The discovery of Streptomyces-produced streptomycin founded the age of tuberculosis therapy. Despite the subsequent development of a curative regimen for this disease, tuberculosis remains a worldwide problem, and the emergence of multidrug-resistant Mycobacterium tuberculosis has prioritized the need for new drugs. Here we show that new optimized derivatives from Streptomyces-derived griselimycin are highly active against M. tuberculosis, both in vitro and in vivo, by inhibiting the DNA polymerase sliding clamp DnaN. We discovered that resistance to griselimycins, occurring at very low frequency, is associated with amplification of a chromosomal segment containing dnaN, as well as the ori site. Our results demonstrate that griselimycins have high translational potential for tuberculosis treatment, validate DnaN as an antimicrobial target, and capture the process of antibiotic pressure-induced gene amplification.

Structure-activity relationships within a series of highly potent 2-carboxyindole-based factor Xa inhibitors incorporating a neutral P1 ligand are described with particular emphasis on the structural requirements for addressing subpockets of the factor Xa enzyme. Interactions with the subpockets were probed by systematic substitution of the 2-carboxyindole scaffold, in combination with privileged P1 and P4 substituents. Combining the most favorable substituents at the indole nucleus led to the discovery of a remarkably potent factor Xa inhibitor displaying a K(i) value of 0.07 nM. X-ray crystallography of inhibitors bound to factor Xa revealed substituent-dependent switching of the inhibitor binding mode and provided a rationale for the SAR obtained. These results underscore the key role played by the P1 ligand not only in determining the binding affinity of the inhibitor by direct interaction but also in modifying the binding mode of the whole scaffold, resulting in a nonlinear SAR.

Covering: up to March 2013. In addition to their prominent role in basic biological and chemical research, natural products are a rich source of commercial products for the pharmaceutical and other industries. Industrial natural product chemistry is of fundamental importance for successful product development, as the vast majority (ca. 80%) of commercial drugs derived from natural products require synthetic efforts, either to enable economical access to bulk material, and/or to optimize drug properties through structural modifications. This review aims to illustrate issues on the pathway from lead to product, and how they have been successfully addressed by modern natural product chemistry. It is focused on natural products of current relevance that are, or are intended to be, used as pharmaceuticals.

Attraktives Chlor: Nichtkovalente Wechselwirkungen zwischen Chlor‐ oder Brom‐Atomen und aromatischen Ringen in Proteinen bieten einen neuen Ansatzpunkt für die Beeinflussung der molekularen Erkennung. Die Einführung dieser Substituenten an spezifischen Positionen zweier Faktor‐Xa‐Inhibitoren erhöht deren freie Bindungsenergie durch die Wechselwirkung mit einer Tyrosineinheit. Das allgemeine Vorkommen dieses Strukturmotivs wird anhand zahlreicher Kristallstukturen und quantenchemischer Rechnungen belegt (siehe Bild).

Attractive chlorine: Noncovalent interactions between chlorine or bromine atoms and aromatic rings in proteins open up a new method for the manipulation of molecular recognition. Substitution at distinct positions of two factor Xa inhibitors improves the free energy of binding by interaction with a tyrosine unit. The generality of this motif was underscored by multiple crystal structures as well as high-level quantum chemical calculations (see picture).