Medicinal and aromatic plants such as Crocus cancellatus, Scilla Siberica subsp. armena, Juniperus oxycedrus subsp. oxycedrus and Anthriscus nemorosa have many different biological activities. While antioxidants are significant in preventing many diseases, inhibition of metabolic enzymes is also important in preventing many significant diseases. In this study, antioxidant activities of water, ethanol, and dichloromethane extracts of four different medicinal and aromatic plant species were determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH·) and 2,20-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS·+) radical scavenging and Cu2+, Fe+3, and Fe3+-2,4,6-tris(2-pyridyl)-S-triazine (TPTZ) reducing assays. Standard antioxidants (BHA, BHT, Trolox, α-Tocopherol) were used in antioxidant assays, and the results were evaluated according to these standards. Enzyme inhibition studies were performed with metabolic enzymes acetylcholinesterase, butyrylcholinesterase, carbonic anhydrase I and II isoenzymes. The ethanol extract of A. nemorosa showed the highest activity in DPPH assay (IC50: 17.36 µg mL-1). In the ABTS assay, the ethanol extract of A. nemorosa plant showed the highest activity (IC50: 7.02 µg mL-1). In the Fe3+ reducing assay, the dichloromethane extract of A. nemorosa showed the highest activity (1.96±0.060 µg mL-1). In the Cu2+ reducing assay, the dichloromethane extract of J. oxycedrus showed the highest activity (1.773±0.066 µg mL-1). In the Fe3+-TPTZ reducing assay, the ethanol extract of S. siberica showed the highest activity (1.256±0.011 µg mL-1). In the enzyme inhibition results, it was determined that all plants and all extracts inhibited the enzymes studied. As a result of this study, it was determined that these four medicinal and aromatic plants have high biological and antioxidant activities.