Identification and quantification of phenolic and volatile constituents in five different Anatolian thyme species using LC–MS/MS and GC-MS, with biological activities

Being widely used in the food industry, thyme is one of the most valuable plants in many aspects, and Turkey is one of the hotspots for thyme industry. Five thyme species, Thymus convolutus (endemic), Thymus fallax, Thymus haussknechtii Velen (endemic), Thymus kotschyanus var. kotschyanus, and Thymus sipyleus from Turkey were subjected in this study. Their essential oils and the extracts of aerial and root parts were obtained. GC-MS analyses showed that camphor was the major compound in T. convolutus (12.7%), and in T. sipyleus (13.1%) essential oils. The major volatile compound of T. fallax was bicyclogermacrene (21.5%), whereas the T. kotschyanus var. kotschyanus essential oil showed a predominance of carvacrol (48.5%), and thymol (22.5%). Carvacrol was also the major compound of T. haussknechtii with 28.2%. LC-MS/MS analyses showed that nicotiflorin (293.28–4201.15 μg/mL), caffeic (516.41–851.28 μg/mL), quinic (344.37–4410.94 μg/mL), rosmarinic (1800.18–9631.71 μg/mL), and fumaric acid (350.88–682.10 μg/mL) were detected as the main compounds in the extracts. All extracts exerted strong antioxidant activity, and the highest radical scavenging activity was demonstrated by T. haussknechtii root extract. T. convolutus and T. haussknechtii aerial parts extracts showed significant antimicrobial activity against C. tropicalis at MIC of 19.53 μg/mL. The extracts were found to be non-toxic against COLO205 and KM12 human colon, and UO-31, and A498 human renal cell lines. Their enzyme inhibitory activities were also evaluated against cholinesterase, tyrosinase and urease enzymes and T. fallax aerial part extract was the most effective with 34.48 ± 0.60% in antibutyrylcholinesterase activity. These species with strong antioxidant and antifungal properties and no toxicity could be beneficial to be used as preservatives in the food processing industry.