Four new steroidal alkaloids, plakinamine I-K (1-3) and dihydroplakinamine K (4), were isolated from the marine sponge Corticium niger. The structures of these compounds were elucidated by interpretation of spectroscopic data. Compounds 1-4 exhibit significant in vitro cytotoxicity.
A new alkaloid antibiotic tetrazomine was isolated from the culture broth of Saccharothrix mutabilis subsp. chichijimaensis subsp. nov., and its structure was determined to be I by means of spectroscopic measurements. It has an unusual structure which consists of six rings, including piperidine, piperazine, oxazole, and pyrrolidine rings.
Reactions of 1-acylamino-2,2-dichloroacrylonitriles, diethyl 1-acylamino-2,2,2-trichloroethyl-phosphonates and 1-acylamino-2,2-dichloroethenylphosphonium salts with natural alkaloid cytisine have been studied. A series of novel multifunctional cytisine derivatives containing pharmacophore 1,3-oxazole moiety have been obtained. Composition and structure of the synthesized compounds have been confirmed by mass spectrometry and NMR spectroscopy data.
Oxysporidinone (1), a novel 3,5-disubstituted N-methyl-4-hydroxy-2-pyridone, was isolated from fermentations of Fusarium oxysporum (CBS 330.95) by counter-current chromatography. The structure was determined by spectroscopic methods including NMR, MS, IR, and UV analysis. Oxysporidinone exhibited growth inhibitory activity against several common plant pathogenic fungi.
The constitutional formulae of two new chromone alkaloids, schumannificine 2 and N-methylschumannificine 3 isolated from the root-bark of SCHUMANNIOPHYTON MAGNIFICUM, H ARMS, have been shown to be linear tetracyclic compounds with ring D being piperidine in nature, on the basis of the chemical evidence and spectral analyses.
