engleski

Influence of low temperature on antioxidant activity of nettle

Nettle (Urtica dioica L.) is a traditional medicinal plant in Croatia. It is considered as an important source of natural antioxidants that have a positive effect on the human health by fighting various diseases and slowing down aging. Nettle grows in different habitats and can easily adapt to changes in environmental conditions. However, prolonged exposure to a certain environmental factor, such as low temperature, can negatively affect the growth and development of plants causing increased formation of reactive oxygen species and the occurrence of oxidative stress. In such conditions, plants activate a highly effective antioxidant system. The aim of this research was to determine the influence of low temperature on nettle’s antioxidant activity. The nettles were grown under controlled conditions (temperature 22±1 °C, photoperiod 16h/8h, light intensity ~ 100 umol m-2s-1). When they reached adult stage, they were exposed to low temperature (10 °C) for various time periods: 12h, 24h and 48h. Untreated plants were considered as a control group. In order to describe the antioxidant activity, the iron reduction antioxidant capacity (FRAP), the content of total soluble polyphenols (PHE) and the content of ascorbic acid (AA) were determined. Exposure to low temperature after only 12h led to a decrease in AA compared to the control group, while the content of PHE did not change during exposure to low temperature. On the other hand, only long-term exposure to low temperature (48h) led to an increase in the antioxidant capacity of the nettle plants. The results indicate that prolonged exposure of nettles to low temperatures promotes the activation of the antioxidant system, while even short exposure to these conditions affects the reduction of secondary metabolites.

Urtica dioica L., antioxidant activity, oxidative stress

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