Surface free energy (SFE) is a property resulted from the chemical structure and the orientation of the molecules at the surface boundary of the materials. For solids, it can be calculated from the contact angles of liquid drops with known surface tension, formed on the solid surface. There are various SFE evaluation methods based on different theoretical assumptions. In this study, SFE and the dispersive, polar, acidic and basic components of the SFE of a polymeric material, poly(methyl methacrylate) (PMMA), were calculated by using Zisman, Saito, Fowkes, Berthelot, Geometric mean, Harmonic mean, and Acid–base approaches. The results obtained from various liquid couples or triplets were compared. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Mahanine, a carbazole alkaloid is a potent anticancer molecule. To recognize the structure-activity correlation, mahanine was chemically modified. Antiproliferative activity of these derivatives was determined in 19 cancer cell lines from 7 different origins. Mahanine showed enhanced apoptosis compared to dehydroxy-mahanine-treated cells, indicating significant contribution of the C-7-OH group. O-Methylated-mahanine and N-methylated dehydroxy-mahanine-treated cells exhibited apoptosis only at higher concentrations, suggesting additional contribution of 9-NH group. Using biophysical techniques, we demonstrated that mahanine interacts with DNA through strong association with phosphate backbone compared to other derivatives but is unable to induce any conformational change in DNA, hence suggesting the possibility of being a minor groove binder. This was corroborated by molecular modeling and isothermal titration calorimetry studies. Taken together, the results of the current study represent the first evidence of involvement of C-7-OH and 9-NH group of mahanine for its cytotoxicity and its minor groove binding ability with DNA.

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