Synthesis and biological evaluation of pentacyclic triterpenoid derivatives as potential novel antibacterial agents

A series of ursolic acid (UA), oleanolic acid (OA) and 18β-glycyrrhetinic acid (GA) derivatives were synthesized by introducing a range of substituted aromatic side-chains at the C-2 position after the hydroxyl group at C-3 position was oxidized. Their antibacterial activities were evaluated in vitro against a panel of four Staphylococcus strains. The results revealed that the introduction of aromatic side-chains at the C-2 position of GA led to the discovery of potent triterpenoid derivatives for inhibition of both drug sensitive and resistant S. aureus, while the other two series derivatives of UA and OA showed no significant antibacterial activity even at high concentrations. In particular, GA derivative showed good potency against all four strains of Staphylococcus (MIC = 1.25 - 5 μmol/L) with acceptable pharmacokinetics properties and low cytotoxicity in vitro. Molecular docking was also performed using S. aureus DNA gyrase structure to rationalize the observed antibacterial activity. Therefore, this series of GA derivatives have strong potential for the development of a new type of triterpenoid antibacterial agent

General Strategy toward Laser Single-Step Generation of Multiscale Anti-Reflection Structures by Marangoni Effect

The anti-reflection of transparent material surfaces has attracted great attention due to its potential applications. In this paper, a single-step controllable method based on an infrared femtosecond laser is proposed for self-generation multiscale anti-reflection structures on glass. The multiscale composite structure with ridge structures and laser-induced nano-textures is generated by the Marangoni effect. By optimizing the laser parameters, multiscale structure with broadband anti-reflection enhancement is achieved. Meanwhile, the sample exhibits good anti-glare performance under strong light. The results show that the average reflectance of the laser-textured glass in the 300–800 nm band is reduced by 45.5% compared with the unprocessed glass. This work provides a simple and general strategy for fabricating anti-reflection structures and expands the potential applications of laser-textured glass in various optical components, display devices, and anti-glare glasses

Oleanolic acid indole derivatives as novel α-glucosidase inhibitors: Synthesis, biological evaluation, and mechanistic analysis

Research efforts have been directed to the development of oleanolic acid (OA) based α-glucosidase inhibitors and various OA derivatives showed improved anti-α-glucosidase activity. However, the inhibitory effects of indole infused OA derivatives on α-glucosidase is unknown. Herein, we synthesized a series of indole-OA (2a-2o) and -OA methyl ester (3a-3 l) derivatives with various electron withdrawing groups inducted to indole benzene ring and evaluated their anti-α-glucosidase activity. Indole OA derivatives (2a-2o) exhibited superior α-glucosidase inhibitory effects as compared to OA methyl ester derivatives (3a-3l) and OA (with IC50 values of 4.02 μM-5.30 μM v.s. over 10 μM and 5.52 µM, respectively). In addition, mechanistic studies using biochemical (kinetic assay), biophysical (circular dichroism), and computational (docking) methods revealed that OA-indole derivatives (2a and 2f) are mixed type of α-glucosidase inhibitors and their inhibitory effects were attributed to their capacity of forming the ligand-enzyme complex with α-glucosidase enzyme. Findings from this study support that OA indole derivatives are promising α-glucosidase inhibitors as a potential management of diabetes mellitus