Characterization and bioevaluation of radioiodinated oseltamivir phosphate for inflammation imaging as a new...

This study explores the dual antibacterial and imaging capabilities of radioiodinated Oseltamivir phosphate [¹³¹I]IodoTam for distinguishing infection from sterile inflammation. Oseltamivir phosphate (Tamiflu) was successfully labeled with iodine-131 via electrophilic substitution, achieving a high radiochemical yield (96.5 ± 1.2 %) under optimal conditions: 100 μg Tam, 100 μg chloramine-T, pH 4, 30-min incubation at room temperature, 25 °C. Quality control confirmed tracer purity through TLC and HPLC techniques. The in vitro antibacterial activity of Tamiflu was evaluated using a standard agar disk diffusion test against Staphylococcus aureus. A clear dose-dependent inhibition was observed, with zones measuring 10-24 mm in diameter at increasing Tamiflu doses (5-50 μg), exceeding the positive control (vancomycin 50 μg, 16 mm zone). Additionally, bacterial binding tests showed substantial uptake of [¹³¹I]IodoTam by S. aureus (56 ± 0.32 %), highlighting its potential targeting ability. In vivo, bioevaluation revealed that the [¹³¹I]IodoTam tracer accumulated more in infected tissue (T/NT = 6.6 at 2 h post-injection) compared to sterile inflamed tissue (T/NT = 2.71 at 2 h post-injection). It was also significantly higher than the ratio of commercially available ^99mTc-ciprofloxacin (T/NT = 3.18 at 1 h post-injection). These findings suggest that [¹³¹I]IodoTam could be a valuable tool for differentiating bacterial infections from sterile inflammation, demonstrating its potential as a dual-action antiviral and antibacterial agent for imaging and therapy in infectious diseases.