both assays was observed at the highest concentrations. 20 ppm and 8 ppm. respectively for all the samples used. In the metal-catalyzed oxidation of lecithin liposomcs, 131-IT (75.49 t 4.27%) exhibited the highest inhibition of TEARS formation at 20 ppm. This was followed by quercetin (71.83 ± 1.41%) and the MAW extract (40.85 t i 4.64%). In the DNA oxidation on the other hand, highest inhibition of TEARS formation at 8 ppm was effected by quercetin (46.97 t 4.55%) and the N.I.NW extract 146.97 ± 4.09%), followed by Riff (43.94 4 0.00%). The MAW extract was also evaluated for its free radical scavenging activity at different concentrations using the DPPI I assay which measures the :than. of the extract to quench the DPPI I radical. I light..st free radical scavenging activity was observed at 300 ppm. the highest concentration used, for all the samples. The highest free radical scavenging activity was exhibited by quercetin (95.55 t 0.88%). followed by BHT (84.89 ± 0.44%) and NIAW extract (56.00 ± 4.89%). The angiogenic activity of the MAW extract at different concentrations (400. 800 and 1200 ppm) was also evaluated using the duck embryo assay. The untreated duck embryo showed normal blood vessel formation. However the extract - and quercetin -treated duck embryos, at all concentrations, showed thinner and reduced formation of blood vessels in comparison with the untreated duck embryo. Moreover, it was observed for both the extract - and quercetin - treated duck embryos that reduction of blood vessel formation increased with increasing concentration.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2005 A13 I57

Document Type

Thesis

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