Carica papaya lipase: An effective biocatalyst for esterification resolution of (RS)-2-(chlorophenoxy)propionic acid

Synthesis of enantiomerically pure 2-aryloxy carboxylic acids and their derivatives

Recent publications on the key preparation methods of the enantiomers of 2-aryloxy carboxylic acids are summarized and comparative analysis of the methods is given. The information is arranged according to the type of the starting compound, being classified into syntheses from enantiomerically pure chiral precursors and syntheses from prochiral precursors, which imply generation of an asymmetric centre in the substrate molecule. Data on the chemical resolution of racemic mixtures of the title compounds are addressed in a separate Section. Attention is focused on the preparation of practically valuable 2-aryloxy acids. Examples of biologically active derivatives of 2-aryloxy carboxylic acids are given.

The bibliography includes 121 references.

(R,S)-2-chlorophenoxyl pyrazolides as novel substrates for improving lipase-catalyzed hydrolytic resolution

The best reaction condition of Candida antartica lipase B as biocatalyst, 3-(2-pyridyl)pyrazole as leaving azole, and water-saturated methyl t-butyl ether as reaction medium at 45°C were first selected for performing the hydrolytic resolution of (R,S)-2-(4-chlorophenoxyl) azolides (1-4). In comparison with the kinetic resolution of (R,S)-2-phenylpropionyl 3-(2-pyridyl)pyrazolide or (R,S)-α-methoxyphenylacetyl 3-(2-pyridyl)pyrazolide at the same reaction condition, excellent enantioselectivity with more than two order-of-magnitudes higher activity for each enantiomer was obtained. The resolution was then extended to other (R,S)-3-(2-pyridyl)pyrazolides (5-7) containing 2-chloro, 3-chloro, or 2,4-dichloro substituent, giving good (E > 48) to excellent (E > 100) enantioselectivity. The thermodynamic analysis for 1, 2, and 4-7 demonstrates profound effects of the acyl or leaving moiety on varying enthalpic and entropic contributions to the difference of Gibbs free energies. A thorough kinetic analysis further indicates that on the basis of 6, the excellent enantiomeric ratio for 4 and 7 is due to the higher reactivity of (S)-4 and lower reactivity of (R)-7, respectively.

Carica papaya lipase: a naturally immobilized enzyme with interesting biochemical properties

Triacylglycerol (TAG) lipases have been thoroughly characterized in mammals and microorganisms, whereas very little is known about plant TAG lipases. The lipolytic activity occurring in all the laticies is known to be associated with sedimentable particles, and all attempts to solubilize the lipolytic activity of Carica papaya latex have been unsuccessful so far. However, some of the biochemical properties of the lipase from Carica papaya latex (CPL) were determined from the insoluble fraction of the latex. The activity was optimum at a temperature of 37°C and a pH of 9.0, and the specific activities of CPL were found to be 2,000 ± 185 and 256 ± 8 U/g when tributyrin and olive oil were used as substrates, respectively. CPL was found to be active in the absence of any detergent, whereas many lipases require detergent to prevent the occurrence of interfacial denaturation. CPL was inactive in the presence of micellar concentrations of Triton X-100, sodium dodecyl sulfate (SDS) and tetradecyl trimethylammonium bromide (TTAB), and still showed high levels of activity in the presence of sodium taurodeoxycholate (NaTDC) and the zwitterionic Chaps detergent. The effects of various proteases on the lipolytic activity of CPL were studied, and CPL was found to be resistant to treatment with various enzymes, except in the presence of trypsin. All these properties suggest that CPL may be a good candidate for various biotechnological applications.