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Pea weevil (Bruchus pisorum L.) oviposition on pods of specific genetic lines of pea (Pisum sativum L.) stimulates cell division at the sites of egg attachment. As a result, tumor-like growths of undifferentiated cells (neoplasms) develop beneath the egg. These neoplasms impede larval entry into the pod. This unique form of induced resistance is conditioned… (More)
The extract from a laboratory culture of an Indonesian isolate of the cyanobacterium Phormidium sp. displayed inhibitory activity in a Ras-Raf protein interaction assay. Assay-guided fractionation led to the isolation of both active and inactive materials of novel structure. The major inactive metabolite, phormidolide, was nevertheless highly toxic to brine… (More)
With high-throughput screening, substituted dibenzo[c,f][2,7]naphthyridine 1 was identified as a novel potent and selective phosphoinositide-dependent kinase-1 (PDK-1) inhibitor. Various regions of the lead molecule were explored to understand the SAR requirement for this scaffold. The crystal structure of 1 with kinase domain of PDK-1 confirmed the binding… (More)
Quantum chemical calculations of one-bond carbon-carbon coupling constants are demonstrated as potential probes for the configurational assignment of organic molecules. The stereochemical analysis of strychnine and its possible stereoisomers is presented as proof of concept.
Chemical investigation of the marine red alga (Rhodophyta) Ceratodictyon spongiosum containing the symbiotic sponge Sigmadocia symbiotica collected from Biaro Island, Indonesia, yielded two isomers of a new and bioactive thiazole-containing cyclic heptapeptide, cis,cis-ceratospongamide (1) and trans, trans-ceratospongamide (2). Isolation of these peptides… (More)
The goal of online prediction with expert advice is to find a decision strategy which will perform almost as well as the best expert in a given pool of experts, on any sequence of outcomes. This problem has been widely studied and O(√ T) and O(log T) regret bounds can be achieved for convex losses (Zinkevich (2003)) and strictly convex losses with bounded… (More)
Two new diketopiperazine dipeptides, cyclomarazines A and B, were isolated and characterized along with the new cyclic heptapeptide cyclomarin D from the marine bacterium Salinispora arenicola CNS-205. These structurally related cyclic peptides each contain modified amino acid residues, including derivatives of N-(1,1-dimethylallyl)-tryptophan and… (More)
The stereochemistry of the tubulin inhibitors taltobulin HTI-286 (2) and HTI-042 (3) was determined by utilizing the DPFGSE 1D NOE experiment. Single crystal X-ray diffraction analysis further confirmed the absolute configuration of these two compounds, which carry the (S,S,S)-configuration necessary for biological activity.
[reaction: see text] Herein we report a new set of silyl ether reagents for determining the enantiomeric purity and absolute stereochemistry of secondary alcohols. These derivatives are easily synthesized, provide straightforward spectroscopic results, and allow for facile recovery of the original chiral alcohol.
The muraymycins, a family of nucleoside-lipopeptide antibiotics, were purified from the extract of Streptomyces sp. LL-AA896. The antibiotics were purified by chromatographic methods and characterized by NMR spectroscopy, degradation studies, and mass spectrometry. The structures of 19 compounds were established. The muraymycins constitute a new antibiotic… (More)