An expeditive and green chemo-enzymatic route to diester sinapoyl-l-malate analogues: sustainable bioinspired and biosourced UV filters and molecular heaters

Engineered mycosporine-based glucoconjugates by enzymatic cascade: Towards innovative ultraviolet filters and antioxidant compounds

Mycosporine-serinol (MSer(OH)) is a small natural molecule with unique ultraviolet (UV) absorbing and antioxidant properties, but its hydrophilic and instable structure hampers its formulation for applications. Inspired by the fact that certain mycosporines are naturally glycosylated, this work assessed the development of an enzymatic route for the glucosylation of MSer(OH) using sucrose, a cheap and abundant resource. The newly characterized α-transglucosylase GS-D Δ1, from Ligilactobacillus animalis DSM 20602, stood out for its ability to glucosylate 96 % of MSer(OH) by grafting 1 to 3 glucosyl units. Then, an enzymatic cascade was established to produce various glucosylated-MSer(OH) differing in terms of linkage specificity and chain length. Their photostability and antioxidant capacities match those of free MSer(OH) or well-known antioxidants, making them potential competitors to commercial sunscreens. Notably, a MSer(OH)-based dextran chain over 108 g.mol-1 exhibited promising properties for cosmetic or medical formulations, as well as anti-UV bio-based materials.

Molecular heaters: a green route to boosting crop yields?

Food production and food security are fast becoming some of the most pressing issues of the 21st century. We are developing environmentally responsible molecular heaters to help boost crop growth and expand geographic areas capable of supporting growth. Sinapic diacid (SDA) is such a molecule, that can act as a light-to-heat agent, converting solar energy into heat delivered to the plant. We have characterised the photophysical properties of SDA extensively, using a combination of steady-state and ultrafast laser spectroscopy techniques complemented with high-level computational studies, and demonstrated both its resilience to prolonged solar irradiation and light-to-heat capabilities. The results we present here illustrate the untapped potential of molecular heaters such as SDA to boost plant yields in existing growing regions and to expand growth into regions hitherto considered too cold for crop growth.

Endocrine disruptor identification and multitoxicity level assessment of organic chemicals: An example of multiple machine learning models

Endocrine-disrupting chemicals (EDCs) pollution is a major global environmental issue. Assessing the multiple toxic effects of EDCs is key to managing their risks. This study successfully developed an EDCs classification and recognition model based on recursive feature elimination and random forest coupling, which passed external validation. Furthermore, the study classified the hormonal effects of EDCs and elucidated their hormonal roles. Molecular dynamics simulations were employed to investigate the toxicity of EDCs, and a regression model for such toxicity was developed using neural networks. A multi-toxicity regression model for EDCs was also developed using the XGBoost algorithm. This model can evaluate carcinogenicity, teratogenicity, and potential developmental toxicity of EDCs. The Spearman and Kendall correlation coefficient methods were used to assess the relations between toxicities. This study combines data filtering with model optimisation to ensure the use of efficient and concise methods. This allows for a comprehensive assessment of EDCs toxicity. It also helps analyse the link between EDCs molecular structure and their toxic effects, providing ideas for designing new chemicals. However, the model exhibits high complexity, and some processes are difficult to fully explain.

Urocanic acid as a novel scaffold for next-gen nature-inspired sunscreens: II. Time-resolved spectroscopy under solution conditions

In recent years the use of synthetic UV filters in commercial skincare formulations has come under considerable scrutiny. Urocanic acid is a naturally occurring UV filter that could serve as a scaffold for developing next-generation biomimetic UV filters. We have carried out time-resolved electronic and vibrational absorption studies on urocanic acid and modified variants in various solvents on timescales spanning eighteen orders of magnitude; from femtoseconds to hours. In combination with quantum chemical calculations these provide vital insight into the photochemical and photophysical properties of urocanic acid and how these are tuned by substitutions and solvents. Moreover, they solve the hitherto conundrum of the wavelength dependence of the photochemistry of trans-urocanic acid in an aqueous environment. Crucially, these studies - together with the accompanying article that reports high-resolution laser spectroscopic studies performed under isolated gas-phase conditions (https://doi.org/10.1039/D4CP02087A) open novel avenues for a rational design of urocanic acid-based UV filters.

Deciphering the enzymatic grafting of vanillin onto lignosulfonate for the production of versatile aldehydes-bearing biomaterials

Modification of lignin plays a crucial role in extending its applications. While chemical functionalization has been extensively applied, exploring the enzyme-catalyzed approach for grafting phenolic molecules presents a promising avenue. Herein, we investigate the controlled laccase-mediated grafting of vanillin onto lignosulfonates (LS) as a sustainable approach to introduce aldehydes into LS, paving the way for further (bio)chemical functionalizations (e.g., reductive amination and Knoevenagel-Doebner condensations). The resulting vanillin-grafted LS is comprehensively characterized (HPLC, SEC, Pyrolysis-GC/MS, FTIR). The study reveals four key steps in the grafting process: (i) vanillin acts as a mediator, generating the phenoxyl radical that initiates LS oxidation, (ii) the oxidation leads to depolymerization of LS, resulting in a decrease in molecular weight, (iii) rearrangement in the vanillin-grafted LS, evidenced by the replacement of labile bonds by stronger 5-5 bonds that resist to pyrolysis, and (iv) if the reaction is prolonged after complete consumption of vanillin, condensation of the vanillin-grafted LS occurs, leading to a significant increase in molecular weight. This study provides valuable insights on the behavior of vanillin and LS throughout the process and allows to identify the optimal reaction conditions, thereby enhancing the production of vanillin-grafted LS for its subsequent functionalization.