In vitro antagonistic inhibitory effects of palm seed crude oils and their main constituent, lauric acid, with oxacillin in Staphylococcus aureus

A step forward on the in vitro and in vivo validation of rifabutin-loaded liposomes for the management of highly virulent MRSA infections

Staphylococcus aureus (S. aureus) infections, especially methicillin resistant (MRSA), constitute an alarming public health issue due to its association with high mortality, morbidity, and hospitalization costs. The increasing antibiotic resistance and biofilm-associated infections of MRSA prompted the discovery of novel and more effective therapeutic strategies. Our team has been working on alternative therapies against S. aureus infections. For this, we have been repurposing an existing antibacterial drug, rifabutin (RFB), through its association to a nanotechnological platform, liposomes, aiming to promote a preferential targeting to infected sites and maximizing its potential antibacterial effect. The therapeutic potential of RFB formulations against a MRSA commercial strain (MRSA ATCC®-33592), either in planktonic or biofilm forms, was assessed. RFB displayed higher antibacterial effects towards biofilm than vancomycin (VCM), the gold standard treatment against MRSA infections, with MBIC50 values of 103 and > 800 μg/mL, respectively. Moreover, the antimicrobial effect of RFB-loaded liposomes demonstrated to be lipid composition-dependent based on MIC50 and MBIC50 values, which was also confirmed by confocal laser scanning microscopy. These studies supported that for positively charged RFB liposomes an electrostatic interaction at biofilm surface occurs without internalization. On the other hand, for RFB-loaded liposomes with neutral surface charge a high internalization within the biofilm was observed. Moreover, this RFB liposomal formulation has also demonstrated to be stable in human plasma, as more than 83 % of RFB was still associated to liposomes 24 h after incubation at 37 °C. The proof of concept of RFB formulations was assessed in MRSA systemic murine models of infection. Therapeutic effect and survival rates were evaluated for animals induced and treated with RFB in free and liposomal forms and compared with negative and positive controls. For the lower infection murine model, 100 % survival was achieved for all groups under study. However, in a higher infection model only for the group of animals treated with RFB incorporated in liposomes a 100 % survival was attained. In terms of bacterial burden, RFB formulations exhibited lower levels when compared to VCM, even using a lower therapeutic dose: 20 vs 40 mg/kg of body weight, respectively. Overall, RFB constitutes an alternative and effective therapeutic strategy towards MRSA infections, being this effect potentiated through its association to a lipid nanoplatform.

Impact of a 7-day short peptide diet on gut microbiota and metabolomics in septic mice

Objective

Our study aim is to explore the mechanisms of short peptide passages on intestinal dysfunction in septic mice utilizing a metabolomics approach, which provides a new scientific basis for the clinical study of sepsis.

Methods

Mices were allocated at random into four groups: control (Con), cecal ligation and puncture followed by one, three or 7 day short-peptide-based enteral nutrition group (CLP + SPEN1), (CLP + SPEN3), and (CLP + SPEN7) groups. A liquid chromatography-mass spectrometry-based metabolomics method was used to analyze changes in serum metabolites in septic mice.

Results

Short peptides showed effectiveness in reducing symptoms, mucosal inflammation, and intestinal function damage scores in septic mice. The 16sRNA analysis showcased significant variances in the distribution of bacterial communities between the CLP + SPEN1, CLP + SPEN3, and CLP + SPEN7 groups. At the phylum level, statistically significant variances in the relative abundance of Proteobacteria, Firmicutes, and Bacteroidetes were recognized. The metabolomics analysis results showed significant separation of metabolites between the CLP + SPEN1 and CLP + SPEN3 groups, as well as significant differences in metabolite profiles between the CLP + SPEN3 and CLP + SPEN7 groups. Utilizing a differential Venn diagram, four metabolites were commonly different; 10-heptadecanoic and dodecanoic acids had statistical significance. The abundance of both dodecanoic and lactic acid bacteria was negatively associated at the genus level.

Conclusion

Short peptides were found to promote the growth of beneficial bacteria, Lactobacillus and uncultured_bacterium_f_Muribaculaceae, while reducing intestinal metabolites such as Dodecanoic acid and 10-Heptadecenoic acid. Moreover the Lactobacillus may play a significant therapeutic role in the treatment of sepsis. However, due to the limited number of experimental samples, the exact mechanism of action of short peptides awaits further confirmation.

Lauric acid-mediated gelatin/hyaluronic acid composite hydrogel with effective antibacterial and immune regulation for accelerating MRSA-infected diabetic wound healing

The infected diabetic wound healing is an increasingly severe healthcare problem worldwide. Bacterial infection and the inflammatory microenvironment hinder diabetic wound healing. Meanwhile, the combination of inhibiting bacterial growth and promoting macrophage polarization in the wound microenvironment is beneficial for treating diabetic wounds. Nowadays, hydrogels, as an emerging wound dressing, have great potential to replace or supplement traditional bandages or gauze. Here, glycyl methacrylate gelatin (Gel-Gym), oxidized hyaluronic acid (HA-CHO) and lauric acid (LA) were used to prepare the composite hydrogel (GH/LA) in addressing the clinical dilemma. The hydrogel could withstand 50 % compression deformation, its swelling rate was as low as 18 %, and its adhesion to pig skin reached 14 kPa. Moreover, a diabetic infected wound model was used to evaluate the feasibility of GH/LA hydrogel in vivo. The hydrogels' antimicrobial, anti-inflammatory and prorestitutive potentials were further investigated, and GH/LA showed a therapeutic effect on diabetic wounds. Interestingly, macrophage polarization into the M2 phenotype was significantly enhanced in the presence of GH/LA via GPR40/NF-κB pathway. This study provided a new avenue for treating methicillin-resistant staphylococcus aureus (MRSA) infected diabetic wounds.

Absence of Synergism between a Dual-AMP Biogel and Antibiotics Used as Therapeutic Agents for Diabetic Foot Infections

Diabetic foot infections (DFIs) are frequently linked to diabetic-related morbidity and death because of the ineffectiveness of conventional antibiotics against multidrug-resistant bacteria. Pexiganan and nisin A are antimicrobial peptides (AMPs), and their application may complement conventional antibiotics in DFI treatment. A collagen 3D model, previously established to mimic a soft-tissue collagen matrix, was used to evaluate the antibacterial efficacy of a guar gum gel containing pexiganan and nisin alone and combined with three antimicrobials toward the biofilms of Staphylococcus aureus and Pseudomonas aeruginosa isolated from infected foot ulcers. Antimicrobials and bacterial diffusion were confirmed by spot-on-lawn and bacterial growth by bacterial count (cfu/mL). Our main conclusion was that the dual-AMP biogel combined with gentamicin, clindamycin, or vancomycin was not able to significantly reduce bacterial growth or eradicate S. aureus and P. aeruginosa DFI isolates. We further reported an antagonism between dual-AMP and dual-AMP combined with antibiotics against S. aureus.

AADB: A Manually Collected Database for Combinations of Antibiotics With Adjuvants

Antimicrobial resistance is a global public health concern. The lack of innovations in antibiotic development has led to renewed interest in antibiotic adjuvants. However, there is no database to collect antibiotic adjuvants. Herein, we build a comprehensive database named Antibiotic Adjuvant DataBase (AADB) by manually collecting relevant literature. Specifically, AADB includes 3,035 combinations of antibiotics with adjuvants, covering 83 antibiotics, 226 adjuvants, and 325 bacterial strains. AADB provides user-friendly interfaces for searching and downloading. Users can easily obtain these datasets for further analysis. In addition, we also collected related datasets (e.g., chemogenomic and metabolomic data) and proposed a computational strategy to dissect these datasets. As a test case, we identified 10 candidates for minocycline, and 6 of 10 candidates are the known adjuvants that synergize with minocycline to inhibit the growth of E. coli BW25113. We hope that AADB can help users to identify effective antibiotic adjuvants. AADB is freely available at http://www.acdb.plus/AADB.

Egyptian mandarin peel oil's anti-scabies potential via downregulation-of-inflammatory/immune-cross-talk: GC-MS and PPI network studies

The current study investigated the scabicidal potential of Egyptian mandarin peel oil (Citrus reticulata Blanco, F. Rutaceae) against sarcoptic mange-in-rabbits. Analysis of the oil's GC-MS identified a total of 20 compounds, accounting for 98.91% of all compounds found. Mandarin peel oil topical application improved all signs of infection, causing a scabicidal effect three days later, whereas in vitro application caused complete mite mortality one day later. In comparison to ivermectin, histopathological analysis showed that the epidermis' inflammatory-infiltration/hyperkeratosis-had disappeared. In addition to TIMP-1, the results of the mRNA gene expression analysis showed upregulation of I-CAM-1-and-KGF and downregulation of ILs-1, 6, 10, VEGF, MMP-9, and MCP-1. The scabies network was constructed and subjected to a comprehensive bioinformatic evaluation. TNF-, IL-1B, and IL-6, the top three hub protein-coding genes, have been identified as key therapeutic targets for scabies. From molecular docking data, compounds 15 and 16 acquired sufficient affinity towards the three screened proteins, particularly both possessing higher affinity towards the IL-6 receptor. Interestingly, it achieved a higher binding energy score than the ligand of the docked protein rather than displaying proper binding interactions like those of the ligand. Meanwhile, geraniol (15) showed the highest affinity towards the GST protein, suggesting its contribution to the acaricidal effect of the extract. The subsequent, MD simulations revealed that geraniol can achieve stable binding inside the binding site of both GST and IL-6. Our findings collectively revealed the scabicidal ability of mandarin peel extract for the first time, paving the way for an efficient, economical, and environmentally friendly herbal alternative for treating rabbits with Sarcoptes mange.

Scabicidal Potential of Coconut Seed Extract in Rabbits via Downregulating Inflammatory/Immune Cross Talk: A Comprehensive Phytochemical/GC-MS and In Silico Proof

Scabies is an invasive skin condition caused by Sarcoptes scabiei mites. The present study investigates the antiscabies potential of coconut seed extract (CSE) in rabbits. GC-MS analysis of the seed oil identified 17 known compounds, while CSE phytochemical investigation afforded 4 known ones. The topical application of seed extract improved all signs of infection, and the improvement started 3 days post application. However, in vitro application of the extract caused 99% mortality of mites 1 day post application. Histopathological examination revealed the absence of inflammatory infiltration and hyperkeratosis of the epidermis, compared with ivermectin-treated groups which revealed less improvement. The mRNA gene expression results revealed a suppression of IL-1β, IL-6, IL-10, MMP-9, VEGF, and MCP-1, and an upregulation of I-CAM-1, KGF as well as TIMP-1. The docking analysis emphasized a strong binding of gondoic acid with IL-1β, IL-6, and VEGF with high binding scores of -5.817, -5.291, and -8.362 kcal/mol, respectively, and a high binding affinity of 3″(1‴-O-β-D-glucopyranosyl)-sucrose with GST with -7.24 kcal/mol. Accordingly, and for the first time, our results highlighted the scabicidal potential of coconut seed extract, which opens the gate for an efficient, cost-effective as well as herbal-based alternative for the control of scabies in rabbits.

In Vitro Selective Combinatory Effect of Ciprofloxacin with Nitroxoline, Sanguinarine, and Zinc Pyrithione against Diarrhea-Causing and Gut Beneficial Bacteria

Antibiotic resistance in diarrhea-causing bacteria and its disruption of gut microbiota composition are health problems worldwide. The development of combinatory agents that increase the selective inhibitory effect (synergism) against diarrheagenic pathogens and, simultaneously, have a lowered impact (antagonism) or no negative action on the gut microbiota is therefore proposed as a new strategy efficient for chemotherapy against diarrheal conditions. In this study, the in vitro selective combinatory effect of ciprofloxacin with nitroxoline, sanguinarine, and zinc pyrithione, representing various classes of alkaloid-related compounds (nitroquinolines, benzylisoquinolines and metal-pyridine derivative complexes) against selected standard diarrhea-causing (Bacillus cereus, Enterococcus faecalis, Listeria monocytogenes, Shigella flexneri, and Vibrio parahaemolyticus) and gut-beneficial (Bifidobacterium adolescentis, Bifidobacterium animalis subsp. lactis, Bifidobacterium breve, Lactobacillus casei, and Lactobacillus rhamnosus) bacteria, was evaluated according to the sum of fractional inhibitory concentration indices (FICIs) obtained by the checkerboard method. The results showed that the individual combination of ciprofloxacin with nitroxoline, sanguinarine, and zinc pyrithione produced a synergistic effect against the pathogenic bacteria, with FICI values ranging from 0.071 to 0.5, whereas their antagonistic interaction toward the Bifidobacterium strains (with FICI values ranging from 4.012 to 8.023) was observed. Ciprofloxacin-zinc pyrithione produced significant synergistic action against S. flexneri, whereas a strong antagonistic interaction was observed toward B. breve for the ciprofloxacin-nitroxoline combination. These findings suggest that certain combinations of agents tested in this study can be used for the development of antidiarrheal therapeutic agents with reduced harmful action on the gastrointestinal microbiome. However, further studies focused on their pharmacological efficacy and safety are needed before they are considered for clinical trials. IMPORTANCE Diarrheal infections, which are commonly treated by antibiotics, are still responsible for over 4 to 5 million cases of human deaths annually. Moreover, the rising incidence of antibiotic resistance and its negative effect on beneficial bacteria (e.g., Bifidobacteria) of the gut microbial community are another problem. Thus, the development of selective agents able to inhibit diarrheal bacteria and, simultaneously, that have no negative impact on the gut microbiota, is important. Our results showed that individual combinations of ciprofloxacin with nitroxoline, sanguinarine, and zinc pyrithione produced synergism against the pathogenic bacteria, whereas their antagonistic interaction toward the beneficial strains was observed. The antagonism can be considered a positive effect contributing to the safety of the therapeutic agents, whereas their synergism against diarrheal bacteria significantly potentiates total antimicrobial efficacy. The certain combinations tested in this study can be used for the development of antidiarrheal agents with reduced harmful action on the gastrointestinal microbiome.

Brazilian tucumã-do-Amazonas (Astrocaryum aculeatum) and tucumã-do-Pará (Astrocaryum vulgare) fruits: bioactive composition, health benefits, and technological potential

Latin America has a wide range of native plants spread through its territory. The palms of the Astrocaryum genus are examples of crops occurring in Central and South America, including the large plant life in Brazil. Although not very well known, the Astrocaryum spp. possess edible and non-edible fractions with potential technological and medicinal uses, as evidenced by recent research. Two native Brazilian fruits, tucumã-do-Amazonas (Astrocaryum aculeatum) and tucumã-do-Pará (Astrocaryum vulgare), typically found in the north and northeast of the country, respectively, stand out for their high antioxidant capacity and rich content in bioactive compounds, mainly carotenoids and phenolic compounds. Accordingly, experimental studies indicate their potential to prevent and treat inflammatory and oxidative stress-related conditions, including cancer. The tucumã plants have also been suggested as tools in the industry, for example for biofuel production, activated carbon technology, and as alternative packaging. Considering the importance of bringing light to underestimated yet culturally relevant native crops with potential benefits for small and large communities, this review aims to present and discuss the characteristics, bioactive composition, health effects, and technological potential of tucumã-do-Amazonas and tucumã-do-Pará fruits.

Lauric Acid Is a Potent Biological Control Agent That Damages the Cell Membrane of Phytophthora sojae

Sustainable management of plant pathogens is becoming more challenging, and novel solutions are needed. Plant biologically active secondary metabolites are important sources of novel crop protection chemistry. Effective individual compounds of these natural products have the potential to be successful new agrochemicals. In this study, we identified lauric acid (LA) from soybean defense leaf volatiles. LA inhibited the growth of Phytophthora sojae, the causal agent of soybean root rot. It influenced mycelial development, sporangium formation, and zoospore generation and germination by damaging the P. sojae cell membrane. Additionally, we showed that LA and several of its derivatives, such as glycerol monolaurate (GML), had similar biological activities. Both LA and GML were safe to soybean plants when used at less than 0.3 g a.i./plant and could promote soybean growth, implying their potential as eco-friendly biological control agents.