Chemical profiling and bioactivity evaluation of thymol rich Coleus aromaticus Benth. essential oil

Coleus aromaticus Benth. (Family: Lamiaceae) is a huge perennial, aromatic and succulent herb native to the Indian subcontinent. The dried leaves have an oregano-like texture making them a perfect culinary food supplement to be used as herbal seasoning for meat and other food products. The present study aimed to identify the bioactive components in the essential oil collected from the fresh aerial parts of Coleus aromaticus Benth. Using GC/MS analysis, 12 terpenoid components were identified, accounting for 97.5% of the overall oil content. Thymol (69.6%), p-cymene (3.9%), (E)-caryophyllene (3.7%), carvacrol (3.2%), α-thujene (3.2%), γ-terpinene (2.9%), and carvacrol methyl ether (2.3%) were identified to be the primary constituents in the oil, which was determined to be dominated by oxygenated monoterpenes (72.8%). Additionally, at the highest dose, CAEO showed significant pesticidal activity, inhibiting the egg hatchability of Meloidogyne incognita by 96.9%, immobilizing it by 52.3%, insecticidal activity on Spodoptera litura by 71.13%, and phytotoxic activity on Raphanus raphanistrum seeds by 97.75%. For speculating the potential method of action of CAEO components, the proteins/enzymes namely acetylcholinesterase (PDB ID: 6XYS), carboxylesterase (PDB ID: 5IVH), and acetohydroxyacid synthase (PBD ID: 1YHZ) were employed. The novel aspect of this study was that the herbal spice material was collected during its vegetative stage from the Tarai region of Pantnagar (India) in order to bio-evaluate its nematicidal, herbicidal, and insecticidal effectiveness. It was found that CAEO is an effective alternative source of natural pesticides and opens the way for additional research on its mechanistic techniques and field tests to determine its pesticidal studies.