RESUMO
The indiscriminate use of antimicrobials in animal husbandry can result in various types of environmental contamination. Part of the dose of these products is excreted, still active, in the animals' feces and urine. These excreta are widely used as organic fertilizers, which results in contamination with antimicrobial molecules. The impacts can occur in several compartments, such as soil, groundwater, and surface watercourses. Also, contamination by antimicrobials fed or administrated to pigs, chickens, and cattle can reach the meat, milk, and other animal products, which calls into question the sustainability of using these products as part of eco-friendly practices. Therefore, a search for alternative natural products is required to replace the conventional antimicrobials currently used in animal husbandry, aiming to mitigate environmental contamination. We thus carried out a review addressing this issue, highlighting wood vinegar (WV), also known as pyroligneous acid, as an alternative antimicrobial with good potential to replace conventional products. In this regard, many studies have demonstrated that WV is a promising product. WV is a nontoxic additive widely employed in the food industry to impart a smoked flavor to foods. Studies have shown that, depending on the WV concentration, good results can be achieved using it as an antimicrobial against pathogenic bacteria and fungi and a valuable growth promoter for poultry and pigs.
RESUMO
AIMS: A paper by Araújo et al. (2018) claims that a variety of compounds present in pyroligneous acid (guaiacol, phenols and furfural) are responsible for the observed antimicrobial activity. We show, on the other hand, that the low pH due to acetic acid present in pyroligneous acid is the real cause of the activity. METHODS AND RESULTS: Pyroligneous acid (PA) was synthesized according to a previous method (Medeiros et al. 2019) with its inhibition activity tested on Escherichia coli and Staphylococcus aureus via the agar diffusion method. The activity of acetic acid at different concentrations was also evaluated for comparison. As expected, crude PA (pH 3.0) and acetic acid produced inhibition halos whose diameters varied according to their employed concentration. However, any PA inhibitory activity completely vanished upon neutralization (pH 7.0), a behaviour also observed for neutralized acetic acid. CONCLUSIONS: The claim that guaiacol, phenols and furfural are responsible for any inhibitory activity is unsubstantiated. The authors should have neutralized the pyroligneous acid if any activity was to be discovered. SIGNIFICANCE AND IMPACT OF STUDY: To increase awareness that interfering species may play a detrimental role on the interpretation of results. In this case, the action of acetic acid is vastly more important for the inhibitory activity than any other compound present in PA.
Assuntos
Antibacterianos , Terpenos , Ácido Acético , Antibacterianos/farmacologia , Staphylococcus aureus , Terpenos/farmacologiaRESUMO
Abstract Pyroligneous acid (PA) was obtained by condensation of the vapors produced in the thermal decomposition of culms residues from Guadua angustifolia Kunth (G. angustifolia) cultivated in Colombia, with and without previous preservation treatment with borax salts. Chemical characterization by GC-MS showed that PA extracts has high content of phenolic compounds. Mequinol, isocreosol, 4-ethylphenol, 4-ethyl-2-methoxyphenol, 3,5-dimethoxy-4-hydroxytoluene and 2,6-dimethoxyphenol were the most abundant substances, identified. The total phenolic content (TPC) and DPPH free radical scavenging activity, were investigated. TPC showed a concentration of 1.959 mg GA g-1±0.010 and 3.844 mg GA g-1±0.027 to PAC and PAS samples. These samples also exhibited high DPPH activity of 70.975%±0.921 and, 16.667%±0.298, respectively. The chemical composition, TPC and DPPH results indicate that the PA extracts obtained from G. angustifolia may be used as a raw material in the food industry as natural preservative, in medicine as alternative to antibiotics and in agriculture as insect repellent and foliar fertilizer.
Assuntos
Espectrometria de Massas , Bambusa/química , Cromatografia Gasosa , Ácido Acético , Antioxidantes/químicaRESUMO
The present study aimed to characterize the chemical composition of pyroligneous acid (PA) obtained from slow pyrolysis of the clone GG100 of Eucalyptus urophylla × Eucalyptus grandis. The efficiency of extraction of organic compounds by using different solvents-dichloromethane (DCM), diethyl ether (DE) and ethyl acetate (EA)-was evaluated. Wood discs were collected and carbonized at a heating rate of 1.25 °C/min until 450 °C. Pyrolysis gases were trapped and condensed, yielding a crude liquid product (CLP), which was refined to obtain pure PA. Then liquid-liquid extraction was carried out. Each extracted fraction was analyzed by GC-MS and the chemical compounds were identified. Experimental results showed that a larger number of chemical compounds could be extracted by using DCM and EA in comparison to diethyl ether DE. A total number of 93 compounds were identified, with phenolic compounds being the major group, followed by aldehydes and ketones, furans, pyrans and esters. Higher contents of guaiacol, phenol, cresols and furfural seem to explain the antibacterial and antifungal activity shown by PA, as reported previously in the literature. Experimental data indicated that the organic phase extracted from GG100 PA consists of a mixture of compounds similar to liquid smokes regularly used in the food industry.