Phenolic extracts of Clinopodium nepeta were prepared and their preliminary phenolic profiles determined using HPLC-DAD with 26 phenolic standards. Apigenin (21.75 ± 0.41 µg/g), myricetin (72.58 ± 0.57 µg/g), and rosmarinic acid (88.51 ± 0.55 µg/g) were the most abundant compounds in DCM (dichloromethane), AcOEt (ethyl acetate), and BuOH (butanol) extracts, respectively. The DCM and AcOEt extracts inhibited quorum-sensing mediated violacein production by C. violaceum CV12472. Anti-quorum-sensing zones on C. violaceum CV026 at MIC (minimal inhibitory concentration) were 10.3 ± 0.8 mm for DCM extract and 12.0 ± 0.5 mm for AcOEt extract. Extracts showed concentration-dependent inhibition of swarming motility on flagellated P. aeruginosa PA01 and at the highest test concentration of 100 μg/mL, AcOEt (35.42 ± 1.00%) extract displayed the best activity. FRAP assay indicated that the BuOH extract (A_0.50 = 17.42 ± 0.25 µg/mL) was more active than standard α-tocopherol (A_0.50 = 34.93 ± 2.38 µg/mL). BuOH extract was more active than other extracts except in the ABTS^●+, where the DCM extract was most active. This antioxidant activity could be attributed to the phenolic compounds detected. C. nepeta extracts showed moderate inhibition on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, and α-amylase. The results indicate that C. nepeta is a potent source of natural antioxidants that could be used in managing microbial resistance and Alzheimer′s disease.

This study explores Daucus crinitus extracts (DCE) and zinc oxide nanoparticles (ZnO-NPs) synthesized using the extracts as corrosion inhibitors for carbon steel (CS) in HCl medium. The synthesized ZnO-NPs were characterized via UV-vis spectroscopy, exhibiting a peak at approximately 375nm. The study employed weight loss (WL) and electrochemical measurements, alongside spectrophotometric evaluation of corrosion products. Surface morphology was assessed via scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). Thermodynamic analysis revealed the physical adsorption of DCE on CS according to the Freundlich adsorption isotherm. Potentiodynamic polarization (PP) measurements indicated DCE as a mixed-type corrosion inhibitor. Electrochemical impedance spectroscopy (EIS) exhibited increased charge transfer resistance and reduced double-layer capacitance with inhibitory addition. The most effective inhibition was observed with butanol extract (BE) and improved more with its corresponding nanoparticles (BENPs), exhibiting inhibitory efficiencies of 80.20 and 91.20, respectively, at 298K with a concentration of 800ppm. The evaluation of corrosion products using colorimetry revealed that the concentration of polyphenols decreased after the inhibitory process. Furthermore, the intensity of ferrous ions (Fe²⁺) decreased as the inhibitory concentration increased. In addition, SEM-EDS analysis confirmed the presence of ZnO-NPs, which enhanced the surface morphology and established a protective layer formed by the adsorbed inhibitors. The SEM-EDS analysis confirmed the presence of ZnO-NPs, the enhancement of surface morphology, and the establishment of a protective layer formed by the adsorbed inhibitors.