## 1 Introduction  
The increased generation of reactive oxygen species (ROS) may be caused by multiple factors, such as unhealthy lifestyles (alcohol, nicotine, stress) as well as food and environmental contamination. Excessive release of ROS may cause severe oxidative damage, leading to numerous disorders [1]. Oxidative and inflammatory processes are the basis for the pathogenesis of numerous civilisation diseases, including atherosclerosis, diabetes, neurodegenerative illnesses and even obesity [2, 3, 4]. The solution to maintaining the appropriate oxidative balance of the organism is a high supply of antioxidants, antioxidants from external sources, with the aim of equalizing and preventing oxidative processes. It is also important to maintain a correct lifestyle, free from stress-inducing factors [5]. Plant resources are an easily accessible natural antioxidant. In recent years, edible plants have been increasing in popularity due to their rich chemical content and healthy properties [6, 7, 8, 9, 10].  
The clover (_Trifolium_ L.) belongs to the _Fabaceae_ family and includes about 300 species present in Europe, Asia and North America [11]. Two species of these perennial plants are common in Europe: the red clover (_Trifolium pratense_) and the white clover (_Trifolium repens_). They grow in the wild, but are also farmed and used mostly as fodder and honey plants. They are also used in phytotherapy and in the kitchen--as an ingredient to various meals and drinks, not only due to their aesthetic value, but also nutritional properties [11]. The white clover is mainly used as a honey and fodder plant. It is valued for its high protein content. In traditional medicine, it was an ingredient of herbal blends used for anti-rheumatic, anti-diarrheal and anti-arthritic purposes [11]. Red clover, the type that is mainly used in medicine, is recommended for numerous ailments, including sore throat, pneumonia, meningitis, pulmonary diseases and skin problems, disorders of the reproductive system, diabetes and even obesity. Numerous studies have proved that the plant facilitates coughing, has antiseptic and anaesthetic properties, and that it also reduces the level of total cholesterol [11; 12; 13; 14; 15; 16; 17].  
Despite studies concerning the antioxidant and anti-inflammatory properties of the red clover, there are still insufficient articles on the influence of this plant on macrophages in the model of induced oxidative stress. ROS may contribute to the activation of numerous mechanisms contributing to the pathogenesis of atherosclerosis, such as: the dysfunction of endothelial cells, monocyte recruitment and their differentiation into macrophages, as well as the stimulation of inflammatory response. Moreover, there are very little data confirming the beneficial influence of the other, less known, but easily available species--the white clover. Therefore, the aim of the study was to determine the effect of white clover and red clover ethanolic flower extracts, rich in polyphenols, on antioxidant potential and protection effect in THP-1. THP 1 cells, monocytes, after transformation into macrophages are involved in reactions related to oxidative stress and inflammation, and also are implicated in many civilization diseases including atherosclerosis.