Publications by authors named "Daniela Rebollar-Ramos"

This study introduces a new NMR-based methodology for identification (ID) and quantification (purity, strength) assays of widely used amino acids. A detailed analysis of four amino acids and their available salts was performed with both a high-field (600 MHz) and a benchtop (60 MHz) NMR instrument. To assess sensitivity constraints, samples for H NMR analysis were initially prepared using only 10 mg of analyte and 1 mg of maleic acid (MA) as an internal calibrant (IC) and secondary chemical shift reference.

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Compound 3, a trimeric anthranilic acid peptide, and another three metabolites were isolated from an organic extract from the culture medium of Malbranchea flocciformis ATCC 34530. The chemical structure proposed previously for 3 was unequivocally assigned via synthesis and X-ray diffraction analysis. Tripeptide 3 showed insulinotropic properties by decreasing the postprandial peak in healthy and hyperglycemic mice.

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An extract from a PDB static culture of exhibited α-glucosidase and PTP-1B inhibitory activities. Fractionation of the active extract led to the isolation of gymnoascolide A (), a γ-butenolide, and xanthones sydowinin A (), sydowinin B (), and AGI-B4 (), as well as orcinol (). Compound exhibited important inhibitory activity against yeast α-glucosidase (IC = 0.

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Fractionation of an aqueous extract from the aerial parts of yielded a new natural product, namely, 4-hydroxy-3-(()-1'-angeloyloxy-()-2',3'-epoxy-3'-methyl)butylacetophenone (), along with eight known compounds, including three flavonoids (-) and five chromenes (-). NMR data interpretation and DFT-calculated chemical shifts combined with DP4+ statistical and -DP4 probability analyses allowed for the complete characterization of compound . The presence of compound in a plant that biosynthesizes 2,2-dimethylchromenes is noteworthy, because an epoxy derivative has long been postulated as the reaction intermediate from the prenylated -hydroxyacetophenones to cyclic dimethylchromenes.

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Natural products are a valuable source of anticancer agents, with many naturally derived compounds currently used in clinical and preclinical treatments. This study aims to investigate the antiproliferative activity and potential mechanism of action of the xanthoquinodin JBIR-99, isolated from fungi Parengyodontium album MEXU 30,054 and identified by single-crystal X-ray crystallography. Cytotoxicity of xanthoquinodin was evaluated in a panel of human cancer cells lines and CCD-112-CoN normal colon cells, using the sulforhodamine B assay.

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From the rice-based culture of Malbranchea flavorosea, three new compounds namely flavoroseoside B (5-desoxy-5-chloro-flavoroseoside) (2), 4-hydroxy-2-O-α-ribofuranosyl-5-methylacetophenone (3), and (S)-3,4-dihydro-3-(1H-indol-3-ylmethyl)-4-methyl-1H-1,4-benzodiazepine-2,5-dione (4), along with three known compounds, rosigenin (5), massarilactone B (6), and riboxylarinol B (7) were obtained. The structures were determined by spectroscopic methods. Compound 4 and its synthetic analog 3,4-dihydro-3-(1H-indol-3-ylmethyl)-1-methyl-1H-1,4-benzodiazepine-2,5-dione (9) inhibited the activity of Ruminococus obeum α-glucosidase enzyme.

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From an extract prepared from the grain-based culture of Malbranchea flavorosea two new polyketides, namely, 8-chloroxylarinol A (1) and flavoroseoside (2), along with the known compounds xylarinol A (3), xylarinol B (4), massarigenins B and C (5 and 6), and clavatol (7), were isolated. The structures of 1 and 2 were elucidated using spectroscopic methods and corroborated by single-crystal X-ray diffraction analysis. In the case of compound 2 the absolute configuration at the stereogenic centers was established according to the method of Flack.

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