Date of Award

2012

Document Type

Master Thesis

Degree Name

Masters of Science (Research)

Department

Department of Biological Sciences and Department of Chemistry

First Advisor

Dr. Deirdre Gilroy

Second Advisor

Dr. Ambrose Furey

Third Advisor

Dr. Joseph Kerry

Abstract

Hawthorn {Crataegus monogyna) is a herb that has been used medicinally since ancient times. In modern medicine it is known for its cardiotonic properties and is used as a cardiovascular protective, hypotensive and hypocholesterolemic agent. In recent years supercritical fluid extraction (SFE) has become more popular as an extraction method for botanical material as it is an environmentally-friendly method that can produce toxic-free extracts. The optimal SFE extraction conditions for the extraction of antioxidant compounds from both, hawthorn leaf & dower and hawthorn berries, using carbon dioxide, were determined in this study. The optimized extracts were then compared to pre-prepared commercial extracts, traditional and sonicated extracts (laboratory prepared) of the same material. The extracts were tested for their total phenolic content using the Folin-Ciocalteu method and their antioxidant activity was determined using the DPPH radical scavenging assay and the FRAP antioxidant assay. The extracts were also tested for their effect on lipid and oxymyoglobin oxidation in bovine muscle model systems. All of the extracts exhibited antioxidant activity in both sets of experiments; however the commercial leaf & flower extract performed the best in all experiments. The SFE extracts did not exhibit high antioxidant activities compared to the other extracts and were amongst the lower performing extracts in the DPPH and FRAP assays. However, the SFE extracts showed more potential in the muscle model systems with the SFE leaf & flower extract ranking among the extracts with better capability of preventing lipid and oxymyoglobin oxidation. It was also determined that there is a significant positive relationship between total phenolic content and the antioxidant activities of the extracts. Antimicrobial activities of the extracts were examined using the disc-diffusion assay. The results determined that none of the extracts tested exhibited bacteriocidal activities.

Access Level

info:eu-repo/semantics/closedAccess

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