In the present study, the essential oils of the five Melaleuca species, ( Melaleuca bracteata, Melaleuca styphelioides, Melaleuca nesophila, Melaleuca leucadendra, and Melaleuca ericifolia ) were analyzed via headspace gas chromatography/ mass spectrometry (HS-GC/MS) analysis the unveiled considerable differences among the five Melaleuca accessions.
Twelve volatile constituents were identified in the essential oils of Melaleuca accessions. Oxygenated monoterpene exemplified by eucalyptol was the main constituent in M. leucadendra and M. nesophila oils representing 97.62% and 95.08% of their aroma correspondingly followed by M. styphelioides (56.10 %), M. ericifolia (29%), and lastly M. bracteata (10.71%).
A consecutive molecular network was constructed via the GNPS (Global Natural Products Social Molecular Networking) for the visual exploration of the volatile constituents among Melaleuca species. The constructed molecular network divulged eucalyptol (1,8 cineole) as the prevailing volatile, especially in M. leucadendra oil. Quantitative estimation of eucalyptol content in the studied species proved M. leucadendra oil as a potential source for its isolation with a content of 6031.8 µg/g dry weight.
In addition, the effect of eucalyptol on the activity of digestive enzymes (α-amylase and pancreatic lipase) was assessed. Eucalyptol showed IC50 values of 75.3±2.1 and 64.6± 1.4 µg/ml for α-amylase and pancreatic lipase inhibition, compared with acarbose and orlistat 34.71±1.3 and 23.8± 0.82 µg/ml, respectively with significant difference of p Further target prediction studies for eucalyptol were applied and proposed the Cytochrome 450 19A1 aromatase enzyme as a possible target of eucalyptol that could be a potential alternative therapy in the management of obesity.