Mohamed Habib Oueslati

The present work reports a green biosynthesis of gold nano particles (EO-AuNPs) using an essential oil (EO) as a reducing agent of the Au(III) in HAuCl4. The EO was extracted by hydro-distillation from Diplotaxis acris flowers. A total of 16 compounds were detected from the EO oil by using GC–MS and 5-methylsulfanylpentanenitrile was identified as the major component (73.60 %). The biosynthesized EO-AuNPs were characterized performing UV–Vis, IR,XRD and TEM analyses.The UV-Vis revealed the typical features of surface plasmon resonance (SPR) of AuNPs at ~526 nm. The FT-IR spectrum of the biosynthesized nano particles exhibited the features of the nitrile (-C≡N) functional group indicating that the -C≡N-bearing EO components are likely acting as reducing and stabilizing agents for the formation of EO-AuNPs. The plausible scheme of EO-AuNPsformation was proposed.The TEM analysis showed that the EO- AuNPs were almost spherical in shape with an average particle size of 12.7 nm. In addition, the antimicrobial activity was carried out by diffusion of agar wells method. The results proved that the EO-AuNPs displayed a potential antimicrobial against gram negative strains, with a maximum zone of inhibition of 16 mm for E. coli at a concentration of 100 µg / ml.

The present research work reports an eco-friendly route for preparing gold nanoparticles (AuNPs) with high catalytic activity using polyphenol extracted from salvia officinalis. In both alkaline (pH ∼ 11) and acidic media (pH ∼ 5), the polyphenol induced rapid reduction of the Au (III) salt and lead to the formation of highly monodisperse and spherical small (S) and larger (L) AuNPs, respectively. The average particle size was found to be ∼ 6 nm for S and ∼ 27 nm for L AuNPs, respectively. FT-IR revealed that polyphenol species are capped onto the nanoparticles surface favorizing a high aqueous colloidal stability of the AuNPs in a wide pH range. In addition, the produced AuNPs exhibited significant size-dependent degradation rate of p-nitrophenol (p-NP) and methylene blue (MB) to p-aminophenol (p-AP) and leucomethylene blue (LMB), respectively. GRAPHICAL ABSTRACT

Background: Lotus taxa (Fabaceae) were well known as an important source of polyphenols and flavonoids. Lotus lanuginosus Vent. is a widespread plant in the northern region of Saudi Arabia. Phytochemical and biological activities screening focusing of the species are rare. Objective: The objectives of this study were to isolate secondary metabolites from the flowers of L. lanuginosus Vent., elucidate their structures, and evaluate their biological activities. Materials and Methods: Chromatography methods of the n-butanolic extract of fresh flowers of L. lanuginosus led five products (1–5). Their structures were characterized based on spectroscopic evidence (ultraviolet, infrared, high-resolution mass spectrometry, and nuclear magnetic resonance) and compared to the spectral data signaled in the literature. Cytotoxic activities of the isolated compounds were evaluated against HCT-116 and MCF-7 cancer cell lines. α-glucosidase and antioxidant activities were also performed. Results: Five compounds were isolated and characterized for the first time in L. lanuginosus Vent.: Lotaustralin (1), kaempferol-7-O-α-L-rhamnopyranoside (2), kaempferol-3-O-apiofuranosyl-7-O-rhamnopyranosyl (3), isorhamnetin-3-O-rutinoside (4), and kaempferol-3-O-(2''-β-D-xylopyranosyl)-α-L-rhamnopyranoside-7-O-α-L-rhamnopyranoside (5). The results of cytotoxic activities against HCT-116 and MCF-7 cancer cell lines of the isolated compounds were presented. Among them, compounds 2 and 3 showed a moderate activity on HCT-116 cancer cells with half maximal inhibitory concentration values ranging between 8 and 31.5 μM. Moreover, compounds (2–5) displayed significant antioxidant and moderate α-glucosidase activities. Discussion and Conclusions: All the isolated products (1–5) are signaled for the first time in L. lanuginosus Vent. Among flavonoids glycosides, compound 2 showed the best cytotoxic activity. By the end of the present study, L. lanuginosus have been characterized as a highly cyanogenic plant and as an important source of polyphenols and flavonoids.