Essential Oils from <i>Phlomis longifolia</i> Boiss. &amp; C.I. Blanche. Aerial Parts (Flowers, Calyxes, Leaves): GC-MS Analyzes and Biological Properties

Objective/Background: Phlomis longifolia Boiss. &amp; C.I. Blanche. is one of the significant medicinal plants extensively utilized in folk medicine in Syria. So, this study aimed to identify the chemical components with potential pharmacological properties of essential oils extracted from the aerial parts of the Syrian P. longifolia plant for the first time. Methods: The aerial parts of the plant were collected from a mountainous area in Latakia Province, Syria. Subsequently, the essential oils were obtained using hydrodistillation with a yield of (0.14% for flowers, 0.075% for calyxes, and 0.19% for leaves) using a Clevenger-type apparatus and analyzed by gas chromatography coupled with mass spectrometry (GC-MS). Results: A total of 63, 61, and 48 compounds, which represent (98.0%, 97.1%, and 97.9%) of the total oils, were identified for flowers, calyxes, and leaves, respectively. The major compounds identified in the flower's essential oil were: widdrol (29.8%), β-caryophyllene (9.7%), and (E)-nerolidyl acetate (5.8%). While in the calyx's essential oil were: (E)-nerolidyl acetate (8.6%), α-humulene (8.1%), and β-caryophyllene (7.7%). As for the leave's essential oil were: (E)-nerolidyl acetate (11.4%), β-caryophyllene (9.5%), α-amorphene (8.8%), caryophyllene oxide (6.7%), α-humulene (5.3%), and 3,5-dihydroxy-6-methyl-2,3-dihydro-4H-pyran-4-one (5.2%). Additionally, the majority of the identified compounds have various biological activities, according to the published literature. Conclusion: In this work, the chemical composition of essential oils extracted from the aerial parts of P. longifolia was determined for the first time by GC-MS. Terpenes were the dominant chemical content of essential oils (83.3% for flowers, 72.7% for calyxes, and 80.9 for leaves), and sesquiterpenes had the highest concentration among them (77.3% for flowers, 65.7% for calyxes, and 77.1% for leaves). These compounds are known for their diverse biological activities and promote the use of such plants in phytopharmaceuticals.