摘要：AbstractThe objective of this study was to investigate the bioactivity ofN-(cinnamylidene) tryptophan (CinTrp), including itsin vitrohemolytic effect on erythrocytes, at different concentrations (20–1000 µg/mL). CinTrp was synthesized by condensing cinnamaldehyde (Cin) and tryptophan (Trp) in a basic medium. Its physicochemical, spectral, and thermal properties were analyzed using Fourier transform infrared, proton and 13-carbon nuclear magnetic resonance, electronic, and mass spectroscopy, as well as thermogravimetric and differential scanning calorimetry. Antibacterial activity against Gram-positive (S. aureus) and Gram-negative (E. coli,P. aeruginosa, andK. pneumoniae) bacteria was assessed using the agar disk-diffusion method, while the hemolytic effect on human erythrocytes was spectrophotometrically determined. Thermal analysis suggested that CinTrp is less stable than its Trp precursor. The antibacterial activity of CinTrp againstE. coliwas close to that of ceftriaxone, while againstK. pneumoniaeit was nearly half that for ampicillin and ceftriaxone standard drugs. No effects onS. aureusandP. aeruginosawere observed. Cell hemolysis test in reference to phosphate-buffered saline (negative) and Triton X-100 (0.1% v/v) (positive) controls indicated low or no effects up to 250 µg/mL (≤1.50% ± 3.06%), with a slight increase up to 750 µg/mL (6.50% ± 2.87%); however, lysis of 23.13% ± 7.76% at 1000 µg/mL was detected. It could be concluded that CinTrp is more active against Gram-negative bacteria and its hemolytic effect on erythrocytes apparently begins above 250 µg/mL. However, additional analyses in terms of the concentration range, methods, and types of microorganisms may be necessary to assuage safety concerns and deepen understanding.
关键词：KeywordsenHemolytic activitySpectroscopic analysisCinnamaldehydeTryptophanAzomethineSchiff base
