Evaluation of chemical stability and toxicity of Minthostachys verticillata essential oil.

ARSAUTE S; MONTIRONI ID; CECCHINI ME; REINOSO E; CARIDDI LN

Congreso; XXXIX Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2022

Minthostachys verticillata (Griseb.) Epling is an aromatic plant characteristic of Argentina. Our research group has characterized the effect of its essential oil (EO) on the immune response of animals. However, to achieve a marketable bioproduct it is necessary to evaluate its stability and toxicity. The aim of this work was to evaluate the chemical stability of EO after storage at -20°C for 12 and 24 months and to determine its toxicity in bovine mammary gland epithelial cells (MAC-T). Leaves of the species M. verticillata from Villa Larca, San Luis, obtained commercially in April 2019, were used. The EO was obtained by hydrodistillation and the identification and characterization of its metabolites was carried out by gas chromatography coupled to mass spectrometry (GC-MS). Six compounds were identified, being pulegone (77.2%) and menthone (8.6%) the majority followed by limonene (1.5%), among others. After 12 months of storage at -20°C a GC-MS was performed again and a variation in the relative percentage of pulegone (58.87%), menthone (18.91%) and limonene (1.47%) was observed. After a further 12 months (total 24 months) of storage at -20°C, the percentages of pulegone, menthone and limonene (57.94%, 22.22% and 4.49%, respectively) remained stable. No organoleptic changes were observed in the EO and the chemotype (pulegone/menthone) was not affected. The cytotoxic effect of EO on MAC-T cells was determined by MTT assay. Different concentrations (10, 25, 50, 100, 250, 500, 750, 1000, and 2000 µg/ml) were evaluated at different exposure times (6, 24 and 48 h). EO did not alter cell viability up to 1000 µg/ml at the times tested. The results obtained are important for the future development of a bioproduct applicable to animal health.