Inula germanica as a Medicinal Plant: Phenolic Compounds, Antioxidant Capacity, and Antimicrobial Effects

This study aimed to determine the total phenolic and flavonoid contents, antioxidant capacities and antimicrobial activities of ethanol and methanol extracts of Inula germanica L. Total phenolic content in plant extracts prepared by Soxhlet extraction method was determined as 179.54 ± 1.62 mg/g in ethanol extract and 134.36 ± 2.44 mg/g in methanol extract. Total flavonoid contents were determined as 73.24 ± 1.33 and 90.18 ± 1.40 mg/g for ethanol and methanol extracts, respectively. In antioxidant analyses, total antioxidant capacity (TAS) of ethanol extract was calculated as 4.875 ± 0.027 mmol/L, total oxidant capacity (TOS) as 10.385 ± 0.100 µmol/L and oxidative stress index (OSI) as 0.213 ± 0.003. In methanol extract, TAS value was determined as 4.406 ± 0.099 mmol/L, TOS value as 12.561 ± 0.138 µmol/L and OSI as 0.285 ± 0.004. In antimicrobial activity tests, it was determined that ethanol extract of I. germanica was effective against microorganisms such as Staphylococcus aureus, S. aureus MRSA, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Candida albicans, C. krusei and C. glabrata with MIC values ranging from 50 to 200 µg/mL. On the other hand, methanol extract showed lower antimicrobial activity with higher MIC values. The obtained findings show that I. germanica is rich in phenolic compounds, its antioxidant capacity is low compared to some species but is significant and it shows antimicrobial activity. The fact that ethanol extract has stronger biological activities emphasizes the importance of extraction method and solvent selection. These results show that I. germanica has potential for pharmaceutical and biotechnological applications and reveal the need for more comprehensive phytochemical and pharmacological studies.