An efficient strategy for screening polyunsaturated fatty acid-producing oleaginous filamentous fungi from soil.

Screening oleaginous microorganisms capable of accumulating considerable lipids is essential for industrial lipid production. Here we demonstrated forty-seven filamentous fungal isolates were obtained from eight soil samples using a new screening strategy with both triphenyltetrazolium chloride (TTC), a redox indicator used for testing oil presence, and cerulenin, an inhibitor of fatty acid synthase (FAS), supplemented in screening medium. Among these fungal isolates, nineteen have high lipid content (>20% dry biomass weight) and were affiliated with the genus Mortierella by morphology identification and phylogenetic analysis based on ITS gene sequences. Notably, one strain designated as SL-4 reached 32% of its biomass weight as lipid, displaying the highest potential. Two candidates with high lipid content as well as biomass production were selected for exploring the effect of different carbon and nitrogen sources on morphology, biomass and lipid accumulation.

Total synthesis of 8-(6″-umbelliferyl)-apigenin and its analogs as anti-diabetic reagents.

The naturally occurring flavone 8-(6″-umbelliferyl)apigenin, a hybrid structure of apigenin and coumarin, as well as seven of its analogues were synthesized for the first time by using iodination and Suzuki coupling reactions as key steps. The synthesis of 8-(6″-umbelliferyl)-apigenin was achieved in seven linear steps from the commercially available 1-(2,4,6-trihydroxyphenyl)ethan-1-one and 7-hydroxyl coumarine with 31% overall yield. Effects of these compounds on glucose disposal were investigated in adipocytes. All of the flavonoid and coumarin hydrids were found to have better bioactivities than their corresponding flavonoid cores. The most potent compound 15 (10 µΜ) could promote glucose consumption by 57% which exhibited similar effect as the positive control metformin at 1 mM. Moreover, fluorescence microscopy showed that four 8-(6″-umbelliferyl)apigenin analogues 2, 15, 30 and 31 could promote the 2-NBDG uptake into 3T3-L1 cells, which consist with those observed in the regulation of glucose.

Synthesis of Substituted Pyrroles via Copper-Catalyzed Cyclization of Ethyl Allenoates with Activated Isocyanides.

A new method for the synthesis of di- and trisubstituted pyrroles via copper-catalyzed cyclization of ethyl allenoates with activated isocyanides has been developed. In contrast to related annulation reactions previously reported, this new process features a skeletal rearrangement in which the aryl sulfonyl moiety, which functions as the electron-withdrawing group in the α-carbon of the isocyanide, was found to migrate to the γ-carbon of the starting allenoate in the final product for the first time.

Synthesis, α-glucosidase inhibitory and molecular docking studies of prenylated and geranylated flavones, isoflavones and chalcones.

Three series of prenylated and/or geranylated flavonoids were synthesized and evaluated for their α-glucosidase inhibitory activity. The 3',5'-digeranylated chalcone (16) was identified as a new α-glucosidase inhibitor whose activity (IC50=0.90 µM) was 50-fold more than that of acarbose (IC50=51.32 µM). Molecular docking studies revealed the existence of strong hydrophobic interaction and H-bonding between compound 16 and α-glucosidase's active site. The inhibitory mode analysis showed that 16 exhibited a competitive inhibitory mode.

Design, synthesis and docking study of novel tetracyclic oxindole derivatives as α-glucosidase inhibitors.

A series of novel tetracyclic oxindole derivatives were synthesized via tandem Suzuki coupling-Michael addition reaction catalyzed by palladium. Twenty derivatives were designed and synthesized in 6-8 steps in 8-20% overall yields. Their structures were confirmed by (1)H, (13)C NMR and LC/MS. These compounds were evaluated for α-glucosidase inhibitory activity in vitro. Compounds 7c, 7d, 7e, 7g, 7h, and 7i exhibited IC50 values of 32.3, 12.1, 15.7, 29.0, 16.0, and 4.8 µM, respectively, with potency all higher than that of the control standard acarbose (IC50=115.8 µM). Molecular docking studies revealed the existence of potential hydrogen bonding and hydrophobic interaction between the enzyme and the active compound 7i.

Synthesis and anti-cancer activity evaluation of novel prenylated and geranylated chalcone natural products and their analogs.

Four natural chalcones bearing prenyl or geranyl groups, i.e., bavachalcone (1a), xanthoangelol (1b), isobavachalcone (1c), and isoxanthoangelol (1d) were synthesized by using a regio-selective iodination and the Suzuki coupling reaction as key steps. The first total synthesis of isoxanthoangelol (1d) was achieved in 36% overall yield. A series of diprenylated and digeranylated chalcone analogs were also synthesized by alkylation, regio-selective iodination, aldol condensation, Suzuki coupling and [1,3]-sigmatropic rearrangement. The structures of the 11 new derivatives were confirmed by (1)H NMR, (13)C NMR and HRMS. The anticancer activity of these new chalcone derivatives against human tumor cell line K562 were evaluated by MTT assay in vitro. SAR studies suggested that the 5'-prenylation/geranylation of the chalcones significantly enhance their cytotoxic activity. Among them, Bavachalcone (1a) displayed the most potent cytotoxic activity against K562 with IC50 value of 2.7 µM. The morphology changes and annexin-V/PI staining studies suggested that those chalcone derivatives inhibited the proliferation of K562 cells by inducing apoptosis.

Design, synthesis and in vitro cytotoxicity evaluation of 5-(2-carboxyethenyl)isatin derivatives as anticancer agents.

Forty four di- or trisubstituted novel isatin derivatives were designed and synthesized in 5-6 steps in 25-45% overall yields. Their structures were confirmed by (1)H NMR and (13)C NMR as well as LC-MS. The anticancer activity of these new isatin derivatives against three human tumor cell lines, K562, HepG2 and HT-29, were evaluated by MTT assay in vitro. SAR studies suggested that the combination of 1-benzyl and 5-[trans-2-(methoxycarbonyl)ethen-1-yl] substitution greatly enhance their cytotoxic activity, whereas an intact carbonyl functionality on C-3 as present in the parent ring is required to such a potency. This study leads to the identification of two highly active molecules, compounds 2h (IC50=3 nM) and 2k (IC50=6 nM), against human leukemia K562 cells.

Catalytic enantioselective addition of terminal 1,3-diynes to N-sulfonyl aldimines: access to chiral diynylated carbinamines.

An efficient method for the asymmetric synthesis of chiral diynylated carbinamines is described. The direct catalytic enantioselective addition of terminal 1,3-diynes to N-sulfonyl aldimines proceeded smoothly under mild reaction conditions to produce diynylated carbinamines in up to 98% yield and 99% ee.

A SeCSe-Pd(II) pincer complex as a highly efficient catalyst for allylation of aldehydes with allyltributyltin.

An air- and moisture-stable SeCSe-Pd(II) pincer complex was synthesized and found to catalyze the nucleophilic allylation of aldehydes with allyltributyltin. The allylation of a variety of aromatic and aliphatic aldehydes to give the corresponding homoallyl alcohols was performed at room temperature to 60 degrees C in yields ranging from 50% (for typical aliphatic aldehydes) to up to 97% (for aromatic aldehydes) using 5 x 10(-3) to 1 mol % of the Pd catalyst. NMR spectroscopic study indicated that a sigma-allylpalladium intermediate was formed and possibly functions as the nucleophilic species that undergoes addition to the aldehydes.

Selenium-ligated palladium(II) complexes as highly active catalysts for carbon-carbon coupling reactions: the Heck reaction.

Three selenium-ligated Pd(II) complexes were readily synthesized and shown to be extremely active catalysts for the Heck reaction of various aryl bromides, including deactivated and heterocyclic ones. The catalytic activity of the selenide-based Pd(II) complexes not only rivals but vastly outperforms that of the corresponding phosphorus and sulfur analogues. Practical advantages of the selenium-based catalysts include their straightforward synthesis and high activity in the absence of any additives as well as the enhanced stability of the selenide ligands toward air oxidation.

Poly(fluoroalkyl acrylate)-bound ruthenium carbene complex: a fluorous and recyclable catalyst for ring-closing olefin metathesis.

The synthesis of a fluorous olefin metathesis catalyst derived from the Grubbs second-generation ruthenium carbene complex is described. The air stable fluorous polymer-bound ruthenium carbene complex 1 shows high reactivity in effecting the ring-closing metathesis of a broad spectrum of diene and enyne substrates leading to the formation of di-, tri-, and tetrasubstituted cyclic olefins in minimally fluorous solvent systems (PhCF3/CH2Cl2, 1:9-1:49 v/v). The catalyst can be readily separated from the reaction mixture by fluorous extraction with FC-72 and repeatedly reused. The practical advantage offered by the fluorous catalyst is demonstrated by its sequential use in up to five different metathesis reactions.

Ligand-free Heck reaction: Pd(OAc)2 as an active catalyst revisited.

Palladium acetate was shown to be an extremely active catalyst for the Heck reaction of aryl bromides. Both the base and the solvent were found to have a fundamental influence on the efficiency of the reaction, with K(3)PO(4) and N,N-dimethylacetamide being the optimal base and solvent, respectively.

OsO(4) in ionic liquid [Bmim]PF(6): a recyclable and reusable catalyst system for olefin dihydroxylation. remarkable effect of DMAP.

[reaction: see text] The combination of the ionic liquid [bmim]PF(6) and DMAP provides a most simple and practical approach to the immobilization of OsO(4) as catalyst for olefin dihydroxylation. Both the catalyst and the ionic liquid can be repeatedly recycled and reused in the dihydroxylation of a variety of olefins with only a very slight drop in catalyst activity.

Synthesis of cyclic sulfones by ring-closing metathesis.

A general and highly efficient synthesis of cyclic sulfones based on ring-closing metathesis has been developed. The synthetic utility of the resulting cyclic sulfones was demonstrated by their participation in stereoselective Diels-Alder reactions and transformation to cyclic dienes by the Ramberg-Bäcklund reaction.