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Phenylpropanoid glycoside analogues: enzymatic synthesis, antioxidant activity and theoretical study of their free radical scavenger mechanism.

López-Munguía A, Hernández-Romero Y, Pedraza-Chaverri J, Miranda-Molina A, Regla I, Martínez A, Castillo E - PLoS ONE (2011)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Departamento Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.

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.

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Full electron donator acceptor map (FEDAM).Dashed lines are only included to aid visualization. Adapted from reference 48 b.
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pone-0020115-g004: Full electron donator acceptor map (FEDAM).Dashed lines are only included to aid visualization. Adapted from reference 48 b.

Mentions: For the ET reaction and the second step of the SPLET mechanism, the electron donor capacity of anti and (anti−H) −1 is important. A simple way to analyze the relative feasibility to donate or accept charge among a set of chemical compounds for full electron transfer processes has been recently reported [48a], [48b]. It is well-known that to characterize the ability to donate or to accept electrons, IEs and EAs are adequate parameters. To analyze the ET process between radical scavengers and free radicals, a full electron donator acceptor map (FEDAM) was defined (Figure 4).


Phenylpropanoid glycoside analogues: enzymatic synthesis, antioxidant activity and theoretical study of their free radical scavenger mechanism.

López-Munguía A, Hernández-Romero Y, Pedraza-Chaverri J, Miranda-Molina A, Regla I, Martínez A, Castillo E - PLoS ONE (2011)

Full electron donator acceptor map (FEDAM).Dashed lines are only included to aid visualization. Adapted from reference 48 b.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3108595&req=5

pone-0020115-g004: Full electron donator acceptor map (FEDAM).Dashed lines are only included to aid visualization. Adapted from reference 48 b.
Mentions: For the ET reaction and the second step of the SPLET mechanism, the electron donor capacity of anti and (anti−H) −1 is important. A simple way to analyze the relative feasibility to donate or accept charge among a set of chemical compounds for full electron transfer processes has been recently reported [48a], [48b]. It is well-known that to characterize the ability to donate or to accept electrons, IEs and EAs are adequate parameters. To analyze the ET process between radical scavengers and free radicals, a full electron donator acceptor map (FEDAM) was defined (Figure 4).

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Departamento Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.

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.

Show MeSH