Glucosinolates (GSLs) are secondary plant metabolites abundantly found in plant order Brassicales. GSLs are constituted by an S-β-d-glucopyrano unit anomerically connected to O-sulfated (Z)-thiohydroximate moiety. The side-chain of the O-sulfate thiohydroximate moiety, which is derived from a different amino acid, contributes to the diversity of natural GSL, with more than 130 structures identified and validated to this day. Both the structural diversity of GSL and their biological implication in plants have been biochemically studied. Although chemical syntheses of GSL have been devised to give access to these secondary metabolites, direct extraction from biomass remains the conventional method to isolate natural GSL. While intact GSLs are biologically inactive, various products, including isothiocyanates, nitriles, epithionitriles, and cyanides obtained through their hydrolysis of GSLs, exhibit many different biological activities, among which several therapeutic benefits have been suggested. This article reviews natural occurrence, accessibility via chemical, synthetic biochemical pathways of GSL, and the current methodology of extraction, purification, and characterization. Structural information, including the most recent classification of GSL, and their stability and storage conditions will also be discussed. The biological perspective will also be explored to demonstrate the importance of these prominent metabolites.

Sinapic acid (SinA) and corresponding esters are secondary metabolites abundantly found in plants of Brassica family. Belonging to the family of p-hydroxycinnamic acids, SinA and its esters analogues are present in different plant parts and involved in multiple biological processes in planta. Moreover, these metabolites are also found in relatively large quantities in agro-industrial wastes. Nowadays, these metabolites are increasingly drawing attention due to their bioactivities which include antioxidant, anti-microbial, anti-cancer and UV filtering activities. As a result, these metabolites find applications in pharmaceutical, cosmetic and food industries. In this context, this article reviews innate occurrence, biosynthesis, accessibility via chemical synthesis or direct extraction from agro-industrial wastes. Biological activities of SinA and its main corresponding esters will also be discussed.

Methyl-coenzyme M reductase (MCR) is the enzyme responsible for nearly all biologically generated methane¹. Its active site comprises coenzyme F₄₃₀, a porphyrin-based cofactor with a central nickel ion that is active exclusively in the Ni(I) state^2,3. How methanogenic archaea perform the reductive activation of F₄₃₀ represents a major gap in our understanding of one of the most ancient bioenergetic systems in nature. Here we purified and characterized the MCR activation complex from Methanococcus maripaludis. McrC, a small subunit encoded in the mcr operon, co-purifies with the methanogenic marker proteins Mmp7, Mmp17, Mmp3 and the A2 component. We demonstrated that this complex can activate MCR in vitro in a strictly ATP-dependent manner, enabling the formation of methane. In addition, we determined the cryo-electron microscopy structure of the MCR activation complex exhibiting different functional states with local resolutions reaching 1.8–2.1 Å. Our data revealed three complex iron–sulfur clusters that formed an electron transfer pathway towards F₄₃₀. Topology and electron paramagnetic resonance spectroscopy analyses indicate that these clusters are similar to the [8Fe-9S-C] cluster, a maturation intermediate of the catalytic cofactor in nitrogenase. Altogether, our findings offer insights into the activation mechanism of MCR and prospects on the early evolution of nitrogenase.

Naturally occurring sinapic acid is a valuable synthon for many high-value applications (e.g. cosmetic, pharmaceutic) that can be found in numerous plants, especially Brasiccacea species (e.g. rapeseed, mustard). It has been demonstrated that alkaline extraction of matter rich in sinapic acid resulted in the conversion of sinapic acid into 6-hydroxy-5,7-dimethoxy-2-naphtanoic acid (DMNA). Although DMNA could be a potential alternative to petro-based naphtanoic acid used in polymers, untill now, no reliable (bio)synthetic procedure existed to synthesize it at the preparative-scale. Herein, starting from sinapic acid, we describe a very simple one-pot two-step chemo-enzymatic pathway to DMNA – and reaction intermediaries bislactone (BL) and thomasidioic acid (TA) – at gram scale using a simple filtration as purification step. Green metrics – Process Mass Index and EcoScale – have been determined to assess the sustainability of this new process. Finally, the antiradical activities of DMNA, BL and TA have been evaluated. GRAPHICAL ABSTRACT

The sustainable extraction of secondary metabolites from Brassica agro-industrial by-products often involves the use of high concentrations of ethanol, and/or high temperatures, which tends to decrease the efficiency of protein extraction (yield, profile, etc.). To understand the limits of the combination of these two extraction processes, aqueous ethanol extraction of secondary metabolites (e.g., phenolic compounds and glucosinolates) from Brassica carinata defatted meal was optimized using Response Surface Methodology. The validated models predicted that aqueous ethanol extraction of defatted Carinata meal, with a low aqueous EtOH concentration (22% EtOH) at moderate T_e (50 °C), enables the efficient recovery of secondary metabolites (sinapine = 9.12 ± 0.05 mg/g_DM, sinigrin = 86.54 ± 3.18 µmol/g_DM) while maintaining good protein extractability (59.8 ± 2.1%) from successive alkaline extractions. The evaluation of functional properties of the resulting protein isolates revealed that aqueous extraction, under optimized conditions, improves foaming activity while preserving emulsion ability.

Tourteaux de Brassica carinata issus de la production du carburant durable pour l'aviation : une ressource renouvelable des molécules à haute valeur: Brassica carinata est largement cultivée dans la région Sud-Est des États-Unis comme une culture hivernales pour des usages non-alimentaires, tel que la production de biocarburant. Les protéines extraites à partir des tourteaux de B. carinata ne sont pas encore approuvées comme l’alimentation dû à la haute teneur en glucosinolates et en acide érucique. En outre, les métabolites secondaires qui sont considérés comme des facteurs antinutritionnels restreignent l’assimilation des protéines par l’organisme. L’élimination de ces métabolites secondaires est donc nécessaire pour une valorisation plus complète des tourteaux Carinata. Malgré des effets négatifs par leur assimilation directe, les métabolites secondaires sont particulièrement intéressants du fait de leurs activités biologiques. La valorisation de l’ensemble des protéines et des métabolites secondaires devrait augmenter les valeurs économiques et écologiques des tourteaux Carinata.Dans un premier temps, les informations structurelles, la composition, l'occurrence naturelle, les méthodes d'extraction et de purification actuelles des protéines de Brassica carinata seront discutées. Ensuite, l'occurrence naturelle, la biosynthèse, l'accessibilité des principaux métabolites secondaires tels que composés phénoliques et glucosinolates seront étudiées. Les propriétés biologiques de ces molécules seront également étudiées afin de confirmer applications potentielles.L’éco-extraction des métabolites secondaires des produits agro-industriels Brassica implique souvent l'utilisation de concentrations élevées d'éthanol et/ou de températures élevées. Par conséquent, les effets d’un procédé d'extraction utilisant une solution hydro-alcoolique comme solvant seront étudiés dans ce manuscrit. Les résultats d’un plan d’expérience nous ont permis d’établir un procédé d'éco-extraction optimisée à partir du tourteau de Carinata. Par la suite, nous étudierons les effets de l’extraction hydro-alcoolique sur l'extractabilité des protéines et les propriétés fonctionnelles qui sont peu étudiées dans la littérature.Les composés phénoliques sont particulièrement intéressants grâce à leurs structures fonctionnalisables. Afin de valoriser davantage ces précieux composés biosourcées, des modifications chimiques sont souvent nécessaires. La transformation d’un des phénols présents dans le tourteau a été proposée et développer afin de donner l’accès à une nouvelle famille de monomères biosourcées.Lors d’un dommage tissulaire, des substances toxiques sont produites suite à la dégradation des glucosinolates catalysée par la myrosinase. Afin de réduire la toxicité de ces métabolites secondaires dans le tourteau de Carinata, une stratégie par voie biochimique sera mise en place en imitant le schéma d'alimentation d'un ravageur de Brassica.