SUMMARY
Plant extracts are used, among others, for the production of cosmetic preparations. However, their long storage may cause the degradation of valuable substances, reducing the antioxidant activity. The Plantago lanceolata L. and the Plantago major L. are applied as agent in the treatment of skin diseases, where they show anti-inflammatory as well as antibacterial activities effect. In study, the plant material was extracted using four solvents: ethanol, methanol, propan-1-ol as well as propan-2-ol (all at three concentration). The ultrasound-assisted extraction was applied for 30 and 60 minutes. After the extraction antioxidant activity (DPPH method) of a part of the extracts were immediately evaluated, while the remaining part of the same extracts was stored for six months and then the antioxidant potential was evaluated. The most beneficial antioxidant properties were found extracts of dried leaves, both P. lanceolate and P. major in 70%(v/v) isopropanol and concentrated methanol determined immediately after their preparation. In the case P. major dried leaves, a longer preparation time led to a significant increase of antioxidant activity. Both species, P. lanceolata and P. major, seem to be valuable plants with high antioxidant activity, for everyday health prevention. Cosmetic preparations containing extracts from these plants seem to be a good solution to provide effective anti-aging protection.