BIOSYNTHESIS OF CITRONELLYL PENTANOATE WITH ENHANCED ANTIFUNGAL ACTIVITY USING LIGNIN-BASED MAGNETIC BIOCATALYSTS

Terpenic esters are compounds of considerable industrial relevance that can be obtained through direct extraction or chemical synthesis. However, these conventional approaches present limitations, making biotechnological production a promising and sustainable alternative. In this study, it was investigated the biosynthesis of citronellyl pentanoate using lipase B from Candida antarctica (CALB) and lipase from Rhizomucor miehei (RML), either in soluble form or immobilized on magnetic cashew apple bagasse (CAB) lignin. After immobilization, the enzymes exhibited satisfactory activity (12.6 ± 0.7 U.g^-1 for CALB; 13.1 ± 0.1 U.g^-1 for RML) and high immobilization yields (71.5 ± 1.2% for CALB; and 79.9 ± 4.6% for RML). Biotransformation assays revealed that the optimal reaction conditions were 50 °C and a 1:1 alcohol-to-acid molar ratio, achieving conversion of citronellol above 90% within 24h for immobilized lipases. The operational stability of the biocatalyst was evaluated over 10 reaction cycles of 24h, verifying that the catalytic activity was maintained, with conversions above 80% at the last cycle. The citronellyl pentanoate attained chromatographic purity of 97.3% and its antimicrobial activity was evaluated. Against Staphylococcus aureus, inhibition zones were 15mm for the ester and 19.5mm for the citronellol, while against Escherichia coli they were 18.5mm and 20mm, respectively. The citronellyl pentanoate showed greater antifungal activity against Fusarium graminearum DSM 4528 than the precursor alcohol (IC₅₀ reduced by ~68%), while it presented less antibacterial activity effectiveness against Pseudomonas syringae pv. tomato DC3000. These results highlight the selective bioactivity of terpenic esters and their potential as targeted antifungal agents. Overall, the synthesis of citronellyl pentanoate proved efficient, achieving high yields with promising biotechnological potential.