## 1 Introduction  
Plants have been used for their medicinal properties throughout history. Originally, they were harnessed by humans in their simplest, unrefined form (leaves, roots, fruits, seeds), and later in the form of herbal remedies (brews, infusions, maccrates, timetures, extracts). Traditional plant-based remedies, which offer both curative and preventive benefits, are attracting increased attention. Sourced from various species of medicinal plants, they are utilized both in traditional medicine practices and in the development of novel medicines, nutraceuticals, dietary supplements, and pharmaceutical products. The International Union for the Conservation of Nature (IUCN) and the Worldwide Fund for Nature (WWF) list 50,000-80,000 plant species that are used medicinally worldwide. Herbal medicines are estimated to account for up to 25% of total consumption in countries such as the United States and United Kingdom, in contrast with India and China, where that proportion can be as high as 80% [1]. The first step in processing medicinal plants into value-added bioresources involves creating herbal preparations (extracts) through a variety of methods, ranging from the simple and traditional to the modern and advanced. Extraction is a process where the active constituents or secondary metabolites of a plant (such as alkaloids, flavonoids, terpen, saponins, steroids, or glycosides) are separated from the neutral or inactive ingredients using an appropriate solvent and a standardized extraction protocol. The solvents commonly used to make medicinal plant extracts can be polar (e.g., water and alcohols), intermediate polar (e.g., acetone and dichloromethane) or non-polar (e.g., n-hexane, ether, and chloroform) [2]. The preparation of medicinal plants for experimental purposes is an initial step and a key part of achieving reliable research results, producing high-quality extracts, and ultimately manufacturing effective medicinal products. The family Lamiaceae encompasses a wide array of plants with biological and medicinal applications. These species feature a distinctive, pleasant fragrance, a rich chemical composition, and a wide range of exhibited bioactivities, including antioxidant activity [3; 4; 5; 6]. Plant-derived antioxidants play an important role in preventing free radical generation and can help counteract various disorders, including cancer, aging, cardiovascular disease, cataracts, immune system suppression, and brain disorders [7]. The antioxidant activity of a plant is correlated with its phenolic compounds content, including phenolic acids and flavonoids [2; 8; 9; 10]. Plants of the genus Thymus and Sideritis are known to contain such phenolic compounds, including rosmarinic acid, quercetin, caffeic acid, luteolin, and apigenin--substances with an established capacity to scavenge free radicals [11; 12; 13; 14]. Species included in the genera Thymus and Sideritis from Lamiaceae family used worldwide, mostly due to their potential health benefits. There are about 250 species recorded within the genus Thymus, distributed throughout the Mediterranean area, Europe, Greenland, Asia, Australia, and America, that are used in pharmaceutical industries, cosmetics, and foods. The genus Sideritis includes 150 species that are widely distributed in the Mediterranean region. Many of them are used as traditional remedies due to their anti-inflammatory, spasmolitic, antiulcer, analgesic, and gastroprotective properties [4; 14]. Thyme (_T. vulgaris_ L.), appears in many different areas worldwide and is the most commercially cultivated species in the genus Thymus. In Europe, the total number of _T. vulgaris_ specimens is estimated to be 202 [5]. Thyme has valuable aromatic and medicinal properties. Among the bioactive components of thyme, polyphenols constitute an important group [5; 10; 14]. One of the species of the genus Sideritis is _S. scardica_ Griseb (known as mountain tea or Greek tea), a source rich in natural antioxidants and polyphenic compounds with particularly beneficial effects for human health.