Carbonic anhydrase enzyme inhibition and biological activities of Satureja hortensis L. essential oil

Recently, there is a great need to discover new natural carbonic anhydrase (CA) inhibitor sources to be used as diuretic, antiglaucoma, anti-obesity, anticancer, and anti-infective drugs. Therefore, evaluation of CA inhibition activity and possible inhibition mechanism of the essential oil of Satureja hortensis L. (SHEO) were investigated for the first time by this study. Additionally, total phenolic content known effective for CA inhibition and the other biological activities was determined for the first time. Since the volatile compound and total phenolic content of essential oil of S. hortensis grown in Bingöl exhibited great differences than those in the literature, the antioxidant and antimicrobial activities of SHEO were also investigated. Carbonic anhydrase inhibition of SHEO was determined as IC₅₀: 0.1 ± 0.002 μg/mL. Further, molecular docking studies between the main volatile compounds and CA have been conducted to better understand the CA inhibition mechanism of SHEO. The main compounds were as β-decalol (19.10%), perillaldehyde (17.11%), perillyl alcohol (16.87%), carvacrol (13.47%), and thymol (12.32%) by GC-MS. β-decalol was detected in an essential oil for the first time. Based on the molecular docking studies, thymol and β-decalol showed great potential for CA inhibition. Besides, total phenolic content was determined as 623 ± 2.88 μg/mL gallic acid equivalent (GAE) and 736 ± 3.46 μg/mL catechin equivalent (CE). The essential oil showed high antioxidant capacity [(SC₅₀: 0.069 ± 0.283 μg/mL for 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and 1031 ± 5.03 μM trolox equivalent antioxidant capacity (TEAC) for ferric reducing power (FRAP)]. The essential oil also showed significant antimicrobial activity against six Gram-positive and six Gram-negative bacteria, and a fungus. Minimal inhibitory concentrations (MICs) were 15.6 μg/mL and 31.2 μg/mL for MRSA ATCC 67101 and C. albicans, respectively. The rest of eleven bacteria exhibited MICs between 3.9-7.8 μg/mL. Consequently, SHEO could be used as antioxidant and antimicrobial agent at very low concentrations. In addition, SHEO significantly inhibited CA, thus, SHEO was a promising source for CA inhibitors and it might have potential to be used for treatment of CA related diseases.