Deep eutectic solvents (DESs) are a relatively new type of solvent that have attracted the attention of the scientific community due to their environmentally friendly properties and their versatility in many applications. Many possible DESs have been described and, thus, it is not easy to unequivocally characterize and generalize their properties. This is especially important in the case of the (eco)toxicity information that can be found for these mixtures. In this review, we collect data on the human and environmental toxicity of DESs, with the aim of gathering and exploring the behavioral patterns of DESs. The toxicity data found were analyzed attending to different factors: hydrogen bond donors or acceptors that form part of the eutectic mixture, pH, and the presence of organic acids in the DES molar ratio of the components, or interactions with natural compounds. In the case of ecotoxicity, results generally depend on the biomodel studied, along with other factors that have been also revised. Finally, we also carried out a revision of the biodegradation of DESs.

Deep eutectic solvents are liquid mixtures of solid components at room temperature, which present exceptional properties: high solvent capacity, high biodegradation, low volatile organic compound character, and relatively low toxicity. Furthermore, there are an important number of DES described, formed by different components and ratios, and thus, the studied applications are also numerous. In this review, we focused on the applications related to health. One of the most promising applications of DES is the development of oral liquid formulations of poorly soluble active pharmaceutical ingredients, although it currently remains at an early stage. We have analyzed the potential and limitations of DES with this regard. Furthermore, DES have been used as synthesis media. In this work, we revised the use of DES to obtain bioactive natural products via synthesis or extraction process. Finally, the usefulness of DES in other interesting applications for promoting health has been also examined: this is the case of genomics studies, nano-carriers for the encapsulation of anticancer drugs or stabilization of samples for medical purposes.

Objective: To study three molecular parameters (number of CGG repeats, X-inactivation ratio, and expression of FMR1 mRNA) in premutation carriers of fragile X syndrome with and without premature ovarian failure (POF) to find differences between these two groups that could be useful in reproductive counseling. Design: A retrospective clinical and molecular genetic study of 42 known premutation carriers of fragile X syndrome aged 40 years or older, 25 with POF and 17 without. A blood sample to obtain mRNA was taken from all of them. They all lived in five autonomous communities in northern Spain. Results: Although the relationship among mRNA levels, X-inactivation ratio, and CGG repeats seems to be similar both in women with POF and in those without: in women with POF, the effect of the CGG repeats on the mRNA levels was statistically significant (P = 0.0437), but in women without POF, it was not (P = 0.0724). Moreover, we confirmed previous results on the nonlinear association between CGG repeat number and the manifestation of POF, showing that the likelihood of having POF was significantly higher with fewer than 100 CGG repeats compared with 100 or more CGG repeats (odds ratio = 13.09, P = 0.0240). Conclusions: Our present work suggests that mRNA and X-inactivation studies in blood are not relevant in predicting POF in female premutation carriers of fragile X syndrome. However, having a permutation of fewer than 100 repeats could represent a significant risk of POF.

Therapeutic Deep Eutectic Systems (THEDESs) are a mixture of components, including an active pharmaceutical ingredient, that have recently emerged because of their interesting properties for drug therapies. In general, they have been recognized to increase the solubility and permeability of some drugs, and consequently, their bioavailability. Moreover, they have also been used for novel formulations of pharmaceuticals. Despite the potential benefits of THEDESs, concerns about their safety and toxicity remain. In this review, we summarize previous studies that have investigated the toxicity of THEDESs. These studies evaluate the toxicity of THEDESs using various methods, including cell cultures, animal models, and human trials. The results of previous findings suggest that THEDESs are generally well-tolerated and have low toxicity. However, further research is needed to fully understand the long-term effects of these systems on human health and to identify any potential adverse effects.