Caracterização cromatográfica e avaliação da atividade antimicrobiana do extrato pirolenhoso obtido a partir de biomassas residuais

Abstract

The biomass processing for the obtention of high value-added chemicals products has become more evident in the past years. Brazil, for generating a considerable amount of waste has a great capability of reusing these materials. In this aspect, the pyrolysis is inserted as a thermo-chemical process of biomass transformation that occurs in the total or partial absence of oxygen originating compounds of shorter chains as non-condensable gases, biochar and liquid product. The pyroligneous extract that is part of the liquid product has a large application as fungicide, herbicide and insecticide. For being a complex mixture some separation and identification techniques such as gas chromatography coupled to mass spectrometry GC / qMS are useful in mapping the compounds there present. Based on that, the following work aims the chromatographic characterization of the pyroligneous extract obtained from several residual biomasses and the study of the antifungal activity of these extracts against fungi that cause onychomycosis, which is a superficial mycosis in the ungual unit. The biomass residues studied were coconut encodarp, dende endocarp, macauba endocarp, ouricuri endocarp, eucalyptus and acai seed for which were made characterizations such as density, elemental analysis, immediate analysis, TG / DTG and FTIR. An experimental design 2³ was performed to determine the best pyrolysis conditions in terms of yield in liquid product with coconut endocarp, whose best conditions were applied to other biomasses. The factors evaluated were temperature (400 and 600 ºC), heating rate (10 and 50 ºC / min) and residence time (1 and 2 h). Significant effects were warming rate and residence time at the lower (400 ºC) and upper (2 h) levels, respectively. The pyroligneous extract compounds were identified by GC / qMS, where the major compounds tentatively identified belong to the group of phenols with area up to 74.64% for the ouricuri endocarp pyroligneous extract (EP - OU), 51.15% for the acai seed pyroligneous extract (EP-SA), 19.22% for (EP-DE) and 10.22% for coconut endocarp pyroligneous extract (EP-CO), followed by the ketone groups with 69.77% for the dende pyroligneous extract (EP-DE) and 39.24% for the coconut endocarp pyroligneous extract (EP-CO). The compounds of the aldehydes chemical group were identified with more significant areas for the acai seed pyroligneous extract (EP-SA) with 31.56% and for the coconut endocarp pyroligneous extract (EP-CO) with 16.66%. From the susceptibility tests carried out, it was inferred that the inhibition halos of the pyroligneous extract without any extraction process were 60-90% more expressive than the inhibition halos of the pyroligneous extract after extraction with dichloromethane. For the fluconazole (25 mg/L), a commercial antifungal, and the pyroligneous extract it is possible to notice that the extract inhibits the growth of all fungi and bacteria in study, while the fluconazole (25 mg/L) has not an antifungal activity for Fusarium sp. I, Fusarium sp. II and Microsporum gypseum nor for the bacteria Staphylococcus aureus. All the extracts evaluated by disk diffusion test showed effective action against the fungi causing onychomycosis.