Utilization of reversed-phase TLC and topological indices to the lipophilicity investigations of naproxen

Aim The lipophilicity of naproxen by reversed-phase thin-layer chromatography (RP-TLC) and new methods of calculation of partition coefficients were developed. Methods Naproxen was investigated with the use RP-TLC on RP2 (Kieselgel 60 F254 silanisiert), RP8F254s, RP18F254s, DiolF254s, and CNF254s plates, and methanol–water (pHwater = 2.56; 5.73; 8.50) and 1,4-dioxane–water (pHwater = 5.73) in different volume compositions as the mobile phases. The chromatographic parameters of lipophilicity (RMW) of the studied naproxen were determined and compared both, with measured (logPexp), and calculated partition coefficients (AlogPs, AClogP, AB/logP, miLogP, AlogP, mlogP, logPKowwin, xlogP2, and xlogP3). New methods were proposed for calculation of logP for naproxen using the RF value and the numerical value of topological index (1χ, 2χ, 1χν, oB). Results It was apparent that the lipophilicities RMW(RP18, pH = 2.56), RMW(RP8, pH = 2.56), RMW(RP8, pH = 5.73), RMW(RP8, pH = 8.50), RMW(CN, pH = 2.56), and RMW(RP8, pH = 5.73, d) values were most similar to the experimental partition coefficient. Therefore, the RP8F254s plate is the best for lipophilicity analysis of naproxen. Conclusion The logP values calculated for naproxen by the use of RF values and topological index oB, using the new approach, correlate the best with experimental partition coefficient. Key words: Naproxen; RP-TLC; Lipophilicity parameter RMW; Theoretical partition coefficient; Topological index.