The presented article focuses on the in vitro inhibition of plant extracts on the human carbonic anhydrase isoforms (hCA I and hCAII), and paraoxonase-1 (PON1) activities. Five different plants (Alcea rosea, Foeniculum vulgare, Elettaria cardamomum, Laurus azorica and Lavandula stoechas) were selected in this study. Methanol, ethanol, and water extracts of plants were prepared and the concentration-dependent inhibition degrees were found for hCA I and hCA II isozymes and hPON1 spectrophotometrically. Thus, IC50 (mg/mL) values were obtained for each extract. Methanolic extract of Elettaria cardamomum has the highest inhibitory effects (0.032 mg/mL). The water extracts of plants showed lower inhibitory impacts compared to the methanol and ethanol extracts.