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Introduction: Products of plant secondary metabolism, such as phenolic compounds, flavonoids, alkaloids, and hormones, play an important role in plant growth, development, stress resistance. The plant family Rubiaceae is extremely diverse and abundant in Central America and contains several economically important genera, e.g. Coffea and other medicinal plants. These are known for the production of bioactive polyphenols (e.g. caffeine and quinine), which have had major impacts on human society. The overall goal of this study was to develop a high-throughput workflow to identify and quantify plant polyphenols. Methods: First, a method was optimized to extract over 40 families of phytochemicals. Then, a high-throughput metabolomic platform has been developed to identify and quantify 184 polyphenols in 15 min. Results: The current metabolomics study of secondary metabolites was conducted on leaves from one commercial coffee variety and two wild species that also belong to the Rubiaceae family. Global profiling was performed using liquid chromatography high-resolution time-of-flight mass spectrometry. Features whose abundance was significantly different between coffee species were discriminated using statistical analysis and annotated using spectral databases. The identified features were validated by commercially available standards using our newly developed liquid chromatography tandem mass spectrometry method. Discussion: Caffeine, trigonelline and theobromine were highly abundant in coffee leaves, as expected. Interestingly, wild Rubiaceae leaves had a higher diversity of phytochemicals in comparison to commercial coffee: defense-related molecules, such as phenylpropanoids (e.g., cinnamic acid), the terpenoid gibberellic acid, and the monolignol sinapaldehyde were found more abundantly in wild Rubiaceae leaves.

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The use of antibiotics in agriculture produces residues in wastewaters. The disposal of such wastewaters in biopurification systems (BPS) employed for the treatment of pesticides could result in the inhibition of the degrading capacity of the biomixtures used in the BPS. We assayed the effect of two commercial formulations of antibiotics used in agriculture, one containing kasugamycin (KSG) and the other oxytetracycline plus gentamicin (OTC+GTM), on the biomixture performance. Doses from 0.1mgkg-1 to 1000mgkg-1 of KSG increased the respiration of the biomixture, and low doses enhanced the mineralization rate of the insecticide 14C-chlorpyrifos. On the contrary, OTC+GTM depressed the respiration of the biomixture and the initial mineralization rate of 14C-chlorpyrifos; nonetheless, the antibiotics did not decrease overall mineralization values. The application of both formulations in the biomixture at a relevant concentration did not harm the removal of the fungicides carbendazim and metalaxyl, or their enhanced degradation; on the other hand, the biomixture was unable to dissipate tebuconazol or triadimenol, a result that was unchanged during the addition of the antibiotic formulations. These findings reveal that wastewater containing these antibiotics do not affect the performance of BPS. However, such a response may vary depending on the type of pesticide and microbial consortium in the biomixture.

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Biopurification systems (BPS) are design to remove pesticides from agricultural wastewater. This work assays for the first time the potential effect of an antibiotic of agricultural use (oxytetracycline, OTC) on the performance of a biomixture (biologically active core of BPS), considering that antibiotic-containing wastewaters are also produced in agricultural labors. The respiration of the biomixture was stimulated in the presence of increasing doses of OTC (≥100mgkg-1), and only slightly increased with lower doses (≤10mgkg-1). When co-applied during the removal of chlorpyrifos, OTC increased chlorpyrifos mineralization rates at low doses, resembling a hormetic effect. The biomixture was also able to remove three herbicides (atrazine, ametryn and linuron) with half-lives of 24.3 d, 43.9 d and 30.7 d; during co-application of OTC at a biomixture-relevant concentration, only the removal of ametryn was significantly inhibited, increasing its half-life to 92.4 d. Ecotoxicological assays revealed that detoxification takes place in the biomixture during the removal of herbicides in the presence of OTC. Overall results suggest that co-application of OTC in a biomixture does not negatively affect the performance of the matrix in every case; moreover, the co-application of this antibiotic could improve the mineralization of some pesticides.

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