Biocompatible Ionic Liquids (Bio-ILs) are a new class of ILs that are task-specifically designed to derive from naturally occurring compounds and/or derivatives thereof, as well as molecules well known for their biocompatibility (e.g., active pharmaceutical ingredients or non-toxic bioactive compounds) in terms of sustainability and biocompatibility. Owing to their remarkable physicochemical properties that can be tailor made to comply with the requirements of each application, Bio-ILs have emerged as novel, efficient and green technology, appropriate for a vast variety of scientific fields. Herein, this review describes the state-of-the-art scientific research regarding the synthesis, characterization and applications of Bio-ILs reported in the literature for the period between 2020 and 2022.

The extraction of valuable phytochemicals from natural sources is an important and constantly evolving research area. Zingiber officinale Roscoe (ginger) contains high amounts of bioactive phytochemicals, which are desirable due to their significant properties. In this work, the ability of different natural deep eutectic solvents (NaDESs) to serve as green solvents for the preparation of high added value extracts from ginger is explored, in combination with ultrasound assisted extraction. The method was optimized by applying a response surface methodology using the NaDES Bet/La/W (1:2:2.5). Three independent variables, namely the extraction time, ultrasound power and NaDES-to-dry-ginger ratio, were investigated by employing a 17-run three-level Box–Behnken Design (BBD) in order to study the correlation between the extraction conditions and the quality of the obtained extracts. The optimum conditions (in order to achieve simultaneously maximum total phenolic content and antioxidant activity), were found to be 23.8 min extraction time, 60 Watt and NaDES/ginger 25:1 w/w. In the optimum conditions the DPPH radical scavenging ability of the extracts was found to reach IC₅₀ = 18.16 mg/mL after 120 min, whereas the TPC was 20.10 ± 0.26 mg GAE/g of dry ginger. The green methodology was also compared with the extraction using conventional solvents. All the obtained extracts were evaluated for their antioxidant activity and their total phenolic content, while the extract derived by the optimum extraction conditions was further investigated for its ability to bind to calf thymus DNA (ctDNA).

Vitis vinifera L. cultivar, “Assyrtiko”, is a famous grape variety native to Santorini island. Its wine production residues are rich in bioactive polyphenols, making them valuable for extraction and use in cosmetics. The aim of this work was the development and optimization of an extraction process from “Assyrtiko” Wine Production Residue (AWPR), using a Natural Deep Eutectic Solvent (NaDES) as the extraction medium. Four NaDESs were synthesized and screened for the extraction, and the extracts were evaluated for Total Phenolic Content (TPC) and Total Flavonoid Content (TFC). The NaDES comprising betaine and 1,3-propanediol was chosen for further analysis because of its effectiveness as an extraction solvent. The extraction process was optimized using a Box–Behnken experimental design. The NaDES %w/w content in the NaDES/water system was found to play the most statistically significant role in the quality of the extracts, assessed via TPC and TFC values. The quality of the extract obtained from the optimal conditions was practically stable with respect to TPC and TFC after long storage, suggesting that NaDESs have a potential “protective” effect for the extracted phytochemicals and give energy-efficient character to the process. This extract was also directly incorporated into a moisturizing cosmetic formulation, which remained homogeneous and stable after testing, demonstrating the extract’s potential for cosmetic applications.