title: Efficient synthesis of hydroxystyrenes via biocatalytic decarboxylation/deacetylation of substituted cinnamic acids by newly isolated Pantoea agglomerans strains.
abstract: BACKGROUND
  Decarboxylation of substituted cinnamic acids is a predominantly followed pathway for obtaining hydroxystyrenes-one of the most extensively explored bioactive compounds in the food and flavor industry (e.g. FEMA GRAS approved 4-vinylguaiacol). For this, mild and green strategies providing good yields with high product selectivity are needed.
  
  
  RESULTS
  Two newly isolated bacterial strains, i.e. Pantoea agglomerans KJLPB4 and P. agglomerans KJPB2, are reported for mild and effective decarboxylation of substituted cinnamic acids into corresponding hydroxystyrenes. Key operational parameters for the process, such as incubation temperature, incubation time, substrate concentration and effect of co-solvent, were optimized using ferulic acid as a model substrate. With strain KJLPB4, 1.51 g L⁻¹ 4-vinyl guaiacol (98% yield) was selectively obtained from 2 g L⁻¹ ferulic acid at 28 °C after 48 h incubation. However, KJPB2 provided vanillic acid in 85% yield after 72 h following the oxidative decarboxylation pathway. In addition, KJLPB4 was effectively exploited for the deacetylation of acetylated α-phenylcinnamic acids, providing corresponding compounds in 65-95% yields.
  
  
  CONCLUSIONS
  Two newly isolated microbial strains are reported for the mild and selective decarboxylation of substituted cinnamic acids into hydroxystyrenes. Preparative-scale synthesis of vinyl guaiacol and utilization of renewable feedstock (ferulic acid extracted from maize bran) have been demonstrated to enhance the practical utility of the process.
authors.affiliation: Natural Plant Products Division, Institute of Himalayan Bioresource Technology, Council of Scientific and Industrial Research, Palampur-176061, HP, India.
authors.forename: Upendra K
authors.initials: UK
authors.lastname: Sharma
authors.forename: Nandini
authors.initials: N
authors.lastname: Sharma
authors.forename: Richa
authors.initials: R
authors.lastname: Salwan
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
authors.forename: Ramesh C
authors.initials: RC
authors.lastname: Kasana
authors.forename: Arun K
authors.initials: AK
authors.lastname: Sinha
mesh_terms: D000107:Acetylation; D001426:Bacterial Proteins / Q000378:metabolism*; D055162:Biocatalysis; D002934:Cinnamates / Q000737:chemistry / Q000378:metabolism*; D003373:Coumaric Acids / Q000737:chemistry / Q000378:metabolism; D005240:Feasibility Studies; D005421:Flavoring Agents / Q000737:chemistry / Q000378:metabolism*; D005503:Food Additives / Q000737:chemistry / Q000378:metabolism*; D006139:Guaiacol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D006900:Hydroxylation; D007194:India; D015394:Molecular Structure; D058889:Molecular Typing; D010084:Oxidation-Reduction; D020636:Pantoea / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D012988:Soil Microbiology; D012997:Solvents / Q000737:chemistry; D013045:Species Specificity; D013379:Substrate Specificity; D014641:Vanillic Acid / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002934:Cinnamates; D003373:Coumaric Acids; D005421:Flavoring Agents; D005503:Food Additives; D012997:Solvents; D006139:Guaiacol; C014245:4-vinylguaiacol; C004999:ferulic acid; D014641:Vanillic Acid