Assessment of Antimicrobial and Anti-Aging Effects of Triterpenoid and Polyphenol Compounds from Olea europaea L: Extraction, Identification and In Vitro Tests

Aim: This study investigated the antimicrobial and anti-aging effects of bioactive compounds derived from Olea europaea L. leaves and flowers, widely used in traditional treatments in European and Mediterranean countries. Materials and Methods: Following solid-liquid extraction and purification steps, the control of purification processes was conducted using thin-layer chromatography (TLC). Identification of the obtained molecules was performed through high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR) analyses. For determining antimicrobial activity, representatives of Gram-positive and Gram-negative bacteria, Bacillus cereus, and Escherichia coli O15:H7, were respectively used for minimum inhibitory concentration (MIC) tests. In the assessment of Oleuropein's in vitro cytotoxicity on human dermal fibroblasts, the MTT assay was employed using HDFa cell lines, while an ELISA Test kit was utilized to determine changes in collagen type-I levels. Results: As a result of the study, molecules oleanolic acid (L1), oleuropein (L2), and ursolic acid (L3) were isolated and identified from olive leaves, whereas oleuropein aglycone (F1) molecule was isolated from olive flowers. According to the results of the Minimum Inhibitory Concentration (MIC) tests, compounds L1, L2, and L3 isolated from the leaves exhibited an inhibitory effect against Bacillus cereus within the concentration range of 5-250 µg/mL, whereas Oleuropein aglycone (F1) did not demonstrate any inhibitory activity. Furthermore, it was found that, except for the Oleuropein (L2) molecule, no other compound was effective against Escherichia coli. In the evaluation of Oleuropein's in vitro cytotoxicity on human dermal fibroblasts, a dose-dependent effect on HDFa cell viability was observed, and collagen type-I levels were significantly higher than levels obtained with vitamin C. Conclusion: Based on the obtained results, it is believed that the active molecules derived from olive plant's leaves and flowers exhibit antimicrobial effects, potentially serving as natural preservatives in the cosmetics industry. Moreover, their contribution to cell regeneration suggests potential use in wound treatments