ABSTRACT
A new cytotoxic stigmastane, 7beta-hydroxy-4,22-stigmastadien-3-one (3), together with two known cytotoxic stigmastanes (1, 2) and a norisoprenoid (4), have been isolated from the aquatic plant pistia stratiotes. The structure determination was accomplished by spectroscopic methods.
Subject(s)
Antineoplastic Agents, Phytogenic/chemistry , Araceae/chemistry , Steroids/toxicity , 3T3 Cells , Animals , Antineoplastic Agents, Phytogenic/isolation & purification , Drug Screening Assays, Antitumor , Magnetic Resonance Spectroscopy , Mass Spectrometry , Mice , Solvents , Spectrometry, Mass, Electrospray Ionization , Spectrophotometry, Infrared , Steroids/isolation & purification , Tumor Cells, CulturedABSTRACT
The invasive growth of the introduced green alga Caulerpa taxifolia, already affecting the richness and diversity of the littoral ecosystems, has become a major ecological problem in the Mediterranean Sea. Previously, we demonstrated that the water pollutant tributyltin induces apoptosis in tissue of the marine sponge Geodia cydonium at concentrations of 3 µM and higher. Here we show that exposure of G. cydonium to low (non-toxic) concentrations of Caulerpa extract or purified caulerpin (10 µg/ml) together with low doses of tributyltin (1 µM; non-toxic), results in a strong apoptotic effect. Evidence is presented that the enhancement of toxicity of tributyltin by Caulerpa extract is at least partially caused by inhibition of the multixenobiotic resistance (MXR) pump by the algal toxin. Caulerpa extract, as well as caulerpin, strongly enhance the accumulation of the test substrate of MXR, rhodamine B, in the gills of the mussel Dreissena polymorpha, used as a model system for testing MXR-inhibiting potential.
ABSTRACT
Several new isolated or fused heterocyclic ring systems that accomodate the isothioureido functionality, often associated with immunosuppressive activity, were synthesized for possible use as immunosuppressive agents. Preparation of these anchored heterocycles was achieved via a multi-step synthesis starting with the key intermediate thiazolyl thiourea derivative (I). Structure of the newly synthesized products was confirmed using both of elemental and spectral analyses.
