Investigation of the Functional Groups of Bioactive Compounds, Radical Scavenging Potential, Antimicrobial Activity and Cytotoxic Effect of Callistemon Citrinus Aqueous Extract on Cell Line HT29: A Laboratory Study

The extensive use of chemical drugs for the treatment and control of chronic and infectious diseases as well as colorectal cancer, has led to an increased demand for natural and safe drugs and preservatives. Therefore, this study aimed to evaluate the presence of functional groups of constituents, total phenol and flavonoids content, radical scavenging potential, and antimicrobial activity of Callistemon citrinus aqueous extract (CCE). Its interaction with common therapeutic antibiotics and cytotoxic effect on cell line HT29 was also evaluated.

In this laboratory study, the presence of functional groups of chemical constituents of C. citrinus aqueous extract was evaluated by Fourier transform infrared (FTIR) spectroscopy. Free radical scavenging activity, total phenol and flavonoids content, antimicrobial activity of C. citrinus aqueous extract and its interaction with chloramphenicol and gentamicin antibiotics, and the viability of cell line HT29 (through MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] test) under different concentrations of C. citrinus aqueous extract were investigated. Data were analyzed using one-way ANOVA followed by Duncan’s test.

The C. citrinus aqueous extract had a considerable antimicrobial effect on Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Staphylococcus aureus, and Listeria innocua. The free radicals scavenging effect of C. citrinus aqueous extract was in the range of 51.33-71.68%. The presence of C-C and OH groups of phenolic compounds of C. citrinus aqueous extract was confirmed by FTIR. After 24 hours, the different concentrations of C. citrinus aqueous extract reduced the growth of cell line HT29 compared to the control group (p<0.05).

The C. citrinus aqueous extract had antimicrobial activity, antioxidant potential and inhibitory effect on cell line HT29. Therefore, the use of C. citrinus aqueous extract could be suggested in pharmaceutical and food industries.