Detailed Chemical Investigation of the Essential Oil and Aroma Contents of 21 <i>Hypericum triquetrifolium</i> Turra Species Collected From Different Localities via a Chemometric Approach

Hypericum species have been used for medicinal purposes since ancient times because of their important pharmacological properties. Hypericum triquetrifolium Turra belongs to the Hypericaceae family and is native to Eastern Europe and the Mediterranean region. In this study, the essential oil and aroma contents of H. triquetrifolium collected from 21 different localities in the eastern region of Turkey were determined via GC-MS/FID. In addition, the antioxidant and enzyme inhibition activities (cholinesterase, tyrosinase and urease) of the essential oils and major components were determined. Finally, the essential oil and aroma contents were evaluated chemically. The major components of H. triquetrifolium collected from 21 different locations were generally determined to be octane, 2-methyl (1.35%-25.18%), α-pinene (1.32%-19.1%), nonane, 3-methyl (2.43%-24.59%) and caryophyllene (3.79%-30.78%). When the aroma content was examined, octane, 2-methyl (14.22%-44%), nonane (6.37%-18.29%), nonane, 3-methyl (7.62-23.12%) and decane, 2-methyl (3.46%-22.74%) were generally identified as the major components. Overall, all samples were found to have moderate antioxidant capacity. In the AChE enzyme inhibition test, at a concentration of 100 μg/mL, samples S-19, S-9 and S-11 (inhibition %: 87.61 ± 0.63; 84.29 ± 1.51; 82.28 ± 0.53, respectively), and in the BChE enzyme inhibition test, the S-1, S-4 and S-6 samples (88.76 ± 0.79; 91.29 ± 1.58; 93.15 ± 2.16, respectively) were found to be more active than the reference galantamine. In the tyrosinase enzyme inhibition test, samples S-5 and S-13 (inhibition %: 57.09 ± 2.53 and 66.86 ± 0.50, respectively) were found to have greater activity than the other samples. A total of 21 H. triquetrifolium samples collected from different regions of Diyarbakır, Mardin, Elazığ, Siirt, Batman and Şanlıurfa Provinces were analysed via principal component analysis (PCA) and cluster analysis (CA) techniques on the basis of volatile and aroma components. PCA revealed that the dominant volatile components in the samples formed three groups, and regional differences had no significant effect on the samples. The first two principal components explained 59.2% of the variance. The antioxidant capacities of essential oils, their high contents of compounds such as α-pinene and caryophyllene, and their strong acetyl and butyrylcholinesterase enzyme inhibition activities are considered to have potential for use in the food, cosmetics and pharmaceutical industries.