Three previously undescribed metabolites from Cordyceps cicadae JXCH-1,an entomopathogenic fungus

Three previously undescribed compounds,cordycicadione(1),cordycicadin F(2),and 7-hydroxybassiatin(3),were isolated from the cultures of Cordyceps cicadae JXCH1,an entomopathogenic fungus.Their structures and relative configurations were elucidated primarily by NMR spectroscopic analysis.The absolute configurations of 1 and 2 were determined by ECD calculations.Single-crystal X-ray diffraction method was adopted to determine the absolute configuration of 3.Compound 2 is a polycyclic polyketide with an unusual enol ether moiety and a spiro ring.The compounds obtained in this study were subjected to screening their inhibition against the proliferation of the human lung cancer cell line A549 and the production of nitric oxide in murine macrophages RAW264.7.

Gelation capability of cysteine-modified cyclo(L-Lys-L-Lys)s dominated by Fmoc and Trt protecting groups

A series of symmetrical peptidomimetics （3-8） based on cysteine-modified cyclo（L-Lys-L-Lys）s were synthesized, and their gelation capability in organic solvents was dominated by fluorenylmethyloxycarbonyl （Fmoc） and triphenylmethyl （Trt） protecting groups and the exchange of thiol-to-disulfide as well. The peptidomimetics holding Trt （3 and 4） showed no gel performance, while the Fmoc groups promoted 5 and 6 to give rise to thermo-reversible organogels in a number of organic solvents. The self-assembled fibrillar networks were distinctly evidenced in the organogels by transmission electron micros- copy （TEM） and scanning electron microscopy （SEM） observations. Fourier transform infrared spectroscopy （FT-IR） and fluorescence analyses revealed that the hydrogen bonding and ^-rt stacking play as major driving forces for the self-assembly of these organogelators. A 13-turn secondary structure was deduced for the organogel of 6 by virtue of X-ray diffraction, FT-IR and circular dichroism （CD） measurements, and an interdigitated bilayer structure was also presented.

Synthesis and Gelation Capability of Fmoc and Boc Mono-substituted Cyclo（L-Lys-L-Lys）s

Fmoc or Boc mono-substituted cyclo（L-Lys-L-Lys）s were synthesized via the reaction of lysine cyclic dipeptide with Fmoc N-hydroxysuccinimide este（Fmoc-OSu） and di-tert-butyl dicarbonate[（Boc）20], respectively. The resulted mono-substituted cyclo（L-Lys-L-Lys）s（2-4） by means of test tube inversion method served as organogelators enabled to form stable thermo-reversible organogels in alcoholic, substituted benzene and chlorinated solvents, with the minimum gelation concentration（MGC） in a range of 1%-4%（mass fraction）. The transmission electron microscopy（TEM） and scanning electron microscopy（SEM） observations reveal that these gelators self-assembled into 3D nanofiber, nanoribbon or nanotube network structures. The rheological measurement exhibited that the sto- rage modulus of gels is higher than the loss one, and the complex viscosity is reduced linearly with the increasing of scanning frequency. The fluorescence spectrum of compound 2 in 1,2-dichloroethane and benzene demonstrates that the emission peak of Fmoc at 320 nm has red-shifted and the intensity decreases gradually, while the intensity of the emission peak at 460 nm substantially enhances as a function of concentration, indicating the existence of π-π stacking interactions and the formation of J-type aggregates. Meanwhile, compound 4 self-assembled into nanotubes via the stacking of multiple bilayer membranes. Fmoc and Boc disubstituted cyclo（L-Lys-L-Lys）（3） holds the relatively lower MGC values, showing the stronger gelation ability in most selected organic solvents due to the presence of both Fmoc and Boc groups.