Sesquiterpene lactones enriched-fractions obtained from Cynara cardunculus extract diaultrafiltration
Daniela Rosa, Teresa Brás, Carlos Rial, Rosa M. Varela, Benvindo Maçãs, Francisco A. Macı́as, Maria F. Duarte
Abstract
Sesquiterpene lactones (SL) are allelopathic compounds that demonstrate great potential of use in sustainable weed management. In this study, membrane processing technology was used for ethanolic Cynara cardunculus leaves extract (CcLE) ultra- and nanofiltration to produce SL-enriched fractions with increased phytotoxic activity. Experiments were conducted to select an ultrafiltration membrane (DuraMem500, DuraMem900 and SuezGH2000) for SL recovery and high molecular weight compounds (MWC) removal. SuezGH2000, which had rejection percentage of 50 % and 88 % for cynaropicrin (Cyn) and chlorophyll, respectively, was used for a sequential purification along with DuraMem200 for lower MWC removal. Since Cyn content on initial feed (11.9 %) and permeate (11.2 %) were similar, as well as phytotoxic activity, the results suggested that DuraMem200 was unsuitable for CcLE fractionation. SuezGH2000 revealed a slight increase on SL content, so, the permeation profile and enhancement of SL content were evaluated. An increase on SL content (36.0–71.0 %) was obtained after 2.3 diavolumes, followed by a decrease between 2.6 and 4.7 diavolumes. Phytotoxic activity evaluations revealed a direct association with SL content with enhancement of activity, particularly at inhibiting shoot growth of Portulaca oleracea . This study revealed SuezGH2000 effectiveness on SL purity improvement on CcLE fractions after 2.3 diavolumes and its potential to be used as a bioherbicide active component. • Enriched fractions were obtained through membrane processing technology. • Suez™GH showed better separation between cynaropicrin and chlorophylls. • Suez™GH enhanced sesquiterpene lactones content from 36 % to 71 %. • Enriched fractions showed enhanced phytotoxic activity against Portulaca oleracea.