# Phytochemical Screening and Antioxidant Activity of Selected Estonian _Galium_ Species
## 1 Introduction  
Ethnomedicine has long used different plants for a variety of disease preventative and therapeutic purposes. Plants are a natural source of active compounds, phytochemicals, many of which with favourable bioactivity for humans. Analytical investigation allows for the determination of the phytochemical composition and confirmation of specific therapeutic properties of the plants already acknowledged for their potential by ethnomedicine [1; 2; 3; 4; 5]. The _Galium_ L. genus, comprising about 667 species found worldwide, over a third of which can be found in Europe, includes several species that have been used in traditional medicine to alleviate a variety of ailments [6; 7]. _Galium vermum_ has been used as a sedative, diuretic, and cholesteric, as well as to treat gout, epilepsy, and spasms; _Galium aparine_ has been used to reduce infection and inflammation, to treat wounds, burns, and skin diseases; _Galium mollugo_ has been used as vulnerary, and to treat hysteria and epilepsy [8; 9; 7]. Many scientific studies have confirmed that the representatives of the _Galium_ genus exhibit a wide range of biological activities, including antioxidant, anticancer, detoxicant, hepatoprotective, antihaemolytic, antibacterial, and antifungal effects [2; 9; 10; 11; 7]. Phytochemicals are typically extracted from plant materials using alcohols or acetone in varying proportions of water, depending on the properties of the compounds of interest [9]. Therefore, a comparative analysis of the earlier literature is complicated due to the use of varyingextraction solvents. The most common analysis methods of plant extracts are HPLC or UHPLC, coupled with DAD and/or MS/MS, sometimes followed by identity confirmation with NMR [9; 12; 13]. Previously, [PERSON] et al. have analysed the iridoid patterns of the Bulgarian _Galium_ species [12], and [PERSON] et al. have studied the polyphenic content of Romanian _Galium_ species [13]. As it is known that the geographic origin and growth environment of a plant play a large role in the phytochemical content of the extract [14], it is likely that the _Galium_ species collected from different locations in Europe exhibit a different phytochemical profile. Therefore, it is important to assess the constituents of all medicinal plants in relation to their growth habitat. To the best of our knowledge, species of _Galium_ native to a northern European country have not yet been thoroughly characterised. Additionally, when evaluating plant extracts as possible therapeutic agents, the assessment of antioxidative capacity is of clear importance. As excess free radicals are known to damage cellular components and thereby be involved in the development of several diseases, the free radical scavenging properties of antioxidants can alleviate or prevent illness [15]. Studies of medicinal plants have demonstrated that the health-promoting properties and therapeutically beneficial qualities can often be attributed to specific polyphenols or iridoids, two of the most prevalent groups of bioactives in many plant extracts, and in the representatives of the _Galium_ genus [9; 11; 16; 17]. Polyphenols are the most abundant secondary metabolites in plants, notably characterised by their potent antioxidant properties [18]. Polyphenols also modulate the activity of many enzyme and cell receptors, scavenge free radicals, regulate nitric oxide, decrease leukocyte immobilization, induce apoptosis, and inhibit cell proliferation and angiogenesis [18; 19; 20; 21; 22; 23]. Therefore, polyphenols possess several mechanisms for preventing and treating illnesses. As deduced from epidemiologic data, polyphenols exert preventative effects over cardiovascular, neurodegenerative, and oxidative stress associated diseases, such as cancer [19; 24; 25; 26; 27]. Plant phenolics include phenolic acids, flavonoids, tannins, stilbenes and lignans. Phenolic acids include derivatives of benzoic acid such as gallic acid, and derivatives of cinnamic acid, such as coumaric, caffe and ferulic acid.