ABSTRACT
Electrospray ionization mass spectrometry-guided isolation of extracts from Didiscus aceratus led to the discovery of several new derivatives of the bioactive bisabolene-type sponge metabolite (S)-(+)-curcuphenol (1). The compounds obtained by this method included a mixture of known (2) and new (3) dihydroxylated analogs as well as a novel family of dimeric derivatives, dicurcuphenols A-E (4-8), and dicurcuphenol ether F (9). Dimers 4-9 were also subsequently obtained through a hemisynthetic method in which 1 was incubated with the enzyme laccase. Atropisomeric dimers 5 and 6 were subjected to vibrational circular dichroism analysis thereby establishing their absolute biaryl axial chirality as P and M, respectively. In contrast to 1, metabolites 2-9 exhibited weak or no cytotoxic or lipoxygenase inhibitory effects.
Subject(s)
Laccase/chemistry , Porifera/chemistry , Sesquiterpenes , Animals , Catalysis , Cell Line, Tumor , Cell Proliferation/drug effects , Crystallography, X-Ray , Dimerization , Drug Screening Assays, Antitumor , Humans , Lipoxygenase Inhibitors , Magnetic Resonance Spectroscopy/methods , Models, Molecular , Molecular Conformation , Sesquiterpenes/chemical synthesis , Sesquiterpenes/isolation & purification , Sesquiterpenes/pharmacology , Spectrometry, Mass, Electrospray Ionization/methods , Stereoisomerism , Structure-Activity RelationshipABSTRACT
It was hypothesized that a simplified and efficient strategy could be developed for large-scale production and purification of the mycotoxin deoxynivalenol from Fusarium graminearum rice cultures for toxicological studies. F. graminearum R6576 was cultured on rice and extracted with methanol, and the extract was concentrated and subjected to silica gel low-pressure liquid chromatography (LPLC) under a hexane-acetone gradient system. Deoxynivalenol isolation was monitored by thin-layer chromatography, and fractions containing deoxynivalenol were pooled, concentrated, and applied to a second LPLC column under the same conditions. An enriched deoxynivalenol fraction was obtained, which yielded a crystalline material. Repeated crystallization yielded spectroscopically pure deoxynivalenol. The identity of this compound was confirmed by HPLC comparison to an authentic deoxynivalenol standard, FABMS analysis, and comparison of the (1)H and (13)C NMR spectra with published data. This simplified purification scheme eliminated many laborious steps and equipment previously required to obtain gram quantities of crystalline deoxynivalenol for biological testing in animal models.
