HS-SPME/GC-MS as a chemotaxonomic tool: a study on selected Lamiaceae species

Chemotaxonomy is a valuable tool for obtaining taxonomic insights to ensure a correct classification, which is crucial for the safe use of plant species. The mint family (Lamiaceae) is known for its essential oils, which have played a crucial role in culinary, medicinal, and horticultural practices throughout history. This study aimed to evaluate the applicability and effectiveness of headspace solid-phase microextraction (HS-SPME) as a reliable analytical tool for chemotaxonomic investigations. It presents findings on volatile phytochemicals of 14 selected Lamiaceae taxa (including 9 species and 5 subspecies_ determined when possible) from Central and Southern Europe. HS-SPME was used for the extraction of volatile organic compounds, followed by GC–MS analysis for profiling. A total of 94 compounds from different groups (fatty acid derivatives, alcohols, hydrocarbons, monoterpenes, sesquiterpenes, phenylpropanoids and isoprenoids) were identified with 24, 56, 59, and 43 volatiles detected in Lamium, Salvia, Stachys and Betonica species, respectively. Multivariate statistical analysis of volatile metabolites revealed a clear clustering of investigated taxa according to their taxonomic classification. It strengthens the efficacy and reliability of using HS-SPME and GC-MS in the profiling of VOCs for chemotaxonomic studies. Hierarchical cluster analysis (HCA) showed greater phytochemical similarity between Salvia and Stachys/Betonica than between Salvia and Lamium. In addition, plants showed intra-genus similarity irrespective of geographical origin, and three distinct chemotypes were identified within each studied genus. HS-SPME/GC–MS combined with multivariate statistical analyses effectively differentiated the studied Lamiaceae taxa according to their VOC profiles. The results demonstrate the potential of HS-SPME and GC–MS based VOC profiling as a complementary chemotaxonomic tool, with leaves providing consistently rich VOC profiles and representing a suitable plant material for comparative analyses across the investigated taxa. HS-SPME–GC-MS enabled solvent-free VOC profiling of Lamiaceae species. VOC fingerprints supported the chemotaxonomic discrimination of taxa at the species or subspecies level. PCA and HCA exhibited strong agreement in sample classification. Genus-specific markers revealed the patterns of chemical diversification. Identification of VOCs with high discriminatory value.