Chemical profiling, antiviral and antiproliferative activities of the essential oil of Phlomis aurea Decne grown in Egypt

Here, we investigated the chemical composition of the edible Phlomis aurea oil and its Anticancer potential on three human Cancer cell lines, as well as its Antiviral activity against Herpes simplex-1 (HSV-1). Exploring Phlomis aurea Decne essential oil by gas chromatography coupled with mass spectrometry (GC/MS) revealed the presence of four major components: germacrene D (51.56%), trans-β-farnesene (11.36%), α-pinene (22.96%) & limonene (6.26%). An antiproliferative effect, as determined by the MTT assay, against human hepatic, breast and colon Cancer cell lines, manifested IC₅₀ values of 10.14, 328.02, & 628.43 μg mL^-1, respectively. Cytotoxicity assay of the Phlomis oil against Vero cell lines revealed a safe profile within the range of 50 μg ml^-1. Phlomis essential oil induced the Apoptosis of HepG2 cells through increasing cell accumulation in sub G1 & G2/M phases, decreasing both S & G0/G1 phases of the cell cycle, triggering both caspases-3 &-9, and inhibiting cyclin dependent kinase-2 (CDK2). The Antiviral activity of the oil against HSV-1 was investigated using the plaque reduction assay, which showed 80% of virus inhibition. Moreover, the molecular docking in silico study of the four major chemical constituents of the oil at the CDK2 binding site demonstrated marked interactions with the ATP-binding site residues through alkyl & Pi-alkyl interactions. Cell cycle distribution of HepG2 cells was studied using flow cytometry to highlight the apoptotic mechanistic approaches by measuring caspases-3 &-9 and CDK2 activities. Thus, the edible Phlomis oil can be regarded as a candidate for in vivo studies to prove that it is a promising natural Antiviral/Anticancer agent.