Isocorilagin, the α-anomer of the ellagitannin corilagin, has been frequently reported in the literature as a constituent of various plant species. Its identification is based mainly on the smaller value for the coupling constant of its anomeric proton when compared to that of corilagin. A careful investigation of the corilagin structure in both methanol and DMSO solutions using NMR, electronic and vibrational CD, and DFT and MD calculations confirmed that isocorilagin is the result of a solvent-induced conformational transition of corilagin, rather than its diastereoisomer. Corilagin changes from B1,4 and (o)S5 conformations of the β-glucose core in DMSO-d6 to an inverted (1)C4 conformation in methanol-d4, which accounts for NMR observables attributed to the alleged α-anomer. This misassignment reinforces the risks of relying upon a single technique for structural elucidation and stereochemical analysis of complex natural products, especially those containing saccharide moieties.

α-Bisabolol is a natural terpene produced by Eremanthus erythropappus and is widely used in cosmetics and pharmaceuticals due to its anti-inflammatory, antibacterial and antimycotic properties. Due to these applications, a control of composition and authenticity of commercial oils rich in this terpene is required, resulting in a demand for new methodologies for quality control. In this work a rapid and efficient method for quantification of α-bisabolol in the essential oil of E. erythropappus (candeia) using H NMR was developed, validated and compared to gas chromatography (GC) method. The quantification of α-bisabolol byH NMR was successfully achieved for most of the essential oil samples of E. erythropappus evaluated, except for those with a more complex composition. To circumvent this limitation a 2D NMR COSY contour map was used. This method proved to be a fast and efficient alternative, providing results with standard deviations SD<0.3%. All evaluated parameters (selectivity, linearity, accuracy/precision, repeatability, robustness and stability of analyte and internal standard in solution) gave satisfactory results. Using the H NMR signals at 5.36 and 5.13ppm, the limit of detection (LOD) and limit of quantification (LOQ) were 0.26 and 2.59mg, respectively. The results obtained by theH NMR method presented SD=0.59%, smaller than the value found for GC (SD=1.18%). Tukey tests have shown that the results obtained by H NMR and COSY methodology are similar to the obtained by the traditional GC-FID technique using external and internal standardization and normalization with 95% confidence.

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A method proposed in recent literature was applied to evaluate the average shear rate (γav) in three pneumatic bioreactors of 5-dm3 working volume: bubble column, split airlift, and concentric-tube airlift. The volumetric oxygen transfer coefficient (k(L) a) is the appropriate characteristic parameter to assess the average shear rate (γav) in this methodology. Correlations for γav as a function of superficial gas velocity in the riser region (U(GR)) and rheological fluid properties (consistency index, K, and flow index, n) were obtained for each model of pneumatic bioreactor studied. The γav values estimated by the proposed methodology lay within the range of values calculated by classical correlations. The proposed correlations were utilized to predict the γav during the Streptomyces clavuligerus cultivations carried out at the same specific air flow rate (3.5 vvm) in the different types of pneumatic bioreactors. The lowest values of γav related to the highest values of consistency index (K) were found for the bubble column bioreactor, and the highest values of γav related to the lowest values of K were found for the concentric-tube airlift bioreactor. Intermediate values were found for the split airlift bioreactor. The results showed that high γav values affect the structural health of the mycelia by the rupture of the hipha.

Sclerotinia sclerotiorum is responsible for the white mold of soybeans, and the difficulty to control the disease in Brazil is causing million-dollar damages. Stachybotrys levispora has shown activity against S. sclerotiorum. In our present investigation, we analyzed the chemical basis of this inhibition. Eight compounds were isolated, and using spectroscopic methods, we identified their structures as the known substances 7-dechlorogriseofulvin, 7-dechlorodehydrogriseofulvin, griseofulvin, dehydrogriseofulvin, 3,13-dihydroxy-5,9,11-trimethoxy-1-methylbenzophenone, griseophenone A, 13-hydroxy-3,5,9,11-tetramethoxy-1-methylbenzophenone, and 12-chloro-13-hydroxy-3,5,9,11-tetramethoxy-1-methylbenzophenone. Griseofulvin inhibited the mycelial growth of S. sclerotiorum at 2 μg mL. Thus, the antagonistic effect of S. levispora to S. sclerotiorum may well be due to the presence of griseofulvins. Our results stimulate new work on the biosynthesis of griseofulvins, to locate genes that encode key enzymes in these routes and use them to increase the production of these compounds and thus potentiate the fungicide effect of this fungus. S. levispora represents an agent for biocontrol, and griseofulvin represents a fungicide to S. sclerotiorum.

Two new polyketide phosphate monoesters, phosdiecin A (1) and phosdiecin B (2), were isolated from a culture of the marine Streptomyces sp. SS99BA-2 using the hyphenated technology LC-SPE/NMR. The compounds showed to be new representatives of an important class of antitumor and antibiotic metabolites known as fostriecins. Their structures, including relative configuration attribution, were fully elucidated through extensive analyses of NMR and MALDI-TOF/TOF HR-MS data. Herein, the application of this system to isolate and identify the new compounds is described.

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