Christian Melander

Research Interests

The Melander lab is interested broadly in applying the principles of synthetic organic chemistry and microbiology to deliver novel molecules that address problems associated with failure in antibiotic therapy for the treatment of bacterial infections. Specifically, we are interested in developing novel approaches to combat biofilm-based infections that typically give rise to chronic infections (such as those found in Cystic Fibrosis patients, indwelling medical devices, and diabetic ulcers), as well as acute bacterial infections caused by multi-drug resistant pathogens.

Bacterial Biofilms

A biofilm is defined as a surface attached community of bacteria encased in an extracellular matrix. Biofilms are typically 100-1000-fold more resistant to antibiotics and are recalcitrant to clearance by the host immune response. To address this problem, we are investigating the effects that simple structural motifs found embedded in complex marine natural products have upon biofilm development and maintenance. We have demonstrated that simple derivatives of the natural products bromageliferin and oroidin will inhibit and disperse biofilms from pathogenic bacteria as well as fungi and mixed species biofilms. We have also established that our 2-aminoimidazole-derived anti-biofilm agents are non-toxic to red blood cells, mammalian cell lines, and model organisms. The mechanistic basis by which these compounds inhibit and disperse biofilms, as well as the effect these compounds have in vivo are being pursued.

Multi-drug Resistant Bacteria

The rise of multi-drug resistant pathogens is threatening the vast medical advancements made possible by antibiotics over the last 70+ years. Surgery, premature infant care, cancer chemotherapy, care of the critically ill, and transplantation medicine to name a few fields are feasible only with the existence of effective antibiotic therapy. To address this issue, the Melander lab is currently pursing two distinct yet complementary avenues. The first focuses on new chemical matter that give rise to narrow spectrum antibiotic profiles (both small molecules and nanoparticles) that are potentially less damaging to commensal flora and less susceptible to resistance evolution. The second avenue relies upon an adjuvant approach, in which a small molecule that targets resistance mechanisms is paired with currently approved antibiotics. This latter approach is underpinned by the discovery that a certain sub-set of our 2-aminoimidazole library is able to render multi-drug resistant bacterial strains susceptible to various classes of conventional antibiotics. We are currently probing the mechanistic basis of this activity, augmenting activity through analogue synthesis, and exploring the in vivo potential of these compounds in animal models of infection.

Selected Publications

• Jenul, C.; Keim, K. C.; Jens, J. N.; Zeiler, M. J.; Schilcher, K.; Schurr, M. J.; Melander, C.; Phelan, V. V. and Horswill, A. R. "Pyochelin Biotransformation by Staphylococcus Aureus Shapes Bacterial Competition with Pseudomonas Aeruginosa in Polymicrobial Infections" 2023 Cell Reports, 42 (6), 112540. DOI: 10.1016/j.celrep.2023.112540.
• Harper, E. I.; Siroky, M. D.; Hilliard, T. S.; Dominique, G. M.; Hammond, C.; Liu, Y. Y.; Yang, J.; Hubble, V. B.; Walsh, D. J.; Melander, R. J.; Melander, C.; Ravosa, M. J. and Stack, M. S. "Advanced Glycation End Products as a Potential Target for Restructuring the Ovarian Cancer Microenvironment: A Pilot Study" 2023 International Journal of Molecular Sciences, 24 (12), 9804. DOI: 10.3390/ijms24129804.
• Liu, C.; Zhang, H.; Peng, X.; Blackledge, M. S.; Furlani, R. E.; Li, H. T.; Su, Z. M.; Melander, R. J.; Melander, C.; Michalek, S. and Wu, H. "Small Molecule Attenuates Bacterial Virulence by Targeting Conserved Response Regulator" 2023 mBio, 14 (3), e00137-23. DOI: 10.1128/mbio.00137-23.
• Marrujo, S. A.; Hubble, V. B.; Yang, J. D.; Wang, M.; Nemeth, A. M.; Barlock, S. L.; Juarez, D.; Smith, R. D.; Melander, R. J.; Ernst, R. K.; Chang, M. Y. and Melander, C. "Dimeric 2-Aminoimidazoles are Highly Active Adjuvants for Gram-Positive Selective Antibiotics Against Acinetobacter Baumannii" 2023 European Journal of Medicinal Chemistry, 253, 115329. DOI: 10.1016/j.ejmech.2023.115329.
• Weig, A. W.; O'Conner, P. M.; Kwiecinski, J. M.; Marciano, O. M.; Nunag, A.; Gutierrez, A. T.; Melander, R. J.; Horswill, A. R. and Melander, C. "A Structure Activity Relationship Study of 3,4'-Dimethoxyflavone for ArlRS Inhibition in Staphylococcus Aureus" 2023 Organic & Biomolecular Chemistry, 21 (16), pp.3373-3380. DOI: 10.1039/d3ob00123g.
• Onyedibe, K. I.; Nemeth, A. M.; Dayal, N.; Smith, R. D.; Lamptey, J.; Ernst, R. K.; Melander, R. J.; Melander, C. and Sintim, H. O. "Re-Sensitization of Multidrug-Resistant and Colistin-Resistant Gram- Negative Bacteria to Colistin by Povarov/Doebner-Derived Compounds" 2023 ACS Infectious Diseases, 9 (2), pp.283-295. DOI: 10.1021/acsinfecdis.2c00417.