Volatiles and seasonal variation of the essential oil composition from the leaves of Clinopodium macrostemum var. laevigatum and its biological activities

• Volatiles and leaf essential oil composition were identified by SPME and GC–MS.
• Seasonal variations of the volatiles were determined by the same techniques.
• The leaf essential oil inhibited lipase, α-glucosidase and acetylcholinesterase.
• The essential oils showed antimicrobial activity against assayed phytophatogens.

Clinopodium macrostemum var. laevigatum is a Mexican medicinal plant appreciated because of the pleasant smell of its leaves. This work describes the seasonal volatile content of the leaves by SPME technique as well as the GC–MS analyses of four seasonal essential oils. Menthone (∼34%) and piperitone oxide (∼30%) were the most abundant compounds in all the seasons studied. Antioxidant activity was determined in the seasonal essential oils by DPPH and β-carotene bleaching methods revealing an IC50 range of 0.92–1.46 and 1.30–1.94 g L−1, respectively. The enzymatic assays with α-glucosidase and porcine pancreatic lipase showed a non-competitive inhibition caused by the essential oil of this plant. Seasonal IC50 range was 0.14–0.29 g L−1 for α-glucosidase and 0.12–0.34 g L−1 for porcine pancreatic lipase. The enzymatic assays with acetylcholinesterase demonstrated that the essential oil produced a competitive inhibition with a seasonal IC50 range of 0.17–0.43 g L−1. The MIC’s in g L−1 of the essential oil demonstrated a remarkable antimicrobial activity on Erwinia carotovora (0.145), Agrobacterium tumefaciens (0.149), Clavibacter michiganensis (0.184), Pseudomonas syringae pv. phaseolitica (0.381), Pseudomonas syringae pv. glycinea (0.437), Escherichia coli strain DH5α (0.515), Fusarium oxysporum (2.3), Aspergillus niger (2.9) and Rhizopus stolonifer (3.6). The antimicrobial activity of the essential oil was maintained in the seasons studied. The described properties of the essential oil of this traditional crop could probably be used to design new products with industrial application.