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Less than 1 % of the annual worldwide consumption of vanillin can be met by extracting the aromatic compound from vanilla (Vanilla planifolia) pods. For 150 years, vanillin has also been derived through chemical synthesis, which remains the main source (>80 %) of vanillin today, despite growing environmental concerns due to considerable chemical waste disposal issues. ‘Natural’ vanillin is in high demand for flavour and fragrance applications. Thus, biotechnological routes using an array of recombinant hosts have been devised to obtain vanillin through fermentation of natural precursors, e.g. ferulic acid, (iso)eugenol and glucose. These processes, often classical biotransformations, result in ‘natural’ vanillin according to European and US legislation. A significant technical hurdle in fully fermentative routes is vanillin toxicity, which impairs cellular proliferation at relatively low, i.e. commercially uninteresting, vanillin concentrations. In addition to adopting the plant-derived solution, i.e. product glycosylation, to sequester and store vanillin glycosides, sophisticated in situ product removal strategies have been used to obtain industrially relevant amounts of ‘natural’ vanillin.

The investigation of biobased systems as photocurable resins for optical 3D printing has attracted great attention in recent years; therefore, novel vanillin acrylate-based resins were designed and investigated. Cross-linked polymers were prepared by radical photopolymerization of vanillin derivatives (vanillin dimethacrylate and vanillin diacrylate) using ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate as photoinitiator. The changes of rheological properties were examined during the curing with ultraviolet/visible irradiation to detect the influences of solvent, photoinitiator, and vanillin derivative on cross-linking rate and network formation. Vanillin diacrylate-based polymers had higher values of yield of insoluble fraction, thermal stability, and better mechanical properties in comparison to vanillin dimethacrylate-based polymers. Moreover, the vanillin diacrylate polymer film showed a significant antimicrobial effect, only a bit weaker than that of chitosan film. Thermal and mechanical properties of vanillin acrylate-based polymers were comparable with those of commercial petroleum-derived materials used in optical 3D printing. Also, vanillin diacrylate proved to be well-suited for optical printing as was demonstrated by employing direct laser writing 3D lithography and microtransfer molding techniques.

Herein, a simple and environmentally friendly approach for biosynthesis of reduce graphene oxide/Fe3O4 nanocomposite (rG–Fe3O4-NC) via sour lemon peel (SLP) as a reducing agent. Fe3O4 nanoparticle [face-centered cubic (fcc) structure] was decorated on the surface of rG by using co-precipitation strategy. The synthesized nanocomposites were characterized by TEM and XRD techniques. Afterward, the carbon paste electrode (CPE) was modified with rG–Fe3O4-NC and utilized as an electroanalytical sensor for monitoring of vanillin in food products in the concentration range of 1.0 nM to 250 µM. The pH investigation confirmed that redox reaction of vanillin was occurred at surface of electrode in the presence of equal values of electron and proton. The recovery data 99.25–103.11% were detected for determination of vanillin in food products using rG–Fe3O4-NC/CPE as new electro-analytical sensor. The rG–Fe3O4-NC/CPE showed good stability in period time 80 days. In brief, rG synthesized by SLP showed good anticancer activity PC3 prostate and MCF7 breast cancer cells.

Rising global interest in environmentally friendly, high-performance polymeric materials has accelerated the innovation of next-generation polyurethane systems. This research introduces a novel bio-based waterborne polyurethane, synthesized with a vanillin-derived green polyol chain extender featuring dynamic imine linkages. Vanillin diol (VAN-OH) was synthesized using a straightforward one-step condensation of vanillin and ethylenediamine, incorporating dynamic Schiff base functionality into the compound. The waterborne polyurethane (WPU) formulation was synthesized by combining the chain extender VAN-OH, dimethylolpropionic acid (DMPA), polytetrahydrofuran (PTHF), and isophorone diisocyanate (IPDI) in the proper molar ratios. The synthesis parameters were improved through a Design of Experiments (DoE) methodology to enhance mechanical characteristics. The WPU incorporating a vanillin-derived diol chain extender (WPU-VAN-OH) films exhibited a tensile strength of 12.8 MPa, three times greater than that of standard WPU at 4.3 MPa, and showed exceptional self-healing capabilities, completely mending surface scratches within 30 min at 80 °C by dynamic imine bond exchange. The material exhibited higher thermal stability, less water absorption (22.8% compared to 32.2% for WPU after 7 days), and superior adhesion to stainless steel (18.17 kgf/cm² versus 8.23 kgf/cm² for WPU). WPU-VAN-OH films presents a sustainable and efficient methodology for formulating polyurethanes characterized by high strength, self-healing properties, and environmental compatibility, appropriate for uses including protective coatings, advanced adhesives, and flexible elastomers.

Efficient lignin valorization could add more than 10-fold the value gained from burning it for energy and is critical for economic viability of future biorefineries. However, lignin-derived aromatics from biomass pretreatment are known to be potent fermentation inhibitors in microbial production of fuels and other value-added chemicals. In addition, isopropyl-β-D-1-thiogalactopyranoside and other inducers are routinely added into fermentation broth to induce the expression of pathway enzymes, which further adds to the overall process cost. An autoregulatory system that can diminish the aromatics’ toxicity as well as be substrate-inducible can be the key for successful integration of lignin valorization into future lignocellulosic biorefineries. Toward that goal, in this study an autoregulatory system is demonstrated that alleviates the toxicity issue and eliminates the cost of an external inducer. Specifically, this system is composed of a catechol biosynthesis pathway coexpressed with an active aromatic transporter CouP under induction by a vanillin self-inducible promoter, ADH7, to effectively convert the lignin-derived aromatics into value-added chemicals using Escherichia coli as a host. The constructed autoregulatory system can efficiently transport vanillin across the cell membrane and convert it to catechol. Compared with the system without CouP expression, the expression of catechol biosynthesis pathway with transporter CouP significantly improved the catechol yields about 30% and 40% under promoter pTrc and ADH7, respectively. This study demonstrated an aromatic-induced autoregulatory system that enabled conversion of lignin-derived aromatics into catechol without the addition of any costly, external inducers, providing a promising and economically viable route for lignin valorization.

The colorimetric assay used for saponin quantification in plant extracts is subject to interference by common solvents used to extract the saponins from plant materials. Therefore, the degree of interference of ten common solvents was investigated. It was found that the presence of acetone, methanol and n-butanol in the reaction solution caused an intense darkening of the reaction solution in the absence of saponins, which likely could lead to erroneous saponin content values. Using aescin to construct standard curves with different solvents—such as water, ethanol, and methanol— also showed significant differences in the standard curves obtained, which led to different values when they were applied to quantify the saponin content of an ethanol extract from dried and powdered Gac (Momordica cochinchinensis Spreng) seed kernels. To improve the method, a solvent evaporation step was added prior to the colorisation reaction to prevent undesired solvent interference during the reaction step. Using this modified protocol for the aescin standard curve and the Gac seed kernel extract eliminated any solvent interference. Thus, this improved protocol is recommended for the quantification of the saponin content of plant extracts irrespective of which extraction solvent is used.

Vanilla is the world’s most popular flavour extracted from the pods of Vanilla planifolia orchid. It is a mixture of ~ 200 compounds but its characteristic flavour and fragrance primarily come from vanillin. While the importance of its wide usage in flavour and fragrance is well established, there have been limited investigations to evaluate its bioactive potential. However, a few studies have reported a promising array of bioactivities that could be exploited for multiple therapeutic applications. Recently, bioactive properties of vanillin, such as neuroprotection, anticarcinogenic, and antioxidant are gaining attention. Besides this, vanillin and its synthetic analogues are found to regulate gene expression and exhibit biological activities. Therefore, here we summarize the potential bioactivates of vanillin and its derivative with an aim to change the perspective from being a popular flavour to a new age therapeutics molecule. Graphic abstract

Background There is an increased level of senescent cells and toll-like teceptor-1, -2, -4, and -6 (TLR) expression in degenerating intervertebral discs (IVDs) from back pain patients. However, it is currently not known if the increase in expression of TLRs is related to the senescent cells or if it is a more general increase on all cells. It is also not known if TLR activation in IVD cells will induce cell senescence. Methods Cells from non-degenerate human IVD were obtained from spine donors and cells from degenerate IVDs came from patients undergoing surgery for low back pain. Gene expression of TLR-1,2,4,6, senescence and senescence-associated secretory phenotype (SASP) markers was evaluated by RT-qPCR in isolated cells. Matrix synthesis was verified with safranin-O staining and Dimethyl-Methylene Blue Assay (DMMB) confirmed proteoglycan content. Protein expression of p16 INK4a , SASP factors, and TLR-2 was evaluated by immunocytochemistry (ICC) and/or by enzyme-linked immunosorbent assay (ELISA). Results An increase in senescent cells was found following 48-h induction with a TLR-2/6 agonist in cells from both non-degenerate and degenerating human IVDs. Higher levels of SASP factors, TLR-2 gene expression, and protein expression were found following 48-h induction with TLR-2/6 agonist. Treatment with o-vanillin reduced the number of senescent cells, and increased matrix synthesis in IVD cells from back pain patients. Treatment with o-vanillin after induction with TLR-2/6 agonist reduced gene and protein expression of SASP factors and TLR-2. Co-localized staining of p16 INK4a and TLR-2 demonstrated that senescent cells have a high TLR-2 expression. Conclusions Taken together our data demonstrate that activation of TLR-2/6 induce senescence and increase TLR-2 and SASP expression in cells from non-degenerate IVDs of organ donors without degeneration and back pain and in cells from degenerating human IVD of patients with disc degeneration and back pain. The senescent cells showed high TLR-2 expression suggesting a link between TLR activation and cell senescence in human IVD cells. The reduction in senescence, SASP, and TLR-2 expression suggest o-vanillin as a potential disease-modifying drug for patients with disc degeneration and back pain.

o-Vanillin is a natural product that has been widely applied in the food and pharmaceutical industries. In this study, we determined that o-vanillin can strongly inhibit the growth of Aspergillus flavus mycelia. However, the inhibition mechanism of o-vanillin is still elusive. The ultrastructural morphology of mycelia was injured, and the cell walls were destroyed. The OH functional groups on cell walls were altered, and the content of protein in mycelial cell walls was reduced by o-vanillin. The content of β-1,3-glucan in cell walls was significantly (P < 0.05) reduced by o-vanillin in a dose-dependent manner, while chitin was not markedly affected. Moreover, o-vanillin led to an increase in the permeability of cell membranes. o-Vanillin also exhibited a promising antifungal effect on contaminated corn kernels. Therefore, o-vanillin inhibited the growth of mycelia by disrupting the integrity of cell walls and cell membranes. This study not only sheds light on the antifungal mechanism of o-vanillin but also indicates that it is a promising agent for the control of A. flavus infection.Key points• o-Vanillin has strong inhibitory effects on A. flavus.• o-Vanillin destroyed the integrity of cell walls and cell membranes.• o-Vanillin could effectively inhibit the growth of A. flavus on corn kernels.

The regulation of topological structure of covalent adaptable networks (CANs) remains a challenge for epoxy CANs. Here, we report a strategy to develop strong and tough epoxy supramolecular thermosets with rapid reprocessability and room-temperature closed-loop recyclability. These thermosets were constructed from vanillin-based hyperbranched epoxy resin (VanEHBP) through the introduction of intermolecular hydrogen bonds and dual dynamic covalent bonds, as well as the formation of intramolecular and intermolecular cavities. The supramolecular structures confer remarkable energy dissipation capability of thermosets, leading to high toughness and strength. Due to the dynamic imine exchange and reversible noncovalent crosslinks, the thermosets can be rapidly and effectively reprocessed at 120 °C within 30 s. Importantly, the thermosets can be efficiently depolymerized at room temperature, and the recovered materials retain the structural integrity and mechanical properties of the original samples. This strategy may be employed to design tough, closed-loop recyclable epoxy thermosets for practical applications. The covalent crosslinked structure of epoxy thermosets difficult their reprocessability and recyclability. Here, the authors report a method for developing closed loop recycling of strong and tough epoxy supramolecular thermosets constructed with hyperbranched topological structure in an energy-saving and easy-to-conduct way.