The potential role of polyphenols in the modulation of skin cell viability by Aspalathus linearis and Cyclopia spp. herbal tea extracts in vitro.
OBJECTIVE
The relationship between polyphenol constituents, antioxidant properties of aqueous and methanol extracts of green tea (Camellia sinensis), the herbal teas, rooibos (Aspalathus linearis) and honeybush (Cyclopia spp.), against skin cell viability was investigated in vitro.


METHODS
The effect of extracts, characterised in terms of polyphenol content and antioxidant properties, on cell viability of premalignant, normal and malignant skin cells was determined.


RESULTS
Phenolic composition, particularly high levels of potent antioxidants, of rooibos and green tea methanol extracts was associated with a strong reduction in cell viability specifically targeting premalignant cells. In contrast, the aqueous extracts of Cyclopia spp. were more effective in reducing cell viability. This correlated with a relatively high flavanol/proanthocyanidin content and ABTS radical cation scavenging capacity. The major green tea flavanol (epigallocatechin gallate) and rooibos dihydrochalcone (aspalathin) exhibited differential effects against cell viability, while the major honeybush xanthone (mangiferin) and flavanone (hesperidin) lacked any effect presumably due to a cytoprotective effect. The underlying mechanisms against skin cell viability are likely to involve mitochondrial dysfunction resulting from polyphenol-iron interactions.


CONCLUSIONS
The polyphenol constituents and antioxidant parameters of herbal tea extracts are useful tools to predict their activity against skin cell survival in vitro and potential chemopreventive effects in vivo.
Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa.
Tandeka Unathi
TU
Magcwebeba
Biomedical Research and Innovation Platform, South African Medical Research Council, Tygerberg, South Africa.
Sylvia
S
Riedel
Biostatistics Unit, South African Medical Research Council, Tygerberg, South Africa.
Sonja
S
Swanevelder
Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa.
Pieter
P
Swart
Agricultural Research Council, Infruitec-Nietvoorbij, Stellenbosch, South Africa.
Dalene
D
De Beer
Agricultural Research Council, Infruitec-Nietvoorbij, Stellenbosch, South Africa.|Department of Food Science, Stellenbosch University, Stellenbosch, South Africa.
Elizabeth
E
Joubert
Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa. gelderblomw@cput.ac.za.|Institute of Biomedical and Microbial Biotechnology, Cape Peninsula University of Technology, Bellville, South Africa. gelderblomw@cput.ac.za.
Wentzel Christoffel
WC
Andreas Gelderblom
D000972:Antineoplastic Agents, Phytogenic / Q000302:isolation & purification / Q000494:pharmacology*; D000975:Antioxidants / Q000302:isolation & purification / Q000494:pharmacology*; D036903:Aspalathus / Q000737:chemistry*; D028241:Camellia sinensis / Q000737:chemistry*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D053998:Cyclopia Plant / Q000737:chemistry*; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D008517:Phytotherapy; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D010946:Plants, Medicinal; D059808:Polyphenols / Q000302:isolation & purification / Q000494:pharmacology*; D011230:Precancerous Conditions / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D012867:Skin / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D013662:Tea
D000972:Antineoplastic Agents, Phytogenic; D000975:Antioxidants; D010936:Plant Extracts; D059808:Polyphenols; D013662:Tea
antioxidant properties; chemoprevention; herbal tea; polyphenols; skin cell viability