Encapsulation of oregano (Coleus amboinicus) ethanolic extract in pectin-gelatin microcapsules for enhancement of free radical-scavenging and antimicrobial activities

Date

10-2012

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Evelyn B. Rodriguez

Restrictions

Restricted: Not available to the general public. Access is available only after consultation with author/thesis adviser and only to those bound by the confidentiality agreement.

Abstract

Oregano (Coleus amboinicus) contains bioactive phenolics such as thymol and carvacrol which can be developed as preservatives in food and cosmetic products and antimicrobial agents in general. In this study, oregano ethanolic extract was encapsulated in pectin-gelatin microcapsules to increase water solubility, enhance free-radical scavenging and antimicrobial activities and control its release.Low-methoxyl pectin with a yield of 5.19% was obtained from dried pomelo (Citrus maxima) peels. Extraction of dried oregano leaves with ethanol yielded 8.82% crude extract which was found to contain 459.34 ± 1.22 mg thymol-carvacrol/g oregano extract. Encapsulation of oregano ethanolic extract by pectin-gelatin coacervation allowed an encapsulation efficiency of 79.36 ± 1.80% and yielded microcapsules with an average size of 170 ± 43 µm and a loading efficiency of 43.29 ± 0.98%. The oral in vitro releasing studies showed a limited release of the core material on simulated gastric fluid (SGF) and a more complete release in simulated intestinal fluid (SIF). The release pattern in SIF showed an initial burst release, followed by sustained release up to the 26th hour. These results indicate that the oregano ethanolic extract-loaded microcapsules could pass through the stomach without being damaged by the acidic environment and move on to the intestines where the core material is more fully released and then finally absorbed. On the other hand, the topical in vitro releasing studies showed that encapsulation allowed a controlled and sustained release of the oregano ethanolic extract in surfactant solution up to the 28th hour. Microencapsulation promoted a 3-fold increase in free-radical scavenging activity of oregano extract. Oregano ethanolic extract was found to be more potent against gram-negative E. coli than gram-positive S. aureus but was not potent against gram-negative K. pnuemoniae. Encapsulation promoted a 5-fold and 8-fold increase in the activity of the extract against S. aureus and E. coli, respectively. At a lower concentration of the core materials, the activity of the microcapsules was comparable to that of spectinomycin. Encapsulation also enhanced the antifungal activity of oregano ethanolic extract against F. oxysporum compared with non-encapsulated extract. The extract and the microcapsules were found to be more potent antifungal agents against F. oxysporum than commercially available products such as dithane and cycloheximide.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2012 C42 F67

Document Type

Thesis

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