Detailed investigation and influence of oxidation degree on synthesis, characterization and antibacterial activity of 13-cyclodextrin

Oxidation of 13-cyclodextrin (13-CD) using varying molar ratios of sodium periodate (NaIO4) was investigated in detail on synthesis, characterization and antibacterial property. Synthesis and characterization results showed that Oxidized 13-cyclodextrins (OX-13-CDs) were obtained and aldehyde (CHO) groups were successfully introduced. Our results demonstrated that aldehyde content and yield increased with increasing NaIO4 molar amount. However, the structure of 13-CD was degraded as a result of glycosidic ring opening with increasing stoichiometric ratio of NaIO4/13-CD to 5/1 and 7/1. Aldehyde functional groups in OX-13-CDs were characterized by employing FTIR, 1H NMR, XRD, SEM techniques and confirmed by the detection of CHO peak at 1730 cm-1 in the FTIR and detection of the aldehyde H peak between 9 to 10 ppm in the 1H NMR spectrum. In addition, SEM and XRD of OX-13-CDs showed alterations in the morphological and crystal structure (transforming from crystalline to amorphous) of 13-CD as a result of increasing oxidation.Especially, antibacterial activity of OX-13-CDs was investigated against both Gram-negative and Gram-positive bacteria by using the minimal inhibitory concentration (MIC) and the Disk diffusion method. The results showed that OX-13-CDs possessed good antibacterial activity, which can destroy the bacterial cell wall, and may be used as an antibacterial agent.