Naturally occurring conjugated polyenes embedded in secondary metabolites represent an underexploited class of renewable building blocks for pericyclic chemistry. Spilanthol, a bioactive N-alkylamide isolated from Heliopsis longipes, contains a conjugated diene motif whose potential as a diene in hetero-Diels–Alder chemistry has not been previously investigated. Herein, we report a focused study of the Lewis acid–mediated cycloaddition between spilanthol and p -anisaldehyde, a representative heterodienophile. Following extraction and purification from plant biomass, spilanthol was subjected to cycloaddition under thermal and Lewis’s acid–mediated conditions. While uncatalysed reactions were ineffective or led to substrate degradation, triphenylcarbonium hexafluorophosphate, boron trifluoride diethyl etherate and silver hexafluoroantimonate efficiently promoted a clean [4+2] hetero-Diels–Alder cycloaddition. In all successful cases, a single oxygen-containing cycloadduct was obtained with complete regio- and endo-selectivity in moderate isolated yield. Structural elucidation was achieved by NMR spectroscopy. These results demonstrate that natural alkamides can act as competent and highly selective dienes in hetero-Diels–Alder reactions when appropriately activated, highlighting spilanthol as a renewable platform for heterocycle generation and biomass-based molecular diversification.

Heliopsis longipes is an endemic Mexican plant traditionally valued for its analgesic properties, mainly associated with the alkamide affinin present in its roots. However, the extraction of this bioactive compound generates a lignocellulosic residue that is typically discarded, despite its potential as a renewable feedstock for chemical valorisation. In this study, an integrated valorisation strategy for H. longipes roots is proposed, combining the selective extraction of affinin with the chemical conversion of the residual biomass into furan-based platform compounds. Affinin was extracted from dried roots using a ternary solvent system composed of ethanol (EtOH), ethyl acetate (AcOEt), and tetrahydrofuran (THF), optimised through a mixture design based on an augmented simplex reticular model. Thin-layer chromatography confirmed the presence of affinin in all extracts. The ternary solvent system exhibited a synergistic effect, yielding an average extraction efficiency of 68.09 ± 5.22 mg g−1, with EtOH-rich formulations showing the highest performance. Following affinin recovery, the remaining lignocellulosic fraction was subjected to acid-catalysed hydrolysis using different Brønsted acids (HCl, H2SO4 and HClO4) to promote the formation of furan derivatives. Among the evaluated catalysts, HCl yielded the highest furfural (26.04%), followed by sulfuric acid (17.36%) and perchloric acid (14.75%). The formation of furanic compounds was confirmed by thin-layer chromatography and UV–visible spectroscopy, which showed characteristic absorption features consistent with furfural and related derivatives. Overall, this work demonstrates the feasibility of an integrated biorefinery approach for H. longipes, enabling the simultaneous recovery of high-value bioactive compounds and renewable chemical intermediates from a single biomass source. This strategy contributes to the sustainable valorisation of endemic plant resources and highlights the potential of agro-industrial residues within circular bioeconomy frameworks.

The growing interest in the sustainable economy has positioned lignocellulosic biomass as a strategic resource. Within this framework, Agave tequilana bagasse is a promising feedstock, although its high lignin content and recalcitrant structure limit its valorisation. This work presents a comparative evaluation of chemical delignification strategies applied to Agave tequilana bagasse. Three delignification routes were investigated: (i) an alkaline organosolv treatment using sodium methoxide (MeONa) in methanol (MeOH), (ii) an oxidative process based on Fenton-like reactions employing hydrogen peroxide (H2O2) and manganese dioxide (MnO2), and (iii) a system using tert-butyl hydroperoxide (tBuOOH) as the oxidising agent. The organosolv process was evaluated using a factorial experimental design, with reagent loading and reaction time as factors. The oxidative systems were evaluated by varying the catalyst-to-biomass ratio, oxidant concentration and reaction time. Delignification efficiency was determined by quantifying residual lignin via acid digestion, gravimetric analysis, and statistical analyses. The results show that oxidative treatments with tBuOOH achieved the highest lignin removal, reaching efficiencies above 80%, while Fenton-like systems with MnO2 exhibited performance comparable to conventional iron-based catalysts, with the additional advantages of operating at neutral pH and generating less secondary waste. The alkaline organosolv process with MeONa enabled moderate but significant lignin removal. Overall, this comparative study highlights the versatility of chemical delignification strategies for Agave tequilana bagasse and their potential within sustainability-oriented frameworks.

Increased food demand and the need for sustainable protein sources have boosted the cultivation of Limnospira platensis ( spirulina ) due to its low production cost and nutritional value . This study evaluated the effect of acoustic stimuli in L . platensis cultures , varying frequency (200 and 2000 Hz ) and intensity (60 and   80 dB ) compared to a control . Specific growth rate and cell productivity in acoustically modulated photobioreactor   were quantified . The results indicate that the combination of 2000 Hz and 60 dB significantly optimized growth , while 200 Hz showed moderate or negative effects . These findings suggest that sound modulation can improve production efficiency and open new sustainable biotechnological strategies for the production of cyanobacteria Limnospira platensis .

This study evaluated the hydrophobic surface modification of bacterial biotextiles (porous elastomers resembling bovine leather) using silica nanoparticles synthesized through the Stöber sol-gel method. Three formulations based on the precursor tetraethyl orthosilicate (TEOS) were evaluated. In the first system, polydimethylsiloxane (PDMS-12) was incorporated as an organic modifier and dibutyltin dilaurate (DBTL) was used as a neutral catalyst, while in the other two systems methyltriethoxysilane (MTES) was used as an organosilane co-precursor together with TEOS, employing basic catalysis (NH 4 OH) and mixed catalysis (acid–base [HCl/NH 4 OH]), respectively. The treatments were applied by immersion onto bacterial biotextiles and subsequently characterized by Fourier transform infrared spectroscopy (FTIR) and goniometry analysis to determine surface wettability. The results evidenced the formation of silica bonds on the biotextile and an increase in the contact angle compared to the untreated material. Among the evaluated formulations, the system based on TEOS, PDMS-12, and the neutral catalyst DBTL showed the most significant surface modification, reflected in a greater structural transformation in the FTIR spectrum and an improvement in water hydrophobicity. These findings demonstrate the potential of sol–gel systems as a strategy to develop functional biotextiles with hydrophobic properties, offering an alternative to conventional coatings based on PFAS and PU.

Polyurethane (PU) waste generated by the footwear industry poses a persistent environmental challenge due to its crosslinked chemical structure and limited mechanical recyclability. Among chemical recycling strategies, glycolysis has emerged as an effective depolymerisation method enabling the recovery of polyol-like fractions with potential industrial reuse. In this study, commercial rigid polyurethane shoe sole waste was subjected to catalysed glycolysis using different glycolytic agents and catalytic systems, with the aim of evaluating polyol recovery efficiency and subsequent material valorisation. Tin (II) 2-ethylhexanoate and potassium acetate were assessed as catalysts under controlled reaction conditions. The recovered polyol fractions were characterised in terms of chemical structure, viscosity and density, and compared with a commercial virgin polyol employed in polyurethane manufacturing. FTIR confirmed the preservation of hydroxyl- and ether-functional groups characteristic of polyether polyols. The recovered materials exhibited physicochemical properties comparable to those of commercial references and demonstrated direct reactivity toward commercial isocyanates without the addition of further catalysts or additives. These results demonstrate that catalysed glycolysis represents a viable and scalable chemical recycling route for polyurethane footwear waste, supporting circular manufacturing schemes and reducing the environmental burden associated with polyurethane disposal.

In this work, we present a generalization of the Poisson-Nernst-Planck-Maxwell (PNPM) formalism by introducing fractional time derivatives. Starting from the fractional continuity and Nernst-Planck equations, we derive a fractional diffusion equation that incorporates both a charge source term and, through an effective constitutive relation, the effects of displacement current. Analytical solutions for the charge density are obtained using integral transform methods and are expressed in terms of Fox H-functions, highlighting the memory-dependent nature of the transport. For the inhomogeneous case with an exponentially decaying source, the solution combines a diffusive Fox H-function kernel with a transient term given by a confluent hypergeometric function. Numerical simulations illustrate the transition from normal diffusion to strong subdiffusion, demonstrating how the fractional order $\alpha$ controls the spreading rate while the source parameters govern particle accumulation and relaxation dynamics. Our results may lead to a physically meaningful framework for interpreting experimental data in complex electrochemical and biophysical systems, linking macroscopic transport observations to the underlying microscopic complexity.