Synthesis and biological evaluation of ricinoleic acid-based lipoamino acid derivatives

Lipozyme® TL IM Biocatalyst for Castor Oil FAME and Triacetin Production by Interesterification: Activity, Stability, and Kinetics

Global climate change and present geopolitical tensions call for novel, renewable, and, ideally, sustainable resources and processes that, in the end, will be integrated in the natural cycles of carbon and water, progressively replacing non-renewable feedstocks. In this context, the production of biofuels and, in consequence, of biodiesel plays a notable role. This work is focused on the production of fatty acid methyl esters (FAME) from castor oil, an abundant non-edible oil, using a sustainable technology approach based on industrial lipases and methyl acetate as a methylating reagent to reduce biocatalyst inactivation. We have selected a stable industrial enzyme preparation to determine its suitability for FAME production: Lipozyme® TL IM (an inexpensive lipase from Thermomyces lanuginosus immobilized by agglomeration in silica gel). Several operational variables affecting the enzyme activity have been studied: methanol excess (6:1 to 13:1), temperature (from 40 to 60 °C), and enzyme concentration (10 and 30% w/w). At all temperatures and reagent ratios, we have also tested the enzyme stability for six cycles, showing its low to negligible inactivation under operational conditions. Finally, a novel multivariable kinetic model has been proposed and fitted to experimental data obtained in a wide experimental range for the first time, showing that direct and reverse in-series reactions are present. We have estimated the values of the kinetic constants and their standard errors, and goodness-of-fit parameters, observing that the kinetic model fitted very reasonably to all retrieved experimental data at the same time.

Valorization of Soy Lecithin by Enzyme Cascade Reactions Including a Phospholipase A2, a Fatty Acid Double-Bond Hydratase, and/or a Photoactivated Decarboxylase

A huge amount of phospholipids or lecithin is produced as a byproduct in the vegetable oil industry. However, most are just used as a feed additive. This study has focused on enzymatic valorization of lecithin. This was exploited by enzymatic transformation of soy lecithin into lysolecithin liposomes, including functional free fatty acids, hydroxy fatty acids, hydrocarbons, or secondary fatty alcohols. One of the representative examples was the preparation of lysolecithin liposomes containing secondary fatty alcohols [e.g., 9-Hydroxyheptadec-11-ene (9) and 9-heptadecanol (10)] by using a phospholipase A2 from Streptomyces violaceoruber, a fatty acid double-bond hydratase from Stenotrophomonas maltophilia, and a photoactivated decarboxylase from Chlorella variabilis NC64A. The engineered liposomes turned out to range ca. 144 nm in diameter by dynamic light scattering analysis. Thereby, this study will contribute to application of functional fatty acids and their derivatives as well as valorization of lecithin for the food and cosmetic industries.

Design, Synthesis and in Vitro Antifungal Mechanism of Novel Phenylalanine Derivatives

To explore novel molecules with unique mechanisms against plant pathogenic fungi, a series of phenylalanine derivatives containing a 1,3,4-oxadiazothioether moiety were designed and synthesized. Bioassays revealed that some target compounds at 100 μg/mL exhibited excellent antifungal activities against Thanatephorus cucumeris, such as G₆ (92.1 %), G₁₀ (94.3 %), G₁₈ (99.1 %), and G₁₉ (98.7 %), better than that of the commercial fungicide azoxystrobin (90.6 %), and the EC₅₀ value of G₁₀ against T. cucumeris was 31.9 μg/mL. Further mechanism studies of T. cucumeris treated with G₁₀ demonstrated that this compound can affect the growth of mycelia by disrupting the integrity of the membrane, and the higher the concentration of the compound is, the greater the degree of membrane integrity damage, similar to the commercial fungicide azoxystrobin. These conclusions provide important information for further mechanism studies of this series of phenylalanine derivatives.

Synthesis and Biological Evaluation of Four New Ricinoleic Acid-Derived 1-O-alkylglycerols

A series of novel substituted 1-O-alkylglycerols (AKGs) containing methoxy (8), gem-difluoro (9), azide (10) and hydroxy (11) group at 12 position in the alkyl chain were synthesized from commercially available ricinoleic acid (12). The structures of these new synthesized AKGs were established by NMR experiments as well as from the HRMS and elementary analysis data. The antimicrobial activities of the studied AKGs 8-11 were evaluated, respectively, and all compounds exhibited antimicrobial activity to different extents alone and also when combined with some commonly used antibiotics (gentamicin, tetracycline, ciprofloxacin and ampicillin). AKG 11 was viewed as a lead compound for this series as it exhibited significantly higher antimicrobial activity than compounds 8-10.

Synergistic Catalytic Synthesis of Gemini Lipoamino Acids Based on Multiple Hydrogen-Bonding Interactions in Natural Deep Eutectic Solvents-Enzyme System

In the previous studies, gemini lipoamino acids (GLAA) were always synthesized by complex multistep organic synthesis, which involved a large number of byproducts and organic solvents. To develop a straightforward, efficient, and renewable synthesis strategy for GLAA, in this study, a type of novel green solvents, natural deep eutectic solvents (NADESs), were adopted as the solvents for these reactions. Five commercial enzymes were involved in the enzyme screening section, and Candida antarctica lipase B (CALB) tended to have the best performance in NADESs systems. The optimization procedure was performed using the Taguchi crossed array method and the highest yield of GLAA (59.14 ± 0.51%) was obtained in choline chloride-glycerol (C-Gly). The purification procedure was carried out with ethyl acetate and water, and the isolate yield ranged from 86.31 ± 2.36 to 91.34 ± 2.26%. With 10 times recycling, the yield of GLAA in C-Gly decreased from 59.14 ± 0.51 to 51.31 ± 0.68%. Interestingly, a synergistic effect of CALB and NADESs was found in the enzymatic synthesis of GLAA, which can be attributed to fatty acids being activated by chloride ions via hydrogen-bonding interactions and resulting in an enhancement in its electron-attracting ability.

Lipoaminoacids Enzyme-Based Production and Application as Gene Delivery Vectors

Biosurfactant compounds have been studied in many applications, including biomedical, food, cosmetic, agriculture, and bioremediation areas, mainly due to their low toxicity, high biodegradability, and multifunctionality. Among biosurfactants, the lipoplexes of lipoaminoacids play a key role in medical and pharmaceutical fields. Lipoaminoacids (LAAs) are amino acid-based surfactants that are obtained from the condensation reaction of natural origin amino acids with fatty acids or fatty acid derivatives. LAA can be produced by biocatalysis as an alternative to chemical synthesis and thus become very attractive from both the biomedical and the environmental perspectives. Gemini LAAs, which are made of two hydrophobic chains and two amino acid head groups per molecule and linked by a spacer at the level of the amino acid residues, are promising candidates as both drug and gene delivery and protein disassembly agents. Gemini LAA usually show lower critical micelle concentration, interact more efficiently with proteins, and are better solubilising agents for hydrophobic drugs when compared to their monomeric counterparts due to their dimeric structure. A clinically relevant human gene therapy vector must overcome or avoid detect and silence foreign or misplaced DNA whilst delivering sustained levels of therapeutic gene product. Many non-viral DNA vectors trigger these defence mechanisms, being subsequently destroyed or rendered silent. The development of safe and persistently expressing DNA vectors is a crucial prerequisite for a successful clinical application, and it one of the main strategic tasks of non-viral gene therapy research.

Selective and eco-friendly synthesis of lipoaminoacid-based surfactants for food, using immobilized lipase and protease biocatalysts

Lipoaminoacids, as surfactants, are an excellent option for food industry due to the currently trends in consumption of functional and natural ingredients. Synthesis of lauroyl glycine lipoaminoacid was carried out with a lipase from Pseudomonas stutzeri and a protease from Bacillus subtilis, which were immobilized in octyl-glyoxyl silica and glyoxyl-silica supports, respectively, comparing their catalytic performance. The enzymatic selectivity towards the lipoaminoacid instead of the dipeptide glycylglycine and synthesis yield were evaluated with respect to the characteristics of the immobilized biocatalysts and synthesis conditions. Three solvents were tested as reaction media for evaluating the expressed activity, stability and catalytic behavior during synthesis. Results indicate that both enzymes favor the lauroyl glycine synthesis over the peptide synthesis, but the immobilized protease has the best balance between selectivity and yield: 40% yield for lauroyl glycine and less than 5% for dipeptide after 96h of synthesis, at 45°C and acetone as solvent.