Green Synthesis of Characterized Silver Nanoparticle Using Cullen tomentosum and Assessment of Its Antibacterial Activity.

Plants serve as an important source of medicine and provide suitable candidate compounds to produce eco-friendly therapeutic agents. They also represent a source of bio-reducer and stabilizer for the development of nanoparticles for downstream applications. This study focused on the green synthesis of silver nanoparticle (CTAgNP) using Cullen tomentosum (Thunb.) J.W. Grimes acetone extract and the evaluation of the antibacterial activity of the plant extract and biogenic nanoparticles against two Gram-positive bacteria strains, namely Bacillus cereus and Staphylococcus aureus. In addition, the phytochemical profile of C. tomentosum was established using liquid chromatography-mass spectrometry (LC-MS). The antibacterial effect of the extract and CTAgNP was moderate based on the minimum inhibitory concentration (MIC) values obtained. The MIC values of 2.6 mg/mL and 3.1 mg/mL were recorded for C. tomentosum extract against B. cereus and S. aureus, respectively. On the other hand, the CTAgNP had MIC values of 1.5 mg/mL and 2.6 mg/mL against B. cereus and S. aureus, respectively. The nanoparticle exhibited surface charge of -37 ± 7.67 mV and average hydro-dynamic size of 145 nm. X-ray diffraction illustrates that metallic nanoparticles were formed and had a face-centered cubic structure. Microscopic and spectroscopic techniques revealed that the CTAgNP was covered by a protective shell layer constituted of organic compounds originating from the plant extract. The acetone extract of C. tomentosum could be useful to the bio-pharma industries in the large-scale manufacture of nanoparticle-based medications to fight against microbes that constitute a threat to the survival of humanity.

Biomass, Essential Oil Yield, and Composition of Marjoram as Influenced by Interactions of Different Agronomic Practices under Controlled Conditions.

Origanum marjorana L. has been valued for centuries for its flavoring attributes and therapeutic properties. The growing demand for its various applications necessitates optimizing agronomic practices for its production. A glasshouse pot trial was conducted to identify optimum agronomic practices for increased herbage and oil yield, as well as oil quality. The effects of varying air temperature regimes (low, medium, and high levels), irrigation (low, medium, and high levels), nitrogen fertilizer application (N = 100, 150, and 200 kg/ha), and soil type (sandy loam, sandy clay loam, and loamy sand) on the productivity of marjoram plants were investigated. The results showed an increase in plant growth and herbage yield as well as chlorophyll content under conditions of high air temperature, low irrigation, and moderate to high nitrogen level applied to sandy loam soil, with an increase in oil yield with loamy sand soil. The major compounds observed in marjoram essential oil were terpinene-4-ol (22.63-36.72%) and (Z)-ß-terpineol (6.85-16.60%), in which terpinene-4-ol was not found to be within the International Organization for Standardization (ISO) limits of acceptability while (Z)-ß- terpineol had no reference limits available. A promising performance of marjoram cultivation under high regimes of air temperature (16.7 to 36.6 °C), nitrogen fertilization (200 kg ha-1 N), and low irrigation (up to 60% soil water depletion from field capacity) on sandy loam soils was demonstrated for improved crop productivity.