Background. The plants brought by Arabs were of real therapeutic values. Ibn Al-Baitar, an Islamic scholar (pharmacist, botanist, and physician), in his encyclopedia wrote the detailed characterization of more than one thousand herbs describing their medicinal value, methods of preparation, and their route of administration. Objectives. The current investigation points towards the quantitative characterization of the phenolic contents among the four edible Malva plants species (Malva sylvestris L., Malva oxyloba Boiss., Malva parviflora L., and Malva aegyptia L.) and also towards assessing their antibacterial activity against one Gram-positive isolate (Staphylococcus aureus) and four Gram-negative strains Escherichia coli, Pseudomonas aeruginosa, Shigella sonnei, and Proteus vulgaris. It also aimed to evaluate the free radical scavenging activity of hexane, methanolic, aqueous, and acetone extracts of four Malva species. Methods. By utilizing the FolinCiocalteu procedure and gallic acid as a reference molecule, the phenolic contents were estimated. In addition, the broth microdilution method was used to evaluate four plants 16 extracts, and the DPPH (2,2-diphenyl-1-picrylhydrazyl) method was utilized to assess the abovementioned extracts against oxidative stress. Results. The results showed that the methanolic extract of M. oxyloba has the highest contents of phenols (191.54±2.84mg of GAE/g) and has the best antioxidant capacity with an IC₅₀ value of 1.94±1.84µg/ml, which is very close to Trolox. Regarding the ferrous ion chelating activity of the extract, the methanolic extract of M. sylvestris exhibits appreciable activity with IC₅₀ values of 52.7±1.8µg/ml. In addition, the plant extract and acetone extract of M. sylvestris showed a strong antibacterial activity with an MIC value of 0.0078mg/ml. Conclusion. The methanolic extract of M. oxyloba has a pharmacological potential as a valuable natural product that can be utilized as a main ingredient in the design and development of new therapeutic formulations. It exerts multiple inhibitory properties against oxidative stress and bacterial growth. As such, it is emerging as a promising therapeutic agent for the treatment of various neurodegenerative diseases and many types of human infectious diseases.

The use of the synthetic drugs has increased in the last few decades; however, these drugs exhibit various side effects. Scientists are therefore seeking alternatives from natural sources. Commiphora gileadensis has long been used to treat various disorders. It is commonly known as bisham or balm of Makkah. This plant contains various phytochemicals, including polyphenols and flavonoids, with biological potential. We found that steam-distilled essential oil of C. gileadensis exhibited higher antioxidant activity (IC_50, 22.2 µg/mL) than ascorbic acid (IC_50, 1.25 µg/mL). The major constituents (>2%) in the essential oil were β-myrcene, nonane, verticiol, β-phellandrene, β-cadinene, terpinen-4-ol, β-eudesmol, α-pinene, cis-β-copaene and verticillol, which might be responsible for the antioxidant and antimicrobial activity against Gram-positive bacteria. The extract of C. gileadensis exhibited inhibitory activity against cyclooxygenase (IC_50, 450.1 µg/mL), xanthine oxidase (251.2 µg/mL) and protein denaturation (110.5 µg/mL) compared to standard treatments, making it a viable treatment from a natural plant source. LC-MS analysis revealed the presence of phenolic compounds such as caffeic acid phenyl ester, hesperetin, hesperidin, chrysin and transient amounts of catechin, gallic acid, rutin and caffeic acid. The chemical constituents of this plant can be explored further to investigate its wide variety of therapeutic potential.

Quorum sensing (QS) is a molecular communication mechanism among bacterial cells. It is critical in regulating virulence factors, motility, antibiotic resistance, and biofilm formation. Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen linked to healthcare-associated infections, food poisoning, and biofilm formation. Treating infections caused by pathogenic bacteria has become a challenge due to the development of multi-antibiotic resistance upon continuous exposure of bacteria to antibiotics. An alternative strategy to conventional antimicrobials to decrease the bacterial pathogenicity is QS inhibition, also known as quorum quenching. Using plant-derived compounds is an environmentally friendly strategy to block the bacterial QS and inhibit bacterial growth. Portulaca oleracea is a popular plant in different countries and is also used in traditional medicine. It is widely consumed raw in salads and as garnishes, though it can be cooked as a vegetarian dish. This study evaluates the antimicrobial activity of the methanolic extract of P. oleracea and its effectiveness in blocking or attenuating the QS of P. aeruginosa. The agar well diffusion method used for screening the antibacterial activity showed a significant growth inhibition of P. aeruginosa by the extract at 500 mg/mL with a minimum inhibitory concentration of 31.25 mg/mL. A bioindicator bacterium, Chromobacterium violaceum CV026, was used to determine the effect of the methanolic extract on the QS of P. aeruginosa. The results indicated a significant reduction in biofilm formation, pyocyanin production, and LasA staphylolytic activity. The phytochemical analysis by Gas Chromatography–Mass Spectrometry showed that the methanolic extract contained several phenols, alkaloids, esters, and other compounds previously reported to have antibacterial and antioxidant effects. These findings highlight the effectiveness of P. oleracea methanolic extract in attenuating the QS and virulence factors of P. aeruginosa. This study suggests that P. oleracea is an important source of natural antimicrobials and its use would be beneficial in food and pharmaceutical applications.

Introduction: A cost-effective and ecologically friendly method of generating silver nanoparticles (AgNPs) includes pathways that utilize a variety of biological sources to decrease metal ions. This study was designed to synthesize AgNPs using a fungus strain Aspergillus flavus and evaluate its antibacterial activities alone or in combination with Foeniculum vulgare (fennel) essential oil (EO). Methods: The antibacterial activity of different concentrations of biosynthesized AgNPs by Aspergillus flavus individually and in combination with fennel EO was investigated using disc diffusion methods and minimal inhibitory concentration (MIC). Bacterial species, including Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterobacter cloacae, Shigella sp., Staphylococcus aureus, and Staphylococcus epidermidis were tested. Results: Formation of dark brown color, ultraviolet-visible (UV/Vis) spectroscopy, transmission electron microscope (TEM), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were used for the characterization of AgNPs. Obvious synergistic effects were observed between AgNPs and EO of fennel (F. vulgare) with all tested bacteria except S. aureus, through increases in fold area of inhibition (IFAs) within the range of 0.15 to 8.87. Although S. aureus had the most susceptibility toward both AgNPs and EO of fennel (24 and 17 mm, respectively), no synergistic activity was exhibited. The best synergistic capacity resulted from AgNPs and fennel EO was observed against S. epidermidis (8.87-fold in IFA). Conclusion: This study revealed that when biosynthesized AgNPs were mixed with the EO of F. vulgare, they became more bacteriostatic and might be developed to treat bacterial infections in the future.