Coffee husk valorization through choline chloride/lactic acid (1:10) green catalyst extraction for lignin monomers recovery

The processing of coffee consists on the separation of the grains from other parts of the fruit, then roasted and extracted to obtain the beverage that is so appreciated worldwide. Several studies have dedicated efforts to treat the residue from coffee processing, while recovering lignols of industrial interest. Given this scenario, the nutrients in the coffee husk can enhance microbial growth, providing optimal conditions for the microorganisms to produce metabolites that may have medicinal properties. Deep eutectic solvents (DES) are a class of solvents and/or catalysts designed on demand for specific uses, being used to enhance extraction processes of coffee husk. Our present study was successful establishing conditions where the coffee husk enhanced the growth of microorganisms from two Brazilian biomes, the endophytic fungus from Cerrado and the actinomycete, from Atlantic Rainforest in Boraceia, São Paulo. The DES composed by ChCl/LA (1:10) was selected as cosolvent for the extraction, while it also optimized microbial cultivation conditions. Coffee husk was an excellent supplement for culture media, once the fungus FE316 produced Fumiquinazoline A, Tripprostatin B and Pseurotin A, while the actinomycete AC154 produced Trichorozin-IV as metabolites only expressed when in addition to the coffee husk. UHPLC-MS/MS analysis enabled the annotation of lignin monomer compounds, such as alkaloids, phenylpropanoids and terpenoids present in the coffee husk, more specifically, caffeic acid, isochlorogenic acid B, chlorogenic acid and coniferyl aldehyde, underscoring the value of this biomass.