Novel Approach for Flavonoid Esters Production: Statistically Optimized Enzymatic Synthesis Using Natural Oils and Application in Cosmetics

Novel enzymatic synthesis of 3-Hydroxybutyryl Naringin and its molecular identification and bioactive characterization

In this study, we synthesized 6''-O-((±)-3-hydroxybutyryl)naringin (3HBN) for the first time through enzymatic esterification of naringin with 3-hydroxybutyric acid (3HB), achieving a high conversion of 80.19 % under optimized conditions within 8 h. Structural analysis via FT-IR and 1H NMR confirmed esterification at the C-6'' hydroxyl position on the glucose moiety of naringin. Although the antioxidant capacity of 3HBN was slightly reduced compared to naringin, its enhanced lipophilicity (log P = -0.05) indicates improved bioavailability and potential for cellular absorption. Bioactivity evaluations confirmed that 3HBN exhibited stronger anti-inflammatory effects than naringin by reducing TNF-α and increasing IL-10 in LPS-stimulated immune cells. These findings suggest that 3HBN is a promising bioactive compound with potential applications across the food, cosmetic, and pharmaceutical industries, offering both enhanced stability and effective bioactivity for targeted health benefits.

Ultrasonication-assisted lipase-catalyzed esterification of chlorogenic acid: A comparative study using fatty alcohol and acids in solvent and solvent-free conditions

Chlorogenic acid, a well-known antioxidant, has potential applications in health care, food, and cosmetic sectors. However, its low solubility hinders its application at the industrial scale. The primary goal of the present study was to increase the lipophilic property of chlorogenic acid through esterification using an ultrasonication approach and Novozym® 435 as the catalyst. The esterification was executed in two ways. In the first method, chlorogenic acid was converted to chlorogenic acid ester using octanol in a solvent-free reaction. Catalytic factors such as reaction time (12 h ∼ 36 h), enzyme dosage (10 ∼ 50 mg), and ultrasonication power (90 ∼ 150 W) were optimized using Box-Behnken design (BBD) while temperature (60 ℃) and molar ration (chlorogenic acid/octanol, 1:500) were kept constant. A maximum conversion rate of 95.3 % was achieved when the esterification was performed for 12 h at 120 W ultrasonication power and 50 mg enzyme dosage. Contrary to the first method, when esterification was done using caprylic acid in the presence of 2-methyl-2-butanol as a solvent, the conversion rate was relatively low. Despite optimization of factors including molar ratio, enzyme dosage, and reaction time, the highest conversion rate achieved was of only 36.8 %. Moreover, molecular docking results revealed that the lowest binding energy was between lipase and octanol. The finding of the study clearly stated that the esterification of chlorogenic acid was more effective in a solvent-free condition as compared to in the presence of solvent.

In vitro skin permeation of flavonoid esters enzymatically derived from natural oils: release mechanism from gel emulsion, stability, and dermatological compatibility

Due to their broad spectrum of biological activities and attractive pharmacological properties, flavonoids are very promising molecules for application in skin care products. In this study, phloridzin and naringin medium- and long-chain fatty acid esters were enzymatically synthesized in reaction with natural oils (coconut and linseed oil) and in vitro transdermal delivery of synthesized esters through artificial Strat-M® membrane was investigated. Experimental results were succesfully fitted using Peppas and Sahlin model which includes the lag phase. Release kinetics of all examined flavonoid esters from gel emulsions through the membrane depended on both diffusion and polymer relaxation effect (0.5 Collapse

Key Words

• Flavonoids
• Strat® M
• enzymatic esterification
• natural oils
• skin permeation

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MESH Headings

• Emulsions
• Skin Absorption/drug effects
• Esters/chemistry
• Flavonoids/administration & dosage
• Flavonoids/pharmacokinetics
• Flavonoids/chemistry
• Gels
• Skin/metabolism
• Administration, Cutaneous
• Plant Oils/chemistry
• Animals

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Affiliation(s)

Ana Milivojević Faculty of Technology and Metallurgy, Department of Biochemical Engineering and Biotechnology, University of Belgrade, Belgrade, Serbia
Marija Ćorović Faculty of Technology and Metallurgy, Department of Biochemical Engineering and Biotechnology, University of Belgrade, Belgrade, Serbia
Anja Petrov Ivanković Innovation Center of Faculty of Technology and Metallurgy, Belgrade, Serbia
Milica Simović Faculty of Technology and Metallurgy, Department of Biochemical Engineering and Biotechnology, University of Belgrade, Belgrade, Serbia
Katarina Banjanac Innovation Center of Faculty of Technology and Metallurgy, Belgrade, Serbia
Rada Pjanović Faculty of Technology and Metallurgy, Department of Chemical Engineering, University of Belgrade, Belgrade, Serbia
Dejan Bezbradica Faculty of Technology and Metallurgy, Department of Biochemical Engineering and Biotechnology, University of Belgrade, Belgrade, Serbia

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Enzymatic Modification of Pomace Olive Oil with Natural Antioxidants: Effect on Oxidative Stability

Enzymatic lipophilization has been proposed as a cost-effective strategy to produce new liposoluble antioxidant compounds. In this study, modified oils rich in structured phenolipids were prepared via one-pot enzymatic acylation of hydroxytyrosol (HTYR), vanillyl alcohol (VA) and homovanillyl alcohol (HVA) with pomace olive oil (POO) in solvent-free conditions using immobilized lipase on biogenic nanoparticles. The effect of temperature (30-70 °C) and enzyme concentration (0.1-1%, w/w) on the efficiency of the bioprocess as well as the reusability of the nanobiocatalyst were thoroughly investigated. The modified oils exhibited increased antioxidant activity compared to the control oil according to DPPH and CUPRAC assays (p < 0.05). The oxidative stability of pomace olive oil was also significantly enhanced after modification, as depicted by the K₂₃₂ values and TBARS contents under accelerated oxidation at 60 °C (p < 0.05). Moreover, a fortified mayonnaise containing modified oil with HTYR was prepared that was noticeably stable compared to the control mayonnaise at 28 °C for 5 months (p < 0.05). Enzymatically modified oils have great potential for application in the nutraceutical and food industry, encouraging the exploitation of immobilized lipases as effective and green catalytic tools.

Development of Water Repellent, Non-Friable Tannin-Furanic-Fatty Acids Biofoams

Tannin-furanic foams were prepared with a good yield using the addition of relatively small proportions of a polyflavonoid tannin extract esterified with either palmitic acid, oleic acid, or lauric acid by its reaction with palmitoyl chloride, oleyl chloride, or lauryl chloride. FTIR analysis allowed us to ascertain the esterification of the tannin, and MALDI-TOF analysis allowed us to identify a number of multi-esterified flavonoid oligomers as well as some linked to residual carbohydrates related to the equally esterified tannin. These foams presented a markedly decreased surface friability or no friability at all, and at densities lower than the standard foam they were compared to. Equally, these experimental foams presented a much-improved water repellence, as indicated by their initial wetting angle, its small variation over time, and its stabilization at a high wetting angle value, while the wetting angle of the standard foam control went to zero very rapidly. This conclusion was supported by the calculation of the total surface energy of their surfaces as well as of their dispersive and polar components.

Catalytic Routes to Produce Polyphenolic Esters (PEs) from Biomass Feedstocks

Polyphenolic esters (PEs) are valuable chemical compounds that display a wide spectrum of activities (e.g., anti-oxidative effects). As a result, their production through catalytic routes is an attractive field of research. The present review aims to discuss recent studies from the literature regarding the catalytic production of PEs from biomass feedstocks, namely, naturally occurred polyphenolic compounds. Several synthetic approaches are reported in the literature, mainly bio-catalysis and to a lesser extent acid catalysis. Immobilized lipases (e.g., Novozym 435) are the preferred enzymes thanks to their high reactivity, selectivity and reusability. Acid catalysis is principally investigated for the esterification of polyphenolic acids with fatty alcohols and/or glycerol, using both homogeneous (p-toluensulfonic acid, sulfonic acid and ionic liquids) and heterogeneous (strongly acidic cation exchange resins) catalysts. Based on the reviewed publications, we propose some suggestions to improve the synthesis of PEs with the aim of increasing the greenness of the overall production process. In fact, much more attention should be paid to the use of new and efficient acid catalysts and their reuse for multiple reaction cycles.

Efficient Production of Naringin Acetate with Different Acyl Donors via Enzymatic Transesterification by Lipases

Naringin, one of the citrus flavonoids and known as a natural antioxidant, has limited bioavailability owing to its low stability and solubility. However, naringin esters formed via acylation have recently been reported to possess improved physical and chemical properties. The development of these compounds has a great potential in the food, cosmetic and pharmaceutical industries, but low conversion and productivity are barriers to industrial applications. This study aimed to improve the conversion of naringin acetate, which is formed via the enzymatic reaction between naringin and an acyl donor. An optimal reaction condition was determined by evaluating the effect of various variables (enzyme type, enzyme concentration, acyl donor, molar ratio of reactants, reaction temperature, and solvent) on the synthesis of naringin acetate. The optimal condition was as follows: 3 g/L of Lipozyme TL IM, molar ratio of 1:5 (naringin:acyl donor), reaction temperature of 40 °C, and acetonitrile as the reaction solvent. Under this condition, the maximum conversion to naringin acetate from acetic anhydride and vinyl acetate was achieved at approximately 98.5% (8 h) and 97.5% (24 h), respectively. Compared to the previously reported values, a high conversion was achieved within a short time, confirming the commercial potential of the process.

Improved Productivity of Naringin Oleate with Flavonoid and Fatty Acid by Efficient Enzymatic Esterification

Naringin is a flavonoid found in citrus fruits. It exhibits biological activities, such as anticancer and antioxidant effects, but it suffers from low solubility and low stability in lipophilic systems. These drawbacks lead to difficulties in the commercial application of naringin, but they can be overcome through esterification. In this study, naringin oleate was synthesized by enzymatic esterification and optimal conditions for the reaction were investigated. Experiments were conducted focusing on the following parameters: enzyme type, enzyme concentration, molar ratio of naringin to oleic acid, reaction temperature, and reaction solvent. We further confirmed the degree of esterification based on the difference in the initial and the final naringin concentrations. A conversion of 93.10% was obtained under optimized conditions (Lipozyme TL IM 10 g/L, molar ratio 1:20, reaction temperature 40 °C, acetonitrile as solvent, and 48 h reaction time). Thus, naringin oleate, a high value-added material that overcomes the low hydrophobicity of naringin and enhances its performance, was obtained through esterification of naringin using oleic acid. This study presented a method for the efficient enzymatic synthesis that could ensure high conversion within a shorter reaction time compared with that required in previously reported methods.