Potentiation of Vancomycin: Creating Cooperative Membrane Lysis through a "Derivatization-for-Sensitization" Approach.

Gram-negative bacteria, especially the ones with multidrug resistance, post dire challenges to antibiotic treatments due to the presence of the outer membrane (OM), which blocks the entry of many antibiotics. Current solutions for such permeability issues, namely lipophilic-cationic derivatization of antibiotics and sensitization with membrane-active agents, cannot effectively potentiate the large, globular, and hydrophilic antibiotics such as vancomycin, due to ineffective disruption of the OM. Here, we present our solution for high-degree OM binding of vancomycin via a hybrid "derivatization-for-sensitization" approach, which features a combination of LPS-targeting lipo-cationic modifications on vancomycin and OM disruption activity from a sensitizing adjuvant. 106- to 107-fold potentiation of vancomycin and 20-fold increase of the sensitizer's effectiveness were achieved with a combination of a vancomycin derivative and its sensitizer. Such potentiation is the result of direct membrane lysis through cooperative membrane binding for the sensitizer-antibiotic complex, which strongly promotes the uptake of vancomycin and adds to the extensive antiresistance effectiveness. The potential of such derivatization-for-sensitization approach was also supported by the combination's potent in vivo antimicrobial efficacy in mouse model studies, and the expanded application of such strategy on other antibiotics and sensitizer structures.

Design, synthesis, and antibacterial evaluation of vancomycin-LPS binding peptide conjugates.

Developing novel antibiotics is urgently needed with emergency of drug resistance. Vancomycin, the last resort for intractable Gram-positive bacterial infections, is ineffective against Gram-negative bacteria and vancomycin resistant bacteria. Herein, we report a series of novel vancomycin derivatives carrying LPS binding peptides, vancomycin-LPS binding peptide conjugates (VPCs). The LPS binding peptides were conjugated onto 4 sites of vancomycin via CuAAC or maleimide- sulfydryl addition, and the formed VPCs were screened against VISA/VRE and Gram-negative strains. VPCs exhibited enhanced activity against vancomycin resistant bacteria and obtained the activity against Gram-negative bacteria in vitro, providing a novel strategy for vancomycin modification and glycopeptide antibiotics synthesis.

A facile method for vancomycin C-terminus functionalization and derivatization through hydrazide.

Over 60-year clinical use of vancomycin led to the emergence of vancomycin-resistant bacteria and threatened our health. To combat vancomycin-resistant strains, numerous vancomycin analogues were developed, such as Telavancin, Oritavancin and Dalbavancin. Extra structures embedded on C-terminus has been proved to be an effective strategy to promote antibacterial activity of vancomycin against vancomycin-resistant strains. Here, we reported a facile strategy, inspired by native chemical ligation, for vancomycin C-terminus functionalization and derivatization. The introduction of C-terminal hydrazide on vancomycin not only provided us an accessible method for C-terminus functionalization through carbonyl azide and thioester, also acted as an efficient site for vancomycin structure modifications. Based on hydrazide-vancomycin, we effectively conjugated cysteine and cysteine containing peptides onto vancomycin C-terminus, and two fluorescent FITC-vancomycin were prepared through Cys-Maleimide conjugation. Meanwhile, we introduced lipophilic structures onto vancomycin C-terminus via the hydrazide moiety. The obtained vancomycin derivatives were evaluated against both Gram-positive and negative bacteria strains.

Protective effects of proanthocyanidins from Rubus amabilis Focke on pancreatic tissues of diabetic mice / 中国药理学通报

Aim To study the protective effect of proanthocyanidins extracted from Rubus amabilis Focke (RPC) on the pancreatic tissues of diabetic mice and the underlying mechanism. Methods C57BL/6 male mice were given a high-sugar and high-fat diet combined with an intraperitoneal injection of STZ to establish the diabetic model. The mice whose FBG were higher than 16. 7 mmol · L

Preparation of Scutellariae Radix total flavonoids-loaded liposomes and their in vitro anti-tumor activity / 中成药

AIM To prepare Scutellariae Radix total flavonoids-loaded liposomes and to evaluate their in vitro anti-tumor activity.METHODS Liposomes were prepared by reverse evaporating method.Taking phospholipid concentration,ratio of phospholipid to cholesterol,ratio of organic phase to aqueous phase and total flavonoids concentration as influencing factors,together with encapsulation efficiency as an evaluation index,Box-Behnken design was applied to optimizing the preparation,after which MTT was employed to detect the obtained liposomes' inhibitory effect on human hepatocellular carcinoma cells HepG2.RESULTS The optimal conditions were determined to be 30 mg/mL for phospholipid concentration,3 ∶ 1 for ratio of phospholipid to cholesterol,2 ∶ 1 for ratio of organic phase to aqueous phase,and 5 mg/mL for total flavonoids concentration.The obtained round and uniform liposomes demonstrated an average particle size of (160.7 ± 12.0) nm,Zeta potential of (-41.4 ±2.3) mV,encapsulation efficiency of (86.19 ±0.44)％,drug loading of (5.32 ± 0.04)％,and accumulative release rate of (80.77 ± 2.53) ％ at 24 h.Compared with total flavonoids,liposomes exhibited stronger inhibitory effect on HepG2 cells with the IC50 of 48.853 μg/mL at 48 h in a time-and dose-dependent manner.CONCLUSION Scutellariae Radix total flavonoids-loaded liposomes stored at low temperature (4 ℃) display sustained-release effect and in vitro anti-tumor activity.