Off-target effect of high-dose sildenafil on adenosine 5'- diphosphate and collagen-induced platelet activation through mitogen-activated protein kinase pathway in treated BALB/C mice and in vitro experiments: A preliminary study.

ABSTRACT: Sildenafil, a common over-the-counter pill often self-administered at high doses for erectile dysfunction, has been reported to rarely cause prothrombotic events and sudden cardiac death in a few case reports. Therefore, we investigated the in vitro and in vivo effect of sildenafil treatment and dosage on platelet activation and mitogen-activated protein kinase (MAPK) phosphorylation. BALB/C mice were segregated into four groups, each having four mice each (control, low [3.25 mg/kg], medium [6.5 mg/kg], and high [13 mg/kg] sildenafil), and after the treatment, blood was drawn from each mouse and washed platelets prepared. Washed platelets were incubated with CD41 PE-Cy7 and Phospho-p38 MAPK PE antibodies and analyzed using a flow cytometer for platelet activation and adenosine 5'- diphosphate (ADP)/collagen-induced MAPK phosphorylation. Washed platelets obtained from the venous blood of 18 human volunteers, were incubated with PAC-1 FITC and Phospho-p38 MAPK PE antibodies, and platelet activation (ADP and collagen), followed by flow cytometry analysis. There was a significant increase in both platelet activation as well as MAPK phosphorylation in the presence of collagen in the high-dose (13 mg/kg) sildenafil group (P = 0.000774). Further, increased platelet activation was observed in samples that were treated with high-dose sildenafil as compared to the untreated samples (P < 0.00001). These studies show the risk of prothrombotic episodes in patients on high-dose sildenafil (100 mg), in those with even mild endothelial dysfunction due to ADP, and collagen-induced platelet activation through MAPK phosphorylation, which was not seen in the low-and intermediate-dose cohorts.

Effect of high-dose intravenous iron injection on hepatic function in a rat model of cirrhosis.

OBJECTIVE: To investigate the hepatic effects of high-dose intravenous (IV) iron, including those on liver function and the degree of fibrosis, in a rat model of cirrhosis. METHODS: We evenly allocated 25 Sprague-Dawley rats into five groups: normal rats (control group), cirrhotic rats receiving IV normal saline (liver cirrhosis [LC] group), and cirrhotic rats receiving 20, 40, or 80 mg/kg IV ferric carboxymaltose (LC-iron20, LC-iron40, and LC-iron80 group, respectively). Biochemical parameters were compared at 0, 7, 14, 21, and 28 days. The degrees of hepatic fibrosis and iron deposition were evaluated. Inflammatory and oxidative stress markers were also compared. RESULTS: There were no significant differences in the 28-day serum alanine aminotransferase levels among the LC-iron20, LC-iron40, and LC-iron80 groups (69 ± 7, 1003 ± 127, 1064 ± 309, 919 ± 346, and 820 ± 195 IU/L in the control, LC, LC-iron20, LC-iron40, and LC-iron80 groups, respectively). Hepatic iron accumulation increased in a dose-dependent manner, but the degree of hepatic fibrosis was comparable among the groups. The inflammatory and oxidative stress marker levels did not differ significantly according to the IV iron dose. CONCLUSIONS: Administration of IV iron at various high doses appears safe in our rat model of cirrhosis.

Novel angiogenesis inhibitors with superoxide anion radical amplification effect: Surmounting the Achilles' heels of angiogenesis inhibitors and photosensitizers.

Angiogenesis inhibitors and photosensitizers are pivotal in tumor clinical treatment, yet their utilization is constrained. Herein, eleven novel angiogenesis inhibitors were developed through hybridization strategy to overcome their clinical limitations. These title compounds boast excitation wavelengths within the "therapeutic window", enabling deep tissue penetration. Notably, they could generate superoxide anion radicals via the Type I mechanism, with compound 36 showed the strongest superoxide anion radical generating capacity. Biological evaluation demonstrated remarkable cellular activity of all the title compounds, even under hypoxic conditions. Among them, compound 36 stood out for its superior anti-proliferative activity in both normoxic and hypoxic environments, surpassing individual angiogenesis inhibitors and photosensitizers. Compound 36 induced cell apoptosis via superoxide anion radical generation, devoid of dark toxicity. Molecular docking revealed that the target-recognizing portion of compound 36 was able to insert into the ATP binding pocket of the target protein similar to sorafenib. Collectively, our results suggested that hybridization of angiogenesis inhibitors and photosensitizers was a potential strategy to address the limitations of their clinical use.

Discovery of an efficacious KDM5B PROTAC degrader GT-653 up-regulating IFN response genes in prostate cancer.

Epigenetic alterations promote cancer development by regulating the expression of various oncogenes and anti-oncogenes. Histone methylation modification represents a pivotal area in epigenetic research and numerous publications have demonstrated that aberrant histone methylation is highly correlated with tumorigenesis and development. As a key histone demethylase, lysine-specific demethylase 5B (KDM5B) demethylates lysine 4 of histone 3 (H3K4) and serves as a transcriptional repressor of certain tumor suppressor genes. Meanwhile, KDM5B inhibits STING-induced intrinsic immune response of tumor cells or recruits SETDB1 through non-enzymatic function to silence reverse transcription elements to promote immune escape. The conventional small molecule inhibitors can only inhibit the enzymatic function of KDM5B with no effect on the non-enzymatic function. In the article, we present the development of the first series of KDM5B degraders based on CPI-455 to inhibit the non-enzymatic function. Among them, GT-653 showed optimal KDM5B degradation efficiency in a ubiquitin proteasome-dependent manner. GT-653 efficiently reduced KDM5B protein levels without affecting KDM5B transcription. Interestingly, GT-653 increased H3K4me3 levels and activated the type-I interferon signaling pathway in 22RV1 cells without significant phenotypic response on cell proliferation.

Effects of caffeine on temporal perception in Rattus norvegicus.

We report two studies that tested the effects of caffeine, the world's most widely used psychoactive drug, on temporal perception. We trained Wistar rats using the Bisection Procedure (Experiment 1) or the Stubbs' Procedure (Experiment 2) to discriminate between short and long light stimuli. Once training finished, we administered caffeine orally (0, 9.6, and 96.0 mg/kg for Experiment 1 and 0, 9.6, 19.2, and 38.4 mg/kg for Experiment 2) 15 minutes prior to testing. Relative to the control condition, the 9.6 mg/kg condition (Experiments 1 and 2) and the 19.2 mg/kg condition (Experiment 2) resulted in an increase in proportion of choosing the long response. Meanwhile, overall accuracy was not affected by any condition in both experiments. Taken together, these results are consistent with the notion that caffeine, at some doses, speeds up temporal perception. However, it is not clear why the effect disappears at higher doses.

Low-Dose Alfentanil Inhibits Sufentanil-Induced Cough During Anesthesia Induction: A Prospective, Randomized, Double-Blind Study.

Background: Cough is one of the most common complications following intravenous administration of sufentanil during anesthesia induction. The study aimed to investigate the protective effect of alfentanil, afentanyl derivative with short onset time and short duration, in reducing sufentanil-induced cough. Patients and methods: Eighty patients that scheduled for thyroid surgery under general anesthesia were randomly divided into the alfentanil group and normal saline group, with 40 cases per group. Patients in the alfentanil group received intravenous administration of 2 µg/kg alfentanil prior to sufentanil injection during general anesthesia induction, while the same dose of normal saline was administered in the normal saline group. The outcomes measures included the incidence and severity of cough and common side effects of opioids following the administration of sufentanil during the induction of general anesthesia, intraoperative hemodynamics parameters and major adverse events during anesthesia recovery period. Results: The incidence of cough within one minute after the injection of sufentanil during anesthesia induction was 40% in the normal saline group, and the pretreatment of alfentanil significantly reduced the incidence of sufentanil-induced cough to 5% (p < 0.05). Correspondingly, the patients in the alfentanil group had decreased severity of sufentanil-induced cough compared with the normal saline group (p < 0.05). No significant differences in the incidences of common side effects of opioids (dizziness, nausea and vomiting, chest tightness and respiratory depression) within one minute after sufentanil injection were found (p > 0.05). Furthermore, there were no significant differences between the two groups in intraoperative hemodynamic parameters, extubation time, or the incidences of emergence agitation, respiratory depression, delayed recovery from anesthesia and postoperative nausea and vomiting during Postanesthesia Care Unit stay (p > 0.05). Conclusion: Pretreatment with low-dose alfentanil (2 µg/kg) effectively and safely reduced both the incidence and severity of sufentanil-induced cough during anesthesia induction. Clinical Trial Registration Number: Chinese Clinical Trial Registry (identifier: ChiCTR2300069286).

Comparison between conventional-dose and high-dose rocuronium use in general anesthesia for Cesarean section.

Background: There have been few studies comparing the effects of high- and low-dose rocuronium during cesarean section by directly measuring the concentration. Therefore, we conducted a study to examine the blood concentrations and clinical effects of both doses of rocuronium on mothers and fetuses. Methods: Eighteen patients were randomly assigned to two groups: C Group (0.6 mg/kg), and H Group, (1.0 mg/kg). The primary outcome was the comparison of umbilical vein rocuronium concentration between two groups. We assessed ease of intubation, time from rocuronium administration to some TOF points, post-anesthesia care unit (PACU) stay time, infused remifentanil dose, maternal rocuronium concentration, and Apgar scores. Results: No differences were observed in demographic data, ease of intubation, PACU stay time, 1 min Apgar scores, umbilical venous blood gas analysis between both groups. However, the time from rocuronium administration to T3 disappearance was shorter (p=0.009) and time to T1 and T2 reappearance were longer (p=0.003, p=0.009) in H group than that in C group. The administered remifentanil dose (p=0.042) was lower in the H group than in the C group. Rocuronium concentrations in the umbilical vein (p=0.004) and maternal vein before cord clamping (p=0.002) and at discharge (p<0.001) were also found to be higher in the H group than in the C group. Conclusions: We observed no prolongation of PACU stay, and no differences in Apgar scores in H group compared to C group. It suggests that 1.0 mg/kg of rocuronium has no negative effects on the fetus and mother in cesarean section.

Dose-Response Study of Phenylephrine for Preventing Spinal-Induced Hypotension During Cesarean Delivery with Combined Spinal-Epidural Anesthesia Under the Effect of Prophylactic Intravenous Ondansetron.

Background: Ondansetron reduces the median effective dose (ED50) of prophylactic phenylephrine to prevent spinal-induced hypotension (SIH) during cesarean delivery. However, the exact dose response of phenylephrine in combination with prophylactic ondansetron for preventing SIH is unknown. Therefore, this study aimed to determine the dose-response of phenylephrine to prevent SIH in cesarean delivery when 4 mg of ondansetron was used as a preventive method. Methods: A total of 80 parturients were enrolled and divided randomly into four groups (n = 20 in each group) who received either 0.2, 0.3, 0.4, or 0.5 µg/kg/min of prophylactic phenylephrine. Ten minutes before the initiation of spinal induction, 4 mg prophylactic ondansetron was administered. The effective dose of prophylactic phenylephrine was defined as the dose required to prevent hypotension after the period of intrathecal injection and up to neonatal delivery. The ED50 and ED90 of prophylactic phenylephrine and 95% confidence intervals (95% CI) were calculated using probit analysis. Results: The ED50 and ED90 for prophylactic phenylephrine to prevent SIH were 0.25 (95% CI, 0.15 to 0.30), and 0.45 (95% CI, 0.39 to 0.59) µg/kg/min, respectively. No significant differences were observed in the side effects and neonatal outcomes between the four groups. Conclusion: The administration of 4 mg of prophylactic ondansetron was associated with an ED50 of 0.25 (95% CI, 0.15~0.30) and ED90 of 0.45 (95% CI, 0.39~0.59) µg/kg/min for phenylephrine to prevent SIH.

[Study of antitumor effects of human placenta hydrolysate on PC-3, OAW-42, BT-474 cell cultures].

AIM: To investigate the antitumor effects of human placenta hydrolysate (HPH) peptides on three hormone-dependent human cell lines: prostate adenocarcinoma, breast carcinoma, and ovarian cancer by metabolic analysis of cell cultures. MATERIALS AND METHODS: The effect of HPH on tumor and control tumor cell lines was evaluated. Study stages: (A) de novo peptide sequencing by collision-induced dissociation mass spectrometry; (B) detection of peptides with anti-tumor properties; (C) expert analysis of the obtained lists of peptides. RESULTS: Dose-dependent cytotoxic effects of HPH on three tumor cell lines are shown: PC-3 (human prostate adenocarcinomas), OAW-42 (human ovarian cancer), BT-474 (human breast carcinomas), and IC50 constants (1.3-2.8 mg/ml) were obtained. The analysis of the HPH peptide fraction showed more than 70 peptides with antitumor properties in the composition of this HPH, including kinase inhibitors: mitogen-activated protein kinases, kappa-bi nuclear factor inhibitor kinase, AKT serine/threonine kinase 1, protein kinase C zeta, interleukin-1 receptor-associated kinase 4 and cyclin-dependent kinase 1. CONCLUSION: The results of the study indicate not only the oncological safety of the HPH used in therapy but also the mild antitumor effects of this HPH at high concentrations.

Impact of chronic lithium treatment on brain oxidative stress and anxiety-like behaviors in rats: Dose-dependent effects.

Lithium (Li) is a mood-stabilizing drug. Although one of the potential mechanisms underlying the neuroprotective effects of lithium is related to its antioxidative effect, its mechanisms of action are not fully understood. Herein we aimed to investigate the impact of varied dosages of long-term lithium therapy on oxidative stress parameters in the brains of healthy rats, and on anxiety-like behaviors, and whether any changes in behavior can be attributed to modifications in oxidative stress levels within the brain. Thirty-two adult Wistar albino male rats were randomly assigned to four treatment groups. While the control (C) group was fed with a standard diet, low Li (1.4 g/kg/diet), moderate Li (1.8 g/kg/diet), and high Li (2.2 g/kg/diet) groups were fed with lithium bicarbonate (Li2CO3) for 30 days. Malondialdehyde increased, while superoxide dismutase and catalase levels decreased in the brains of the high Li group animals. In addition, anxiety-like behaviors of animals increased in the high Li group considering fewer entries to and less time spent in the open arms of the elevated plus maze test. Our findings underscore the potential adverse effects of prolonged lithium treatment, especially at doses approaching the upper therapeutic range. The induction of toxicity, manifested through heightened oxidative stress, appears to be a key mechanism contributing to the observed increase in anxiety-like behaviors. Consequently, caution is warranted when considering extended lithium therapy at higher doses, emphasizing the need for further research to delineate the precise mechanisms underlying these effects and to inform safer therapeutic practices.

A Novel Tetramethylpyrazine Chalcone Hybrid- HCTMPPK, as a Potential Anti-Lung Cancer Agent by Downregulating MELK.

Purpose: Lung adenocarcinoma currently ranks the leading causes of cancer-related mortality worldwide. Many anti-inflammation herbs, like tetramethylpyrazine, have shown their anti-tumor potentials. Here, we evaluated the role of a novel chalcone derivative of tetramethylpyrazine ((E) -1- (E) -1- (2-hydroxy-5-chlorophenyl) -3- (3,5,6-trimethylpyrazin-2-yl) -2-propen-1, HCTMPPK) in lung adenocarcinoma. Methods: The effects of HCTMPPK on cell proliferation, apoptosis, and invasion were investigated by in-vitro assays, including CCK-8, colony formation assay, flow cytometry, transwell assay, and wound-healing assay. The therapeutic potential of HCTMPPK in vivo was evaluated in xenograft mice. To figure out the target molecules of HCTMPPK, a network pharmacology approach and molecular docking studies were employed, and subsequent experiments were conducted to confirm these candidate molecules. Results: HCTMPPK effectively suppressed the proliferative activity and migration, as well as enhanced the apoptosis of A549 cells in a concentration-dependent manner. Consistent with this, tumor growth was inhibited by HCTMPPK significantly in vivo. Regarding the mechanisms, HCTMPPK down-regulated Bcl-2 and MMP-9 and up-regulating Bax and cleaved-caspase-3. Subsequently, we identified 601 overlapping DEGs from LUAD patients in TCGA and GEO database. Then, 15 hub genes were identified by PPI network and CytoHubba. Finally, MELK was verified to be the HCTMPPK targeted site, through the molecular docking studies and validation experiments. Conclusion: Overall, our study indicates HCTMPPK as a potential MELK inhibitor and may be a promising candidate for the therapy of lung cancer.

First-in-human safety, tolerability, and pharmacokinetic results of DFV890, an oral low-molecular-weight NLRP3 inhibitor.

This first-in-human study evaluated the safety, tolerability, single- and multiple-dose pharmacokinetic profiles with dietary influence, and pharmacodynamics (PD) of DFV890, an oral NLRP3 inhibitor, in healthy participants. In total, 122 participants were enrolled into a three-part trial including single and 2-week multiple ascending oral doses (SAD and MAD, respectively) of DFV890, and were randomized (3:1) to DFV890 or placebo (SAD [3-600 mg] and MAD [fasted: 10-200 mg, once-daily or fed: 25 and 50 mg, twice-daily]). DFV890 was generally well-tolerated. Neither deaths nor serious adverse events were reported. A less than dose-proportional increase in exposure was observed with the initially used crystalline suspension (3-300 mg); however, an adjusted suspension formulation using spray-dried dispersion (SDD; 100-600 mg) confirmed dose-proportional increase in exposure. Relative bioavailability between crystalline suspension and tablets, and food effect were evaluated at 100 mg. Under fasting conditions, Cmax of the tablet yielded 78% compared with the crystalline suspension, and both formulations showed comparable AUC. The fed condition led to a 2.05- and 1.49-fold increase in Cmax and AUC0-last compared with the fasting condition. The median IC50 and IC90 for ex-vivo lipopolysaccharide-stimulated interleukin IL-1ß release inhibition (PD) were 61 (90% CI: 50, 70) and 1340 ng/mL (90% CI: 1190, 1490). Crystalline tablets of 100 mg once-daily or 25 mg twice-daily were sufficient to maintain ~90% of the IL-1ß release inhibition over 24 h at steady state. Data support dose and formulation selection for further development in diseases, in which an overactivated NLRP3 represents the underlying pathophysiology.

Re-discover the value of protein binding assessments in hepatic and renal impairment studies and its contributions in drug labels and dose decisions.

One of the key pharmacokinetic properties of most small molecule drugs is their ability to bind to serum proteins. Unbound or free drug is responsible for pharmacological activity while the balance between free and bound drug can impact drug distribution, elimination, and other safety parameters. In the hepatic impairment (HI) and renal impairment (RI) clinical studies, unbound drug concentration is often assessed; however, the relevance and impact of the protein binding (PB) results is largely limited. We analyzed published clinical safety and pharmacokinetic studies in subjects with HI or RI with PB assessment up to October 2022 and summarized the contribution of PB results on their label dose recommendations. Among drugs with HI publication, 32% (17/53) associated product labels include PB results in HI section. Of these, the majority (9/17, 53%) recommend dose adjustments consistent with observed PB change. Among drugs with RI publication, 27% (12/44) of associated product labels include PB results in RI section with the majority (7/12, 58%) recommending no dose adjustment, consistent with the reported absence of PB change. PB results were found to be consistent with a tailored dose recommendation in 53% and 58% of the approved labels for HI and RI section, respectively. We further discussed the interpretation challenges of PB results, explored treatment decision factors including total drug concentration, exposure-response relationships, and safety considerations in these case examples. Collectively, comprehending the alterations in free drug levels in HI and RI informs treatment decision through a risk-based approach.

Safety, tolerability, and pharmacokinetics of single- and multiple-ascending doses of olamkicept: Results from randomized, placebo-controlled, first-in-human phase I trials.

Olamkicept selectively inhibits the cytokine interleukin-6 (IL-6) trans-signaling pathway without blocking the classic pathway and is a promising immunoregulatory therapy for inflammatory bowel disease (IBD). These first-in-human, randomized, placebo-controlled, single- (SAD) and multiple-ascending dose (MAD) trials evaluated olamkicept safety, tolerability, pharmacokinetic, and pharmacodynamic characteristics. Doses tested in the SAD trial included seven single intravenous doses (0.75, 7.5, 75, 150, 300, 600, and 750 mg) and one subcutaneous (SC) dose (60 mg) given to healthy subjects (N = 64), and three intravenous doses (75 mg, 300 mg, and 750 mg) given to patients with Crohn's disease (CD; N = 24). Doses tested in the MAD trial included multiple intravenous doses (75, 300, and 600 mg once weekly for 4 weeks) given to healthy subjects (N = 24). No severe or serious treatment-emergent adverse events (TEAEs) were recorded. The most common TEAEs were headache, nasopharyngitis, and myalgia in the SAD trial, and diarrhea, headache, and cough in the MAD trial. Infusion-related reactions occurred in one and two subjects in the SAD and MAD trial, respectively, leading to treatment discontinuation in the MAD trial. Olamkicept showed dose-independent pharmacokinetics after single and multiple administrations, and there was no major difference in systemic exposure between healthy subjects and patients with CD. Complete target engagement (inhibition of phosphorylation of signal transducer and activator of transcription-3) was achieved in blood around or above olamkicept serum concentrations of 1-5 µg/mL. Overall, these results suggest that olamkicept is safe and well-tolerated in healthy subjects and patients with CD after single intravenous/SC and multiple intravenous administrations.

Dose escalation of biologic treatment in patients with moderate-to-severe psoriasis in Japan.

Patients receiving interleukin (IL)-inhibiting biologics for moderate-to-severe psoriasis (PsO) may be treated with escalated doses to optimize outcomes. This study evaluated escalation prevalence in a Japanese claims analysis of patients with PsO diagnosis preceding IL-inhibiting biologic treatment and ≥1 post-induction maintenance claim (index date) with sufficient data availability from January 2014 to May 2022. Patients with non-persistence were excluded. Expected daily dose (EDD) was calculated as the recommended maintenance dose divided by the treatment interval. Dose escalation was defined as ≥2 claims showing a ≥20% increase in the observed average daily dose (ADD) over the EDD (with sensitivities requiring ≥1 claim and ≥30%). Significant differences were tested using multivariable regressions. The study included 982 unique patients treated with brodalumab (BRO; n = 104), guselkumab (GUS; n = 207), ixekizumab (IXE; n = 159), risankizumab (RIS; n = 135), secukinumab (SEC; n = 215) and ustekinumab (UST; n = 196). Within 12 months, dose escalation was observed for all IL-inhibiting biologics other than GUS and RIS: 44.4% for UST, 37.2% for IXE, 3.4% for SEC and 1.4% for BRO. In multivariable-adjusted analyses, odds of dose escalation were significantly lower for all products relative to UST. In sensitivities, escalation was observed for all products except RIS.

Hyperglycemia-simulating environment attenuated experimentally induced calcification in cultured human aortic valve interstitial cells.

Objectives: The role of diabetes mellitus as a risk factor for the development of calcific aortic valve disease has not been fully clarified. Aortic valve interstitial cells (VICs) have been suggested to be crucial for calcification of the valve. Induced calcification in cultured VICs is a good in vitro model for aortic valve calcification. The purpose of this study was to investigate whether increased glucose levels increase experimentally induced calcification in cultured human VICs. Design: VICs were isolated from explanted calcified aortic valves after valve replacement. Osteogenic medium induced calcification of cultured VICs at different glucose levels (5, 15, and 25 mM). Calcium deposits were visualized using Alizarin Red staining and measured spectrophotometrically. Results: The higher the glucose concentration, the lower the level of calcification. High glucose (25 mM) reduced calcification by 52% compared with calcification at a physiological (5 mM) glucose concentration (correlation and regression analysis: r = -0.55, p = .025 with increased concentration of glucose). Conclusions: In vitro hyperglycemia-like conditions attenuated calcification in VICs. High glucose levels may trigger a series of events that secondarily stimulate calcification of VICs in vivo.

Arginine and tryptophan-rich dendritic antimicrobial peptides that disrupt membranes for bacterial infection in vivo.

The potent antibacterial activity and low resistance of antimicrobial peptides (AMPs) render them potential candidates for treating multidrug-resistant bacterial infections. Herein, a minimalist design strategy was proposed employing the "golden partner" combination of arginine (R) and tryptophan (W), along with a dendritic structure to design AMPs. By extension, the α/ε-amino group and the carboxyl group of lysine (K) were utilized to link R and W, forming dendritic peptide templates αRn(εRn)KWm-NH2 and αWn(εWn)KRm-NH2, respectively. The corresponding linear peptide templates R2nKWm-NH2 and W2nKRm-NH2 were used as controls. Their physicochemical properties, activity, toxicity, and stability were compared. Among these new peptides, the dendritic peptide R2(R2)KW4 was screened as a prospective candidate owing to its preferable antibacterial properties, biocompatibility, and stability. Additionally, R2(R2)KW4 not only effectively restrained the progression of antibiotic resistance, but also demonstrated synergistic utility when combined with conventional antibiotics due to its unique membrane-disruptive mechanism. Furthermore, R2(R2)KW4 possessed low toxicity (LD50 = 109.31 mg/kg) in vivo, while efficiently clearing E. coli in pulmonary-infected mice. In conclusion, R2(R2)KW4 has the potential to become an antimicrobial regent or adjuvant, and the minimalist design strategy of dendritic peptides provides innovative and encouraging thoughts in designing AMPs.

Novel natural osthole-inspired amphiphiles as membrane targeting antibacterials against methicillin-resistant Staphylococcus aureus (MRSA).

Methicillin-resistant Staphylococcus aureus (MRSA) is a widespread pathogen causing clinical infections and is multi-resistant to many antibiotics, making it urgent need to develop novel antibacterials to combat MRSA. Herein, we designed and prepared a series of novel osthole amphiphiles 6a-6ad by mimicking the structures and function of antimicrobial peptides (AMPs). Antibacterial assays showed that osthole amphiphile 6aa strongly inhibited S. aureus and 10 clinical MRSA isolates with MIC values of 1-2 µg/mL, comparable to that of the commercial antibiotic vancomycin. Additionally, 6aa had the advantages of rapid bacteria killing without readily developing drug resistance, low toxicity, good membrane selectivity, and good plasma stability. Mechanistic studies indicated that 6aa possesses good membrane-targeting ability to bind to phosphatidylglycerol (PG) on the bacterial cell membranes, thereby disrupting the cell membranes and causing an increase in intracellular ROS as well as leakage of proteins and DNA, and accelerating bacterial death. Notably, in vivo activity results revealed that 6aa exhibits strong anti-MRSA efficacy than vancomycin as well as a substantial reduction in MRSA-induced proinflammatory cytokines, including TNF-α and IL-6. Given the impressive in vitro and in vivo anti-MRSA efficacy of 6aa, which makes it a potential candidate against MRSA infections.