Estimating the Octanol/Water Partition Coefficient for Aliphatic Organic Compounds Using Semi-Empirical Electrotopological Index

A new possibility for estimating the octanol/water coefficient (log P) was investigated using only one descriptor, the semi-empirical electrotopological index (ISET). The predictability of four octanol/water partition coefficient (log P) calculation models was compared using a set of 131 aliphatic organic compounds from five different classes. Log P values were calculated employing atomic-contribution methods, as in the Ghose/Crippen approach and its later refinement, AlogP; using fragmental methods through the ClogP method; and employing an approach considering the whole molecule using topological indices with the MlogP method. The efficiency and the applicability of the ISET in terms of calculating log P were demonstrated through good statistical quality (r > 0.99; s < 0.18), high internal stability and good predictive ability for an external group of compounds in the same order as the widely used models based on the fragmental method, ClogP, and the atomic contribution method, AlogP, which are among the most used methods of predicting log P

Algebraic conditions, in terms of the solvent partition constants, for the separation of chemical classes by gas–liquid chromatography

<p>The interdependence between the solvation Gibbs energy of several functional groups and the solvent partition coefficients was studied, starting from gas chromatographic data. Single-parameter relationships were derived for the –OH, -CHO, -CO, -O-,-COO (acetate), -COO (methyl ester)-, and -CN group increments. The obtained equations were found to be temperature independent, and could be successfully used for the evaluation of 19 stationary phases with respect to certain separation questions. The selectivity problem was converted into an inequality system. The graphical solution of such a system provides an image of the separation abilities of a sorbent material with respect to a given pair of solutes, and allows an efficient comparison of a great number of stationary phases. The graphs are also illustrative for the temperature effect on the selectivity features.</p

Bioactivity and chemical composition of humulus lupulus for cosmetic use

Humulus lupulus L. is use as a flavoring and stabilizing agent for beer, giving aromas and flavors. Can also be use in cosmetics,for its antibacterial/antioxidant effect. Prepare a cosmetic gel formulations with phenolic extracts of the flowers and vegetative parts and analyze their stability, antioxidant/antimicrobial activity. Phenolic compounds were extracted with ethanol/water. Humulus lupulus varieties used were (vegetative parts):Chinook, Cascade, Polaris, Centennial, Nugget, and (flowers):Cascade, Polaris, Nugget and Centennial. Gel formulations were prepared, using Carbopol and MethylCellulose, with 3 concentrations: 2.5, 5 and 7.5%. For stability we test:pH, density, temperature, light, centrifuge, vibration and UV spectrophotometric analysis. Organoleptic characteristics:odor, color and aspect was test. Extracts were evaluated for antimicrobial activity by agar diffusion assays of E.coli and Candida albicans. pH have no alteration. Centrifuge and vibration tests, most of the gel formulations did not present phase separation. Density was 1.2-1.3 g/cm3 . Candida Albicans test, have no result but bacteria test shown that E.coli was sensible for all concentrations. Flower hydroalcoolic extract are richest in phenolic compounds than the vegetative parts. Phenols composition is different in all varieties. Gels are stable and can be used as a cosmetic in further studies. Humulus lupulus showed positive antibacterial result.info:eu-repo/semantics/publishedVersio