1. Fast-Acting Antibacterial, Self-Deactivating Polyionene Esters
Christian Krumm, Lena Benski, Joerg C Tiller, Manfred Köller, Franziska Oberhaus, Jens Wilken, Sylvia Trump ACS Appl Mater Interfaces . 2020 May 13;12(19):21201-21209. doi: 10.1021/acsami.9b19313.
Biocidal compounds that quickly kill bacterial cells and are then deactivated in the surrounding without causing environmental problems are of great current interest. Here, we present new biodegradable antibacterial polymers based on polyionenes with inserted ester functions (PBI esters). The polymers are prepared by polycondensation reaction of 1,4-dibromobutene and different tertiary diaminodiesters. The resulting PBI esters are antibacterially active against a wide range of bacterial strains and were found to quickly kill these cells within 1 to 10 min. Because of hydrolysis of the ester groups, the PBI esters are degraded and deactivated in aqueous media. The degradation rate depends on the backbone structure and the pH. The structure of the polymers also controls the deactivation mechanism. While the more hydrophilic polymers require hydrolyses of only 19 to 30% of the ester groups to become practically inactive, the more hydrophobic PBI esters require up to 85% hydrolysis to achieve the same result. Thus, depending on the environmental conditions and the chemical nature, the PBI esters can be active for only 20 min or for at least one week.
2. α-Imino Esters in Organic Synthesis: Recent Advances
Bagher Eftekhari-Sis, Maryam Zirak Chem Rev . 2017 Jun 28;117(12):8326-8419. doi: 10.1021/acs.chemrev.7b00064.
α-Imino esters are useful precursors for the synthesis of a variety of types of natural and unnatural α-amino acid derivatives, with a wide range of biological activities. Due to the adjacent ester group, α-imino esters are more reactive relative to other types of imines and undergo different kinds of reactions, including organometallics addition, metal catalyzed vinylation and alkynylation, aza-Henry, aza-Morita-Baylis-Hillman, imino-ene, Mannich-type, and cycloaddition reactions, as well as hydrogenation and reduction. This review discusses the mechanism, scope, and applications of the reactions of α-imino esters and related compounds in organic synthesis, covering the literature from the last 12 years.
3. Catalytic antibodies
A Tramontano, R A Lerner, K D Janda Science . 1986 Dec 19;234(4783):1566-70. doi: 10.1126/science.3787261.
Monoclonal antibodies elicited to haptens that are analogs of the transition state for hydrolysis of carboxylic esters behaved as enzymic catalysts with the appropriate substrates. These substrates are distinguished by the structural congruence of both hydrolysis products with haptenic fragments. The haptens were potent inhibitors of this esterolytic activity, in agreement with their classification as transition state analogs. Mechanisms are proposed to account for the different chemical behavior of these antibodies with two types of ester substrates. The generation of an artificial enzyme through transition state stabilization by antibodies was thus demonstrated. These studies indicate a potentially general approach to catalyst design.
