Quantitative and qualitative evaluation of 60 Labiatae species, growing in Greece, regarding the content of selected abietane-type diterpenes using 1H-qNMR.

Carnosic acid (CA) and carnosol (CS) are abietane-type diterpenes with plenty of biologic properties [1] [2]. Quantitative and qualitative evaluation of 60 plant species of Lamiaceae, growing in Greece, regarding their content in CA, 12-methoxy-carnosic acid (12MΟCA), CS and 7-methoxy-epirosmanol (7MER) using ¹H-qNMR is presented.The methanolic extracts from leaves of species: Ballota, Hyssopus, Lavandula, Marubium, Nepeta, Phlomis, Ocimum, Origanum, Rosmarinus, Salvia, Stachys, Coridothymus, Mentha, Melissa, Sideritis, Satureja, Teucrium, Lamium and Betonica, were analysed using as standards the isolated and fully structurally characterized metabolites by our group. At least one of the target compounds was detected in 29 species: Rosmarinus (2), Salvia (23), Melissa, Ocimum, Mentha (2). 7MER has not been determined in any of the extracts. All three CA, CS and 12OMCA, were identified only in Salvia (9) and Rosmarinus (2). The richest source in CA was S. pomifera subsp. pomifera (Cretan sage) (21.6±0.6 mg/g dry leaves)>S. fruticosa (Greek sage) (12.5±1.6 mg/g)>S. officinalis L. (Common sage) (11.7±4.3 mg/g), in CS was S. officinalis (1.1±0.4 mg/g)>R. officinalis L. (1.1±0.1 mg/g)>S. canariensis (1.1±0.3 mg/g) while in 12OMCA was S. microphylla (10.7±3.3 mg/g)>S. officinalis (6.1±2.3 mg/g)>S. fruticosa (3.1±0.3 mg/g). Salvia and Rosemary revealed as best sources for CA, CS and 12MOCA among the studied species. ¹H-qNMR spectroscopy offers a useful tool for the quantitative and qualitative analysis of the examined compounds in complex extracts, in a simple, rapid and direct way without sample deterioration.

• References

• 1 Loussouarn M. et al. Plant Physiol. 2017;175(3):1381-4.
• 2 Koutsoulas et al. Molecules. 2019 12;24(16).