Evolution of Phytochemical Variation in Myrtle (Myrtus communis L.) Organs during Different Phenological Stages

Myrtle (Myrtus communis L.) is an important medicinal plant, of which all parts have pharmaceutical and nutritional applications and which is distributed throughout the southwest regions of Iran. The aerial parts of myrtle were collected at different phenological stages (vegetative, flowering, unripe fruit and ripening fruit stages, after the fully mature fruit dispersal stage) from Fars Province of Iran and were analyzed with GC-FID and GC-MS. All the data were submitted to multivariate statistical analysis, showing many differences among the various plant parts and their phenological stages. Monoterpene hydrocarbons (18.9-50.5%) and oxygenated monoterpenes (38.2-72.4%) were the most abundant class in the volatile emissions, with alpha-pinene, 1,8-cineole, limonene, linalool, alpha-terpineol, linalyl acetate and geranyl acetate being the main constituents in the majority of the examined samples. alpha-Pinene content ranged from 8.88% at the after fully mature fruit dispersal stage (leaves) to 32.84% at the flowering stage in the leaves. Limonene, which is the dominant component at the flowering stage, was 23.97% in the flowers, while the limonene amount was 0.14-1.42% at other harvest stages. The greatest 1,8-cineole amount was obtained prior to flowering, 45.98%, while the lowest amount was obtained at the flowering stage, in the flowers. The total phenol and flavonoid contents varied between different myrtle parts: the highest total phenol and flavonoid contents were obtained for the extract made of the before-flowering stage in leaves (66.52 mg GAE/g and 7.49 mg QE/g extracts). Overall, the study indicated that collecting myrtle at the vegetative and flowering stages, especially the leaves organs, would be of considerable importance.