Activity of the Caged Xanthone Morellic Acid against Vancomycin-Resistant Enterococcus Infection by Targeting the Bacterial Membrane.

Vancomycin-resistant Enterococcus (VRE) is an important nosocomial opportunistic pathogen that is associated with multidrug resistance. Here, we demonstrate that morellic acid inhibits VRE by restoring its sensitivity to vancomycin and ampicillin with low drug resistance and efficient biofilm clearance effects. Morellic acid binds to inner membrane phospholipids, such as phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and cardiolipin (CL) of VRE, such that the fluidity and proton-motive force (PMF) interfere with the damaged inner membrane, causing intracellular reactive oxygen species (ROS) accumulation and bacterial death. Transcriptional analyses supported this effect on inner membrane-related pathways such as fatty acid biosynthesis and glycerophospholipid metabolism. Moreover, morellic acid significantly eliminated residual bacteria in the spleen, liver, kidneys, and abdominal effusion in mice. Our findings indicate the potential applications of morellic acid as an antibacterial agent or adjuvant for treating VRE infections.

Oleanolic acid derivatives against drug-resistant bacteria and fungi by multi-targets to avoid drug resistance.

Mixed infections caused by drug-resistant bacteria and fungi pose a severe threat to human health, and multi-target drugs may provide an effective approach to combat drug-resistant pathogens. Therefore, this study aimed to investigate the efficacies of some oleanolic acid (OA) derivatives against multidrug-resistant (MDR) bacteria and fungi using in vitro and in vivo experiments. Novel amphiphilic OA derivatives were designed and optimised, in which compounds G1 and J1 exhibited effective antimicrobial activity (MICs = 1-2 µg/mL), high selectivity against MDR strains, rapid bactericidal activity, and good predictive pharmacokinetics. Mechanistically, both compounds prevented drug resistance by disrupting the bacterial cell membrane, inserting into the DNA, and binding to DNA gyrase. Additionally, J1 reduced microbial count in a mouse MRSA skin infection model and accelerated wound healing much better than vancomycin. Conclusively, this study presents a new class of potential drugs for resistant bacteria and fungi.

Three New Ent-Kaurane Diterpenes with Antibacterial Activity from Sigesbeckia orientalis.

Three novel ent-kaurane diterpenes, namely sigesbeckin A-C (1-3), in conjunction with eight previously identified analogues (4-11), were isolated from Sigesbeckia orientalis. Their chemical structures were resolved through multiple spectroscopic analyses. All compounds were assessed for antimicrobial bioactivity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) strains. In particular, compounds 1 and 5 demonstrated moderate efficacy, with MIC values of 64 µg/mL. Moreover, compounds 3, 5, and 11 were found to synergize with doxorubicin hydrochloride (DOX) and vancomycin (VAN) against MRSA and VRE. The aforementioned findings offer valuable insights for the development of novel alternatives to antibiotics, which can effectively tackle the escalating issue of antibiotic resistance.

A new therapeutic strategy for infectious diseases against intracellular multidrug-resistant bacteria.

Bacterial infections result in 7,700,000 deaths per year globally, with intracellular bacteria causing repeated and resistant infection. No drug is currently licenced for the treatment of intracellular bacteria. A new screening platform mimicking the host milieu has been established to explore phytochemical antibiotic adjuvants. Previously neglected isoprenylated flavonoids were found to be effective against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Specifically, the synergistic effect between glabrol and streptomycin against intracellular bacteria was observed for the first time. The glabrol-streptomycin combination targets bacterial inner membrane phospholipids, disrupts arginine biosynthesis, inhibits cell wall proteins and biofilm formation genes (agrA/B/C/D), and promotes ROS production, causing subsequent membrane and wall damage. To enhance the selective uptake of combination drug into infected cells, hyaluronic acid-streptomycin-lipoic acid-glabrol nanoparticles (HSLGS-S) were designed and synthesized to trigger the intracellular delivery of the glabrol-streptomycin combination. Thus, the treatment can be transported into the infected intracellular region and selectively release the glabrol-streptomycin combination to the bacterial at site. The bioactivity of HSLGS-S in clearing intracellular bacteria was 20-fold higher than that of the glabrol-streptomycin combination alone in vitro and 2- to 10-fold higher in vivo.

New resorcylic acid derivatives of Lysimachia tengyuehensis against MRSA and VRE by interfering with bacterial metabolic imbalance.

The abuse of antibiotics leads to the rapid spread of bacterial resistance, which seriously threatens human life and health. Now, 8 resorcylic acid derivatives, including 4 new compounds (1-4) were isolated from Lysimachia tengyuehensis by bio-guided isolation, and they inhibited both methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) (MIC = 4-8 µg/mL). Notably, 1 and 2 rapidly killed MRSA and VRE within 40 min without drug resistance in 20 days. Mechanically, they potently disrupted biofilm and cell membrane by interfering with bacterial metabolic imbalance. The structure-activity relationship (SAR) revealed that the lipophilic long carbon chains (C-5/C-6) and hydrophilic hydroxyl/carboxyl groups were essential for the anti-MRSA and VRE bioactivity. Additionally, they effectively recovered MRSA-infected skin wounds and VRE-infected peritoneal in vivo. Resorcylic acid derivatives showed significant anti-MRSA and VRE bioactivity in vitro and in vivo with potential application for the first time.

Formononetin Derivative for Osteoporosis by Simultaneous Regulating Osteoblast and Osteoclast.

Seven new formononetin derivatives (1-7) were designed and prepared from formononetin (phase II phytoestrogen). The derivatives 9-butyl-3-(4-methoxyphenyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]oxazin-4-one (2) and 9-(furan-3-ylmethyl)-3-(4-methoxyphenyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]oxazin-4-one (7) promoted significant osteoblast formation by modulating the BMP/Smad pathway. Compound 7 exhibited potent antiosteoclastogenesis activity in RANKL-induced RAW264.7 cells and ovariectomy (OVX)-induced osteoporosis in mice by regulation of the RANK/RANKL/OPG pathway. Compound 7 regulated osteoblast and osteoclast simultaneously and showed better effect than the well-known drug ipriflavone in vivo, suggesting 7 as a patented antiosteoporosis candidate.

Structure optimizing of flavonoids against both MRSA and VRE.

Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE) cause more than 100,000 deaths each year, which need efficient and non-resistant antibacterial agents. SAR analysis of 162 flavonoids from the plant in this paper suggested that lipophilic group at C-3 was crucial, and then 63 novel flavonoid derivatives were designed and total synthesized. Among them, the most promising K15 displayed potent bactericidal activity against clinically isolated MRSA and VRE (MICs = 0.25-1.00 µg/mL) with low toxicity and high membrane selectivity. Moreover, mechanism insights revealed that K15 avoided resistance by disrupting biofilm and targeting the membrane, while vancomycin caused 256 times resistance against MRSA, and ampicillin caused 16 times resistance against VRE by the same 20 generations inducing. K15 eliminated residual bacteria in mice skin MRSA-infected model (>99 %) and abdominal VRE-infected model (>92 %), which was superior to vancomycin and ampicillin.

A dual mechanism with H2S inhibition and membrane damage of morusin from Morus alba Linn. against MDR-MRSA.

It's urgent to discover new antibiotics along with the increasing emergence and dissemination of multidrug resistant (MDR) bacterial pathogens. In the present investigation, morusin exhibited rapid bactericidal activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) by targeting the phospholipid of bacterial inner membrane, increasing membrane rigidity and disrupting bacterial homeostasis together with the membrane permeability, which caused fundamental metabolic disorders. Furthermore, morusin can also accumulate ROS, suppress H2S production, and aggravate oxidative damage in bacteria. Importantly, morusin also inhibited the spread of wounds and reduced the bacterial burden in the mouse model of skin infection caused by MRSA. It's a chance to meet the challenge of existing antibiotic resistance and avoid the development of bacterial resistance, given the multiple targets of morusin.