Unprecedented diterpenoid dimers with soluble epoxide hydrolase inhibitory effect from Euphorbia fischeriana.

Biseuphoids A (1) and B (2), two unprecedented ent-abietane-type diterpenoid dimers linked by monomeric blocks through C-17-C-12' and C-17-C-11', respectively, were isolated from Euphorbia fischeriana, along with their biogenesis related diterpenoid monomers, 17-hydroxyjolkinolide B (3), caudicifolin (4), and fischeriabietane C (5). Their structures were elucidated by extensive spectroscopy assisted by quantum chemical NMR and ECD calculations. The unusual dimeric skeletons are possibly derived from the adduct of diterpenoid monomers through Michael-like reactions. The novel dimers 1 and 2 exhibited inhibitory activities on soluble epoxide hydrolase (sEH) with IC50 values of 8.17 and 5.61 µM, respectively. Molecular dynamics studies illustrated that both 1 and 2 can occupy the catalytic pocket of sEH by forming stable hydrogen bonds with the key amino acid residues including Gln384, Asn378, Pro361, Ala365, Asn366, and Asn472.

Cytotoxic diterpenoid dimer containing an intricately caged core from Euphorbia fischeriana.

Bislangduoids A and B, a novel class of dimeric diterpenoids based on ent-abietanes tethered by C-17-C-15' bridge, were identified as trace components from a traditional Chinese medicine Euphorbia fischeriana (Langdu). Bislangduoid A features a highly oxidized scaffold incorporating a cage-like pentacyclic core. Their structures were elucidated by extensive spectroscopic techniques, electronic circular dichroism, and NMR calculations. The biosynthetic pathway for the dimeric skeleton and the unique caged moiety via Michael and acetal-formation reactions was proposed. Bislangduoid A showed pronounced cytotoxicity against HepG2 cells through the mitochondria-dependent apoptosis pathway.

Bisfischoids A and B, dimeric ent-abietane-type diterpenoids with anti-inflammatory potential from Euphorbia fischeriana Steud.

Two undescribed ent-abietane-type diterpenoid dimers with nonacyclic backbone formed by intermolecular [4 + 2] cycloaddition into a spirocyclic skeleton, bisfischoids A (1) and B (2), along with a known one fischdiabietane A (3), were identified from Euphorbia fischeriana Steud. Their structures were elucidated by extensive spectroscopic analysis, ECD and NMR calculation combined with DP4+ probability analysis, as well as X-ray diffraction. The anti-inflammatory potential of dimers 1-3 were examined using their inhibitory effects on soluble epoxide hydrolase (sEH), which revealed that 1 and 2 exhibited promising activities with inhibition constant (Ki) of 3.20 and 1.95 µM, respectively. Further studies of molecular docking and molecular dynamics indicated that amino acid residue Tyr343 in the catalytic cavity of sEH was the key site for their inhibitory function.

Recent studies on terpenoids in Aspergillus fungi: Chemical diversity, biosynthesis, and bioactivity.

Metabolites from fungi are a major source of natural small molecule drugs in addition to plants, while fungal derived terpenoids have been confirmed to have great potentials in many diseases. Aspergillus fungi are distributed in every corner of the earth, and their terpenoid metabolites exhibit promising diversity in term of both their chemistry and bioactivity. This review attempted to provide timely and comprehensive coverage of chemical, biosynthesis, and biological studies on terpenoids discovered from the genus Aspergillus, including mono-, sesqui-, di-, sester-, tri-, and meroterpenoids, in the last decade. The structural characteristics, biosynthesis, and pharmacological activities of 288 terpenoids were introduced.

[Effects of sub-low temperature and drought stress on characteristics of photosynthetic and fluorescence kinetics in tomato leaves].

By using tomato as material potted in climatic chamber, the photosynthetic characteristics and allocation of energy and electron flow were studied under sub-low temperature (8-15 °C) and drought (55%-65% of field moisture capacity) conditions. The results showed that the photosynthetic pigment content declined under sub-low temperature stress, but increased under drought stress. Both sub-low temperature stress and drought stress significantly decreased the intercellular CO2 concentration, stomatal conductance and photosynthetic rate, and increased the stomatal limita- tion, which further decreased or increased under simultaneous treatment of sub-low temperature and drought stress. The photorespiration significantly increased under separate treatment of sub-low temperature and drought stress, but decreased under simultaneous treatment. The stress declined the Fo, Fv/Fm and Fv'/Fm', which showed the damage of photosystem. It increased the distribution of energy to PS I and declined the photochemical efficiency, total electron flow and alternating electron flow. Thermal dissipation and the ratio of alternating electron flow were elevated to dissipate the excess energy. Compared with separate treatment of sub-low temperature and drought stress, the simultaneous treatment made thermal dissipation higher, but did not make alternating electrons flow further increase.