Datura stramonium Flowers as a Potential Natural Resource of Bioactive Molecules: Identification of Anti-Inflammatory Agents and Molecular Docking Analysis.

The present study investigated the antioxidant, antibacterial, antiviral and anti-inflammatory activities of different aerial parts (flowers, leaves and seeds) of Datura stramonium. The plant material was extracted with 80% methanol for about 24 h. The sensitivity to microorganisms analysis was performed by the microdilution technique. Antioxidant tests were performed by scavenging the DPPH and ABTS radicals, and by FRAP assay. Anti-inflammatory activity was evaluated through the inhibition of nitric oxide production in activated macrophage RAW 264.7 cells. Cell viability was assessed with an MTT assay. Results show that the flower extract revealed a powerful antimicrobial capacity against Gram-positive bacteria and strong antioxidant and anti-inflammatory activities. No significant cytotoxicity to activated macrophages was recorded. High resolution electrospray ionization mass spectrometry and nuclear magnetic resonance analysis identified two molecules with important anti-inflammatory effects: 12α-hydroxydaturametelin B and daturametelin B. Molecular docking analysis with both pro-inflammatory agents tumor necrosis factor alpha and interleukin-6 revealed that both compounds showed good binding features with the selected target proteins. Our results suggest that D. stramonium flower is a promising source of compounds with potential antioxidant, antibacterial, and anti-inflammatory activities. Isolated withanolide steroidal lactones from D. stramonium flower extract with promising anti-inflammatory activity have therapeutic potential against inflammatory disorders.

Quercetin extraction from small onion skin (Allium cepa L. var. aggregatum Don.) and its antioxidant activity.

In the present study, the maximum yield of quercetin was optimized for the ethanol extraction of small onions (Allium cepa L. var. aggregatum Don.), and the antioxidant activity was investigated in vitro. The extraction of quercetin from the small onion skin was carried out through ethanol solvent extraction with different ratios of ethanol and water. Ethanol: water ratio produced the highest quercetin from the onion skin. RP-HPLC analysis of the extracted material showed 2, 122 mg/g of quercetin and 0.34 mg/g of isorhamnetin. A total of 301.03 mg GAE/g dry weight and 156 mg/g quercetin equivalents were found in the onion skin extract. DPPH and ABTS free radical scavenging potentials of the tested extract (90:10 v/v) were dose-dependent, with IC50 values of 62.27 µg/mL and 53.65 µg/mL, respectively. Therefore, the present study reports that small onion skin extract rich in quercetin may serve as a promising antioxidant and anticancer agent.

Antimicrobial activity and molecular identification of Streptomyces strains isolated from Saudi Arabia.

Actinomycetes are group of Gram-positive bacteria with high GC-content in their DNA. They are extremely useful for the pharmaceutical industry due to their seemingly unlimited capacity to produce secondary metabolites with diverse biological activities and chemical structure. The genus Streptomyces constitutes 50% of the total population of soil actinomycetes and about 75% of commercially and medicinally useful antibiotics that have been derived from this genus. The present study aimed in isolation of bioactive compound showing antimicrobial activities from soil Streptomyces, previously isolated and morphologically characterized from Jazan in Saudi Arabia. Six potent Streptomyces strains: JS3, JS4, JS6, JD7, JA8 and JA10 were chosen for antimicrobial activity screening against 5 human pathogenic bacteria and 5 phytopathogenic fungi before molecular identification was done. For antibacterial activity, the results showed that inhibition zones were found to range between 3.25-26.875 mm diameters, while for antifungal activity, it ranged between 13.3-40 mm diameters. The entire sequence of the 16S rDNA was determined for the strains JS6, JD7, JA8 and JA10 and deposited in the GenBank. Future studies of actinomycetes isolated from the Kingdom of Saudi Arabia's soils will assist in the discovery of new compounds that would be of industrial, pharmaceutical and agricultural importance.