Chemical composition, antimicrobial activity, and antioxidant capacity of Baker and Baker: Two endemic species from Madagascar as sources of essential oils.

Background: The aerial parts of Baker and Baker are used by the population of the Vakinankaratra and Itasy regions (Madagascar) to treat breathing difficulty, fever and/or headache, wounds, and sores.

Purpose: This work aimed to characterise plant materials from . and to report i) chemical composition, ii) antimicrobial properties, and iii) antioxidant capacity of the essential oils extracted from the aerial parts of these species.

Materials And Methods: The essential oils from (MMO) and (MFO) were obtained by hydrodistillation. Their chemical composition was quantified using gas chromatography coupled with mass spectrometry (GC-MS). MMO and MFO were also tested against 7 microbial strains using the disk diffusion method and their antioxidant capacity was assessed using the DPPH scavenging assay.

Results: Hydrodistillation yielded 0.26% MMO and 0.29% MFO (w/w) in relation to the fresh weight. Twenty-seven compounds were identified by GC-MS in MMO extract against 36 in MFO one. The main compounds in MMO were pulegone (24.67%), -menthone (24.67%), eucalyptol (8.12%), -caryophyllene (4.98%), -guanene (4.47), -menthone (3.85%), -pulegone (3.34%), azulene (3.28%) and 2-isopropyl-5-methylcyclohexenone (2.82%). The main compounds in the MFO were eudesma-4,11-dien-2-ol (13.88%), -guanene (6.62%), pulegone (6.40%), cyperone (5.56%), 4--dehydrobietinol acetate (5.39%), eucalyptol (5.12%), -menthone (4.67%), limonene (3.77%) and sabinene (2.29%). Regarding the chemotaxonomy, was very different from and both species also differed from the other species, as confirmed by multivariate statistical analysis. Both MMO and MFO exerted activities against a large microbial spectrum; the antimicrobial activity of MMO was higher than MFO one against and due to the presence of pulegone as the main component. MFO showed an excellent scavenging capacity with an SC value of 2.17 ± 0.03 μg/mL.

Conclusion: The biological properties of the essential oils extracted from the selected species may explain their therapeutic value showing that Malagasy species may be very important as new natural sources of bioactive compounds. This study may promote the effectiveness and quality of Malagasy species, contributing to sustainable development and commercial valorisation of traditional preparations based on natural local resources.