A compound isolated from Alpinia officinarum Hance. inhibits swarming motility of Pseudomonas aeruginosa and down regulates virulence genes

Alpinia officinarum Hance Essential Oil as Potent Antipseudomonal Agent: Chemical Profile, Antibacterial Activity, and Computational Study

Alpinia officinarum Hance, is an aromatic and medicinal herb with a very interesting history and prominent chemical and biological prospects. We aimed to investigate the antibacterial activity of Alpinia officinarum essential oil and the preferred molecular targets of its constituents together with their pharmacokinetic properties and toxicity profile. According to GC-MS analysis, eucalyptol was the main compound (27.52 %) identified in Alpinia officinarum essential oil, followed by α-terpineol, and β-sesquiphellandrene. As opposed to the weak antiradical activity estimated by DPPH and ABTS tests, the essential oil caused inhibition of all the bacteria following well-diffusion and microdilution methods, especially the gram-negative Pseudomonas aeruginosa and Escherichia coli. It displayed exceptionally remarkable activity against Pseudomonas aeruginosa by totally inhibiting its growth on the agar plate exceeding the effect of chloramphenicol standard. This bactericidal effect was confirmed by very low MIC and MBC values of 0.82 and 6.562 μg/mL, respectively. The molecular docking showed interesting binding affinity between the major compounds and various drug targets in Pseudomonas aeruginosa, also good pharmacokinetic and toxicity behavior. These encouraging findings are particularly relevant in light of the increasingly pressing challenge to find alternative substances with antibacterial aptitude to address the issue of antibiotic resistance among infectious bacteria.

Phytochemical and pharmacological properties of the genus Alpinia from 2016 to 2023

Covering 2016 up to the end of 2023Alpinia is the largest genus of flowering plants in the ginger family, Zingiberaceae, and comprises about 500 species. Many Alpinia are commonly cultivated ornamental plants, and some are used as spices or traditional medicine to treat inflammation, hyperlipidemia, and cancers. However, only a few comprehensive reviews have been published on the phytochemistry and pharmacology of this genus, and the latest review was published in 2017. In this review, we provide an extensive coverage of the studies on Alpinia species reported from 2016 through 2023, including newly isolated compounds and potential biological effects. The present review article shows that Alpinia species have a wide spectrum of pharmacological activities, most due to the activities of diarylheptanoids, terpenoids, flavonoids, and phenolics.

VmsR, a LuxR-Type Regulator, Contributes to Virulence, Cell Motility, Extracellular Polysaccharide Production and Biofilm Formation in Xanthomonas oryzae pv. oryzicola

LuxR-type regulators play pivotal roles in regulating numerous bacterial processes, including bacterial motility and virulence, thereby exerting a significant influence on bacterial behavior and pathogenicity. Xanthomonas oryzae pv. oryzicola, a rice pathogen, causes bacterial leaf streak. Our research has identified VmsR, which is a response regulator of the two-component system (TCS) that belongs to the LuxR family. These findings of the experiment reveal that VmsR plays a crucial role in regulating pathogenicity, motility, biofilm formation, and the production of extracellular polysaccharides (EPSs) in Xoc GX01. Notably, our study shows that the vmsR mutant exhibits a reduced swimming motility but an enhanced swarming motility. Furthermore, this mutant displays decreased virulence while significantly increasing EPS production and biofilm formation. We have uncovered that VmsR directly interacts with the promoter regions of fliC and fliS, promoting their expression. In contrast, VmsR specifically binds to the promoter of gumB, resulting in its downregulation. These findings indicate that the knockout of vmsR has profound effects on virulence, motility, biofilm formation, and EPS production in Xoc GX01, providing insights into the intricate regulatory network of Xoc.

Antibacterial Activity and Components of the Methanol-Phase Extract from Rhizomes of Pharmacophagous Plant Alpinia officinarum Hance

The rhizomes of Alpinia officinarum Hance (known as the smaller galangal) have been used as a traditional medicine for over 1000 years. Nevertheless, little research is available on the bacteriostatic activity of the herb rhizomes. In this study, we employed, for the first time, a chloroform and methanol extraction method to investigate the antibacterial activity and components of the rhizomes of A. officinarum Hance. The results showed that the growth of five species of pathogenic bacteria was significantly inhibited by the galangal methanol-phase extract (GMPE) (p < 0.05). The GMPE treatment changed the bacterial cell surface hydrophobicity, membrane fluidity and/or permeability. Comparative transcriptomic analyses revealed approximately eleven and ten significantly altered metabolic pathways in representative Gram-positive Staphylococcus aureus and Gram-negative Enterobacter sakazakii pathogens, respectively (p < 0.05), demonstrating different antibacterial action modes. The GMPE was separated further using a preparative high-performance liquid chromatography (Prep-HPLC) technique, and approximately 46 and 45 different compounds in two major component fractions (Fractions 1 and 4, respectively) were identified using ultra-HPLC combined with mass spectrometry (UHPLC-MS) techniques. o-Methoxy cinnamaldehyde (40.12%) and p-octopamine (62.64%) were the most abundant compounds in Fractions 1 and 4, respectively. The results of this study provide data for developing natural products from galangal rhizomes against common pathogenic bacteria.

The Impact of an Efflux Pump Inhibitor on the Activity of Free and Liposomal Antibiotics against Pseudomonas aeruginosa

The eradication of Pseudomonas aeruginosa in cystic fibrosis patients has become continuously difficult due to its increased resistance to treatments. This study assessed the efficacy of free and liposomal gentamicin and erythromycin, combined with Phenylalanine arginine beta-naphthylamide (PABN), a broad-spectrum efflux pump inhibitor, against P. aeruginosa isolates. Liposomes were prepared and characterized for their sizes and encapsulation efficiencies. The antimicrobial activities of formulations were determined by the microbroth dilution method. Their activity on P. aeruginosa biofilms was assessed, and the effect of sub-inhibitory concentrations on bacterial virulence factors, quorum sensing (QS) signals and bacterial motility was also evaluated. The average diameters of liposomes were 562.67 ± 33.74 nm for gentamicin and 3086.35 ± 553.95 nm for erythromycin, with encapsulation efficiencies of 13.89 ± 1.54% and 51.58 ± 2.84%, respectively. Liposomes and PABN combinations potentiated antibiotics by reducing minimum inhibitory and bactericidal concentrations by 4–32 fold overall. The formulations significantly inhibited biofilm formation and differentially attenuated virulence factor production as well as motility. Unexpectedly, QS signal production was not affected by treatments. Taken together, the results indicate that PABN shows potential as an adjuvant of liposomal macrolides and aminoglycosides in the management of lung infections in cystic fibrosis patients.

Self-healing functionalization of sulfonated hafnium oxide and copper oxide nanocomposite for effective biocidal control of multidrug-resistant bacteria

The combination of copper and sulfonated hafnium oxide nanoparticles could be used as an alternative antimicrobial agent to combat multidrug resistant bacteria and membrane biofouling.