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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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Lipase-catalyzed acylation of galactosides.30 mM of aromatic galactosides were reacted with an equivalent amount of donor substrates with Novozym 435 (20 mg/mL) and 100 mg/mL of molecular sieves (5Å, 8–12 mesh) in 2-methyl-2-propanol. The enzymatic reaction was carried out for 24 h at 75°C with constant stirring.
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pone-0020115-g003: Lipase-catalyzed acylation of galactosides.30 mM of aromatic galactosides were reacted with an equivalent amount of donor substrates with Novozym 435 (20 mg/mL) and 100 mg/mL of molecular sieves (5Å, 8–12 mesh) in 2-methyl-2-propanol. The enzymatic reaction was carried out for 24 h at 75°C with constant stirring.

Mentions: In the present study, we describe an alternative and efficient two-step biosynthetic route to obtain bifunctional analogs of PPG. The first step is related to the galactosylation of vanillyl alcohol (1) and homovanillyl alcohol (2) performed with a β-galactosidase from K. lactis (Figure 2). The second step concerns to an esterification reaction between dihydroferulic or dihydrocaffeic acids and the primary hydroxyls of the galactosyl residue using CaL-B (Figure 3). In order to analyze if the antioxidant ability is modified in these new compounds, we investigated the effect of structural differences on the free radical scavenging ability of substrates and PPGs with the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) assay. The structural differences included the length of the aliphatic chain in the aglycon, the presence of α-β unsaturation in the propanoid chain of the acyl residue and the number of hydroxyl groups in the aromatic rings.


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)

Lipase-catalyzed acylation of galactosides.30 mM of aromatic galactosides were reacted with an equivalent amount of donor substrates with Novozym 435 (20 mg/mL) and 100 mg/mL of molecular sieves (5Å, 8–12 mesh) in 2-methyl-2-propanol. The enzymatic reaction was carried out for 24 h at 75°C with constant stirring.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0020115-g003: Lipase-catalyzed acylation of galactosides.30 mM of aromatic galactosides were reacted with an equivalent amount of donor substrates with Novozym 435 (20 mg/mL) and 100 mg/mL of molecular sieves (5Å, 8–12 mesh) in 2-methyl-2-propanol. The enzymatic reaction was carried out for 24 h at 75°C with constant stirring.
Mentions: In the present study, we describe an alternative and efficient two-step biosynthetic route to obtain bifunctional analogs of PPG. The first step is related to the galactosylation of vanillyl alcohol (1) and homovanillyl alcohol (2) performed with a β-galactosidase from K. lactis (Figure 2). The second step concerns to an esterification reaction between dihydroferulic or dihydrocaffeic acids and the primary hydroxyls of the galactosyl residue using CaL-B (Figure 3). In order to analyze if the antioxidant ability is modified in these new compounds, we investigated the effect of structural differences on the free radical scavenging ability of substrates and PPGs with the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) assay. The structural differences included the length of the aliphatic chain in the aglycon, the presence of α-β unsaturation in the propanoid chain of the acyl residue and the number of hydroxyl groups in the aromatic rings.

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