Geraniol (GA) is a terpene compound of natural origin that exhibits strong biological activity. The possibility of using GA as a potential compound with antimicrobial activity is currently of great interest to scientists. The aim of the present study was to comprehensively evaluate the activity of GA against selected strains of Gram-positive bacteria, Gram-negative bacteria, and fungi that pose a significant threat in clinical practice. Among the Gram-positive bacteria studied were Streptococcus spp., Neisseria gonorrhoeae, and Listeria monocytogenes. Among the Gram-negative bacteria tested were Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. The fungal pathogens analyzed included Candida albicans and Candida glabrata. The results showed that GA exhibited strong antimicrobial activity against most of the microorganisms tested. Gram-positive strains were more susceptible to GA compared to Gram-negative strains, probably due to differences in cell wall structure. In the case of fungi, significant efficacy was noted against Candida albicans. This study confirms the potential of GA as an alternative antimicrobial agent, especially against antibiotic-resistant bacterial strains and fungal pathogens. These results open up new perspectives for the application of GA in medicine and the pharmaceutical industry. The study on creams demonstrated that GA possesses strong antimicrobial properties, effectively inhibiting bacterial growth regardless of the concentration used (0.5–12%) and the type of culture medium, confirming its potential as a natural preservative agent in the cosmetic and pharmaceutical industries. Moreover, the research on the anticancer activity of GA revealed its cytotoxic effects against colon cancer cells (LoVo cell line, IC50 = 32.1 μg/mL) and glioma cells (U87 cell line, IC50 = 41.3 μg/mL), particularly at higher concentrations, indicating its promising therapeutic potential.
Fajdek-Bieda et al. (Tue,) studied this question.