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Abstract. Marine algae are prolific sources of sulfated polysaccharides, which may explain the low incidence of certain cancers in countries that traditionally consume marine food. Breast cancer is one of the most common types of non-skin cancer in females. In this study, extracted sulfated carrageenan (ESC), predominantly consisting of ι-carrageenan extracted from the red alga Laurencia papillosa, was characterized using Fourier transform infrared spectrometry. The biological effects of the identified extract were investigated and its potential cytotoxic activity was tested against the MDA-MB-231 cancer cell line. The biological biometer of the inhibitory concentration of the polysaccharide-treated MDA-MB-231 cells was determined as 50 µM. Treatment with 50 µM ESC inhibited cell proliferation and promptly induced cell death through nuclear condensation and DNA fragmentation. Characterization of polysaccharide-treated MDA-MB-231 cell death revealed that induction of apoptosis occurred via the activation of the extrinsic apoptotic caspase-8 gene. The apoptotic signaling pathway was regulated through caspase-3, caspase-9, p53, Bax and Bcl-2 genes. These findings suggest that ESC may serve as a potential therapeutic agent to target breast cancer via prompting apoptosis.

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Several independent synthetic routes are described leading to the formation of a novel unsaturated tetracyclic phosphorus carbon cage compound tBu4C4P6 (1), which undergoes a light‐induced valence isomerization to produce the first hexaphosphapentaprismane cage tBu4C4P6 (2). A second unsaturated isomer tBu4C4P6 (9) of 1 and the bis‐[W(CO)5] complex 13 of 1 are stable towards similar isomerization reactions. Another starting material for the synthesis of the hexaphosphapentaprismane cage tBu4C4P6 (2) is the trimeric mercury complex [(tBu4C4P6)Hg]3 (11), which undergoes elimination of mercury to afford the title compound 2. Single‐crystal X‐ray structural determinations have been carried out on compounds 1, 2, 9, 11, and 13.

Treatment of the cage compound P6C4(t)Bu4 with M(N(SiMe3)2)2 (M = Ge or Sn) or Pb(C6H3(NMe2)2- 2,6) at room temperature results in their specific insertion into the P-P bond connecting the two 5-membered P3C2(t)Bu2 rings. The products were fully characterised by multinuclear NMR spectroscopy and single crystal X-ray diffraction studies.

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