The lyotropic polymorphism of two pharmacologically active molecules

The two drugs considered are amiodarone hydrochloride (AC), used in heart therapy and palmitoyl timolol malonate (PTM), a prodrug of timolol and a medicament for glaucoma. These crystalline compounds are poorly soluble in water at room temperature, but form transparent phases, which are sols or gels, much more concentrated than the critical micellar concentration (CMC), when the crystals are heated in the presence of water to temperatures from 50 to 80 degrees C and cooled to room temperature. These transparent pseudo-solutions were also obtained by dissolution in chloroform, followed by rapid solvent evaporation and addition of water. A lamellar phase was also observed, with its classical textures: myelin forms, oily streaks and polygonal fields. Two transparent and isotropic phases, one more concentrated than the lamellar phase and the other one less concentrated, are presumed to be inverse sponges. The water-rich phase, mainly studied with amiodarone, formed a milky cloud on further dilution and a model has been proposed. From these two examples, some remarks of a geometrical kind are presented on the rich polymorphism of certain water-lipid systems.     

Improving the sampling efficiency of Monte Carlo molecular simulations: an evolutionary approach

We present a new approach in order to improve the convergence of Monte Carlo (MC) simulations of molecular systems belonging to complex energetic landscapes: the problem is redefined in terms of the dynamic allocation of MC move frequencies depending on their past efficiency, measured with respect to a relevant sampling criterion. We introduce various empirical criteria with the aim of accounting for the proper convergence in phase space sampling. The dynamic allocation is performed over parallel simulations by means of a new evolutionary algorithm involving ‘immortal’ individuals. The method is bench marked with respect to conventional procedures on a model for melt linear polyethylene. We record significant improvement in sampling efficiencies, thus in computational load, while the optimal sets of move frequencies are liable to allow interesting physical insights into the particular systems simulated. This last aspect should provide a new tool for designing more efficient new MC moves.     

BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES—VIII. CELLULAR DISTRIBUTION INV–79 CHINESE HAMSTER CELLS AND PHOTOTOXICITY OF SELECTIVELY SULFONATED ALUMINUM PHTHALOCYANINES

Abstract— Water soluble chloro aluminum phthalocyanines sulfonated to different degrees are studied for phototoxicity and cellular distribution inV–79 Chinese hamster cells. The more hydrophobic disulfonated dyes, with sulfonate substituents on adjacent benzyl groups of the phthalocyanine ring structure, exhibited the best cell penetrating properties and the highest phototoxicity. Fluorescence microscopy revealed that the dye was uniformly distributed in the cytoplasm but absent in the nucleus. The greater cell membrane penetrating properties of the lower as compared to the higher sulfonated dyes are attributed to the amphiphilic nature of the former.     

SULFONATED PHTHALIMIDOMETHYL ALUMINUM PHTHALOCYANINE: THE EFFECT OF HYDROPHOBIC SUBSTITUENTS ON THE in vitro PHOTOTOXICITY OF PHTHALOCYANINES

The photocytotoxicity of sulfonated phthalimidomethyl aluminum phthalocyanine, a more hydrophobic photosensitizer as compared to phthalocyanine substituted with sulfonate groups only, was investigated. Inclusion of 1-2 phthalimidomethyl groups into disulfonated aluminum phthalocyanine, resulted in increased partition coefficients between n-octanol and water, and a six-fold increase in both cellular uptake and photocytotoxicity towards Chinese hamster lung fibroblast cells (line V-79). Reducing the number of phthalimidomethyl groups, or increasing the degree of sulfonation, lead to a decrease in the partition coefficient, cellular uptake, and phototoxicity. The quantum yield of singlet oxygen was comparable for all dyes tested in this series, indicating that no significant change in this photophysical parameter resulted from phthalimidomethylation. These results suggest that the addition of 1-2 phthalimidomethyl groups to disulfonated aluminum phthalocyanine improves cellular uptake, but, as the relative efficiency of cell killing was not effected, the intracellular distribution on photosensitive molecules may not be modified.