June 8, 2022: Naike Schwenner successfully defended her Master thesis: “Bioactivity of N-succinylated chitosans and in vitro and in silico studies of antifungal compounds”

Today, Naike Schwenner successfully defended her Master thesis which she had performed in the framework of the BMBF-funded Indo-German Bioeconomy International project Bio-Fun, initiated and led by our bioinformatician Dr. Ratna Singh. Naike's project concerned the identification of candidate inhibitors for chitin deacetylases as potential novel antifungal agents. She was able to verify the inhibitory activity of several compounds which had been identified in silico by Dr. Singh as interesting candidates, but the experiments to substantiate the relevance of this inhibitory activity by analysis of the chitin and chitosan content in the cell walls of fungal hyphae grown in the presence or absence of the inhibitors failed due to technical problems. To overcome these, Naike even traveled to the Julius-Kühn-Institute in Braunschweig to work there under the direct supervision of an expert in the field, Dr. Yvonne Becker, but to no avail. Fortunately, Naike had started, in parallel, a side project under the supervision of our biochemist Dr. Stefan Cord-Landwehr and supported by our colleague Dr. Dominique Gillet from the French chitosan company Gillet Chitosan, in which she prepared chitosan derivatives with different degrees of N-succinylation to analyze their biological functionalities, including antimicrobial and plant strengthening activities. Succinylation adds negative charges to the otherwise positively charged chitosan, so that the balance between succinylation and acetylation determines the net charge of the polymers. Preparing such a series of chitosan derivatives and systematically analyzing their biological activities had been a plan since almost twenty years! As expected given that the cationic nature of chitosans is partly responsible for their bioactivities, succinylation had a strong effect on these, particularly on antimicrobial activities. But there were also unexpected observations regarding plant strengthening and enzymatic degradability, which warrant further analyses. Perhaps, Naike can still support us a little in these before she leaves for a doctoral project in Sweden.