Novel berberine derivatives as adjuvants in the battle against Acinetobacter baumannii: A promising strategy for combating multi-drug resistance

The development of resistance against most of the available antibiotics has made Acinetobacter baumannii(A.baumannii)a pathogen of high risk.In this study,thirty novel berberine derivatives are rationally designed,synthesized,and evaluated for their synergistic antibacterial activities against A.baumannii.Among them,compound 2d shows the most potent synergetic effect to aztreonam against A.baumannii,including carbapenem-resistant and extended-spectrumβ-lactamases-producing strains.Moreover,synergistic effects were observed for the combinations of 2d and different antibacterial used in clinical practices,indicating its potent broad-spectrum antibiotic-sensitizing effects against A.baumannii.The combination of 2d and aztreonam significantly improves the survival rates of G.mellonella larvae compared with aztreonam treatment alone.Mechanism studies indicate that 2d inhibits the drug efflux and iron acquisition of the bacteria by targeting the AdeB transporter protein,thus achieving a synergistic antimicrobial efficacy with different antibacterial agents.Therefore,berberine derivatives represent a new family of antimicrobial adjuvants against A.baumannii,with the advantage of dual-function antibacterial effect,and are worthy of further investigation.

Novel berberine derivatives:Design,synthesis,antimicrobial effects,and molecular docking studies

A series of berberine derivatives were synthesized by introducing substituted benzyl groups at C-9.All these synthesized compounds（4a–4m）were screened for their in vitro antibacterial activity against four Gram-positive bacteria and four Gram-negative bacteria and evaluated for their antifungal activity against three pathogenic fungal strains.All these compounds displayed good antibacterial and antifungal activities,compared to reference drugs including Ciprofloxacin and Fluconazole;Compounds 4f,4g,and 4l showed the highest antibacterial and antifungal activities.Moreover,all the synthesized compounds were docked into topoisomerase Ⅱ-DNA complex,which is a crucial drug target for the treatment of microbial infections.Docking results showed that H-bond,π-πstacked,π-cationic,andπ-anionic interactions were responsible for the strong binding of the compounds with the target protein-DNA complex.

Synthesis of 9-Substituted Berberine Derivatives with Microwave Irradiation

Hyperglycemia is frequently accompanying with hyperlipidemia. To explore the potent drugs with dual-activity and dual-site effects that could reduce blood glucose and blood lipid at the same time, fibrate group with lipid-lowering effect on the 9th position of berberine（BBR） was introduced using the drug design combination principle and the multi-target collaborative treatment method, Moreover, the molecular structure of BBR was modified, and six 9-substituted derivatives of BBR were designed and synthesized, among which, five compotmds have never been reported before. In addition, the molecular structttres of these derivatives were identified using liquid chromato- graphy-mass spectrometry（LC-MS）, IH nuclear n^tgnetic resonance（1H NMR） and 13C NMR, respectively. Fu^her- more, the microwave irradiation experimental technique was applied in the synthesis reaction using the novel micro- wave synthesizer, which accelerated the reaction rate, enhanced the reaction yield, reduced the reaction by-products, and simplified the post-processing steps. In the meantime, the 9-position regioselective demethylation of BBR was explored through quantum chemical calculation during the synthesis of berberrubine. The computations were consistent with the experimental results, which contributed to deducing the mechanism of its selective methylation.

Coordinated regulation of BACH1 and mitochondrial metabolism through tumor-targeted self-assembled nanoparticles for effective triple negative breast cancer combination therapy

The poor prognosis of triple negative breast cancer(TNBC)results from a lack of approved targeted therapies coupled with aggressive proliferation and metastasis,which is associated with high recurrence and short overall survival.Here we developed a strategy by employing tumor-targeted selfassembled nanoparticles to coordinately regulate BACH1(BTB domain and CNC homology 1)and mitochondrial metabolism.The BACH1 inhibitor hemin and mitochondria function inhibitor berberine derivative(BD)were used to prepare nanoparticles(BH NPs)followed by the modification of chondroitin sulfate(CS)on the surface of BH NPs to achieve tumor targeting(CS/BH NPs).CS/BH NPs were found to be able to inhibit tumor migration and invasion by significantly decreasing the amounts of tumor cell metabolites,glycolysis and metastasis-associated proteins,which were related to the inhibition of BACH1 function.Meanwhile,decreased mitochondrial membrane potential,activated caspase 3/9 and increased ROS production demonstrated coordinated regulation of BACH1 and mitochondrial metabolism.In a xenograft mice model of breast cancer,CS/BH NPs significantly inhibited tumor growth and metastasis due to the synergetic effect of hemin and BD without showing obvious toxicities for major organs.In sum,the results of efficacy and safety experiments suggest potential clinical significance of the prepared self-assembled CS/BH nanoparticles for the treatment of TNBC.