Antioxidant Activity of Six Essential Oils and its Molecules in Ecuadorian Andean Medicinal Plants

Background: This research values the antioxidant activity and its responsible molecules in six essential oils from medicinal plants in the Ecuadorian Andes. Methods: The chemical composition of essential oils was determined using gas chromatography coupled mass spectrometry. For evaluated the antioxidant activity of essential oils was use tree spectrophotometric methods: diphenyl-1-picrylhydrazyl (DPPH), 2,2’-Azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and β-Carotene bleaching test. The essential oils with good activity were determined the responsible molecules using the Bioautographic HP-TLC-DPPH method. Results: The scavenging capacity of the radicals was assessed with DPPH and ABTS methods, the best results were found in the oils of M. mollis IC50 DPPH 2.80 mg/ml and IC50 ABTS 0.205 mg/mL and in A. glutinosa IC50 DPPH 12.972 mg/mL and IC50 ABTS 0.321 mg/mL, the results were compared with a pattern of natural reference in this case, the essential oil of T. vulgaris IC50 DPPH 0.474 mg/mL and IC50 ABTS 0.272 mg/mL. The evaluation of the antioxidant activity was determined by the β-carotene bleaching test, the most notable activity results were from M. mollis IC50 0.119 mg/mL, A. glutinosa IC50 0.062 mg/mL and B. latifolia IC50 0,064 mg/mL. DPPH bioautography revealed the active molecules antioxidants in oils for M. mollis were thymol acetate (7.73%) and carvacrol acetate (24.52%), for A. glutinosa was γ-muurolene (2.68%), and for B. latifolia Z-caryophyllene (2.99%), aristolochene (0.11%) and cis-cadin-4-en-7-ol (4.11%). Conclusion: The results of antioxidant activity shown in descending order that the essential oils of: M. mollis, A. glutinosa and B. latifolia, are those with the highest activity using the DPPH and ABTS methods. The β-Carotene bleaching test method confirms the 3 oils as the most active in the following order: A. glutinosa, B. latifolia and M. mollis. An antioxidant bioautographic study identified the molecules responsible for the activity in three essential oils with good activity.