Xyloketal F: A Strong L‐Calcium Channel Blocker from the Mangrove Fungus Xylaria sp. (#2508) from the South China Sea Coast

Abstract

Xyloketal F (1), an unusual metabolite with strong L‐calcium channel blocking activity, was isolated from the mangrove endophytic fungus Xylaria sp. (#2508) collected at the South China Sea coast. Its structure was elucidated by spectral and single‐crystal X‐ray diffraction analysis. The absolute configuration of 1 was determined by the method of quantum‐mechanical calculation of CD spectra. Compound 1 was also synthesized by condensation of xyloketal B with formaldehyde. The L‐calcium channel blocking activities of xyloketals B, A, and F were determined, and at the same concentration (0.03 μmol/L), the inhibiting rates were 12.05 %, 21.47 %, and 50.33 % respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Bioactive Natural Products from the Endophytic Fungus Ascochyta sp. from Meliotus dentatus – Configurational Assignment by Solid‐State CD and TDDFT Calculations

“…For the configurational assignment of natural products, we recently used quantum-mechanical calculation of their CD spectra, which were then compared with the experimental ones. [9][10][11]12] Since the X-ray coordinates of 1a were available, our solid-state TDDFT CD methodology [1] could also be applied in the present case, significantly simplifying the procedure by using the X-ray structure as input for the calculation and the experimental solid-state CD spectrum for comparison. The solution (acetonitrile) and solid-state (KCl disc) CD spectra of 1a are very similar (Figure 3), implying a substantial structural rigidity.…”

Three xanthones from a marine-derived mangrove endophytic fungus

“…Marine fungus, especially mangrove endophytic fungus, has proved to be an abundant resource for novel natural compounds [1][2][3][4][5][6][7][8][9][10][11][12][13]. During our screening for novel structures from marine-derived mangrove endophytic fungus from the South China Sea, a fungal strain (isolate 1850) was found to produce three xanthones (1-3).…”

The Chemical Investigations of the Mangrove Plant Avicennia marina and its Endophytes!

“…2508) from the seeds of A. marina in Mai Po, Hong Kong. In the previous study, the fungus was shown to produce xyloketals A-I (67-75) [24][25][26][27][28] and xyloallenolide A (76) [29], two chemical families with novel frameworks, and exhibited strong activity against Lcalcium channels and inhibition of acetylcholine esterase. Subsequently, fermentation of the fungus in large scale yielded three metabolites [30], named xyloketal J (77), xyloester A (78), and xyloallenolide B (79) (which belong to a new series of compounds), and a known substituted dihydrobenzofuran (80).…”