Phenolic compounds in "siling labuyo" (Capsicum frutescens, Linn.) fruit: profile angiogenic potential and antioxidant activity on DNA and lipid oxidation

Date

4-2005

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Evelyn B. Rodriguez

Co-adviser

Maxima E. Flavier

Committee Member

Evamarie P. Capareda

Abstract

The phenolic compounds in "siting labuyo" ((apsicum fruiescens. Linn.) fruit were isolated in three ways: extraction by 7: 7: 6 methanol: acetone: water (MAW); extraction by 60% methanol followed by hydrolysis with I N WI; and saponification of the MAW extract with 4 N NaOH. A descending two dimensional paper chromatography technique was employed to obtain the phenolic profile of the extracts. The phenolics were identified or classified into compound types according to their chromatographic mobility and color under visible and UV light, both in the presence or absence of ammonia. The major phenolics were elided from paper. rechromatographed together with some standards and subjected to UV spectral analysis. The major phenolics of the MAW extract were quercetin-3-0-rhamnoside and luteolin-7-0-glucoside. Lutcolin and quercetin were the major components of the acid- hydrolyzed extract, while that of the base- hydrolyzed extract was a cinnamic acid. C-glycosylflavones were identified in all the extracts. The total phenolic contents of the extracts were determined using the Folio Ciocaltcau reagent The MAW extract gave 2019 mg GAE/ kg fresh sample and 3536 mg CE/ kg fresh sample. On the other hand, the acid- hydrolyzed extract gave 2420 mg GAE/ kg fresh sample and 4091 mg CE/ kg fresh sample. The lowest phenolic content was found in the base- hydrolyzed extract: 1253 mg GAE/ kg fresh sample and 217 mg CE, kg fresh sample. The MAW extract was evaluated for its antioxidant activity on the metal-catalyzed oxidation of lecithin liposomes and the Fenton-induced oxidation of calf thymus DNA by measuring percentage inhibition of TBARS formation. Of the different concentrations tested, the 20 ppm MAW extract effected the highest inhibition of TBARS formation (48.7%) in lecithin oxidation. At the same concentration, BHT, quercetin and capsaicin effected 71.1%. 68.4%, and 42.1% inhibition, respectively. In the DNA oxidation, the 8 ppm MAW extract caused the highest inhibition (40.5%). BHT. quercetin and capsaicin effected 41.9%, 45.9%, and 36.5% inhibition, respectively, at the same concentration. In both assays, the inhibitory action of phenolics in the systems used was accounted to their combined chelating effect and radical scavenging activity. The free- radical scavenging activity of the MAW extract, at different concentrations, was measured using the DPPII radical. At 300 ppm, the MAW extract

scavenged the UPPH radical by 60.1% for only 5 minutes. Under the same conditions, quercetin exhibited the highest free- radical scavenging activity (98.6%), while BHT had only 25.2% scavenging activity. Using the duck embryo assay, the angiogenic activity of different concentrations of the MAW extract (400, 800 and 1200 ppm) was evaluated. Quercetin, of the same concentrations, was used for a parallel study. The untreated duck embryo showed a normal blood vessel formation. However, the extract- and quercetin- treated embryos, at all concentrations, had thinner and reduced formation of blood vessels in comparison with the untreated duck embryo.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2005 C4 L33

Document Type

Thesis

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