Thermodynamic and structural properties of lipid-photosensitizer conjugates mixed with phospholipids: Impact on the formation and stability of nano-assemblies.

The photosensitizer Phenalenone (PN) was grafted with one or two lipid (C18) chains to form pure nano-assemblies or mixed lipid vesicles suitable for photodynamic therapy. Mixtures of PN-C18 conjugates with stearoyl-oleoyl phosphatidylcholine (SOPC) form vesicles that disintegrate into bilayer sheets as the concentration of PN-C18 conjugates increases. We hypothesized that PN-C18 conjugates control the thermodynamic and structural properties of the mixtures and induce the disintegration of vesicles due to PN π-π-interactions. Monolayers were analyzed by surface pressure and grazing incidence X-ray diffraction (GIXD) measurements, and vesicles by differential scanning calorimetry and cryo-TEM. The results showed that PN-triazole-C18 (1A) and PN-NH-C18 (1B) segregate from the phospholipid domains. PN-(C18)2 (conjugate 2) develops favorable interactions with SOPC and distearoyl-phosphatidylcholine (DSPC). GIXD demonstrates the contribution of SOPC to the structuring of conjugate 2 and the role of the major component in controlling the structural properties of DSPC-conjugate 2 mixtures. Above 10 mol% conjugate 2 in SOPC vesicles, the coexistence of domains with different molecule packing leads to conjugate segregation, vesicle deformation, and the formation of small bilayer discs stabilized by the inter-bilayer π-π stacking of PN molecules.

Trypethelone and phenalenone derivatives isolated from the mycobiont culture of Trypethelium eluteriae Spreng. and their anti-mycobacterial properties.

The metabolites of the mycobiont culture of the lichen Trypethelium eluteriae were isolated by column chromatography and preparative TLC. Nine compounds (1-9) including two new trypethelones, 8-methoxytrypethelone (6) and 5'-hydroxy-8-ethoxytrypethelone (9), together with four known trypethelones (3-4, 7-8), and two known phenalenones (1-2) were characterized. It is the first report of 8-methoxytrypethelone methyl ether (5) purification as a racemic mixture in T. eluteriae. Earlier, 7-hydroxyl-8-methoxyltrypethelone (10) was reported as new compound with erroneous spectroscopic data. This compound was identified later as 8-hydroxytrypethelone methyl ether (4). X-ray crystallographic structures of compounds 5-7 were elucidated for the first time. Phenalenones (1-2) and trypethelones (5-6 and 9) were the additional compounds discovered in the cultured mycobiont of T. eluteriae. Six compounds (1-2, 5-8) were screened against Mycobacterium tuberculosis H37Rv and two compounds (7-8) against non-tuberculosis mycobacteria and other human pathogenic bacteria. Compound (7) inhibited M. tuberculosis H37Rv strain with an MIC of 12.5 µg/mL.

Anti-Complementary Components of Helicteres angustifolia.

A first phenalenon derivative with an acetyl side chain at C-8, 8-acetyl-9-hydroxy-3-methoxy-7-methyl-1-phenalenon (compound 1), and a pair of new sesquilignan epimers at C-7″ of hedyotol C and hedyotol D analogs, hedyotol C 7″-O-ß-d-glucopyranoside (compound 2) and hedyotol D 7″-O-ß-d-glucopyranoside (compound 3) were isolated from the aerial parts of Helicteres angustifolia together with nine known compounds (4-12). Their structures were elucidated on the basis of spectroscopic methods, including mass spectroscopy, and 1D and 2D nuclear magnetic resonance. Eleven isolates exhibited anti-complementary activity. In particular, compounds 4 and 5 exhibited potent anti-complementary activities against the classical and alternative pathways with CH50 values of 0.040 ± 0.009 and 0.009 ± 0.002 mM, and AP50 values of 0.105 ± 0.015 and 0.021 ± 0.003 mM, respectively. The targets of compounds 4 and 5 in the complement activation cascade were also identified. In conclusion, the anti-complementary components of H. angustifolia possessed chemical diversity and consisted mostly of flavonoids and lignans in this study.