Polyphenol Profile and Biological Activity of the Extracts from Sideritis scardica Griseb. (Lamiaceae) Herb

Abstract

Background/Objectives: The beneficial and multifaceted effects of Sideritis scardica Griseb. extracts are attributed to the presence of polyphenolic compounds, particularly phenolic acids. Methods: The research was carried out for S. scardica herb of different origins (Albania, Bulgaria, North Macedonia, and Türkiye). Identification of compounds was performed using the HPLC/ESI-QTOF-MS method; phenolic acids and flavonoids were determined spectrophotometrically. The antioxidant activity of methanol extracts from studied herbs was determined using the Folin-Ciocalteu, DPPH, and FRAP methods, and the antimicrobial activity was evaluated using the broth microdilution method in accordance with the guidelines of the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Results: We demonstrated the presence 18-20 active compounds, depending on the origin of the raw material, with verbascoside being the predominant compound in all samples. The raw material was characterized by significant polyphenol content and high antioxidant activity. DPPH tests revealed the highest antioxidant activity, ranging from 86.5% to 87.9%, in samples from Bulgaria, North Macedonia, and Türkiye, and the latter showed the strongest antimicrobial activity, particularly against Gram-positive pathogens and Candida spp. Conclusions: This research is the first report comparing the chemical composition and biological activity of S. scardica raw material of different origins. Our findings indicate that S. scardica herb extracts have significant phytotherapeutic potential, although this varies depending on the origin of the raw material, and point to the need for further research on this plant material, particularly in terms of the level of active compounds and their possible synergistic effects with conventional drugs, as well as the need for standardization.

Keywords: antimicrobial activity; antioxidant activity; herbal extracts; variability of chemical composition.

Figure 1

Base peak chromatogram of the S. scardica extract (Sh1; Bulgaria) by high-performance liquid chromatography–electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC/ESI-QTOF-MS). Identified compounds (1–20) are summarized in Table 1.

Figure 2

Base peak chromatogram of the S. scardica extract (Sh2; Türkiye) by high-performance liquid chromatography–electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC/ESI-QTOF-MS). Identified compounds (1–20) are summarized in Table 1.

Figure 3

Base peak chromatogram of the S. scardica extract (Sh3; Macedonia) by high-performance liquid chromatography–electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC/ESI-QTOF-MS). Identified compounds (1–20) are summarized in Table 1.

Figure 4

Base peak chromatogram of the S. scardica extract (Sh4; Albania) by high-performance liquid chromatography–electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC/ESI-QTOF-MS). Identified compounds (1–20) are summarized in Table 1.

Figure 5

The antioxidant activity of the studied sideritis herb extracts was evaluated using multiple analytical methods (Sh1—herb from Bulgaria; Sh2—herb from Türkiye; Sh3—herb from Macedonia; Sh4—herb from Albania). Bars of the same color represent values that did not differ significantly.

Figure 6

Antimicrobial activity (MIC doses) of S. scardica extracts against tested microorganisms (Sh1—herb from Bulgaria; Sh2—herb from Türkiye; Sh3—herb from Macedonia; Sh4—herb from Albania).