## 1 Introduction
Moreover, the potential reduction in the use of toxic chemicals, lower energy requirements, and compactness render UAE a green, eco-friendly, and cost-effective technique [13]. Researchers have studied the application of UAE to isolate bioactive compounds from various spices for many years. For instance, [PERSON] et al. [5] used conventional maceration and UAE to extract the oleoresin from nutmeg. The obtained results revealed that applying UAE at 40% of the maximal power for 10 min led to a similar oleoresin yield (8.26%) compared to the yield achieved by maceration lasting three days (9.63%). Furthermore, UAE has enabled the enrichment of nutmeg oleoresin in \(\beta\)-sesquiphellandrene, piperitol isomer, and \(\alpha\)-ionone, which were not found in oleoresin obtained by maceration. Interestingly, yields of coriander seed extracts prepared by conventional (maceration and Soxhlet extraction) and unconventional (UAE and rapid solid-liquid dynamic extraction) methods were significantly different [14]. In fact, the highest extraction yield was observed for the sample obtained using the UAE method (2.36% \(w/w\)), followed by maceration (2.17% \(w/w\)), Soxhlet (1.18-1.63% \(w/w\)), and rapid solid-liquid dynamic extraction (0.57-0.73% \(w/w\)). Additionally, pepper seed oil prepared by UAE for 50 min had a significantly higher antioxidant capacity (AC) determined by ferric reducing antioxidant power (FRAP = 315.92 umol Trolox (TE)/L) assay than the sample obtained by Soxhlet extraction performed for 6 h (FRAP = 290.45 umol TE/L) [15]. These outcomes clearly demonstrated the advantages of using UAE to isolate bioactive substances from different spices in a short time while maintaining satisfactory efficiency. Recently, deep eutectic solvents (DESs) have been widely studied due to their unique properties, such as biodegradability, environmental friendliness, ease of preparation, and low cost [16; 17]. Briefly, DESs are mixtures of compounds that act as hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs), contributing to their lower melting points compared to the individual compounds [16]. Due to their beneficial features, DESs have found applications in various fields, including catalysis reactions, organic synthesis, electrochemical materials, and the extraction of bioactive compounds [17; 18]. However, their high viscosity could be a significant obstacle in some fields, especially in analytical chemistry, as it can limit mass transfer and decrease extraction efficiency [19]. Therefore, caution is required, as excessive water dilution may disrupt the DES system by weakening the hydrogen bond interactions between HBA and HBD [20; 21]. To support adjusting the properties of DESs to individual needs, experiments and simulations performed by [PERSON] et al. [21] demonstrated that exceeding a 50% molar fraction of water in the DES system dampened the intramolecular interactions in the DES. In the area of extraction, DESs based on tetrabutylammonium bromide (N\({}_{4444}\)Br) and long-chain alcohols have proven effective for headspace single-drop microextraction of terpen from spices, including cinnamon, cumin, fennel, clove, thyme, and nutmeg [22]. Notably, the DES based on N\({}_{4444}\)Br and dodecanol was the most effective, leading to its selection for further experiments. Other studies have explored the extraction process of bioactive substances from cinnamon and sapan wood using a DES based on choline chloride (ChCl) and glycerol (Gly), comparing this approach to conventional extraction processes such as maceration and reflux conducted with ethanol [23]. Results showed that samples extracted using this DES had a higher content of bioactive compounds. Lastly, a natural DES (NADES) composed of betaine, lactic acid, and water was found effective in the extraction of bioactive compounds from ginger, yielding a higher total phenolic content (TPC) compared to samples obtained using ethanol, water, or an ethanol and water mixture [24].