Antibacterial Activity of Novel 18β-Glycyrrhetinic Hydrazide or Amide Derivatives

A review of typical biological activities of glycyrrhetinic acid and its derivatives

Glycyrrhetinic acid, a triterpenoid compound primarily sourced from licorice root, exhibits noteworthy biological attributes, including anti-inflammatory, anti-tumor, antibacterial, antiviral, and antioxidant effects. Despite these commendable effects, its further advancement and application, especially in clinical use, have been hindered by its limited druggability, including challenges such as low solubility and bioavailability. To enhance its biological activity and pharmaceutical efficacy, numerous research studies focus on the structural modification, associated biological activity data, and underlying mechanisms of glycyrrhetinic acid and its derivatives. This review endeavors to systematically compile and organize glycyrrhetinic acid derivatives that have demonstrated outstanding biological activities over the preceding decade, delineating their molecular structures, biological effects, underlying mechanisms, and future prospects for assisting researchers in finding and designing novel glycyrrhetinic acid derivatives, foster the exploration of structure-activity relationships, and aid in the screening of potential candidate compounds.

Discovery of Novel Pentacyclic Triterpene Acid Amide Derivatives as Excellent Antimicrobial Agents Dependent on Generation of Reactive Oxygen Species

Developing new agricultural bactericides is a feasible strategy for stopping the increase in the resistance of plant pathogenic bacteria. Some pentacyclic triterpene acid derivatives were elaborately designed and synthesized. In particular, compound A₂₂ exhibited the best antimicrobial activity against Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas axonopodis pv. citri (Xac) with EC₅₀ values of 3.34 and 3.30 mg L^-1, respectively. The antimicrobial mechanism showed that the compound A₂₂ induced excessive production and accumulation of reactive oxygen species (ROS) in Xoo cells, leading to a decrease in superoxide dismutase and catalase enzyme activities and an increase in malondialdehyde content. A₂₂ also produced increases in Xoo cell membrane permeability and eventual cell death. In addition, in vivo experiments showed that A₂₂ at 200 mg L^-1 exhibited protective activity against rice bacterial blight (50.44%) and citrus canker disease (84.37%). Therefore, this study provides a paradigm for the agricultural application of pentacyclic triterpene acid.

Evaluation of the Abilities of Three Kinds of Copper-Based Nanoparticles to Control Kiwifruit Bacterial Canker

Kiwifruit bacterial canker caused by Pseudomonas syringae pv. actinidiae reduces kiwifruit crop yield and quality, leading to economic losses. Unfortunately, few agents for its control are available. We prepared three kinds of copper-based nanoparticles and applied them to control kiwifruit bacterial canker. The successful synthesis of Cu(OH)2 nanowires, Cu3(PO4)2 nanosheets, and Cu4(OH)6Cl2 nanoparticles were confirmed by transmission and scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. The minimum bactericidal concentrations (MBCs) of the three nanoparticles were 1.56 μg/mL, which exceeded that of the commercial agent thiodiazole copper (MBC > 100 μg/mL). The imaging results indicate that the nanoparticles could interact with bacterial surfaces and kill bacteria by inducing reactive oxygen species’ accumulation and disrupting cell walls. The protective activities of Cu(OH)2 nanowires and Cu3(PO4)2 nanosheets were 59.8% and 63.2%, respectively, similar to thiodiazole copper (64.4%) and better than the Cu4(OH)6Cl2 nanoparticles (40.2%). The therapeutic activity of Cu4(OH)6Cl2 nanoparticles (67.1%) bested that of Cu(OH)2 nanowires (43.9%), Cu3(PO4)2 nanosheets (56.1%), and thiodiazole copper (53.7%). Their therapeutic and protective activities for control of kiwifruit bacterial canker differed in vivo, which was related to their sizes and morphologies. This study suggests these copper-based nanoparticles as alternatives to conventional bactericides for controlling kiwifruit diseases.

A review of approaches to control bacterial leaf blight in rice

The Gram-negative bacteria Xanthomonas oryzae pv. oryzae, the causative agent of bacterial leaf blight (BLB), received attention for being an economically damaging pathogen of rice worldwide. This damage prompted efforts to better understand the molecular mechanisms governing BLB disease progression. This research revealed numerous virulence factors that are employed by this vascular pathogen to invade the host, outcompete host defence mechanisms, and cause disease. In this review, we emphasize the virulence factors and molecular mechanisms that X. oryzae pv. oryzae uses to impair host defences, recent insights into the cellular and molecular mechanisms underlying host-pathogen interactions and components of pathogenicity, methods for developing X. oryzae pv. oryzae-resistant rice cultivars, strategies to mitigate disease outbreaks, and newly discovered genes and tools for disease management. We conclude that the implementation and application of cutting-edge technologies and tools are crucial to avoid yield losses from BLB and ensure food security.

Synthesis, Antibacterial and Anthelmintic Activity of Novel 3-(3-Pyridyl)-oxazolidinone-5-methyl Ester Derivatives

In this study, a series of 3-(3-pyridyl)-oxazolidone-5-methyl ester derivatives was synthesized and characterized by 1H NMR, 13C NMR, and LC-MS. The conducted screening antibacterial studies of the new 3-(3-pyridyl)-oxazolidone-5-methyl ester derivatives established that the methyl sulfonic acid esters have broad activity spectrum towards Staphylococcus aureus, Streptococcus pneumoniae, Bacillus subtilis and Staphylococcus epidermidis. Among them, compound 12e has the most potent activity, with an MIC of 16 μg/mL against B.subtilis, and could reduce the instantaneous growth rate of bacteria. Furthermore, molecular docking studies were also simulated for compound 12e to predict the specific binding mode of this compound. In addition, anthelmintic activity of these compounds was also evaluated against adult Indian earthworms (Pheretima posthuman). The results showed that compound 11b had the best effect. These results above can provide experimental reference for the development of novel antibacterial and anthelmintic drugs.

Multifunctional ionic liquid-assisted interfacial engineering towards ZnS nanodots with ultrastable high-rate lithium storage performance

In this article, a new zinc-containing ionic liquid (IL) [HMMIm]₂[ZnCl₄] (HMMIm = 1-hexyl-2,3-dimethyl-imidazolium) is designed, which acts as a multifunctional source for the interfacial engineering of ZnS nanodots (NDs). Given the electrostatic interaction driven by the imidazolium cation, the steric effect of the alkyl chain, and the in situ released Zn ion from the IL, [HMMIm]₂[ZnCl₄] shows great advantages in controlling the formation of ZnS NDs. Based on this strategy, a nanocomposite consisting of homodispersed ZnS NDs anchored on sulfur/nitrogen dual-doped reduced graphene oxide (ZnS-NDs@SNG) is prepared. When evaluated as an anode material for lithium-ion batteries (LIBs), the nanocomposite delivers high reversible specific capacity, excellent high-rate performance, and superior cycling life. In particular, a discharge capacity of 648.1 mA h g^-1 can be achieved at a high current density (10.0 A g^-1) over 5000 cycles. Benefitting from the multifunctional IL and the simple synthesis protocol, the IL-assisted interfacial engineering strategy will enable a new avenue for the controllable synthesis of metal-sulfide-based anode materials.