Acid Alkyl Research Articles

The Inhibitory Effect of Gallic Acid Alkyl Esters on Lipid Oxidation of Intactly Soaked Oyster Meats and Oyster Meat Homogenates during Refrigerated Storage

AbstractIn this study, the antioxidant effects of gallic acid (GA) and its alkyl esters including methyl gallate (MG), butyl gallate (BG), octyl gallate (OG), and lauryl gallate (LG) in whole oyster meats and oyster meat homogenates during cold storage are investigated. The oxidation degree of lipid is measured by peroxide value (POV), thiobarbituric acid active substances (TBARS), and polyunsaturated fatty acid (PUFA) percentage. The results show that the lipid oxidation in the two types of samples is inhibited by GA alkyl esters, and the antioxidant effects first increase and then decrease along with the extension of the chain length, among the esters, BG and OG are relatively more effective. Therefore, it is speculated that the antioxidant capacity of GA alkyl esters may be influenced by hydrophobicity and follows a “cut‐off effect” in whole oyster meats and oyster meat homogenates.Practical application: Seafood is easily oxidized even under cold storage because it contains more PUFA. Antioxidants are widely used to inhibit lipid oxidation. In this study, the antioxidant capacity of GA alkyl esters in whole oyster meats and oyster meat homogenates is investigated, which improves the selection of suitable antioxidants to strengthen the oxidation stability of oyster samples for cold storage.

Production of Methanol Tolerant Cell-bound Lipase of Magnusiomyces spicifer SPB2 and Application as Whole-cell Biocatalyst in Transesterification Reaction

Cell-bound lipase (CBL) is a potential biocatalyst for production of fatty acid alkyl ester (FAAE), which is feasible replacement for diesel fuel. This study aimed to improve both hydrolysis and transesterification activities of CBL from the yeast Magnusiomyces spicifer SPB2, which could be employed as whole-cell biocatalyst for transesterification reactions through optimizing the growth medium using Taguchi orthogonal array experimental method (L9). The optimized medium, resulting the highest CBL transesterification activity, consisted of soybean oil, peptone, Gum Arabic and an initial pH of 5. Interestingly, the fatty acid methyl ester (FAME) yield increased up to 33.28 times when compared with non-optimized medium. Moreover, cell morphology of M. spicifer SPB2 varied depending on the culture medium component. The single cell was more active to be used as the whole-cell biocatalyst than the pseudomycelial form for transesterification reaction. The highest FAME yield was 93.86 % when refined palm oil to methanol molar ratio of 1:8 was used as substrates. Whole-cell lipase from M. spicifer showed favorable activity to iso-butanol as an acyl accepter, resulting in fatty acid butyl ester (FABE) yield of 86.80 % at 1:3 molar ratio of palm oil to iso-butanol. The FAME and FABE yields dramatically decreased from 93.86 and 86.80 % to 57.02 and 4.48 %, respectively after the reuse of the enzyme to the second batch of reaction. These results indicated that the whole-cell biocatalyst developed from M. spicifer was an efficient and economical approach to improve enzyme activity and stability in the transesterification reaction. HIGHLIGHTS Methanol tolerant cell-bound lipase and extracellular lipase of spicifer SPB2 were produced The whole-cell biocatalyst of spicifer SPB2 was developed for FAME production The optimized medium was developed to prepare whole-cell lipases from spicifer SPB2 Gum Arabic was the most influencing factor for synthetic activity of whole-cell CBL from yeast Single cell morphology exhibited higher transesterification activity than pseudomycelial form GRAPHICAL ABSTRACT

Fatty Acid Alkyl Ester Production by One-Step Supercritical Transesterification of Beef Tallow by Using Ethanol, Iso-Butanol, and 1-Butanol

The effect of temperature was studied on the synthesis of fatty acid alkyl esters by means of transesterification of waste beef tallow using ethanol and, iso-butanol and 1-butanol at supercritical conditions. These alcohols are proposed for the synthesis of biodiesel in order to improve the cold flow properties of alkyl esters. Alcohol–beef tallow mixtures were fed to a high-pressure high-temperature autoclave at a constant molar ratio of 45:1. Reactions were carried out in the ranges of 310–390 °C and 310–420 °C for ethanol and iso-butanol, respectively; meanwhile, synthesis using 1-butanol was assessed only at 360 °C. After separation of fatty acid alkyl esters, these samples were characterized by nuclear magnetic resonance (NMR) and gas chromatography coupled to mass spectrometry (GC-MS) to quantify yields, chemical composition, and molecular weight. Results indicated that yields enhanced as temperature increased; the maximum yields for fatty acid ethyl esters (FAEEs) were attained at 360 °C, and for fatty acid butyl esters (FABEs) were achieved at 375 °C; beyond these conditions, the alkyl ester yields reached equilibrium. Concerning the physicochemical properties of biodiesel, the predicted cetane number and cloud point were enhanced compared to those of fatty acid methyl esters.

Techno-Economic Analysis of Interesterification for Biodiesel Production

Interesterification is an alternative reaction for the production of fatty acid alkyl esters from triglycerides, a pathway that avoids unwanted byproduct formation. In this work, the technical and economic feasibility of soybean oil interesterification for biodiesel production on a commercial scale is assessed. The interesterification kinetics of triolein (model soybean oil) and methyl acetate using ferric sulfate as a heterogeneous acid catalyst are experimentally determined, and the results are used to parameterize a kinetic model. Process simulations are developed using Aspen Plus V11 for acid and alkaline heterogeneously catalyzed interesterification plants at varying production rates and methyl acetate-to-oil molar ratios (MAOMRs). At all production capacities and MAOMRs tested, the acid-catalyzed processes are found to have more favorable process energy consumption and profitability metrics compared to the alkaline-catalyzed processes. The most economically promising design operates at a production capacity of 30,000 metric tons/yr and an MAOMR of 10:1 with a net present value of $34 million after 20 years and a biodiesel breakeven price of $0.78/kg. This case has a process energy demand of 35,000 MJ/h, resulting in a process energy ratio of 0.25. This work indicates that interesterification shows commercial viability and is a promising alternative to transesterification for biodiesel production.

Interfacial behavior of gallic acid and its alkyl esters in stripped soybean oil in combination with monoacylglycerol and phospholipid

The effect of gallic acid alkyl esters and their combination with monoacylglycerol (MAG) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) on the formation of hydroperoxides and hexanal were determined during the oxidation of stripped soybean oil. Interfacial tension, water content, and droplet size were evaluated to monitor the physical properties of the oil system. Adding MAG and DOPC, especially MAG/DOPC, to the oil promoted the partitioning of antioxidants into the water–oil interfaces by further reducing the interfacial tension. The stripped oil containing methyl gallate (MG) accompanied by MAG/DOPC had lower values of the critical micelle concentration of hydroperoxides and larger micellar size at the induction period. This confirms that MG was able to more effectively reduce the free hydroperoxides concentration and inhibit them in an interfacial way. The conjunction of surfactants has been shown as a promising strategy to improve the interfacial and antioxidant activity of gallates in the oxidative stability of soybean oil.

Factors Affecting on Process of Synthesizing Biodiesel and Arranging Production Steps: a Review Study

Biodiesel is a recycled and biological fatty acid ester manufactured from animal fat, used cooking oil, botanical oil, and algae. Biodiesel is a viable replacement and more environmentally friendly and sustainable alternative for diesel oil since it is made from renewable resources and has qualities similar to diesel oil. When producing biodiesel from renewable resources, the trans-esterification method is utilized. This method manufactures fatty acid alkyl ester (biodiesel) and crude glycerol, which is accomplished by replacing the organic group (alkyl) of alcohol with the organic group of the primary triglyceride component of the raw materials. When the biodiesel specifications meet the global standard established by the European Union's EN14214 or the American Society for Testing Materials (ASTM) for alternative fuels, it can be used in its purest form, known as B100 or blended with petroleum diesel at any concentration. B100 is the purest form of biodiesel. The temperature of the reaction, molar ratio of alcohol to oil, type of alcohol used, type of catalyst utilized and the concentration of the catalyst are all parameters that must be considered during the biodiesel synthesis process. Moreover, the amount of time that the reaction is allowed to continue, the existence of humidity, and the amount of free fatty acids also significantly influence the production process. To minimize the costs of producing biodiesel, selecting the most effective methods is essential.

Bioaccumulation and toxicity of perfluorooctanoic acid and perfluorooctane sulfonate in marine algae Chlorella sp.

The ocean is an important sink for perfluorinated alkyl acids (PFAAs), but the toxic mechanisms of PFAAs to marine organisms have not been clearly studied. In this study, the growth rate, photosynthetic activity, oxidative stress and bioaccumulation were investigated using marine algae Chlorella sp. after the exposure of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate acid (PFOS). The results showed that PFOA of <40 mg/L and PFOS of <20 mg/L stimulated algal reproduction, and high doses inhibited the algal growth. The absorbed PFOA and PFOS by algal cells damaged cell membrane and caused metabolic disorder. The photosynthesis activity was inhibited, which was revealed by the significantly reduced maximal quantum yield (Fv/Fm), relative electron transfer rate (rETR) and carbohydrate synthesis. However, the chlorophyll a content increased along with the up-regulation of its encoding genes (psbB and chlB), probably due to an overcompensation effect. The increase of ROS and antioxidant substances (SOD, CAT and GSH) indicated that PFOA and PFOS caused oxidative stress. The BCF of marine algae Chlorella sp. to PFOA and PFOS was calculated to be between 82 and 200, confirming the bioaccumulation of PFOA and PFOS in marine algae. In summary, PFOA and PFOS can accumulate in Chlorella sp. cells, disrupt photosynthesis, trigger oxidative stress and inhibit algal growth. PFOS shows higher toxicity and bioaccumulation than PFOA. The information is important to evaluate the environmental risks of PFAAs.

Effects of free nitrous acid combined with alkyl polyglucoside on short-chain fatty acids production from waste activated sludge anaerobic fermentation and fermentation liquor for polyhydroxyalkanoates synthesis

Free nitrous acid (FNA) pretreatment and alkyl polyglucoside (APG) addition are environmentally-friendly methods for enhancing waste activated sludge (WAS) anaerobic fermentation (AF) performances. The short-chain fatty acids (SCFAs) produced are available substrates for polyhydroxyalkanoates (PHAs) synthesis to reduce the C-source cost. This study aims to investigate the optimal fermentation conditions of FNA + APG treatment and the performance of PHAs synthesis by the SCFAs from AF system. Through investigating the FNA + APG combined treatment effects, key enzyme activities, and microbial community variation, the AFL from optimal fermentation condition was utilized as a C-source for PHAs synthesis. Experimental results indicated that 0.653 mg/L FNA + 0.075 g/g VSS APG treatment could synergistically achieve the maximum total SCFAs yield of 324.94 mg COD/g VSS at day 5 of AF, which was much more than those of sole FNA or APG treatment. Mechanism analysis indicated that FNA + APG treatment could promote WAS solubilization, hydrolysis and acidogenesis, while severely inhibiting methanogenesis. Microbial community analysis results demonstrated that SCFA producers, including Enterococcus and Clostridium, became the dominant genera in the FNA + APG reactor. Finally, AF liquor after ammonia removal was applied for batch-mode PHAs synthesis, and PHA yields increased to a maximum of 44.44 % of biomass (w/w) after five operation periods.

Calibration of Perfluorinated Alkyl Acid Uptake Rates by a Tube Passive Sampler in Water.

Per- and polyfluoroalkyl substances (PFAS) are a group of 4000+ man-made compounds of great concern due to their environmental ubiquity and adverse effects. Despite a general interest, few reliable detection tools for integrative passive sampling of PFAS in water are available. A microporous polyethylene tube with a hydrophilic-lipophilic balance sorbent could serve as a flow-resistant passive sampler for PFAS. The tube's sampling rate, Rs, was predicted based on either partitioning and diffusion, or solely diffusion. At 15 °C, the laboratory measured Rs for perfluorohexanoic acid of 100+/-81 mL day-1 were better predicted by a partitioning and diffusion model (48+/-1.8 mL day-1) across 10-60 cm s-1 water flow speeds (15+/-4.2 mL day-1 diffusion only). For perfluorohexane sulfonate, Rs at 15°C were similarly different (110+/-60 mL day-1 measured, 120+/- 63 versus 12+/-3.4 mL day-1 in respective models). Rs values from field deployments were in-between these estimates (46 +/-40 mL day-1 for perfluorohexanoic acid). PFAS uptake was not different for previously biofouled membranes in the laboratory, suggesting the general applicability of the sampler in environmental conditions. This research demonstrates that the polyethylene tube's sampling rates are sensitive to the parameterization of the models used here and partitioning-derived values should be used.

New Polymer Composites with Aluminum Phosphates as Hybrid Flame Retardants.

Polymeric aluminum organophosphates are a class of nanostructured aluminum-based compounds that can be considered organic and inorganic hybrid materials. Aluminum phosphates have attracted considerable interest due to their ability to enhance composite materials' mechanical characteristics, lightweight, and thermal properties. Extensive studies have shown the potential of aluminum organophosphates as a component in the development of fire-retardant materials. Aluminum-organophosphorus hybrid (APH) materials have been prepared by reacting aluminum oxide hydroxide (boehmite) with alkyl and aryl phosphoric acids and used to prepare composites with epoxy resin. Boehmite is an aluminum oxide hydroxide (γ-AlO(OH)) mineral, a component of the aluminum ore bauxite. In this work, the composites based on epoxy resin Epidian 601 and commercial curing agent IDA were obtained. Pure boehmite and APH hybrids were added as flame retardants. FTIR and TGA analysis showed that obtained APH possesses a hybrid structure, high thermostability, and various morphologies. These new APH were incorporated into epoxy resin. The infrared spectroscopy confirmed the structure of hybrids and composites. Pyrolysis combustion flow calorimetry (PCFC) and cone calorimeter analyses were performed to assess the flame retardant properties of the composites. The results showed that the incorporation of 17 wt% APH allows a reduction of heat release rate but to a limited extent in comparison to pure boehmite, which is due to the different decomposition mechanisms of both boehmite and hybrids. The cone calorimetry test showed that residue contents correspond quite well to the mineral fraction from boehmite only. The hybrid APHs appear no more efficient than pure boehmite because the mineral fraction in APH is reduced while phosphate fraction cannot promote significant charring.

Recent advances in catalytic decarboxylative transformations of carboxylic acid groups attached to a non-aromatic sp2 or sp carbon.

Chemists learn the most important transformations of the carboxylic acid functionality (COOH) from as early as the first semester of their studies. Carboxylic acids are not only safe to store and handle, but also broadly accessible with great structural diversity either from commercial sources or by means of a large variety of well-known synthesis routes. Consequently, carboxylic acids have long been recognized as a highly adaptable starting material in organic synthesis. A large body of reactions of carboxylic acids are based on catalytic decarboxylative conversions, in which the COOH group of carboxylic acids is catalytically replaced without trace by extrusion of CO2 chemo- and regioselectively. Within the last two decades, the area of catalytic decarboxylative transformations has expanded significantly by utilizing various classes of carboxylic acids as the substrate, including (hetero)aromatic acids, alkyl acids, α-keto acids, α,β-unsaturated acids and alkynoic acids. A literature survey reveals that compared to aromatic acids, the number of original research papers on decarboxylative reactions of α-keto acids, α,β-unsaturated acids and alkynoic acids has been rising every year lately, particularly within past five to six years. The prime aim of the current review is to give an overview of the decarboxylative transformations of α-keto acids, α,β-unsaturated acids and alkynoic acids that have been developed since 2017. The article focuses on the decarboxylative functionalizations that occur in the presence or absence of transition metal catalysts and/or under photoredox catalysis.

Selective alkylation of mandelic acid to diarylacetic acids over a commercial zeolite.

A commercial zeolite is shown to be a highly effective heterogeneous catalyst for the Friedel-Crafts alkyation of mandelic acid with aromatic substrates. The reaction yields mixed diarylacetic acids in one step avoiding the need for inert atmosphere techniques or superacids. The observed reaction pathways are zeolite framework dependent with only the FAU framework giving very high selectivity to the mixed diarylacetic acids.

Structure-activity relationship read-across and transcriptomics for branched carboxylic acids.

The purpose of this study was to use chemical similarity evaluations, transcriptional profiling, in vitro toxicokinetic data, and physiologically based pharmacokinetic (PBPK) models to support read-across for a series of branched carboxylic acids using valproic acid (VPA), a known developmental toxicant, as a comparator. The chemicals included 2-propylpentanoic acid (VPA), 2-ethylbutanoic acid, 2-ethylhexanoic acid (EHA), 2-methylnonanoic acid, 2-hexyldecanoic acid, 2-propylnonanoic acid (PNA), dipentyl acetic acid or 2-pentylheptanoic acid, octanoic acid (a straight chain alkyl acid), and 2-ethylhexanol. Transcriptomics was evaluated in 4 cell types (A549, HepG2, MCF7, and iCell cardiomyocytes) 6 h after exposure to 3 concentrations of the compounds, using the L1000 platform. The transcriptional profiling data indicate that 2- or 3-carbon alkyl substituents at the alpha position of the carboxylic acid (EHA and PNA) elicit a transcriptional profile similar to the one elicited by VPA. The transcriptional profile is different for the other chemicals tested, which provides support for limiting read-across from VPA to much shorter and longer acids. Molecular docking models for histone deacetylases, the putative target of VPA, provide a possible mechanistic explanation for the activity cliff elucidated by transcriptomics. In vitro toxicokinetic data were utilized in a PBPK model to estimate internal dosimetry. The PBPK modeling data show that as the branched chain increases, predicted plasma Cmax decreases. This work demonstrates how transcriptomics and other mode of action-based methods can improve read-across.

Metal-Organic Frameworks as bio- and heterogeneous catalyst supports for biodiesel production

Abstract As biodiesel (BD)/Fatty Acid Alkyl Esters (FAAE) is derived from vegetable oils and animal fats, it is a cost-effective alternative fuel that could complement diesel. The BD is processed from different catalytic routes of esterification and transesterification through homogeneous (alkaline and acid), heterogeneous and enzymatic catalysis. However, heterogeneous catalysts and biocatalysts play an essential role towards a sustainable alternative to homogeneous catalysts applied in biodiesel production. The main drawback is the supporting material. To overcome this, currently, Metal-Organic Frameworks (MOFs) have gained significant interest as supports for catalysts due to their extremely high surface area and numerous binding sites. This review focuses on the advantages of using various MOFs structures as supports for heterogeneous catalysts and biocatalysts for the eco-friendly biodiesel production process. The characteristics of these materials and their fabrication synthesis are briefly discussed. Moreover, we address in a general way basic items ranging from biodiesel synthesis to applied catalysts, giving great importance to the enzymatic part, mainly to the catalytic mechanism in esterification/transesterification reactions. We provide a summary with recommendations based on the limiting factors.

Antimicrobial properties of phenolic acid alkyl esters

The series of phenolic acid (2-, 3-, 4-monohydroxy- and 2,4-, 2,5-dihydroxy) alkyl esters (methyl, ethyl, propyl, and butyl) were prepared, and their antimicrobial activities were determined. The antimicrobial activity against the tested microorganisms Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus brasiliensis was investigated and expressed by minimum inhibitory concentration (MIC) in the range of 1.2–20 mM. The inhibitory activity of higher esters of phenolic acids was found to be higher than that of methyl esters and acids. The minimum inhibitory concentration (MIC) of tested compounds was compared with that of 4-hydroxybenzoic acid and its esters (parabens).

Computational Study of the Gas-Phase Thermal Degradation of Perfluoroalkyl Carboxylic Acids.

Perfluoroalkyl carboxylic acids (PFCAs) are persistent and ubiquitous pollutants. Environmental remediation is often achieved by absorption on matrices followed by high-temperature thermal treatment to desorb and decompose the PFCAs. Detailed product studies of the thermal degradation of PFCAs have been hampered by the complex nature of product mixtures and associated analytical challenges. On the basis of high-level computational studies, we propose reaction pathways and mechanisms for the high-temperature mineralization of a series of linear PFCAs with a backbone length from C-4 to C-8. The favored initial reaction pathways are nonselective C-C bond homolytic cleavages (with bond dissociation energies of ∼75-90 kcal/mol), resulting in carbon-centered radicals which can undergo β-scissions (Ea ≈ 30-40 kcal/mol) which can be preceded by F atom shifts (Ea ≈ 30-45 kcal/mol). In competing barrierless processes, the carbon-centered radicals can lose •F, resulting in the formation of volatile perfluoroalkenes (ΔH ≈ 50-80 kcal/mol). A variety of competing fragmentation processes yield shorter chain perfluorinated PFCAs, isomeric alkenes, alkenoic acids, alkyl, and alkyloic acid radicals. The results provide the energetics for primary, secondary, and tertiary reaction products and insight into the fundamental understanding of the pyrolytic pathways of PFCAs leading to their mineralization.

Direct Organocatalytic Reductive Alkylation of Syncarpic Acid: Scope and Applications.

Biologically important 4-alkylsyncarpic acids, which resemble the core structure of many natural products, were synthesized in one-pot through the organocatalytic three-component reductive alkylation with excellent yields and C-selectivity. Synthetic applications of 4-alkylsyncarpic acids were demonstrated by converting into the functionally rich molecules through different reactions like Michael, retro-Michael, reduction, and oxidation reactions. In a continuation, formal total synthesis of (±)-triumphalone, (±)-isotriumphalone, and monomeric phloroglucinol derivatives was reported in a few steps starting from 4-alkylsyncarpic acids in overall very good yields. Further showcasing the importance of C-alkylated products, 4-benzylsyncarpic acid and its Michael adduct with methyl vinyl ketone were synthesized in a gram scale without compromising rate/yields.

Fluoro-functionalized ionic covalent organic frameworks (F-iCOFs) for highly selective enrichment and sensitive determination of perfluorinated sulfonates by MALDI-MS.

An easily prepared fluoro-functionalized ionic covalent organic framework (F-iCOF) has been implemented into MALDI-TOF MS, enabling the highly selective enrichment and sensitive determination of perfluorinated sulfonate (PFS) contaminants in a rapid and convenient manner. The good thermal stability and excellent optical absorption properties of F-iCOF makes it a brilliant matrix with no background noise. Moreover, benefitting from the large surface area, appropriate pore size, good water dispersibility, and abundant fluorine atom and cationic characteristic of F-iCOF, it exhibited superior adsorption capacity and enrichment selectivity towards PFSs. Good signal responses for PFSs were obtained in the presence of various interfering compounds such as BSA, HA, or even more than 100-fold excess of glutamic acid and similar instructure sodium alkyl sulfonates, highlighting the specific selectivity of F-iCOF. Calibrationcurves for potassium perflurobutane sulfonate (PFBSK) in tap water and whole blood were established with good linear correlation in the range 1-500pgmL^-1. The limits of detection and quantification for PFBSK were as low as 0.04pgmL^-1 and 0.05pgmL^-1, respectively, which are comparable or better than the existing methods for the determination of PFSs.

Preparation, Characterization, and Evaluation of Emission and Performance Characteristics of Thumba Methyl Ester (Biodiesel).

Thumba oil with a higher triglyceride content can be a promising feed for synthesizing a fatty acid alkyl ester as an alternative to pure diesel. The current study investigates the emission and performance characteristics of thumba methyl ester (TME) in compression ignition (CI) engines corresponding to variable loads and compression ratios (CRs), respectively. TME was prepared at an optimized pressure of 5 bar by hydrodynamic cavitation. The properties of TME-diesel blends with varied volume percentages of biodiesel, such as 5, 10, 15, 20, and 25, denoted B5, B10, B15, B20, and B25, respectively, were compared to pure TME (100% biodiesel) and pure diesel (100%). The B20 biodiesel blend has been observed as the optimal one based on the lower emission composition and higher brake thermal efficiency. For B20 fuel, injection at 23° before the top dead center (TDC) and a CR of 18 resulted in the lowest brake specific fuel consumption of 0.32 kg/kW h and a maximum brake thermal efficiency of 36.5%. Using titanium dioxide nanoparticles in the pre-stage of TME manufacturing has ultimately reduced the nitrogen oxide, hydrocarbon, and carbon monoxide emissions. At a CR of 18 and advanced injection 23° before TDC for a CI engine, TME derived from thumba oil has the potential to be a viable diesel substitute.

Lipoic/Capsaicin-Related Amides: Synthesis and Biological Characterization of New TRPV1 Agonists Endowed with Protective Properties against Oxidative Stress.

α-Lipoic acid is a sulfur-containing nutrient endowed with pleiotropic actions and a safe biological profile selected to replace the unsaturated alkyl acid of capsaicin with the aim of obtaining lipoic amides potentially active as a TRPV1 ligand and with significant antioxidant properties. Thus, nine compounds were obtained in good yields following a simple synthetic procedure and tested for their functional TRPV1 activity and radical-scavenger activity. The safe biological profile together with the protective effect against hypoxia damage as well as the in vitro antioxidant properties were also evaluated. Although less potent than capsaicin, almost all lipoic amides were found to be TRPV1 agonists and, specifically, compound 4, the lipoic analogue of capsaicin, proved to be the best ligand in terms of efficacy and potency. EPR experiments and in vitro biological assays suggested the potential protective role against oxidative stress of the tested compounds and their safe biological profile. Compounds 4, 5 and 9 significantly ameliorated the mitochondrial membrane potential caused by hypoxia condition and decreased F2-isoprostanes, known markers of oxidative stress. Thus, the experimental results encourage further investigation of the therapeutic potential of these lipoic amides.