Thionin Production in Elicited Plant Cell Suspension and its Application as Antibacterial, Anticancer and Anti-Inflammatory Agent

Antibiotic resistance poses a global health threat. It reduces the effectiveness of antibiotics against bacterial infections. Antimicrobial peptides, including thionins, offer a promising alternative due to their broad-spectrum activity and lower likelihood of resistance development.

This study focuses on the production of thionin from barley cell suspension cultures, induced with biotic and abiotic agents, and its evaluation for antibacterial, anticancer, and anti-inflammatory activities. Barley calli were initiated and subcultured in media containing various elicitors, such as Fusarium metabolites, polyethylene glycol, and nano-chitosan.

The combination of nano-chitosan and Fusarium metabolites yielded the highest thionin production and optimal growth. The purified thionin demonstrated strong antibacterial activity, with a minimum inhibitory concentration of approximately 1.2 µg/mL, surpassing that of ciprofloxacin. This activity is likely due to increased bacterial membrane permeability, indicated by a high electrolyte leakage rate of around 70%, and DNA disruption, evidenced by an 81% reduction in DNA content in thionin-treated bacteria. Additionally, thionin treatment inhibited nearly 100% of biofilm formation. In anticancer assays, thionin exhibited significant cytotoxicity against multiple cancer cell lines, with low IC50 values of 0.29 µg/mL against liver cancer cells and 0.17 µg/mL against colon cancer cells. The anticancer mechanism involved the induction of apoptosis markers, including increased nuclear intensity, membrane permeability, mitochondrial membrane permeability, and cytochrome c release. Importantly, thionin showed lower hemolytic activity compared to doxorubicin. Moreover, thionin displayed superior anti-inflammatory activity relative to aspirin.

These findings underscore the potential of barley-derived thionin as a versatile therapeutic agent against antibiotic-resistant infections, cancer, and inflammation.