Research Projects

Skin Cancer Research – Prof Wentzel Gelderblom

Skin Cancer Research – Prof Wentzel Gelderblom

Prof Wentzel Gelderblom

Prof Wentzel Gelderblom

Chief Specialist Scientist – PROMEC Unit, Medical Research Council

Email: Wentzel.gelderblom@mrc.ac.za

Title of the project

Therapeutic properties of rooibos and honeybush extracts against skin carcinogenesis (project ended 31 March 2010)

Highlights of the project

The methanol extracts of rooibos and green tea were more active at inhibiting ATP production in immortalised keratinocytes (HaCaT) compared to the aqueous counterparts. Extracts of the four honeybush spp exhibited far weaker activity, which was related to the weaker antioxidant properties of the main polyphenolic constituents. In contrast to the rooibos and green tea extracts, the aqueous extracts of the honeybush were more active than the methanolic extracts, suggesting that compounds other than polyphenols could contribute to the observed properties of honeybush as they are more concentrated in the methanolic extracts. An in vitro inflammatory assay using phorbol ester and ionomycin, a calcium ionophore, has been established in HaCaT cells, with ionomycin giving a better response with respect to interleukin 1α (IL-1α) production. Although the tea extracts inhibited an inflammatory response, an underlying cytotoxicity complicated the interpretation of the findings. When utilising UV-B irradiation a greater response on IL-1α production was noticed in the absence of any cytotoxic effects and this model will be further developed to assess the anti-inflammatory effects of the herbal tea extracts.

What has been achieved?

Problem statement:
South Africa has one of the highest incidence rates of skin cancer in the world, surpassed only by Australia, with the most important risk factor being high exposure to the sun’s ultraviolet (UV) light. Carcinogenesis follows three distinctive stages. During Initiation, mutated or altered cells develop and exhibit different properties compared to normal cells. If another stimulus is introduced (cancer promotion), these cells have a growth advantage resulting in their progression and development into cancer. Altered oxidative status and inflammation are prominent characteristics associated with cancer promotion, which is a reversible process making it an ideal target for chemo-prevention with the indigenous South African herbal teas rooibos and honeybush. Completed studies showed that the herbal infusions exhibited many health promoting properties, including anti-mutagenicity, anti-oxidant
and anti-cancer activities.

Project description:
Aqueous and methanolic extracts were prepared of unfermented rooibos and honeybush herbal teas. The antioxidant properties of these extracts were assessed by determining their polyphenolic content, the free radical scavenging and iron reducing properties. This was followed by cell culture experiments, monitoring the effect of the tea extract on cell growth parameters in cancerous and normal skin cells.

Main results:
Studies in cancerous and normal skin cells showed that the herbal extracts modulate cell growth parameters which could be related to the alteration in the oxidative status. An inflammatory model in skin cells was developed with the UV-B method showing the most promising results. These different assays forms part a battery of in vitro and in vivo biomarker assays to validate the chemopreventive properties of the herbal tea constituents.

Impact & Relevance:
The South African herbal teas rooibos and honeybush have been shown to exhibit a variety of health promoting properties, including anti-cancer activity. This project will provide the necessary information for the development of a therapeutic or cancer chemopreventive skin product.

How was this project of value in the struggle against cancer?

South Africa has one of the highest incidence rates of skin cancer in the world. Rooibos and honeybush herbal teas are indigenous and readily available natural resources. A specifically designed and tested skin product will provide a scientifically sound, inexpensive and non-invasive tool for skin cancer therapy and/or chemoprevention.

Peer-reviewed Publications

  1. Snijman PW, Swanevelder S, Joubert E, Green IR, Gelderblom WCA (2007) The antimutagenic activity of the major flavonoids of rooibos (Aspalathus linearis) — some dose-response effects on mutagen activation-flavonoid interactions.  Mutat Res.  613: 111-123
  2. Joubert E, Richards ES, Van der Merwe JD, de Beer D, Manley M and Gelderblom WCA (2008). Effect of species variation and processing on phenolic composition and in vitro antioxidant activity of aqueous extracts of Cyclopia spp. (honeybush tea).  J Agric Food Chem, 56, 954-963
  3. Joubert E., Gelderblom WCA, Louw A, de Beer D (2008) South African herbal teas: Aspalathus linearis, Cyclopia spp. and Athrixia phylicoides – a reviewJ Ethnophamacology, 119, 376-412.
  4. Gelderblom WCA, Gamieldien K, Joubert E. (2008) Black and other teas. In Chemoprevention of Cancer and DNA Damage by Dietary Factors. Knasmuller S, DeMarini DM, Johnson I T, Gerhauser C. (Eds). Wiley-VCH Germany pp, 609-633
  5. Marnewick JL, Van Der Westhuizen L, Van Der Westhuizen FH, Elizabeth Joubert E, Swanevelder S, Swart P, Gelderblom WCA. (2009) Chemoprotective properties of rooibos (Aspalathus linearis), honeybush (Cyclopia intermedia), green and black (Camellia sinensis) teas against cancer promotion induced by fumonisin B1 in rat liverFood Chem Toxicol, 47, 220-229.
  6. Joubert E, Gelderblom WCA and De Beer D (2009) Phenolic contribution of South African Herbal teas to a healthy dietNatural Product Communications. 5, 701-718.

Conferences

  • Gamieldien K, Joubert E, Sissing LG, Marnewick JL, Samodien S, de Kock M, Gelderblom WCA. Chemopreventive properties of South African herbal teas, rooibos and honeybush, utilising different cell cultures and site specific rat experimental modelsCancer Research in Action Conference. Emperors Palace, Johannesburg. 20-22 August 2008 (Poster)
  • Gamieldien K. Therapeutic properties of South African herbal teas. Master Class on Diet Health and Development: What is the Evidence? 22ndBiannual Congress of the Nutrition Society and the 10th Biannual Congress of the Association of Dietetics in South Africa. 28 Sept-02 October 2008. University of Pretoria (Oral).
  • Gamieldien K, Joubert E, van der Merwe D, Abrahams S, de Kock M, Gelderblom, WCA. Characterization of the major antimutagenic and antioxidant principles of unfermented rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia) herbal teasPAEMS 2008, Cape Town International Convention Centre, 3-5 November (Oral).
  • Gelderblom WCA, Burger HM, Abel S, Gamieldien K.  Antioxidant supplements: The good the bad and the unnecessaryIndigenous plant use forum, Graaff-Reinet, 7 to 10 July 2008 (Oral).
  • Gelderblom WCA,  Gamieldien K, Sissing L, Van der Merwe JD, Joubert E.  Health promoting properties of rooibos and honeybush herbal teasCancer Research in Action Conference. Emperors Palace, Johannesburg. 20-22 August 2008 (Oral).
  • Gelderblom WCA, E Joubert, H Burger and S Abel. Plant flavonoids as dietary supplements. Potential risk in cancer chemoprevention.  Master Class on Diet Health and Development: What is the Evidence? 22nd Biannual Congress of the Nutrition Society and the 10th Biannual Congress of the Association of Dietetics in South Africa. 28 Sept-02 October 2008. University of Pretoria (Oral).
  • Magcwebeba TU, Gamieldien K, Joubert E, Swart P, Gelderblom WCA. Investigating the chemopreventive activity of selected South African herbal teas, rooibos (Aspaluthus linearis) and Honeybush (Cyclopia spp.) in normal and cancer human skin cells. PAEMS 2008, Cape Town International Convention Centre, 3-5 November (Poster).
  • Sissing L. Investigations into the cancer modulating properties of South African herbal teas inn oesophageal carcinogenesis. Master Class on Diet Health and Development: What is the Evidence? 22nd Biannual Congress of the Nutrition Society and the 10th Biannual Congress of the Association of Dietetics in South Africa. 28 Sept-02 October 2008. University of Pretoria (Oral).
  • Sissing L., Gamieldien K, and Gelderblom W.C.A.  Anti-proliferative and pro-apoptotic effects of South African herbal teasPAEMS 2008, Cape Town International Convention Centre, 3-5 November (Poster).

Knowledge Transfer and Capacity Development:

  • Dr K Gamieldien presented a three year research proposal based on the cancer modulating properties of rooibos and honeybush teas to the members of South African Rooibos Council (SARC) Board and Research Committees in Clanwilliam, March 2008
  • Dr WCA Gelderblom presented a lecture to the Rooibos Council on the cancer modulating properties of South African herbal teas in Clanwilliam, March 2008

PAUSET/LAY PUBLICATIONS

  • Dr K Gamieldien presented a lecture on the “Cancer modulating properties of rooibos and honeybush teas” to the members of South African Rooibos Council (SARC) board and research committees on the 26 March 2008 in Clanwilliam.Prof Gelderblom presented a lecture on “Characterisation of the major biological properties of Rooibos” to the members of South African Rooibos Council (SARC) board and research committees on the 26th March 2008 in Clanwilliam.
  • The attendance by Prof WCA Gelderblom, Prof E. Joubert Dr. K. Gamieldien and Ms D. van der Merwe at the 1st Rooibos Science Cafe and their research findings on the anti-cancer properties of rooibos were reported in South African Food Review, February 2008, vol.35, p31.
  • Prof WCA Gelderblom, Prof E. Joubert, Dr. K. Gamieldien and Ms D. van der Merwe were sited in the Food and Beverage Reporter on the benefits of rooibos tea. March 2008, p 42.

Congress abstracts

  • Gelderblom WCA, Sissing L, Samodien S, Abrahams S, Magcwebeba T, Windvogel S, van der Merwe JD, Marnewick JL, De Beer D, Joubert E. Cancer chemopreventive properties of honeybush. Conference on the “Exploration and Commercialization: Opportunities and challenges” Indigenous Plant Use Forum. ARC Infruitec-Nietvoorbij, Stellenbosch. 6-9 July 2009. (Oral)
  • Magcwebeba TU, Joubert E, Bouic P, De Beer D, Swart P, Gelderblom W. Investigating the modulatory effect of rooibos and selected honeybush tea extract on the in vitro production of primary cytokine IL-1α and TNF-α. Conference on the “Exploration and Commercialization: Opportunities and challenges” Indigenous Plant Use Forum. ARC Infruitec-Nietvoorbij, Stellenbosch. 6-9 July 2009. (Oral)
  • Magcwebeba TU, Joubert E, Riedel S, Swart P, Gelderblom W. Investigating the anti-proliferative activity of selected South African herbal teas

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