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Modulation of UVB-induced inflammation and oxidative stress by unfermented rooibos and honeybush aqueous extracts: A comparative study
Thesis (PhD)--Stellenbosch University, 2024.
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| Language: | English |
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613758017241088 |
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| access_status_str | Open Access |
| author | Keet, Lana |
| author2 | Lilly, Mariska |
| author_browse | Keet, Lana Lilly, Mariska |
| author_facet | Lilly, Mariska Keet, Lana |
| author_sort | Keet, Lana |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/131709 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:41:12.661Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/131709 Modulation of UVB-induced inflammation and oxidative stress by unfermented rooibos and honeybush aqueous extracts: A comparative study Keet, Lana Lilly, Mariska Louw, Ann Abel, Stefan Stellenbosch University. Faculty of Science. Dept. of Biochemistry. Exposure to Ultraviolet B Ultraviolet radiation -- Health aspects Antioxidants -- Therapeutic use Herbal teas -- Health aspects Honeybush extracts -- Therapeutic use Keratinocytes -- Cytology Skin Phospholipids Oxidative stress -- Pathophysiology Gene expression Rooibos tea -- Therapeutic use UCTD Thesis (PhD)--Stellenbosch University, 2024. ENGLISH ASTRACT: Exposure to Ultraviolet B (UVB) radiation induces various biological responses that may contribute to skin cancer development. Natural compounds such as tea polyphenols have demonstrated protective effects against UVB-induced damage. Rooibos (Aspalathus linearis) and honeybush (Cyclopia spp.) are two South African herbal plants that have gained attention for their potential health benefits. Rooibos has recently been registered by the European Commission in its lists of Protected Designations of Origin (PDO) and Protected Geographical Indication (PGI) and therefore has protected status as it is only allowed to be grown in the Cederberg area of the Western Cape, South Africa. The current study explores the preventive effects of unfermented rooibos and honeybush herbal tea aqueous extracts on oxidative stress, inflammation and phospholipid alterations in HaCaT human keratinocytes exposed to UVB. The study utilises a pre-exposure HaCaT model, where cells are treated with tea extracts prior to UVB exposure. An array of assays and techniques were utilized to determine the antioxidant and anti-inflammatory effects on specific cytokines, genes and proteins involved in these processes, as well as ion mobility-mass spectrometry (IM-MS) to investigate effects on the major keratinocyte phospholipids. HPLC analysis showed the presence of the dihydrochalcones, aspalathin and nothofagin, the flavones, isoorientin and orientin, as well as the flavonols, rutin, isoquercitrin, and hyperoside in the rooibos extract. The major compounds found in honeybush extract included the xanthones, mangiferin and iso-mangiferin, and the flavanone, hesperidin. Rooibos demonstrated superior free radical scavenging activity against ABTS and DPPH, antioxidant capacity (ORAC), ferric iron reducing potential (FRAP) and greater inhibition of iron-induced peroxidation (LPO) compared to honeybush. Both teas also exhibited cell-based antioxidant properties by increasing glutathione (GSH) levels, and the increase in GPX1 and CAT expression, while only rooibos upregulated Nrf2 expression. Microarray analysis confirmed the antioxidant activity of both teas in the increased expression of GCLM, GPX and PRDX. The results indicate that honeybush reduces UVB-induced interleukin (IL)-1α accumulation and IL-6 secretion, while both teas decrease IL-8 secretion and NF-κB activation, demonstrating the anti-inflammatory effect of rooibos and honeybush. The treatment of keratinocytes with rooibos and honeybush alone did not affect the levels of any of the lipid species identified in the current study. However, exposure of the cells to UVB significantly decreased the levels of all of evaluated phospholipids. Neither rooibos nor honeybush were able to significantly counteract this decrease in phospholipid levels, with honeybush even further decreasing PC 34:1, PC 36:1, PC 36:4, PE 38:4 and SM 34:1 levels. Rooibos and honeybush contain completely different polyphenol profiles, which is reflected in their activities, with rooibos displaying more antioxidant activity while honeybush has greater anti-inflammatory activity. This research has the potential to inform the production of sunscreen products utilizing natural extracts to protect against the harmful effects of UVB exposure. AFRIKAANSE OPSOMMING: Blootstelling aan ultraviolet B (UVB)-bestraling veroorsaak verskeie biologiese reaksies wat kan bydra tot die ontwikkeling van velkanker. Natuurlike verbindings soos teepolifenole toon beskermende effekte teen skade deur UVB veroorsaak. Rooibos (Aspalathus linearis) en heuningbos (Cyclopia spp.) is twee Suid-Afrikaanse kruietees wat aandag trek vir hul potensiële gesondheidsvoordele. Rooibos is onlangs deur die Europese Kommissie geregistreer op sy lyste van Beskermde Benamings van Oorsprong (BBO) en Beskermde Geografiese Aanduidening (BGA), en het daarom beskermde status aangesien dit slegs in die Cederberg- area van die Wes-Kaap, Suid-Afrika, gekweek mag word. Die huidige studie ondersoek die voorkomende effekte van ongefermenteerde rooibos- en heuningbos-kruietee-water-ekstrakte op oksidatiewe stres, inflammasie en fosfolipiedveranderings in HaCaT-menslike keratinosiete wat aan UVB blootgestel is. Die studie maak gebruik van 'n vooraf-blootstelling HaCaT-model, waar selle met tee-ekstrak behandel word voor UVB-blootstelling. 'n Verskeidenheid toetse en tegnieke is gebruik om die antioksidant- en anti-inflammatoriese effekte op spesifieke sitokiene, gene en proteïene betrokke by hierdie prosesse te bepaal. Die effekte op die hooof keratinosiet-fosfolipiede was ook ondersoek, deur middel van ionmobiliteit- massaspektrometrie (IM-MS). Hoë druk vloeistof chromatografie (HPLC)-analise het die teenwoordigheid van die dihydrochalcones, aspalathien en nothofagien, die flavone, isoorientien en orientien, asook die flavonole, rutien, isoquercitrien en hyperoside in die rooibos-ekstrak aangedui. Die hoofverbindings wat in die heuningbos-ekstrak gevind is, sluit die xanthones, mangiferien en iso-mangiferien, en die flavanoon, hesperidien, in. Rooibos het beter opruiming van radikale getoon teen 2,2'-asinobis(3-etiel-bensotiasolien-6-sulfonsuur (ABTS) en 1,1-difeniel-2-pikrielhidrasiel (DPPH), antioksidant kapasiteit (ORAC), ferriese yster reduseringspotensiaal (FRAP) en groter inhibisie van yster-geïnduseerde peroksidasie (LPO) in vergelyking met heuningbos. Beide tees het ook selgebaseerde antioksidant vermoëens getoon deur glutationien (GSH)-vlakke te verhoog, en die verhoogde vlakke van GPX1 en CAT, terwyl slegs rooibos die Nrf2-vlakke opreguleer. Die antioksidant aktiwiteit van beide tees was deur microarray analise bevestig in die verhoogde vlakke van GCLM, GPX en PRDX. Die resultate dui daarop dat heuningbos die UVB-geïnduseerde ophoping van IL-1α en IL-6 sekresie verminder, terwyl beide tees IL-8 sekresie en NF-κB aktivering verminder, wat dui op die anti-inflammatoriese effek van rooibos en heuningbos. Die behandeling van keratinosiete met rooibos en heuningbos alleenlik het nie die vlakke van enige van die lipiedspesies wat in die huidige studie geïdentifiseer is, beïnvloed nie. Blootstelling van die selle aan UVB het egter die vlakke van al die geëvalueerde fosfolipiede aansienlik verminder. Nie rooibos of heuningbos kon hierdie afname in fosfolipiedvlakke aansienlik teenwerk nie, met heuningbos wat selfs 'n verdere afname in PC 34:1, PC 36:1, PC 36:4, PE 38:4 en SM 34:1 vlakke veroorsaak het. Rooibos en heuningbos bevat heeltemal verskillende polifenolprofiele, wat weerspieël word in hul aktiwiteite, met rooibos wat meer antioksidant aktiwiteit toon, terwyl heuningbos groter anti-inflammatoriese aktiwiteit het. Hierdie navorsing het die potensiaal om die produksie van sonbeskermingsprodukte te bevorder met die gebruik van natuurlike ekstrakte om teen die skadelike effekte van UVB-bestraling te beskerm. Doctoral 2025-02-20T06:26:25Z 2025-02-20T06:26:25Z 2024-12 Thesis https://scholar.sun.ac.za/handle/10019.1/131709 en Stellenbosch University xxii, 182 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Exposure to Ultraviolet B Ultraviolet radiation -- Health aspects Antioxidants -- Therapeutic use Herbal teas -- Health aspects Honeybush extracts -- Therapeutic use Keratinocytes -- Cytology Skin Phospholipids Oxidative stress -- Pathophysiology Gene expression Rooibos tea -- Therapeutic use UCTD Keet, Lana Modulation of UVB-induced inflammation and oxidative stress by unfermented rooibos and honeybush aqueous extracts: A comparative study |
| title | Modulation of UVB-induced inflammation and oxidative stress by unfermented rooibos and honeybush aqueous extracts: A comparative study |
| title_full | Modulation of UVB-induced inflammation and oxidative stress by unfermented rooibos and honeybush aqueous extracts: A comparative study |
| title_fullStr | Modulation of UVB-induced inflammation and oxidative stress by unfermented rooibos and honeybush aqueous extracts: A comparative study |
| title_full_unstemmed | Modulation of UVB-induced inflammation and oxidative stress by unfermented rooibos and honeybush aqueous extracts: A comparative study |
| title_short | Modulation of UVB-induced inflammation and oxidative stress by unfermented rooibos and honeybush aqueous extracts: A comparative study |
| title_sort | modulation of uvb induced inflammation and oxidative stress by unfermented rooibos and honeybush aqueous extracts a comparative study |
| topic | Exposure to Ultraviolet B Ultraviolet radiation -- Health aspects Antioxidants -- Therapeutic use Herbal teas -- Health aspects Honeybush extracts -- Therapeutic use Keratinocytes -- Cytology Skin Phospholipids Oxidative stress -- Pathophysiology Gene expression Rooibos tea -- Therapeutic use UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/131709 |
| work_keys_str_mv | AT keetlana modulationofuvbinducedinflammationandoxidativestressbyunfermentedrooibosandhoneybushaqueousextractsacomparativestudy |