Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Identification and characterization of bioactivity of simulated gastrointestinal digested indigenous southern African honey samples
Thesis (PhD)--University of Pretoria, 2018.
Saved in:
| Other Authors: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
University of Pretoria
2018
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613695688835072 |
|---|---|
| access_status_str | Open Access |
| author2 | Bester, Megan J. |
| author_browse | Bester, Megan J. |
| author_facet | Bester, Megan J. |
| collection | Thesis |
| dc_rights_str_mv | © 2018 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD)--University of Pretoria, 2018. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/65821 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:40:14.504Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2018 |
| publishDateRange | 2018 |
| publishDateSort | 2018 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/65821 Identification and characterization of bioactivity of simulated gastrointestinal digested indigenous southern African honey samples Bester, Megan J. june.serem@up.ac.za Gaspar, A.R.M. (Anabella Regina Marques) Serem, June Cheptoo UCTD Antibacterial Anti-inflammatory Antioxidant Polyphenol Health sciences theses SDG-03 SDG-03: Good health and well-being Thesis (PhD)--University of Pretoria, 2018. Development of disease in the gastrointestinal tract is predominantly due to oxidative damage, infection and inflammation which if left unresolved lead to conditions such as inflammatory bowel disease. Functional foods can prevent/reduce the effects of oxidative damage, infection and inflammation. Honey is a well described functional food due to its several bioactivities. However, a functional food needs to be bioavailable and some bioactive molecules found in honey such as methylglyoxal (MGO) and polyphenols have been reported to have reduced activity following digestion. Therefore, the aim of this study was to determine the effects of digestion on the antioxidant, antibacterial and anti-inflammatory activities of southern Africa honey samples. Manuka (control) and three honey samples from the southern African region, Agricultural Eucalyptus (AE), south eastern Mozambique (SEMh), Western Cape, Fynbos (WC) were subjected to simulated gastroduodenal digestion and the bioactivities of the undigested (UD), gastric digested (GD) and gastroduodenal (GDD) fractions were determined. Total polyphenol content, Trolox equivalent antioxidant capacity and oxygen radical absorbance capacity were determined. Cellular antioxidant activity (CAA) using the human colon adenocarcinoma (Caco-2) cells and the dichlorofluorescein diacetate assay was also determined. A polyphenol mixture (PP) and a synthetic honey (sugars and polyphenols) were also digested and the antioxidant properties determined. Antibacterial effects against Gram-negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) and Gram-positive Bacillus subtilis (B. subtilis) and Staphylococcus aureus (S. aureus) bacteria were then evaluated using the microbroth dilution, minimum inhibitory concentration (MIC) assay. The contribution of sugars, MGO, H2O2, polyphenols and cationic peptides to antibacterial activity was also evaluated. Cytotoxicity against the mouse fibroblast (L929) cells, inhibition of nitric oxide (NO) formation, inhibition of E. coli induced NO levels in L929 cells and inhibition of LPS induced activation of human platelets was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H tetrazolium bromide assay, sodium nitroprusside assay and scanning electron microscopy, respectively. All honeys had antioxidant activity similar to Manuka honey. With GD the antioxidant properties of all honey fractions was unchanged. Following GDD, antioxidant activity was either unchanged or increased. In contrast, for CAA a strong pro-oxidant effect was observed. Using PP mixtures, findings were that this effect was not due to pH dependent polyphenol degradation associated with an increase in hydrogen peroxide (H2O2) levels, but possibly due to the presence of β-Carotene, which in the presence of O2 forms the carotenoid peroxyl radical. All honeys had MIC’s between 25 – 30% (v/v) against all tested bacteria, with the exception of MANc 6.25% (v/v) against S. aureus and AE 40% (v/v) against B. subtilis. With GD, the antibacterial activity, was unchanged. With GDD the antibacterial activity of MANc was retained. The activity of AE, SEMh and WC was unchanged against P. aeruginosa and S. aureus but was reduced against E. coli and B. subtilis. The MIC of MGO was 0.8 - 1.2 mM against all bacteria while the MIC for H2O2 was 9 mM for all bacteria except B. subtilis (90 mM). Honey sugars did not achieve MIC. Therefore, the activity of AE, SEMh and WC was concluded not to be due to MGO or H2O2 as higher levels than what is present in honey were needed to achieve MIC, but due to sugars in combination with an unidentified component. At honey concentrations that did not lead to cytotoxicity (<3% v/v), NO formation was reduced by 50%, 62%, 63% and 50% for MAN UMF10+, AE, SEMh and WC, respectively. E. coli induced NO formation in L929 cells and platelet activation was inhibited to varying degrees, with AE and SEMh honeys being the most effective. In conclusion, at physiologically relevant levels, the beneficial effects of honey in a gastric environment was the reduction of oxidative damage and inflammation while in a gastroduodenal environment the predominant effect was anti-inflammatory. Keywords: Antibacterial, anti-inflammatory, antioxidant, bioactive, digestion, functional food, gastroduodenal, Manuka honey, oxidative damage, polyphenol. em2025 Anatomy PhD Unrestricted SDG-03: Good health and well-being 2018-07-24T07:37:15Z 2018-07-24T07:37:15Z 2018-09-07 2018 Thesis Serem, JC 2018, Identification and characterization of bioactivity of simulated gastrointestinal digested indigenous southern African honey samples, PhD Thesis, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/65821> S2018 http://hdl.handle.net/2263/65821 en © 2018 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | UCTD Antibacterial Anti-inflammatory Antioxidant Polyphenol Health sciences theses SDG-03 SDG-03: Good health and well-being Identification and characterization of bioactivity of simulated gastrointestinal digested indigenous southern African honey samples |
| title | Identification and characterization of bioactivity of simulated gastrointestinal digested indigenous southern African honey samples |
| title_full | Identification and characterization of bioactivity of simulated gastrointestinal digested indigenous southern African honey samples |
| title_fullStr | Identification and characterization of bioactivity of simulated gastrointestinal digested indigenous southern African honey samples |
| title_full_unstemmed | Identification and characterization of bioactivity of simulated gastrointestinal digested indigenous southern African honey samples |
| title_short | Identification and characterization of bioactivity of simulated gastrointestinal digested indigenous southern African honey samples |
| title_sort | identification and characterization of bioactivity of simulated gastrointestinal digested indigenous southern african honey samples |
| topic | UCTD Antibacterial Anti-inflammatory Antioxidant Polyphenol Health sciences theses SDG-03 SDG-03: Good health and well-being |
| url | http://hdl.handle.net/2263/65821 |