Enzymatic removal of carboxyl protecting groups. III. Fast removal of allyl and chloroethyl esters by Bacillus subtilis esterase (BS2)

(Chemical Equation Presented) An esterase from Bacillus subtilis (BS2) allows the fast and selective removal of allyl, 2-chloroethyl, and 2,2,2-chloroethyl esters under mild conditions in high yields. In addition, BS2 easily hydrolyzes phenacyl esters, while the hydrolysis of sterically hindered diphenylmethyl esters is slow, requiring longer reaction time and higher enzyme/substrate ratio. © 2007 American Chemical Society

Enzymatic removal of carboxyl protecting groups. 2. Cleavage of the benzyl and methyl moieties

Enzymes are versatile reagents for the efficient removal of methyl and benzyl protecting groups. An esterase from Bacillus subtilis (BS2) and a lipase from Candida antarctica (CAL-A) allow a mild and selective removal of these moieties in high yields without affecting other functional groups. © 2005 American Chemical Society

Resolution of N-Protected amino alcohols by porcine pancreatic lipase

The resolution of 2-amino alcohols protected by urethane-type groups either via porcine pancreatic lipase (PPL) hydrolysis of the corresponding racemic acetates or via PPL catalyzed transesterification of racemic alcohols was studied. In both cases, Boc protecting group led to better chemical yields and enantiopurities than Z and Fmoc protecting groups. Furthermore, a simple and efficient method for the synthesis of the medicinally interesting optically pure (R)-2- aminohexadecanol was developed. © 2010 Bentham Science Publishers Ltd

Study of the removal of allyl esters by Candida antarctica lipase B (CAL-B) and pig liver esterase (PLE)

A number of allyl esters of various carboxylic acids and N-protected amino acids were synthesized and their hydrolysis by Candida antarctica lipase B and pig liver esterase was studied. In order to test the selectivity, the enzymatic hydrolysis of the corresponding methyl and ethyl esters was also examined. Both enzymes easily remove the allyl esters of monocarboxylates. The chemo- and regio-selectivity for the hydrolysis of glutamate diesters was studied, too, and it was found that the preference for the hydrolysis of a particular ester group depends not only on the ease of the hydrolysis observed for the esters of monocarboxylic acids, but also on the position (α- or γ-). © 2009 Elsevier B.V. All rights reserved

Enzymatic removal of carboxyl protecting groups. 1. Cleavage of the tert-butyl moiety

(Chemical Equation Presented) A recent discovery that a certain amino acid motif (GGG-(A)X-motif) in lipases and esterases determines their activity toward tertiary alcohols prompted us to investigate the use of these biocatalysts in the mild and selective removal of tert-butyl protecting groups in amino acid derivatives and related compounds. An esterase from Bacillus subtilis (BsubpNBE) and lipase A from Candida antarctica (CAL-A) were identified as the most active enzymes, which hydrolyzed a range of tert-butyl esters of protected amino acids (e.g., Boc-Tyr-OtBu, Z-GABA-OtBu, Fmoc-GABA-O tBu) in good to high yields and left Boc, Z, and Fmoc-protecting groups intact. © 2005 American Chemical Society

The Microbiota Is Essential for the Generation of Black Tea Theaflavins-Derived Metabolites

BACKGROUND: Theaflavins including theaflavin (TF), theaflavin-3-gallate (TF3G), theaflavin-3′-gallate (TF3′G), and theaflavin-3,3′-digallate (TFDG), are the most important bioactive polyphenols in black tea. Because of their poor systemic bioavailability, it is still unclear how these compounds can exert their biological functions. The objective of this study is to identify the microbial metabolites of theaflavins in mice and in humans. METHODS AND FINDINGS: In the present study, we gavaged specific pathogen free (SPF) mice and germ free (GF) mice with 200 mg/kg TFDG and identified TF, TF3G, TF3′G, and gallic acid as the major fecal metabolites of TFDG in SPF mice. These metabolites were absent in TFDG- gavaged GF mice. The microbial bioconversion of TFDG, TF3G, and TF3′G was also investigated in vitro using fecal slurries collected from three healthy human subjects. Our results indicate that TFDG is metabolized to TF, TF3G, TF3′G, gallic acid, and pyrogallol by human microbiota. Moreover, both TF3G and TF3′G are metabolized to TF, gallic acid, and pyrogallol by human microbiota. Importantly, we observed interindividual differences on the metabolism rate of gallic acid to pyrogallol among the three human subjects. In addition, we demonstrated that Lactobacillus plantarum 299v and Bacillus subtilis have the capacity to metabolize TFDG. CONCLUSIONS: The microbiota is important for the metabolism of theaflavins in both mice and humans. The in vivo functional impact of microbiota-generated theaflavins-derived metabolites is worthwhile of further study