Search Results (2)

The aqueous extract of the leaves of Odontonema strictum (OSM) is used in folk medicine for its antihypertensive properties, and it contains a wide range of secondary metabolites, mostly polyphenols such as verbascoside and isoverbascoside, which could play a major role in the preparation of silver nanoparticles. In this study, we aimed to prepare AgNPs for the first time using the OSM leaf extract (OSM-AgNPs) to investigate their free radical-scavenging potency against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydrogen peroxide (H₂O₂). Dynamic light scattering (DLS), UV/Vis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS) were used to characterize the OSM-AgNPs. With a size around 100 nm and a ζ-potential of −41.1 mV, OSM-AgNPs showed a good stability and a better colloidal property due to electrostatic repulsion and the dispersity. The strong absorption peak at 3 keV in the EDX spectra indicated that silver was the major constituent. Additionally, the existence of silver atoms was confirmed by the Ag 3d_5/2 peak around 367 eV in the XPS spectra. IC₅₀ values of 116 μg/mL and 4.4 μg/mL were obtained for the scavenging activities of DPPH and H₂O₂, respectively. The synthetic OSM-AgNPs can be further exploited as potential antioxidant agents. Full article

Red firespike (Odontonema strictum) is a tropical flowering plant that was selected as a potential flowering potted plant for its attractive red floral spikes. The objective of this study was to evaluate how light intensity, photoperiod, and temperature affect the growth and flowering of firespike. In Experiment 1, plants were grown under 0%, 45%, or 65% shade and two photoperiod conditions; long-day (LD = ≥14 h) and short-day (SD = 9 h), for 16 weeks. Plants grown under 45% shade + LD were tallest at 35.9 cm, while plants grown under 65% shade + SD were shortest at 22.8 cm. During the finishing stage, the number of inflorescences increased when plants were grown under 45% shade + SD, 45% shade + LD, and no shade, with 6, 7, and 9 inflorescences, respectively. In addition, the first open flower was observed in the 0% shade group (control) 92 days after starting the experiment. The time to first open flower increased when the plants were grown under 65% shade, either under SD or LD. In Experiment 2, plants were grown in controlled environment growth chambers with average daily temperatures of 15, 25, or 35 °C and an irradiance of 200 µmol·m⁻²·s⁻¹ for 9 h per day. Plants grown at 25 °C were the tallest and had the largest leaf area. Plants grown at 15 and 35 °C had 28% and 22% less leaf area, respectively. The average number of inflorescences in plants grown at 25 °C was 1.6, while no inflorescence development was observed in plants grown at 15 or 35 °C by the termination of the experiment. There were no differences between plant growth index or branch number in response to temperature. Under the experimental conditions tested, the most rapid and uniform flowering of firespike occurred when plants were grown under no shade or at 25 °C. Full article