Phytochemical Investigation of Tecoma capensis Flower Aqueous Extract and In Vitro Biological Studies: Anti‐Bacterial and Anti‐Proliferative Activities of its Silver Nanoparticles.

In this study, we report the synthesis of silver nanoparticles (AgNPs) from Tecoma capensis flower aqueous extract (TcAqFE). The impact of AgNPs on microstructural, optical, antibacterial and antiproliferative properties have been investigated through UV‐visible spectroscopy, X‐ray diffraction, transmission electron microscopy (TEM), fourier infra‐red spectroscopy (FTIR), agar well diffusion technique assay and MTT. The particles size estimated from TEM and XRD is in the range of 1–10 nm. The XRD pattern reveals that the Tecoma capensis silver nanoparticles (TcAgNPs) have a cubic crystal structure. FTIR spectra showed band positions at 1071, 1358, 1620, 1962, 2150, 2920 and 3361 cm−1. Surface plasmon resonance (SPR) in AgNPs became evident with an absorption peak at 407 nm. GC‐MS analysis of ethanolic flower extract revealed the presence of major phytochemical constituents, including Butanal (57.14 %), Propanol (20.23 %), Ethanone (4.88 %), Mesitylene (3.70 %), Hexanal (3.33 %), 4‐Cyclopentene‐1,3‐diol, trans (3.16 %), Furan (2.94 %), 5‐Hepten‐2‐one (2.58 %), and Acetic acid (1.68 %). The antibacterial assay results clearly indicate that the TcAgNPs exhibited the maximum activity against Salmonella typhi, with inhibition zone (IZ) values of (40±1.4 mm), followed by Bacillus subtilis (35.66±2.0 mm), Staphylococcus aureus (32.6±0.64 mm), Escherichia. coli (29.66±2.05 mm), Listeria monocytogenes (27±1.63 mm), and Klebsiella pneumoniae exhibiting the least IZ values (23±1.6 mm). Minimum inhibitory concentration (MIC) values ranged from 0.20 to 2.81 mg/mL. The highest MIC value 2.81 mg/mL was observed in case of Salmonella typhi, while Staphylococcus aureus (0.20 mg/mL), displayed the lowest MIC values. The MIC of Gentamycin also ranged from 0.012 to 0.024 mg/mL. MTT assay demonstrated that the aqueous extract was potent against the cancer cell line A549, with a GI50 of 71.79 μg/mL. These results suggest that TcAgNPs have therapeutic potential and can serve as antibacterial and antiproliferative agents to protect against several ailments. [ABSTRACT FROM AUTHOR]