title: Phenylpropanoid glycoside analogues: enzymatic synthesis, antioxidant activity and theoretical study of their free radical scavenger mechanism.
abstract: Phenylpropanoid glycosides (PPGs) are natural compounds present in several medicinal plants that have high antioxidant power and diverse biological activities. Because of their low content in plants (less than 5% w/w), several chemical synthetic routes to produce PPGs have been developed, but their synthesis is a time consuming process and the achieved yields are often low. In this study, an alternative and efficient two-step biosynthetic route to obtain natural PPG analogues is reported for the first time. Two galactosides were initially synthesized from vanillyl alcohol and homovanillyl alcohol by a transgalactosylation reaction catalyzed by Kluyveromyces lactis β-galactosidase in saturated lactose solutions with a 30%-35% yield. To synthesize PPGs, the galactoconjugates were esterified with saturated and unsaturated hydroxycinnamic acid derivatives using Candida antarctica Lipase B (CaL-B) as a biocatalyst with 40%-60% yields. The scavenging ability of the phenolic raw materials, intermediates and PPGs was evaluated by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) method. It was found that the biosynthesized PPGs had higher scavenging abilities when compared to ascorbic acid, the reference compound, while their antioxidant activities were found similar to that of natural PPGs. Moreover, density functional theory (DFT) calculations were used to determine that the PPGs antioxidant mechanism proceeds through a sequential proton loss single electron transfer (SPLET). The enzymatic process reported in this study is an efficient and versatile route to obtain PPGs from different phenylpropanoid acids, sugars and phenolic alcohols.
authors.affiliation: Departamento Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.
authors.forename: Agustín
authors.initials: A
authors.lastname: López-Munguía
authors.forename: Yanet
authors.initials: Y
authors.lastname: Hernández-Romero
authors.forename: José
authors.initials: J
authors.lastname: Pedraza-Chaverri
authors.forename: Alfonso
authors.initials: A
authors.lastname: Miranda-Molina
authors.forename: Ignacio
authors.initials: I
authors.lastname: Regla
authors.forename: Ana
authors.initials: A
authors.lastname: Martínez
authors.forename: Edmundo
authors.initials: E
authors.lastname: Castillo
mesh_terms: D001592:Benzyl Alcohols / Q000737:chemistry; D002109:Caffeic Acids / Q000737:chemistry; D003373:Coumaric Acids / Q000737:chemistry; D016166:Free Radical Scavengers / Q000138:chemical synthesis* / Q000737:chemistry*; D005656:Fungal Proteins; D005690:Galactose / Q000737:chemistry; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry; D007716:Kluyveromyces / Q000201:enzymology; D008049:Lipase / Q000378:metabolism*; D011789:Quantum Theory; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D001592:Benzyl Alcohols; D002109:Caffeic Acids; D003373:Coumaric Acids; D016166:Free Radical Scavengers; D005656:Fungal Proteins; D006027:Glycosides; D006878:Hydroxides; C000995:3,4-dihydroxyphenylpropionic acid; C031356:hydroxide ion; D008049:Lipase; C431349:lipase B, Candida antarctica; D001616:beta-Galactosidase; C520807:dihydroferulic acid; D005690:Galactose; C024078:vanillyl alcohol