Taicia Pacheco Fill

A Common Origin for Guanidinobutanoate Starter Units in Antifungal Natural Products

Keeping it basic: Arginine provides the exotic 4-guanidinobutanoate starter unit for two different types of zwitterionic polyketide (an example for one type is shown in the picture) produced by the same Streptomyces bacterium. The three-step precursor pathway is initiated by a remarkable decarboxylating monooxygenase with high specificity for arginine.

Four Additional Meroterpenes Produced by Penicillium sp Found in Association with Melia azedarach. Possible Biosynthetic Intermediates to Austin

Four additional meroterpenes were isolated and identified from rice cultures of Penicillium sp, a fungus obtained from the root bark of Melia azedarach. These new compounds were named preaustinoid B2 (1), preaustinoid A3 (2), austinolide (3), and isoaustinone (4) in analogy with the formerly described compounds. The structures were identified by extensive spectroscopic studies, including 1 D and 2 D NMR spectroscopy and HRMS. Compounds 1 - 4 are probably biosynthetic intermediates to Austin.

Unsymmetrical 1,5-diaryl-3-oxo-1,4-pentadienyls and their evaluation as antiparasitic agents.

In this work the synthesis and antiparasitical activity of new 1,5-diaryl-3-oxo-1,4-pentadienyl derivatives are described. First, compounds 1a, 1b, 1c and 1d were prepared by acid-catalyzed aldol reaction between 2-butanone and benzaldehyde, anisaldehyde, p-N,N-dimethylaminobenzaldehyde and p-nitrobenzaldehyde. Reacting each of the methyl ketones 1a, 1b, 1c and 1d with the p-substituted benzaldehydes under basic-catalyzed aldol reaction, we further prepared compounds 2a-2p. All twenty compounds were evaluated for antiproliferative activity, particularly for promastigote of Leishmania amazonensis and epimastigote of Trypanosoma cruzi. All compounds showed good activity while nitro compounds 2i and 2k showed inhibition activity at a few μM.

Diclofenac on Boron-Doped Diamond Electrode: From Electroanalytical Determination to Prediction of the Electrooxidation Mechanism with HPLC-ESI/HRMS and Computational Simulations

Using square-wave voltammetry coupled to the boron-doped diamond electrode (BDDE), it was possible to develop an analytical methodology for identification and quantification of diclofenac (DCL) in tablets and synthetic urine. The electroanalytical procedure was validated, with results being statistically equal to those obtained by chromatographic standard method, showing linear range of 4.94 × 10(-7) to 4.43 × 10(-6) mol L(-1), detection limit of 1.15 × 10(-7) mol L(-1), quantification limit of 3.85 × 10(-7) mol L(-1), repeatability of 3.05% (n = 10), and reproducibility of 1.27% (n = 5). The association of electrochemical techniques with UV-vis spectroscopy, computational simulations and HPLC-ESI/HRMS led us to conclude that the electrooxidation of DCL on the BDDE involved two electrons and two protons, where the products are colorful and easily hydrolyzable dimers. Density functional theory calculations allowed to evaluate the stability of dimers A, B, and C, suggesting dimer C was more stable than the other two proposed structures, ca. 4 kcal mol(-1). The comparison of the dimers stabilities with the stabilities of the molecular ions observed in the MS, the compounds that showed retention time (RT) of 15.53, 21.44, and 22.39 min were identified as the dimers B, C, and A, respectively. Corroborating the observed chromatographic profile, dimer B had a dipole moment almost twice higher than that of dimers A and C. As expected, dimer B has really shorter RT than dimers A and C. The majority dimer was the A (71%) and the C (19.8%) should be the minority dimer. However, the minority was the dimer B, which was formed in the proportion of 9.2%. This inversion between the formation proportion of dimer B and dimer C can be explained by preferential conformation of the intermediaries (cation-radicals) on the surface.

Enzymatic Potential of Mucor inaequisporus for Naringin Biotransformation, Accessed by Fractional Factorial Design and Mass Spectrometry Analysis

Whole cells of Mucor inaequisporus were used for biotransformation of the flavonoid naringin, as a green method for structural diversification of this class of natural product. The metabolism of the fungus was challenged against naringin under several culturing conditions, using statistical optimization. Eight parameters were evaluated comprising type and concentration of carbon source, substrate concentration, substrate addition time, shaking, luminosity, temperature and extraction time. Sixteen different culture conditions were tested in this screening. After LC-MS analysis, several biotransformation products were identified and naringenin was identified as the major product. Eleven biotransformation products were detected in Ft-HRMS analyses and identified as naringenin as major compound, 4’-methoxynaringenin, 4’-methoxynaringin, rhoifolin, apigenin, methoxyapigenin, acetylated naringin, and also two biflavonoids and two triflavonoids. Ft-HRMSn showed to be a powerful technique for structural elucidation of flavonoid biotransformation products. The fungus was capable to perform deglycosylation, reduction and O-methylation reactions at this substrate indicating good enzymatic potential, since these reactions weren’t observed before for this fungus-genus.

Diclavatol and tetronic acids from Penicillium griseoroseum

In our continuous studies on the chemistry of the endophytic fungus Penicillium griseoroseum, an endophyte isolated from fruits of Coffea arabica, we isolated clavatol, a dimethylated tetraketide, and its dimer which appears to be a novel natural compound. The studies also resulted in the identification of two known tetronic acids, viridicatic acid and terrestric acid, found in ethyl acetate and n-butanol extracts. Spectroscopic studies using 1-D and 2-D NMR and MS/MS analysis were performed to determine the structures of these compounds, first reported by this Penicillium. Two other tetronic acids congeners were identified through HPLC/MS/MS studies, based on fragmentation pattern of ions produced from ionised tetronic acids, and UV light absorptions.

Co-production of bisphenylpropanoid amides and meroterpenes by an endophytic Penicillium brasilianum found in the root bark of Melia azedarach.

A fungus, isolated from the root bark of Melia azedarach (Meliaceae), from which a series of meroterpenes have been reported, was identified as Penicillium brasilianum based on analysis of the ITS region of ribosomal DNA. From a rice culture of this fungus, the known phenylpropanoid amides brasiliamide A and B were obtained together with and a new, slightly modified congener, along with the meroterpenoids preaustinoid A1, preaustinoid B2 and austinolide. The compounds were isolated by the use of combined chromatographic procedures and identified by physical methods, mainly 1D and 2D NMR experiments, with distinction for 1H{15N} HMBC applied to brasiliamide A. The amides were tested for their antimicrobial activity and showed only weak inhibitory effects, against a set of pathogenic bacteria

Time course production of indole alkaloids by an endophytic strain of Penicillium brasilianum cultivated in rice

During our studies concerning endophytic fungi, two indole alkaloids were co-produced with verruculogen by Penicillium brasilianum isolated from Melia azedarach (Meliaceae). The compounds were isolated by the use of combined chromatographic procedures and identified by physical methods, mainly 1D- and 2D-NMR experiments. This article also describes the production of verruculogen TR-2, first described for this species of Penicillium, and a verruculogen TR-2C-11 epimer, that is a novel fungal natural product. The kinetic production of verruculogen and verruculogen TR-2 produced by P. brasilianum were evaluated in order to understand the involvement of verruculogen TR-2 in verruculogen biosynthesis.

Preaustinoid A: a meroterpene produced by Penicillium sp.

The title meroterpene preaustinoid A (systematic name: methyl 15-hydroxy-2,6,6,10,13,15-hexamethyl-17-methylene-7,14,16-trioxotetracyclo[11.3.1.02,11.05,10]heptadecane-1-carboxylate), C26H36O6, features a fused four-ring arrangement. Three rings are in different distorted chair conformations and the other is in a distorted boat conformation. The absolute configuration was established based on [αD] = −4.97° (c = 1.10 g l−1, CH2Cl2). In the crystal, the molecules are connected into supramolecular chains via O—H⋯O hydrogen bonds.

Insights into Penicillium brasilianum Secondary Metabolism and Its Biotechnological Potential

Over the past few years Penicillium brasilianum has been isolated from many different environmental sources as soil isolates, plant endophytes and onion pathogen. All investigated strains share a great ability to produce bioactive secondary metabolites. Different authors have investigated this great capability and here we summarize the metabolic potential and the biological activities related to P. brasilianum’s metabolites with diverse structures. They include secondary metabolites of an alkaloid nature, i.e., 2,5-diketopiperazines, cyclodepsipeptides, meroterpenoids and polyketides. Penicillium brasilianum is also described as a great source of enzymes with biotechnological application potential, which is also highlighted in this review. Additionally, this review will focus on several aspects of Penicillium brasilianum and interesting genomic insights.