Comparative GC–MS Characterization and Antimicrobial and Antioxidant Activities of Essential Oils from Two Chemotypes of Matricaria pubescens

Amid the accelerating spread of antibiotic resistance, medicinal and aromatic plants stand out as powerful natural reservoirs of bioactive compounds, offering innovative prospects for next-generation antimicrobial therapies. To explore its therapeutic potential, this study evaluated the antimicrobial and antioxidant activities of Matricaria pubescens from Southeastern Morocco, supported by a thorough chemical profiling of its essential oils. The oils were obtained by steam distillation and analyzed using gas chromatography–mass spectrometry (GC–MS). The results revealed two distinct chemotypes, with isochrysanthemic ethyl ester (32.7%) as the dominant compound in chemotype EO1 and α-ocimene (19.62%) as the major constituent in chemotype EO2. Antioxidant activities were assessed using DPPH, ABTS, and reducing power assays, while antimicrobial activities were evaluated against bacteria, fungi, and yeasts using both disc diffusion and broth microdilution methods. Both oils exhibited notable antioxidant activities. Significant antimicrobial effects were observed, with Bacillus subtilis, Escherichia coli, and Staphylococcus aureus being the most sensitive strains, whereas Pseudomonas aeruginosa exhibited the highest resistance among all tested microorganisms, with the lowest MIC recorded for B. subtilis (0.612 mg/mL). These findings emphasize that M. pubescens could serve as a valuable source of biologically active compounds, particularly in the development of agents to combat microbial resistance, and further support its potential applications in pharmaceutical, cosmetic, and food industries.