Vibrational Optical Activity Study of Four Antibiotic (Lipo)glycopeptides: Vancomycin, Oritavancin, Dalbavancin, and Teicoplanin.

The antibiotic glycopeptide class, of which vancomycin is the original compound, has received due attention over the past few decades in search of antibiotics to overcome resistances developed by bacteria. Crucial for the understanding and further development of glycopeptides that possess desired antibacterial effects is the determination of their conformational behavior, as this sheds light on the mechanism of action of the compound. Among others, vibrational optical activity (VOA) techniques (vibrational circular dichroism and Raman optical activity) can be deployed for this, but the question remains to what extent these spectroscopic techniques can provide information concerning the molecular class under investigation. This contribution takes the last hurdle in the search for the capabilities of the VOA techniques in the conformational analysis of the antibiotic glycopeptide class by extending research that was previously conducted for vancomycin toward its three derivatives: oritavancin, dalbavancin, and teicoplanin. The principal information that can be drawn from VOA spectra is the conformation of the rigid cyclic parts of the glycopeptides and the aromatic rings that are part hereof. The addition or removal of carbohydrates does not induce noticeable VOA spectral responses, preventing the determination of the conformation they adopt.