Search

The endophytic fungus Guignardia mangiferae isolated from Ilex cornuta leaves was shown to produce a family of meroterpenes with toll-like receptor 3 regulating activity (1-9), of which 1-3 possessed new structures. The absolute stereochemistry of 1-3 was assigned through a combination of nuclear magnetic resonance experiments, chemical derivation, CD spectra, and single-crystal X-ray diffraction analyses (CuKα). The precursor labeled cultivation suggests that these meroterpenes are most likely assembled through terpenoid-shikimate pathways. Moreover, meroterpenes 1-3, 5-7, and 9 selectively upregulate, but 4 and 8 downregulate the toll-like receptor 3 expression in mouse dendritic cells at 10.0 µM. [ABSTRACT FROM AUTHOR]

Four new 8,9,30-phragmalin orthoesters (1-4), along with six related known compounds, namely xyloccensins O-S(5-9)a n dV(10), were isolated and characterized from the twigs and leaves of the Chinese mangrove Xylocarpus granatum.The structures of the new compounds were determined on the basis of extensive spectroscopic analysis and by comparison with those of related known compounds in the literature. The absolute configuration of xyloccensin Q (7) was revised as its enantiomer by X-ray diffraction analysis employing graphitemonochromated Cu Kα radiation (λ = 1.54178 Å) with a Flack parameter of - 0.04 and was further secured by a time-dependent density functional theory electronic circular dichroism (TDDFT ECD) calculation. Consequently, the absolute configurations of xyloccensins O (5), P(6), R (8), S (9), and V (10) were all corrected as their corresponding enantiomers, respectively. Xyloccensin S (9) exhibited inhibitory activity against protein tyrosine phosphatase 1B, a potential drug target for the treatment of type II diabetes and obesity, with an IC50 value of 8.72 µg/mL. [ABSTRACT FROM AUTHOR]