First stereoselective total synthesis of trichodermone A

The first stereoselective total synthesis of trichodermone A using Baylis-Hillman and ring-closing metathesis (RCM) reactions as key steps is reported.     

Robust mixed 10/12 helices promoted by "alternating chirality" in a new family of C-linked carbo-beta-peptides

The C-linked carbo-beta-peptides, oligomers of a new class of C-linked carbo-beta3-amino acids, have been shown to generate mixed 12/10 and 10/12 helices. The design involves use of "alternating chirality" of the epimeric (at the amine center) monomers to control the stability of these helices. The observation of stable 12/10 helix in a tripeptide and 10/12 helix in a tetrapeptide is unprecedented.     

On Perfect Isometries for Tame Blocks

Any 2-block of a finite group G with a quaternion defect groupQ₈ is Morita equivalent to the corresponding block of the centraliserH of the unique involution of Q₈ in G; this answers positivelyan earlier question raised by M. Broué. 2000 MathematicsSubject Classification 20C20.     

InCl3 catalyzed C-C coupling of aryl alcohols and TosMIC

The InCl₃ mediated C-C coupling reaction between aryl alcohols and TosMIC gives the corresponding amides in good to high yields.     

Novel protocol for the generation of β-branched Baylis-Hillman adducts from ethyl sorbate and aryl aldehydes

A novel protocol for the generation of β-branched Baylis-Hillman adducts in moderate yields (52-68%) as E/Z mixtures from commercially available dienoates such as ethyl sorbate and aryl aldehydes catalyzed by DABCO in DMSO is reported.     

Mass spectral study of alkali-cationized Boc-carbo-beta3-peptides by electrospray tandem mass spectrometry

Electrospray tandem mass spectrometry was used to study the dissociation reactions of [M+Cat]+ (Cat = Na+ and Li+) of Boc-carbo-beta3-peptides. The collision-induced dissociation (CID) spectra of [M+Cat-Boc]+ of these peptides are found to be significantly different from those of [M+H-Boc]+ ions. The spectra are more informative and display both C- and N-terminus metallated ions in addition to characteristic fragment ions of the carbohydrate moiety. Based on the fragmentations observed in the CID spectra of the [M+Cat-Boc]+ ions, it is suggested that the dissociation involves complexes in which the metal ion is coordinated in a multidentate arrangement involving the carbonyl oxygen atoms. The CID spectra of [M+Cat-Boc]+ ions of the peptide acids show an abundant N-terminal rearrangement ion [b(n)+17+Cat]+ which is absent for esters. Further, two pairs of positionally isomeric Boc-carbo-beta3-peptide acids, Boc-NH-Caa(S)-beta-hGly-OH (11) and Boc-NH-beta-hGly-Caa(S)-OH (12), and [Boc-NH-Caa(S)-beta-hGly-Caa(S)-beta-hGly-OH] (13) and [Boc-NH-beta-hGly-Caa(S)-beta-hGly-Caa(S)-OH] (14), were differentiated by the CID of [M+Cat-Boc]+ ions. The CID spectra of compounds 11 and 13 are significantly different from those of 12 and 14, respectively. The abundance of [b(n)+17+Cat]+ ions is higher for peptide acids 12 and 14 with a sugar group at the C-terminus when compared to 11 and 13 which contain a sugar moiety at the N-terminus. The observed differences between the CID spectra of these isomeric peptides are attributed to the difference in the preferential site of metal ion binding and also on the structure of the cyclic intermediate involved in the formation of the rearrangement ion.     

Molecular structure of thiocyanatotris (2,2′-iminodiethanoldithiocarbamato) tellurium(IV) monohydrate

The synthesis, properties, and structural characterization of the title compound, C₁₆H₃₀N₄O₄S₇Te(IV)·H₂O, are reported. The crystals are monoclinic, space groupP2₁/n, withZ=4 in a unit cell of dimensionsa=13.291(5),b=21.306(6),c=10.450(1) Å, 0=104.25(2)° and,V _c=2868 ų. The structure was solved by the heavy atom method and refined by full-matrix least squares toR=0.025 andR _w =0.027 for 2894 reflections. The dithiocarbamate groups are linked in an unequal bidentate manner with Te-S average distance 2.695(1) Å. The thiocyanate group is bonded through the sulfur atom with much larger Te-S length [2.964(2) Å].     

Insight into OroxylinA-7-O-β-d-Glucuronide-Enriched Oroxylum indicum Bark Extract in Oral Cancer HSC-3 Cell Apoptotic Mechanism: Role of Mitochondrial Microenvironment

Oroxylum indicum, of the Bignoniaceae family, has various ethnomedical uses such as an astringent, anti-inflammatory, anti-bronchitis, anti-helminthic and anti-microbial, including anticancer properties. The druggability of OI stem bark extract was determined by its molecular docking interactions with PARP and Caspase-3, two proteins involved in cell survival and death. Note that 50 µg/mL of Oroxylum indicum extract (OIE) showed a significant (p < 0.05%) toxicity to HSC-3 cells. MTT aided cell viability and proliferation assay demonstrated that 50 µg/mL of OIE displayed significant (p < 0.5%) reduction in cell number at 4 h of incubation time. Cell elongation and spindle formation was noticed when HSC-3 cells were treated with 50 µg/mL of OIE. OIE initiated DNA breakage and apoptosis in HSC-3 cells, as evident from DNA ladder assay and calcein/EB staining. Apoptosis potential of OIE is confirmed by flow cytometer and triple-staining (live cell/apoptosis/necrosis) assay. Caspase-3/7 fluorescence quenching (LANCE) assay demonstrated that 50 µg/mL of OIE significantly enhanced the RFU of caspases-3/7, indicating that the apoptosis potential of OIE is probably through the activation of caspases. Immuno-cytochemistry of HSC-3 cells treated with 50 µg/mL of OIE showed a significant reduction in mitochondrial bodies as well as a reduction in RFU in 60 min of incubation time. Immunoblotting studies clearly showed that treatment of HSC-3 cells with OI extract caused caspase-3 activation and PARP deactivation, resulting in apoptotic cell death. Overall, our data indicate that OIE is an effective apoptotic agent for human squamous carcinoma cells and it could be a future cancer chemotherapeutic target.