## 4 Discussion
Consequently, the strongest antibacterial activity of \(H\). _delplicum_ can be attributed not only to its high phenolic content but also to other compounds, such as phenolic acids with interesting antimicrobial activity [42] and the presence of naphtodianthrones and/or phloroglucinols [41]. In general, regarding the results of the antibacterial activity of the extracts, it should be noted that apart from flavonoids such as luteolin [43; 44] and kaempfer [43; 44; 45; 46], other compounds such as chlorogenic acid and neo-chlorogenic acid are also discussed as occurring in the genus _Hypericum_[44; 45; 46; 47]. In addition to flavonoids, it has been demonstrated that chlorogenic acid is a compound with exceptional antibacterial activity [48; 49]. Differences regarding the bactericidal activity of the above extracts indicate that not only quantitative but also qualitative differences may produce synergistic effects that potentiate the activity of the extract and contribute to its overall activity. A broad spectrum of antimicrobial activity has been demonstrated for various _Hypericum_ species against Gram-positive and Gram-negative microorganisms. _H. _perforatum_ is the most studied species, and several solvents, such as ethanol, methanol, and chloroform, have been used by researchers to isolate its secondary metabolites [21; 23; 50; 51]. Similarly, various microorganisms, such as \(S\). _subtilis_, \(S\). _aureus_, \(E\). _f faecalis_, and \(E\). _coli_, have been tested for their susceptibility to _Hypericum_ extracts [50; 51]. For example, in the study by [PERSON] et al. [51], six Gram-positive bacteria were treated with different extracts of \(H\). _perforatum_. It was concluded that the ethanolic and chloroform extracts were the most potent because the MIC values were lower. Nevertheless, all extracts presented antimicrobial activity, and when such activity was compared to that of standard compounds, namely hyperforin and hypericin, it was demonstrated that both standard compounds inhibited the majority of the microorganisms under investigation, while the concentration requested to inhibit growth of the microorganisms was, for most of the bacteria, close to that of the extracts [51]. Similarly, different subspecies of \(H\). _perforatum_ and other _Hypericum_ species that belong to different sections from Central Italy were examined for their antimicrobial activity [50]. Among all the tested extracts, those of the \(H\). _perforatum_ subspecies were the most active, while only the extract of \(H\). _perforatum_ subsp. _veronense_ managed to inhibit the growth of \(E\)._coli_. Additionally, \(H\). _tetraperum_ inhibited fewer microorganisms, and the zone of inhibition of bacterial growth was smaller than that formed when microorganisms were treated with the extract of \(H\). _perforatum_. In the same study, the antimicrobial activity of \(H\). _hirsutum_ (secret. _Taenicorpium_) was also evaluated. The \(H\). _fragile_ reported in our study belongs to the same section, thus we compared the antimicrobial activity of this extract with \(H\). _hirsutum_, for which no data have been published so far. In contrast to \(H\). _hirsutum_, for which no inhibition against _E. faecalis_ was observed, _H. fragile_ showed a broader spectrum of antimicrobial activity because the extract hindered both _S. aureus_ and _E. faecalis_. It is possible that different extraction procedures resulted in differences in the phytochemical composition of these extracts, which in turn affected the obtained results [50]. _H. delplicum_ is another species for which data regarding its antimicrobial activity are not available. However, the above-mentioned study [50] and the study by [PERSON] et al. [23] examine \(H\). _montanum_ and _H. caprifolium_, respectively, species that belong to the same section (sect. _Adenospelum_) as _H. delplicum_. The results are partially in accordance with our findings because the extract of \(H\). _caprifolium_ was also active against Gram-negative bacteria, a result not observed for \(H\). _delplicum_. _H.