Wavelength Calibration Uncertainty in Protein Circular Dichroism Data Bank Spectra

Algorithms to objectively compare the circular dichroism spectra of biopharmaceuticals, as a measure of consistent higher order structure, are sensitive to errors in spectropolarimeter wavelength calibration. A public database, the Protein Circular Dichroism Data Bank contains 108 unique calibration spectra of d-camphor-10-sulphonic acid, mainly collected on synchrotron-based instruments. Deconvolution of these spectra and statistical evaluation of the peaks located near 290 and 190 nm shows significant mean peak wavelength differences between instruments, with data ranges of 1.8 and 2.3 nm. Peak positions and peak height ratios for individual instruments changed significantly through time, and the difference between wavelength maxima was instrument dependent.

Muyocopronones A and B: azaphilones from the endophytic fungus Muyocopron laterale

Two new azaphilones, namely muyocopronones A (1) and B (2), were isolated from the cultures of an endophytic fungus Muyocopron laterale ECN279. Their structures were elucidated by extensive spectroscopic analysis. Their absolute configurations were determined using the modified Mosher’s method and through comparisons of experimental and calculated electronic circular dichroism data. In addition, muyocopronone B (2) was found to exhibit a weak antibacterial activity against some Gram-positive bacteria.

Seven New Drimane-Type Sesquiterpenoids from a Marine-Derived Fungus Paraconiothyrium sporulosum YK-03

Seven new drimane-type sesquiterpenoids, namely the sporulositols A–D (1–4), 6-hydroxydiaporol (5), seco-sporulositol (6) and sporuloside (7) were isolated from the ethyl acetate extract of fermentation broth for a marine-derived fungus Paraconiothyrium sporulosum YK-03. Their structures were elucidated by analysis of extensive spectroscopic data, and the absolute configurations were established by crystal X-ray diffraction analysis and comparisons of circular dichroism data. Among them, sporulositols A–E (1–4) and seco-sporulositol (6) represent the first five examples of a unique class of drimanic mannitol derivatives, while compounds 6 and 7 may represent two new series of natural drimanes, possessing an aromatic ring with a rare 4,5-secodrimanic skeleton and an unusual CH3-15 rearranged drimanic α-D-glucopyranside, respectively. Furthermore, the origin of mannitol moiety was investigated by reliable HPLC and NMR analyses.