Abstract
Ultraviolet radiation induces DNA damage and oxidative stress which can
result in skin inflammation, photoaging, and photocarcinogenesis. The
flavonoid luteolin that is present in high amounts in the dyers weld,
Reseda luteola, is one of the most potent antioxidative plant
metabolites and also has ultraviolet-absorbing properties.
The aim of this study was to determine whether tocopherol and ubiquinone add
synergistic antioxidative values to luteolin. None of the substances showed
cytotoxic effects in concentrations from 0.25 to 4 µg/mL. The
photoprotective and antioxidant effect of equivalent concentrations of
luteolin, tocopherol, and ubiquinone and their combination in a ratio of
4 : 4 : 1 were studied in solar simulator irradiated human skin fibroblasts.
Luteolin had a half-maximal radical scavenging concentration of 2 µg/mL,
whereas tocopherol and ubiquinone were only effective at higher
concentrations. None of the substances showed a phototoxic effect, and only
luteolin had a moderate photoprotective effect at 2 µg/mL. The combination
of luteolin, tocopherol, and ubiquinone exerted a synergistic radical
scavenging effect already at a concentration of 0.25 µg/mL and a complete
photoprotection at 2 µg/mL.
In summary, our findings suggest that the potent antioxidant and
photoprotective effect of flavonoids like luteolin may be further increased
by the addition of low concentrations of other antioxidants such as
tocopherol and ubiquinone.
Key words
luteolin - tocopherol - ubiquinone - reactive oxygen species -
Reseda luteola
- Resedaceae
