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

Date

10-2005

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Evelyn B. Rodriguez

Abstract

ROSALES, JOANNE DE CHAVEZ. College of Arts and Sciences, University of the Philippines Los Banos. October 2005. Phenolic Compounds in "Siling Labuyo" (Capsicum frutescens, Linn.) Leaves: Profile, Angiogenic Potential and Antioxidant Activity on DNA and Lipid Oxidation.

ADVISER: Evelyn B. Rodriguez, Ph.D.

The phenolic compounds in "siting labuyo" leaves were extracted in three ways: extraction with 7:7:6 methanol:acetone:water (MAW extract); hydrolysis with I N FICI in 50% methanol (acid-hydrolyzed extract); and saponification of the MAW extract with 4 N NaOH (base-hydrolyzed extract). A descending two-dimensional paper chromatography technique was employed to obtain the phenolic profile of the extracts. The phenolics were identified 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, rechromatographed in one-dimension together with standards and subjected to UV spectral analysis. The major phenolics of the MAW extract were apigenin-7-0-glucoside and quercetin-3-0-rhamnoside. Apigenin and quercetin were the major components of the acid-hydrolyzed extract while that of the base-hydrolyzed extract was a cinnamic acid.

The total phenolic contents of the extracts were determined using the Folin-Ciocalteau reagent and catechin and gallic acid as standards. The MAW extract gave 839 mg CE/kg fresh sample and 468 mg GAE/kg fresh sample.The acid-hydrolyzed extract gave the highest phenolic contents: 1133 mg CE/kg fresh sample and 816 mg GAE/kg fresh sample. The lowest phenolic contents were found in the base-hydrolyzed extract: 131 mg CE/kg fresh sample and 103 mg GAE/kg fresh sample.

The antioxidant activity of the MAW extract was determined through its ability to inhibit lipid peroxidation. At 20 ppm, BHT (75.47%.± 4.27%) effected the highest inhibition of TBARS formation followed by quercetin (71.83% ± 1.41%) and extract (35.21% .± 2.82%). The evaluation of the antioxidant activity of the MAW extract in Fenton-induced oxidation of DNA showed the following relative percent inhibition of MARS formation: quercetin (46.97% ± 4.55%) > BHT (43.94% ± 0.00%) > extract (32.88% ± 3.00%).

The free radical scavenging activity of the MAW extract was measured using the DPP1-1 radical. At 300 ppm, the MAW extract scavenged the DPPH radical by 29.33% ± 0.00%. Quercetin exhibited the highest free radical scavenging activity of 95.56% ± 0.89%, followed by BHT (84.89% ± 0.45%).

The angiogenic activity of different concentrations of the MAW extract was evaluated using the duck embryo assay. The untreated duck embryo showed a normal blood vessel formation while the extract- and quercetin-treated embryos, at all concentrations, had reduced formation of blood vessels.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

This document is currently not available here.

Share

COinS