Phenolic acids enzymatic lipophilization

Lipases in lipophilization reactions

Lipases are used in various sectors, as pharmaceutical, food or detergency industry. Their advantage versus classical chemical catalysts is that they exhibit a better selectivity and operate in milder reaction conditions. Theses enzymes can also be used in lipophilization reactions corresponding to the grafting of a lipophilic moiety to a hydrophilic one such as sugar, amino acids and proteins, or phenolic compounds. The major difficulty to overcome in such enzyme-catalyzed reaction resides in the fact that the two involved substrates greatly differ in term of polarity and solvent affinity. Therefore, several key parameters are to be considered in order to achieve the reaction in satisfactory kinetics and yields. The present review discusses the nature of such parameters (eg solvent nature, water activity, chemical modification of substrates) and illustrates their effect with examples of lipase-catalyzed lipophilization reactions of various sugar, amino acids or phenolic derivatives.

Structural characterisation by ESI-MS of feruloylated arabino-oligosaccharides synthesised by chemoenzymatic esterification

The chemoenzymatic synthesis of feruloylated arabino-oligosaccharides has been achieved, using a feruloyl esterase type C from Sporotrichum thermophile (StFaeC). The structure of the feruloylated products was confirmed by ESI-MS(n).

The feruloyl esterase system of Talaromyces stipitatus: Determining the hydrolytic and synthetic specificity of TsFaeC

The active site of the recombinant Talaromyces stipitatus type-C feruloyl esterase (TsFaeC) was probed using a series of C1-C4 alkyl ferulates and methyl esters of phenylalkanoic and cinnamic acids. The enzyme was active on 23 of the 34 substrates tested. Lengthening or shortening the aliphatic side chain while maintaining the same aromatic substitutions completely abolished the enzyme activity. Maintaining the phenylpropenoate structure but altering the substitutions of the aromatic ring demonstrated the importance of hydroxyl groups on meta and/or para position of the benzoic ring. The highest catalytic efficiency of TsFaeC for methyl cinnamates was shown on methyl 3,4-dihydroxy cinnamate and on its hydro form (3,4-dihydroxy-phenyl-propionate). Maintaining the ferulate structure but altering the esterified alkyl group, the comparison of k(cat) and k(cat)/K(m) values showed that the enzyme hydrolysed faster and more efficiently than ethyl ferulate. Alkyl ferulates were applied also for substrate selectivity mapping of feruloyl esterase to catalyze feruloyl group transfer to l-arabinose, using as a reaction system a ternary water-organic mixture consisting of n-hexane, t-butanol and water. The reaction parameters affecting the feruloylation rate and the conversion of the enzymatic synthesis, such as the composition of the reaction media, temperature, substrate and enzyme concentration have been investigated.

Regioselective esterase-catalyzed feruloylation of L-arabinobiose

The regioselective chemoenzymatic synthesis of O-[5-O-(trans-feruloyl)-alpha-L-arabinofuranosyl]-(1-->5)-L-arabinofuranose has been achieved. The reaction parameters affecting the feruloylation rate and conversion of the enzymatic synthesis, such as the composition of the reaction medium, substrate and enzyme concentration, have been investigated.

Astonishing diversity of natural surfactants: 5. Biologically active glycosides of aromatic metabolites

This review article presents 342 aromatic glycosides, isolated from and identified in plants and microorganisms, that demonstrate different biological activities. They are of great interest, especially for the medicinal and/or pharmaceutical industries. These biologically active natural surfactants are good prospects for the future chemical preparation of compounds useful as antioxidant, anticancer, antimicrobial, and antibacterial agents. These glycosidic compounds have been classified into several groups, including simple aromatic compounds, stilbenes, phenylethanoids, phenylpropanoids, naphthalene derivatives, and anthracene derivatives.