Abstract:

A "green" method available for the epoxidation of alkenes (terpenes), based on the perhydrolysis of carboxylic acids and esters, is through the use of lipases (triacylglycerol hydrolases, 3.1.1.3.) in the presence of an oxidizing agent. In this study, twelve commercial lipases from different sources, that is, Candida antarctica B (CAL-B, 10,000 PLU/g); Burkholderia cepacia (PS-C Amano® I, 1.638 U/g); PS Amano® SD; 30,000 U/g; PS Amano®, 30,000 U/g; PS Amano® IM, 500u/g; PS-C Amano® II, 1,000 U/g; Rhizopus oryzae (150 u/mg); Candida rugosa (30,000 u/g); Pseudomonas fluorescens (26,600 U/g); Aspergillus niger (120,000 u/g); Rhizomucor miehei (5-6 BAUN/g); and Mucor miehei (5-6 BAUN/g), were used in the chemoenzymatic epoxidation of caryophyllene (0.6 mL, 2.5 mmol) using aqueous hydrogen peroxide (1.2 mL, 30%) as the oxidant agent and octanoic acid (0.16 mL, 1 mmol) as the acyl donor in dichloromethane at ~25°C. Also, two native lipases from A. niger (LAN 18.2 U/mL) and Rhizopus oligosporus, (LRO 14.9 U/mL) isolated from microorganisms of a soil from the Bueno Brandão region (MG, Brazil), and nine mycelium-bound lipases from Amazon region fungi (UEA_01, UEA_06, UEA_07, UEA_23, UEA_27, UEA_28, UEA_41, UEA_53 and UEA_115), were screened in this study (Scheme 1).