Cymbopogon winterianus essential oil as an alternative source for producing terpenic esters with potential plant-protective antifungal activity using lipase immobilized on a lignin composite

Abstract

Enzymatic esterification was evaluated as an alternative route to synthesis a new semi-synthetics compounds from Cymbopogon winterianus oil that can be applied as greener pesticides. The oil's major constituents were citronellal (40.32 % v/v), geraniol (26.77 % v/v) and citronellol (8.64 % v/v). Esterification catalyzed by lipase B from Candida antarctica immobilized on magnetic cashew apple bagasse lignin resulted in yields of 96.1 % for citronellyl butyrate and 96.9 % for geranyl butyrate after 24 h, significantly higher than the yields obtained by free enzyme, being 41.9 % and 52.2 %, respectively. The biocatalyst remained stable over five reaction cycles, yielding 88.1 % for citronellyl butyrate and 80.0 % for geranyl butyrate in the last cycle. The antifungal activity of citronellyl butyrate and geranyl butyrate esters against Fusarium graminearum were improved compared to its respective alcohols, showing a reduction of 66.8 % and 30.1 % in its half-maximal inhibitory concentration, respectively. The esterified citronella oil in the highest concentration evaluated (43,372 μg/mL) decreased by 87.5 % the disease incidence and thus the disease severity of Botrytis cinerea infection in Phaseolus vulgaris plants. Therefore, a pathway was proposed to obtain new value-added products which hold the potential to be applied as biopesticides for sustainable agriculture.