Anti-Aspergillus activity of green coffee 5-O-caffeoyl quinic acid and its alkyl esters.

The antifungal activities of 5-O-caffeoyl quinic acid (5-CQA) and of methyl, butyl, octyl, and dodecyl esters or 5-CQA, were tested on five toxigenic moulds from the Aspergillus genus (Aspergillus flavus, Aspergillus nomius, Aspergillus ochraceus, Aspergillus parasiticus, Aspergillus westerdijkiae). These mycotoxin producers' moulds may contaminate many types of food crops throughout the food chain posing serious health hazard to animals and humans. The use of chemical methods to decrease mycotoxin producer moulds contamination on food crops in the field, during storage, and/or during processing, has been proved to be efficient. In this work, the antifungal effect of 5-CQA and a homologous series of 5-CQA esters (methyl, butyl, octyl, dodecyl), was investigated using the microdilution method and the minimum inhibitory concentrations (MIC50 and MIC80). All molecules presented antifungal activity, and two esters showed a MIC for all fungi: octyl (MIC50 ≤ 0.5-0.75 mg/mL, MIC80 = 1.0-1.5 mg/mL) and dodecyl (MIC50 = 0.75-1.25 mg/mL) chlorogenates. Dodecyl chlorogenate showed a MIC80 (1.5 mg/mL) only for A. parasiticus. The maximum percent of growth inhibition on aspergillii was observed with octyl (78.4-92.7%) and dodecyl (54.5-83.7%) chlorogenates, being octyl chlorogenate the most potent antifungal agent. It was thus concluded that lipophilization improved the antifungal properties of 5-CQA, which increased with the ester alkyl chain length, exhibiting a cut-off effect at 8 carbons. As far as we know, it is the first report demonstrating that lipophilization may improve the antifungal activity of 5-CQA on five toxigenic moulds from the Aspergillus genus. Lipophilization would be a novel way to synthesize a new kind of antifungal agents with a good therapeutic value or a potential use as preservative in food or cosmetics.

New highly hydrated cellulose microfibrils with a tendril helical morphology extracted from agro-waste material: application to removal of dyes from waste water.

Cocoa bean shells (CBS) are a by-product of the cocoa bean processing industry. They represent 12-20 wt% of dry cocoa beans, after having been separated from these by a roasting process. CBS often end up as a waste product which contains around 34 wt% of cellulose. The transformation of this waste into valuable and marketable products would help to improve waste disposal. Indeed, the large annual production of this waste makes it a sustainable and renewable bio-source for the production of chemicals and fibers for advanced applications. In this work, new cellulose microfibrils (CMFs) with a tendril helical morphology and highly hydrated gel-like behavior were successfully extracted from CBS waste using a controlled chemical extraction process. During this study, several physico-chemical characterizations were carried out in order to identify the properties of each of the products at different stages of treatment. Microscopic observations show that the extracted CMFs have a tendril helical shape like climbing plant tendrils. Due to this special morphology, the extracted CMFs show a highly hydrated state forming a gel network without additional modifications. The as-extracted CMFs were used as adsorbent material for the removal of methylene blue from concentrated aqueous solution, as an application to wastewater treatment for the removal of basic dyes. Swelling properties, adsorption kinetics and isotherms were carried out in batch experiments. The results indicated that the CMFs have a high swelling capacity (190%). The pseudo second order model can be effectively used to evaluate the adsorption kinetics and the adsorption isotherms can also be described well by the Langmuir isotherm model with a maximum adsorption capacity of 381.68 mg g-1. Thus, the as-extracted CMFs with unique characteristics have the potential to be used as efficient adsorbent material for the removal of different cationic dyes from industrial wastewater.

Effect of cysteinyl caffeic acid, caffeic acid, and L-dopa on the oxidative cross-linking of feruloylated arabinoxylans by a fungal laccase.

To study a way to covalently link arabinoxylans and proteins using a fungal laccase from the fungus Pycnoporus cinnabarinus, the effect of cysteinyl caffeic acid on the cross-linking of wheat arabinoxylans was investigated by means of capillary viscometry and RP-HPLC of alkali labile phenolic compounds. Cysteinyl caffeic acid provoked a delay in gelation and in the consumption of the esterified ferulic acid on arabinoxylans. When reacting free ferulic acid and cysteinyl caffeic acid with laccase, the ferulic acid consumption and the dehydrodimers production were also diminished. These results suggest that cysteinyl caffeic acid is oxidized while reducing the semiquinones of ferulic acid produced by laccase. Thus, ferulic acid could not be oxidized into dimers until all cysteinyl caffeic acid was consumed, preventing the cross-linking of feruloylated arabinoxylan chains. A similar mechanism is proposed in the case of caffeic acid and of L-Dopa.

Enzymatic solubilization of arabinoxylans from isolated rye pentosans and rye flour by different endo-xylanases and other hydrolyzing enzymes. Effect of a fungal caccase on the flour extracts oxidative gelation.

Water-extractable (WEP) and water-unextractable (WUP) pentosans were isolated from a rye flour. The effect of a commercial enzyme preparation, Grindamyl S 100 (GS100), containing pentosanase activities, was investigated on WEP, WUP, a mix of WEP and WUP, and the rye flour, with the aim to monitor the solubilization and depolymerization of high molecular weight arabinoxylans and the effect on the viscosity of the reaction medium. The effects of other hydrolyzing enzymes were also tested. Three xylanases were used: xylanase 1 (Xyl-1) from Aspergillus niger, the main activity present in GS100; xylanase 2 (Xyl-2) from Talaromyces emersonii; and xylanase 3 (Xyl-3) from Bacillus subtilis. Xyl-3 was used in combination with Xyl-1, (1,4)-beta-D-arabinoxylan arabinofuranohydrolase, endo-beta-D-glucanase, or ferulate esterase from A. niger, but no synergism was observed. GS100 and xylanases increased the arabinoxylan solubilization, Xyl-3 and Xyl-1 being those that presented the best yields of extraction without extensive depolymerization of water-extractable arabinoxylans. Both xylanases were affected by an inhibitor in rye flour. Flour treated with hot ethanol was used to study the oxidative gelation of flour extracts treated with xylanases, in the presence of laccase from Pycnoporus cinnabarinus. Two doses of xylanases were tested (0.5 and 2.5 units). Only the flour extracts treated with 0.5 unit of Xyl-1 thickened.