NADES-based essential oil extraction and isolation of new epoxysesquiterpene from Ageratina adenophora flowers

During the past decade, natural deep eutectic solvents (NADESs) have emerged as a green alternative to conventional organic solvents due to properties like low toxicity, diverse metabolite solubility, and biodegradability. In the present study, choline chloride (CC) and lactic acid (LA)-based NADES has been utilized as pre-extraction media prior to the hydrodistillation of Ageratina adenophora flowers. CC and LA were used in three different molar ratios (1:1, 1:2 and 1:3) along with water to extract essential oil from flowers. The essential oil yield was found to be increased from 2.84 mg/g to 13.52 mg/g using NADES-assisted hydrodistillation. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were used to analyse the chemical diversity of the essential oils. In addition, a new epoxy containing sesquiterpene molecule named 5,11-epoxycadin-3,4-en-8one, was also isolated from the essential oil without chromatography techniques. The molecular structure and absolute configuration have been deduced using NMR spectroscopy (1D & 2D NMR), and single-crystal X-ray diffraction (SC-XRD), respectively. Also, the morphology of the crystal surface was studied using scanning electron microscopy (SEM). Furthermore, the anti-acetylcholinesterase activity of the essential oils and isolated new molecule has also been investigated.