Walter A. Frank

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7-Benzylamino-6-chloro-2-piperazino-4-pyrrolidinopteridine (7a) is a potent inhibitor of the cAMP-specific phosphodiesterase isoenzyme family PDE4 and induces growth inhibition in a panel of tumor cell lines. In this study, we describe a synthesis that yields 7a and novel derivatives free of positional isomers. The synthesis of alkylamino substituted(More)
A series of novel 5H-benzo[b]carbazoles related to the ellipticines was obtained from the reactions of p-benzoquinones with 2-aminomethylene-1-indanones. Most of the compounds were evaluated for their antitumour activity in the National Cancer Institute's in vitro human tumour cell line screening panel. Among them, particularly derivative 15c bearing a(More)
Ubiquitination of proteins is a critical step in the controlled degradation process of many polypeptides. Here we show that sponges, the simplest multicellular group of eukaryotic organisms, are also equipped with the ubiquitin pathway. The polyubiquitin cDNA was isolated and characterized from the marine sponge Geodia cydonium. The open reading frame(More)
Synthetically prepared congeners of sponge-derived bastadin derivatives such as 5,5'-dibromohemibastadin-1 (DBHB) that suppress the settling of barnacle larvae were identified in this study as strong inhibitors of blue mussel phenoloxidase that is involved in the firm attachment of mussels to a given substrate. The IC₅₀ value of DBHB as the most active(More)
Four new metabolites, aglacins A-D (1-4), were identified from the methanol extract of the stem bark of Aglaia cordata. These compounds represent a new class of aryltetralin cyclic ether lignan. The structure of aglacin A (1) including the absolute configuration was elucidated by interpretation of spectral data, X-ray crystal structure determination, and(More)
Several series of benzofurans, benzothiophenes, and benzothiazoles, all featuring the thioamide group, were synthesized and tested as novel K(ATP) channel openers in artificial cell systems: CHO cells transfected with SUR1/Kir6.2, and HEK 293 cells transfected with SUR2B/Kir6.1; these served as model systems for insulin-secreting pancreatic β cells and(More)
2-Substituted 3-ethynylquinoxalines can be rapidly synthesized in generally excellent yields by a consecutive four-component synthesis starting from electron-rich π-nucleophiles, oxalyl chloride, terminal alkynes, and 1,2-diaminoarenes. The title compounds are highly fluorescent with a pronounced emission solvatochromism. The photophysical properties and(More)