High throughput workflow for coacervate formation and characterization in shampoo systems.

Cationic cellulosic polymers find wide utility as benefit agents in shampoo. Deposition of these polymers onto hair has been shown to mend split-ends, improve appearance and wet combing, as well as provide controlled delivery of insoluble actives. The deposition is thought to be enhanced by the formation of a polymer/surfactant complex that phase-separates from the bulk solution upon dilution. A standard characterization method has been developed to characterize the coacervate formation upon dilution, but the test is time and material prohibitive. We have developed a semi-automated high throughput workflow to characterize the coacervate-forming behavior of different shampoo formulations. A procedure that allows testing of real use shampoo dilutions without first formulating a complete shampoo was identified. This procedure was adapted to a Tecan liquid handler by optimizing the parameters for liquid dispensing as well as for mixing. The high throughput workflow enabled preparation and testing of hundreds of formulations with different types and levels of cationic cellulosic polymers and surfactants, and for each formulation a haze diagram was constructed. Optimal formulations and their dilutions that give substantial coacervate formation (determined by haze measurements) were identified. Results from this high throughput workflow were shown to reproduce standard haze and bench-top turbidity measurements, and this workflow has the advantages of using less material and allowing more variables to be tested with significant time savings.

Transformations of hydroxy cyclic sulfates: stereospecific conversion into 2,3,5-trisubstituted tetrahydrofurans.

1,2-Cyclic sulfates have been prepared from O-protected ricinoleate and ricinelaidate esters. Upon deprotection of the 12-hydroxy moiety, the resulting 12-hydroxy-9,10-cyclic sulfates underwent stereospecific cyclization to the corresponding 2,3,5-trisubstituted tetrahydrofurans. The cyclization occurs by backside attack of the hydroxy oxygen on the distal carbon of the 1,2-cyclic sulfate, with inversion at that center.

Analogs of diaminopimelic acid as inhibitors of meso-diaminopimelate dehydrogenase and LL-diaminopimelate epimerase.

Analogs 1-8 of diaminopimelic acid (DAP) were synthesized and tested for inhibition of purified meso-DAP D-dehydrogenase from Bacillus sphaericus and of LL-DAP epimerase from Escherichia coli. The dehydrogenase was assayed by monitoring NADPH formation spectrophotometrically at 340 nm. N-Hydroxy DAP 4, N-amino DAP 5, and 4-methylene DAP 6 are substrates of the dehydrogenase with relative rates exceeding those of the meso isomers of the thia analogs 1ab, 2ab, and 3ab. DAP epimerase was assayed by coupling the epimerization of LL-DAP to DL-DAP (Km = 0.26 mM) with the dehydrogenase-catalyzed oxidation of DL-DAP by NADP. Lanthionine isomers 1ab and 1c were stronger inhibitors of the epimerase (Ki = 0.18 mM, Ki' = 0.67 mM, and Ki = 0.42 mM, respectively) than the corresponding meso-sulfoxide 2ab or the meso-sulfone 3ab. Other isomers of 2 and 3, as well as compounds 7 and 8, showed no epimerase inhibition. N-Hydroxy DAP 4 was the most potent competitive inhibitor (Ki = 0.0056 mM) of the epimerase, whereas N-amino DAP 5 is weaker (Ki = 2.9 mM) and 4-methylene DAP 6 is a noncompetitive inhibitor (Ki' = 0.95 mM). Although none of the analogs tested showed time-dependent inactivation of either enzyme, compounds 4, 5, 6, and 7 display substantial antibacterial activities. Possible mechanisms of epimerase inhibition and significance of the DAP pathway as a target for antibiotics are discussed.