Enzymatic Synthesis of Glucose Fatty Acid Esters Using SCOs as Acyl Group-Donors and Their Biological Activities

Hatim A El-Baz,Hekmat R Madian,Jazem A Mahyoub,Marianna Dourou,George Aggelis,Tamer S Saleh,Mohammed N Baeshen,Ahmed M Elazzazy

doi:10.3390/app11062700

Abstract

Sugar fatty acid esters, especially glucose fatty acid esters (GEs), have broad applications in food, cosmetic and pharmaceutical industries. In this research, the fatty acid moieties derived from polyunsaturated fatty acids containing single-cell oils (SCOs) (i.e., those produced from Cunninghamella echinulata, Umbelopsis isabellina and Nannochloropsis gaditana, as well as from olive oil and an eicosapentaenoic acid (EPA) concentrate) were converted into GEs by enzymatic synthesis, using lipases as biocatalysts. The GE synthesis was monitored using thin-layer chromatography, FTIR and in situ NMR. It was found that GE synthesis carried out using immobilized Candida antarctica B lipase was very effective, reaching total conversion of reactants. It was shown that EPA-GEs were very effective against several pathogenic bacteria and their activity can be attributed to their high EPA content. Furthermore, C. echinulata-GEs were more effective against pathogens compared with U. isabellina-GEs, probably due to the presence of gamma linolenic acid (GLA) in the lipids of C. echinulata, which is known for its antimicrobial activity, in higher concentrations. C. echinulata-GEs also showed strong insecticidal activity against Aedes aegypti larvae, followed by EPA-GEs, olive oil-GEs and N. gaditana-GEs. All synthesized GEs induced apoptosis of the SKOV-3 ovarian cancer cell line, with the apoptotic rate increasing significantly after 48 h. A higher percentage of apoptosis was observed in the cells treated with EPA-GEs, followed by C. echinulata-GEs, U. isabellina-GEs and olive oil-GEs. We conclude that SCOs can be used in the synthesis of GEs with interesting biological properties.

Highlights

Sugar fatty acid esters, the so-called sugar esters (SEs), are biodegradable, odorless, non-irritating and non-toxic surfactants with broad applications in the food [1,2], cosmetic [3] and pharmaceutical [4] industries
For glucose fatty acid esters (GEs) synthesis, the olive oil-derived free fatty acids (FFAs) and fatty acid methyl esters (FAMEs) were used as model substrates to optimize the lipase-catalyzed reaction of esterification and transesterification (Figure 1)
The reaction was carried out in a solvent system consisting of a tert-amyl alcohol and DMSO mixture as described elsewhere [11,40,41] for 50 h at 55 ◦ C with shaking at 100 rpm, and the progress of the reaction was monitored by thin-layer chromatography (TLC) analysis

Summary

Introduction

The so-called sugar esters (SEs), are biodegradable, odorless, non-irritating and non-toxic surfactants with broad applications in the food [1,2], cosmetic [3] and pharmaceutical [4] industries. SEs are synthesized from renewable resources, such as sugars and fatty acids (FAs). Different types of sugars (e.g., sucrose, fructose, glucose and lactose) can be used as acylacceptors to produce SEs by esterification with FAs or transesterification with FA esters used as acyl-donors [7,8,9]. Glucose (Glc), a cheap and broadly available carbohydrate, has only one primary hydroxyl group, which predetermines a highly regioselective synthesis of SEs called glucose fatty acid esters (GEs) [10,11]. GEs can be synthesized both chemically and enzymatically [15,16]. Available immobilized lipases, such as Candida antarctica B lipase, are used to catalyze the acylation of glucose with various FAs [20,21]

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