Phytosynthesis of Silver Nanoparticles Using Leonurus cardiaca L. Extracts

Abstract

The present work describes, for the first time in the literature, the phytosynthesis of silver nanoparticles using Leonurus cardiaca L. extracts. The influence of the extraction method (classical temperature extraction and microwave extraction), as well as of the extract concentration on the characteristics of the nanoparticles, was studied using analytical methods, such as UV-Vis spectrometry, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. Experimental data suggest that use of lower extract concentration leads to smaller dimensions nanoparticles, the same effect using the extract obtained by microwave-assisted extraction. The smallest recorded crystallite sizes (by X-ray diffraction) were under 3 nm. The antioxidant properties (determined by the DPPH assay) and the antimicrobial potential (determined against Gram-negative and Gram-positive strains) are enhanced by the phytosynthesis process (as demonstrated by the comparison of the nanoparticles’ properties with the parent extracts). The present work could also represent an important step in obtaining nanoparticles with enhanced properties and controlled morphologies, but also offers information on the phytosynthesis of metallic nanoparticles using low extract concentrations.

Development of Biologically Active Phytosynthesized Silver Nanoparticles Using Marrubium vulgare L. Extracts: Applications and Cytotoxicity Studies

“…The solutions were kept at room temperature and ambient conditions, without any stirring. The formation of silver nanoparticles can be visually monitored by the apparition of a specific ruby-red color [31,32]. After 24 h, the NPs suspensions were immediately analyzed by UV-Vis spectrophotometry, and the remaining solutions were preserved in the dark at 4 • C and further used for the described tests.…”

“…The total phenolics content was determined using a colorimetric method (Folin-Ciocâlteu reagent method), as previously described [31,32], involving the formation of a blue complex upon the reduction of the Folin-Ciocâlteu reagent by phenolics present in the extracts. The Folin-Ciocâlteu reagent (Merck KGaA, Darmstadt, Germany) and sodium carbonate solution (Merck KGaA, Darmstadt, Germany) were commercially available and used without any purification.…”

“…The optical density was determined at 765 nm using a Rigol Ultra 3660 UV-Vis spectrophotometer (Rigol Technologies, Beijing, China). The determined values were compared to a standard curve prepared with gallic acid solutions, and the final results were expressed as milligrams of gallic acid equivalents (GAE)/gram of dried matter [31,32].…”

“…The formation of silver nanoparticles under the action of horehound extracts was first monitored using UV-Vis spectrophotometry. Silver nanoparticles usually exhibit absorption maxima in the 400-550 nm region, the exact position of the specific peak being size-dependent [31,32]. For the determinations, a Rigol Ultra 3660 (Rigol Technologies Inc., Beijing, China, optical resolution 0.5 nm, 1 cm path length quartz cuvette) device was used, with a wavelength range of 370-600 nm.…”

Stachydrine Relieved the Inflammation and Promoted the Autophagy in Diabetes Retinopathy Through Activating the AMPK/SIRT1 Signaling Pathway

“…Traditional Chinese Medicine has made certain progress in preventing and treating DR. 17 Leonurus heterophyllus has been applied in the clinical treatment of gynecological and obstetric diseases. 18 Stachydrine (STA) is a water-soluble alkaloid extracted from Leonurus heterophyllus , which can inhibit cell apoptosis, maintain myocardial cell homeostasis, and reduce endothelial dysfunction. 19 , 20 Recently, research found that STA was an effective compound of Tangwang Mingmu granule, which was a traditional Chinese medicine and widely used in the DR treatment.…”