Sustainable Straightforward Synthesis and Evaluation of the Antioxidant and Antimicrobial Activity of Sinapine and Analogues

Abstract

Naturally occurring sinapine was successfully synthesized through a proline-mediated Knoevenagel-Doebner condensation in ethanol. This synthetic process involving bio-based syringaldehyde, Meldrum's acid and choline chloride, offers a sustainable alternative to the existing low yield pathways. This two-step strategy gives access to sinapine in a 52% overall yield, and has been implemented to the synthesis of sinapine analogs using 4hydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde and vanillin as precursors giving target molecules with 34-61% overall isolated yields. Purity of synthetic sinapine and that of its analogs (ca. 95%) was assessed by NMR and HPLC-MS analysis. Furthermore, antioxidant and antimicrobial activities were assessed and confirmed the potential of this series of molecules.

Synthesis of Biobased Phloretin Analogues: An Access to Antioxidant and Anti-Tyrosinase Compounds for Cosmetic Applications

“…B-ring syringol moieties seemed to also influence the antioxidant activity, but to a lesser extent, as evidenced by the EC 50 values of the compounds a11, b11, a12 and b12. As was already observed by Mouterde et al, by comparing the wholeness of EC 50 values, an additional hydroxy group impacted more strongly the antioxidant activity than a methoxy [57].…”

Sinapic Acid and Sinapate Esters in Brassica: Innate Accumulation, Biosynthesis, Accessibility via Chemical Synthesis or Recovery From Biomass, and Biological Activities

“…Inhibition of a broad range of Gram-negative and Gram-positive bacteria have also been demonstrated using a SinA fraction isolated from the ethanolic extract of rapeseed (Nowak et al, 1992). The antimicrobial activities of sinapine (Mouterde et al, 2020) and other SinEs (Peyrot et al, 2020b) against Escherichia coli have also been recently highlighted. These literature reports strongly suggest that SinA and its derivatives are potential biobased antimicrobial reagents.…”

“…For instance, caffeic acid shows better antioxidant activity than that of SinA (Mathew et al, 2015). Furthermore, extra methoxyl group on the p-hydroxycinnamic acid core further improves the radical scavenging activities of these metabolites (Mouterde et al, 2020).…”

“…Mouterde et al have recently reported a more straightforward multigram-scale synthetic process for (2) (Figure 12) (Mouterde et al, 2020). Their approach relies on the well-established Knoevenagel-Doebner condensation of syringaldehyde and choline malonate.…”

Optimization of the Recovery of Secondary Metabolites from Defatted Brassica carinata Meal and Its Effects on the Extractability and Functional Properties of Proteins

“…Sinigrin hydrate and sinapic acid, used as external standards, were purchased from Sigma-Aldrich. Pure synthetic sinapine chloride was synthesized in our laboratory and used as the standard for HPLC analysis [22,28]. The ethanol solution used for extraction was purchased from ThermoFisher.…”