## 1 Introduction  
Antimicrobial resistance towards monotherapy or multiple antibiotic therapy is a spiraling problem because a growing number of infections are becoming harder to treat with current antibiotic treatments, and thereafter serious or even lethal health risks are raised. Multidrug-resistant organisms (MDROs), as reported by official organizations (WHO, ECDC), include, among others, _Mycobacterium tuberculosis_, _Enterococcusecium_, _Enterobacter cloacea_, _Klebsiella pneumoniae_, and _Staphylococcus aureus_[1, 2]. Hence, there is a critical need for new antimicrobial compounds to fight drug-resistant microorganisms. Most antibiotics that are used originate from microbes, which means they are basically naturally derived products. Consequently, plant-derived products are a great alternative to the discovery of new biologically active compounds to use against hospital-acquired infections or community-acquired pathogens. Plant-derived products are mixtures of secondary metabolites that consist of many diverse compounds classified based on structural differences. Among them, phenolic compounds are the largest and best studied group. More than 8000 phenolics with documented molecular structures have been described so far [3, 4, 5]. These secondary metabolites are studied with great interest by researchers due to their multiple biological activities [6; 7].Especially, the study of phenolic compounds against antimicrobial resistance is challenging, and several studies confirm theirin vitroefficacy against a vast range of Gram-positive and Gram-negative bacteria [6; 8; 9; 10]. The genus _Hypericum_ belongs to the Hyperiaceae family, which encompasses approximately 500 species divided into 36 sections based mainly on morphological characteristics [11; 12]. Historically, the use of the plant as a remedy has its roots in ancient civilizations. Treatment of wounds, burns, and bruises was among the most popular uses of _H. perforatum_, whereas gastrointestinal diseases, dysmenorrhea problems, acute mastitistis, and depression were also handled with the herb [13; 14; 15; 16]. Nowadays, these healing properties of _Hypericum perforatum_ and other species of the genus are attributed to its complex chemical composition. Naphtodianthrones (including hypericin), phloroglucinols (including hyperorin), flavonoids (such as rutin, quercetin, and myricetin glucosides), xanthones (including cis-kielcorin), and phenolic acids (such as coumaroylquinic acid and chlorogenic acid) are the main classes of compounds identified in _Hypericum_ extracts [2; 17; 18; 19]. However, despite the large number of recognized species, the one most studied for its bioactivity remains _H. perforatum_, and many formulations of dietary supplements designed to ease central nervous system disorders are available [20]. In addition, studies on the antimicrobial activity of _H. perforatum_ and other species of the genus have been published in the past few years [21; 22; 23]. Most focus was given to hypericin and hyperorin as the compounds responsible for the antimicrobial activity [21; 22; 23]. Nevertheless, the complex chemical profile of _Hypericum_ species in combination with the already known activity of the secondary metabolites produced by the plants indicates that such biological activity is the result of synergistic action between all or some of the compounds that are present in the species [9]. Despite the frequent use of _H. perforatum_ in modern society, studies on other species of the genus are lacking. Screening of more _Hypericum_ species or species not yet studied is important and can be a strong stimulus for further research on the genus _Hypericum_ and the development of new products to introduce to the pharmaceutical market. Therefore, with the aim of providing new data regarding infrequently studied species of the genus _Hypericum_, this study evaluates nine _Hypericum_ species, namely _H. perforatum_ and _H. terapterum_ (sect. _Hypericum_), _H. perfoliatum_, _H. remelicaum_ subsp. _apollins_, _H. vesiculosum_ and _H. cycladicum_ (sect.