Despite the high medical need for oral peptide delivery, instability in the gastrointestinal tract and low mucosal permeation still impede this preferred route of administration. Herein, a liposomal nanocarrier combining two self‐reliant strategies to overcome these delivery barriers is reported. This approach enables the design of a nanocarrier system with synergistic properties: tetraether lipids derived from archaea are incorporated into liposomes to provide the particles with the stability required to traverse the stomach. When the surface of the resulting inert particles is modified with cell‐penetrating peptides, mucosal permeation can be achieved. The designed nanocarrier is proven effective by the high mucosal uptake of the glycopeptide antibiotic vancomycin in Ussing chamber studies. Efficacy in vivo is demonstrated in naïve rats, where a highly increased oral bioavailability is obtained for vancomycin, a drug known to be minimally absorbed. In contrast, administration of liposomes with single modification (tetraether lipids) leads to a substantially lower bioavailability. Therapeutic efficacy is proven by the antimicrobial activity of vancomycin in a Galleria mellonella and a systemic infection mouse model. The high oral bioavailability in absence of cytotoxic effects demonstrates that this nanocarrier delivery strategy might boost the oral application of macromolecular drugs in general.

Increasing antibacterial drug resistance threatens global health, unfortunately, however, efforts to find novel antibacterial agents have been scaled back by the pharmaceutical industry due to concerns about a poor return on investment. Nevertheless, there is an urgent need to find novel antibacterial compounds to combat antibacterial drug resistance. The synthesis of novel drugs from natural sources is mostly cost-intensive due to those drugs’ complicated structures. Therefore, it is necessary to find novel antibacterials by simple synthesis to become more attractive for industrial production. We succeeded in the discovery of four antibacterial compound (sub)classes accessible in a simple one-pot reaction based on fluorinated benzothiophene-indole hybrids. They have been evaluated against various S. aureus and MRSA strains. Structure- and substituent-dependent activities have been found within the (sub)classes and promising lead compounds have been identified. In addition, bacterial pyruvate kinase was found to be the molecular target of the active compounds. In conclusion, simple one-pot synthesis of benzothiophene-indoles represents a promising strategy for the search of novel antimicrobial compounds.

Ongoing resistance developments against antibiotics that also affect last-resort antibiotics require novel antibacterial compounds. Strategies to discover such novel structures have been dimerization or hybridization of known antibacterial agents. We found novel antibacterial agents by dimerization of indols and hybridization with carbazoles. They were obtained in a simple one-pot reaction as bisindole tetrahydrocarbazoles. Further oxidation led to bisindole carbazoles with varied substitutions of both the indole and the carbazole scaffold. Both the tetrahydrocarbazoles and the carbazoles have been evaluated in various S. aureus strains, including MRSA strains. Those 5-cyano substituted derivatives showed best activities as determined by MIC values. The tetrahydrocarbazoles partly exceed the activity of the carbazole compounds and thus the activity of the used standard antibiotics. Thus, promising lead compounds could be identified for further studies.