We report the synthesis and characterization of a meso-meso directly linked bisporphyrin 6 bearing both alkyl and aryl residues. Oxidative fusing results in a mesomeso,β−β,β−β-linked bisporphyrin. The first crystal structure analysis of a meso-meso directly linked porphyrin dimer 6 shows the inequivalency of the two porphyrin units with regard to the macrocycle conformation. Quite distinct mixings of distortion modes were observed for the two aromatic macrocycles.

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Free base stannyl porphyrins and free base porphyrin dimers have been successfully synthesized via copper-free Stille coupling in 21-67% yields. This approach provides an access to stannyl porphyrin synthons that were previously unavailable. Moreover, variation of the reaction conditions selectively provides access to either stannyl porphyrins or porphyrin dimers. Full (119/117)Sn NMR analysis was used for characterization of the stannyl porphyrins and detailed (119)Sn-(1)H-(13)C NMR analyses were carried out on a series of the starting tin reagents and the stannyl porphyrins. These investigations indicate that significant structural information can be gathered by use of commonly known NMR techniques. Photophysical properties of the novel porphyrins prepared including absorption, emission, and fluorescence lifetimes were investigated. The stannyl porphyrins emitted in the visible region, and in all cases large Stokes shifts were observed. The emission intensities of the stannyl porphyrins were 100-fold higher than those of the starting bromoporphyrins. Measured fluorescence lifetime (S(0)-->S(1)) of the stannyl and dimeric porphyrins were in the 7.7-12 ns region.

Four diketopiperazine derivatives; cyclo(-Pro-Val) (1), (-)-cyclo(-Pro-Tyr) (2), (-)-cyclo(-Pro-Phe) (3) and (+)-cyclo(-Pro-Leu) (4) were isolated from the ethyl acetate extract of Glaciozyma antarctica PI12, a cold-adapted yeast that belongs to family Kriegeriales. The compounds were isolated by radial chromatography and thin layer chromatography techniques and the chemical structures were elucidated by infrared (IR), ultraviolet (UV), nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry.

A new dipeptide, (-)-glaciantarcin (1) and three known compounds, cyclo(-Pro-Gly) (2), 1-(2-deoxypentofuranosyl)-5methyl-2,4(1H,3H)-pyrimidinedione (3) and vidarabine (Ara-A) (4), were isolated from Glaciozyma antarctica PI12, a cold-adapted yeast. The chemical structures were elucidated by FT-IR, NMR and mass spectrometry. The cytotoxicity and antioxidant activities of compounds 1-4 were evaluated by using the MTT bioassay on MCF-7 (human breast cancer cell line), PC-3 (human prostate cancer cell line) and HEK-293 (normal human embryonic kidney cell line) and DPPH free radical scavenging activity, respectively. At concentration of 400 µM, all compounds showed the highest activity on MCF-7, with compound 1 at 65%, compound 2 (70%), compound 3 (66%) and compound 4 (58%) cell viability. All compounds exhibited weak antioxidant properties. To the best of our knowledge, this is the first report of compounds 1-4 from Glaciozyma antactica.