Introduction and objective:
Aloe vera, Bryophyllum pinnatum, Callisia fragrans and Pelargonium graveolens are medicinal plants traditionally used in folk medicine to treat a variety of diseases. The aim of the study is to evaluate the antioxidant properties of Callisia fragrans, and to the best of the authors’ knowledge is the first such study on the topic.

Material and methods:
The focus of the study was on the antioxidant activities of plant ethanol extracts in an in vitro model of the mouse L929 fibroblastic cell line, in which oxidative stress was induced by hydrogen peroxide (H₂O₂). Extracts were obtained from biennial plants? Fibroblasts were first stimulated with 100 µM H₂O₂ for 3 h and subsequently incubated with various concentrations of plant extracts: 3.5 g/ml (extract 1); 1.75 g/ml (extract 2); and 0.875 g/ml (extract 3) for 24 h.

Results:
A significant decrease in ferric reducing antioxidant power (FRAP) and malondialdehyde (MDA) were observed in cell lysates treated with Aloe vera, Bryophyllum pinnatum and Pelargonium graveolens extracts. The concentration of carbonyl groups was statistically lower in cell lysates treated with Aloe vera and Pelargonium graveolens extracts. Significant increase in protein carbonyl groups concentration was observed in cell lysates treated with Callisia fragrans, but no significant changes were noticed in MDA and FRAP concentrations.

Conclusions:
The results obtained confirmed antioxidant activities of Aloe vera, Bryophyllum pinnatum and Pelargonium graveolens, which may contribute to their protective effects in cutaneous diseases. They also have the ability to protect fibroblasts in skin by a decrease in ROS production, and by the inhibition of lipid and protein oxidation. Therefore, they can be used in dermatology for the treatment of cutaneous diseases in the form of external skin care products. Callisia fragrans, however, showed the opposite trend, indicating a possible pro-oxidant behaviour requiring further investigation.