Effects of 1,8-cineole on Carbohydrate Metabolism Related Cell Structure Changes of Salmonella

DIA-based serum proteomics revealed the protective effect of modified siwu decoction against hypobaric hypoxia

ETHNOPHARMACOLOGICAL RELEVANCE

Siwu decoction (SWD) is a common traditional formula for nourishing blood, and its derived formulas are also widely used in traditional Chinese medicine (TCM) clinic. However, the protective effects of SWD and its derived formulas on blood deficiency and blood stasis caused by rushing to the plateau are rarely reported, and the underlying mechanism has not been fully elucidated.

AIM OF THE STUDY

This study explores the pharmacological effects and mechanisms of modified siwu decoction (MSWD) adding Persicae Semans (Prunus persica (L.) Batsch) and Carthami Flos (Carthamus tinctorius L.) against hypobaric hypoxia (HH). The acute toxicity of MSWD was also evaluated to further validate the potential of MSWD as a therapeutic candidate for HH.

MATERIALS AND METHODS

Hypoxic models of C57BL/6 J and KM male mice were used to evaluate the pharmacological effect of MSWD. 2 μL serum sample of C57BL/6 J mice was digested into peptide mixtures and analyzed with DIA mode on an Orbitrap Fusion Lumos mass spectrometer after LC separation. The peptide and protein identifications were limited to a 1% FDR. Screening of differential expressed proteins, correlation analysis, hierarchical clustering analysis, principal components analysis and Mfuzz analysis were all performed by R packages. The protein-protein interaction network was analyzed using the STRING website and constructed with Cytoscape software.

RESULTS

MSWD showed a protective effect against acute hypoxia exposure through increasing the number of red blood cells and improving hemodynamics indexes in mice. Meanwhile, the biochemical results showed that MSWD could reduce the inflammation and oxidative stress, reduce the content of organ injury biomarkers and significantly improve the high-intensity exercise ability of mice. Subsequently, serum DIA proteomic results revealed significant changes in proteomic characteristics after MSWD intervention. Specifically, proteins related to oxidative stress and ubiquitin-proteasome system, such as Sod1, Gstp1, Vcp and Usp14, were down-regulated after MSWD intervention, suggesting that the protective effect of MSWD involved the reduction of oxidative stress and energy expenditure. MSWD also intervened in energy metabolism and lipid metabolism processes by altering the expression levels of Eno1, Sphk1 and Apoa1 to ameliorate hypoxia-induced disorders. At the same time, MSWD acute toxicity test showed no obvious toxicity.

CONCLUSIONS

MSWD has a good protective effect against HH by ameliorating hypoxia-induced disorders of energy and lipid metabolism, supporting MSWD as a safe drug candidate for the prevention and treatment of acute hypoxia fatigue.

1,8-cineole (eucalyptol): A versatile phytochemical with therapeutic applications across multiple diseases

1,8-cineole (Eucalyptol), a naturally occurring compound derived from botanical sources such as eucalyptus, rosemary, and camphor laurel, has a long history of use in traditional medicine and exhibits an array of biological properties, including anti-inflammatory, antioxidant, antimicrobial, bronchodilatory, analgesic, and pro-apoptotic effects. Recent evidence has also indicated its potential role in managing conditions such as Alzheimer's disease, neuropathic pain, and cancer. This review spotlights the health advantages of 1,8-cineole, as demonstrated in clinical trials involving patients with respiratory disorders, including chronic obstructive pulmonary disease, asthma, bronchitis, and rhinosinusitis. In addition, we shed light on potential therapeutic applications of 1,8-cineole in various conditions, such as depression, epilepsy, peptic ulcer disease, diarrhea, cardiac-related heart diseases, and diabetes mellitus. A comprehensive understanding of 1,8-cineole's pharmacodynamics and safety aspects as well as developing effective formulations, might help to leverage its therapeutic value. This thorough review sets the stage for future research on diverse health benefits and potential uses of 1,8-cineole in tackling complex medical conditions.

Murepavadin induces envelope stress response and enhances the killing efficacies of β-lactam antibiotics by impairing the outer membrane integrity of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen that can cause a variety of acute and chronic infections. The bacterium is highly resistant to numerous antibiotics. Murepavadin is a peptidomimetic antibiotic that blocks the function of P. aeruginosa lipopolysaccharide (LPS) transport protein D (LptD), thus inhibiting the insertion of LPS into the outer membrane. In this study, we demonstrated that sublethal concentrations of murepavadin enhance the bacterial outer membrane permeability. Proteomic analyses revealed the alteration of protein composition in bacterial inner and outer membranes following murepavadin treatment. The antisigma factor MucA was upregulated by murepavadin. In addition, the expression of the sigma E factor gene algU and the alginate synthesis gene algD was induced by murepavadin. Deletion of the algU gene reduces bacterial survival following murepavadin treatment, indicating a role of the envelope stress response in bacterial tolerance. We further demonstrated that murepavadin enhances the bactericidal activities of β-lactam antibiotics by promoting drug influx across the outer membrane. In a mouse model of acute pneumonia, the murepavadin-ceftazidime/avibactam combination showed synergistic therapeutic effect against P. aeruginosa infection. In addition, the combination of murepavadin with ceftazidime/avibactam slowed down the resistance development. In conclusion, our results reveal the response mechanism of P. aeruginosa to murepavadin and provide a promising antibiotic combination for the treatment of P. aeruginosa infections.IMPORTANCEThe ever increasing resistance of bacteria to antibiotics poses a serious threat to global public health. Novel antibiotics and treatment strategies are urgently needed. Murepavadin is a novel antibiotic that blocks the assembly of lipopolysaccharide (LPS) into the Pseudomonas aeruginosa outer membrane by inhibiting LPS transport protein D (LptD). Here, we demonstrated that murepavadin impairs bacterial outer membrane integrity, which induces the envelope stress response. We further found that the impaired outer membrane integrity increases the influx of β-lactam antibiotics, resulting in enhanced bactericidal effects. In addition, the combination of murepavadin and a β-lactam/β-lactamase inhibitor mixture (ceftazidime/avibactam) slowed down the resistance development of P. aeruginosa. Overall, this study demonstrates the bacterial response to murepavadin and provides a new combination strategy for effective treatment.

Exploration of Synergistic Pesticidal Activities, Control Effects and Toxicology Study of a Monoterpene Essential Oil with Two Natural Alkaloids

With the increasing development of pest resistances, it is not easy to achieve satisfactory control effects by using only one agrochemical. Additionally, although the alkaloid matrine (MT) isolated from Sophora flavescens is now utilized as a botanical pesticide in China, in fact, its pesticidal activities are much lower in magnitude than those of commercially agrochemicals. To improve its pesticidal activities, here, the joint pesticidal effects of MT with another alkaloid oxymatrine (OMT) (isolated from S. flavescens) and the monoterpene essential oil 1,8-cineole (CN) (isolated from the eucalyptus leaves) were investigated in the laboratory and greenhouse conditions. Moreover, their toxicological properties were also studied. Against Plutella xylostella, when the mass ratio of MT and OMT was 8/2, good larvicidal activity was obtained; against Tetranychus urticae, when the mass ratio of MT and OMT was 3/7, good acaricidal activity was obtained. Especially when MT and OMT were combined with CN, the significant synergistic effects were observed: against P. xylostella, the co-toxicity coefficient (CTC) of MT/OMT (8/2)/CN was 213; against T. urticae, the CTC of MT/OMT (3/7)/CN was 252. Moreover, the activity changes over time of two detoxification enzymes, carboxylesterase (CarE) and glutathione S-transferase (GST) of P. xylostella treated with MT/OMT (8/2)/CN, were observed. In addition, by scanning electron microscope (SEM), the toxicological study suggested that the acaricidal activity of MT/OMT (3/7)/CN may be related to the damage of the cuticle layer crest of T. urticae.

The Interference Mechanism of Basil Essential Oil on the Cell Membrane Barrier and Respiratory Metabolism of Listeria monocytogenes

In order to prevent food-borne diseases caused by Listeria monocytogenes (L. monocytogenes) safely and effectively, plant essential oils that have no toxic side effects and are not prone to drug resistance have become the focus of research. This article takes basil (Ocimum basilicum L.) essential oil (BEO) as the research object and explores its antibacterial mechanism against L. monocytogenes. The site of action was preliminarily determined to provide a theoretical basis for the development of natural antibacterial agents. The results show that BEO has good antibacterial activity against L. monocytogenes. After 8 h of treatment with BEO (1 mg/ml), the number of remaining bacteria reached an undetectable level. Combining spectroscopic analysis techniques (Raman, UV, and fluorescence spectroscopy) and fluorescence microscopy imaging techniques, it was found that BEO increased the disorder of the hydrocarbyl chain of phospholipid tail, which in turn led to increased cell membrane permeability, thereby causing the leakage of intracellular proteins and DNA. Meanwhile, respiratory metabolism experiments showed that BEO inhibited the EMP pathway by inhibiting the activity of key enzymes. From the molecular docking results, this inhibition may be attributed to the hydrophobic interaction between α-bergamotene and the amino acid residues of phosphofructokinase (PFK) and pyruvate kinase (PK). In addition, BEO can also cause oxidative stress, and reactive oxygen species (ROS) may also be related to the damage of cell membranes and enzymes related to respiratory metabolism.

Mechanisms, Anti-Quorum-Sensing Actions, and Clinical Trials of Medicinal Plant Bioactive Compounds against Bacteria: A Comprehensive Review

Bacterial strains have developed an ability to resist antibiotics via numerous mechanisms. Recently, researchers conducted several studies to identify natural bioactive compounds, particularly secondary metabolites of medicinal plants, such as terpenoids, flavonoids, and phenolic acids, as antibacterial agents. These molecules exert several mechanisms of action at different structural, cellular, and molecular levels, which could make them candidates or lead compounds for developing natural antibiotics. Research findings revealed that these bioactive compounds can inhibit the synthesis of DNA and proteins, block oxidative respiration, increase membrane permeability, and decrease membrane integrity. Furthermore, recent investigations showed that some bacterial strains resist these different mechanisms of antibacterial agents. Researchers demonstrated that this resistance to antibiotics is linked to a microbial cell-to-cell communication system called quorum sensing (QS). Consequently, inhibition of QS or quorum quenching is a promising strategy to not only overcome the resistance problems but also to treat infections. In this respect, various bioactive molecules, including terpenoids, flavonoids, and phenolic acids, exhibit numerous anti-QS mechanisms via the inhibition of auto-inducer releases, sequestration of QS-mediated molecules, and deregulation of QS gene expression. However, clinical applications of these molecules have not been fully covered, which limits their use against infectious diseases. Accordingly, the aim of the present work was to discuss the role of the QS system in bacteria and its involvement in virulence and resistance to antibiotics. In addition, the present review summarizes the most recent and relevant literature pertaining to the anti-quorum sensing of secondary metabolites and its relationship to antibacterial activity.

Assessing the Biostimulant Effects of a Novel Plant-Based Formulation on Tomato Crop

The aim of this research was to evaluate the biostimulant effects of an eco-product (EP) containing essential oils of rosemary and eucalyptus on tomato crop. Experiments were conducted to evaluate EP effects on plant growth and physiological parameters (e.g., chlorophyll content), total phenols and antioxidant activity, enzyme activities (e.g., catalase), plant macronutrient content and fresh tomato fruit quality. The application of an EP once (EP-1x) increased tomato plant height by 19%, stomatal conductance, and chlorophyll content compared to the control (sprayed with water). EP triplicate (EP-3x) application significantly increased yield (0.79 kg plant−1) compared to the control (0.58 kg plant−1). However, application of EP-3x was associated with a higher percentage of fruit cracking in comparison to the control. Total phenols and antioxidant activity were affected from both the use of EP and application frequency. EP application decreased by 27.3% the leaf damage index in comparison to the control. Nutrient content in leaves (N, Mg) was significantly decreased in the case of EP-3x treatment. Fruit firmness was decreased by 19.9% in the case of EP-1x application. Fruit marketability and tomato-like aroma, fresh weight and soluble solids did not differ among the treatments. Further research is required to examine the potential use of essential oils as biostimulants.

Authentication, phytochemical characterization and anti-bacterial activity of twoArtemisiaspecies

Artemisia species are aromatic herbs used as food and/or ethnomedicine worldwide; however, the use of these plants is often impeded by misidentification. Here, molecular and chemotaxonomic approaches were combined to assist in the morphology-based authentication of Artemisia species, and Artemisia indica and Artemisia argyi were identified. The plant extracts and compounds obtained from these species, 1,8-cineole, carveol, α-elemene, α-farnesene, methyl linolenate, diisooctyl phthalate inhibited the growth of food-borne harmful bacteria. Mechanistic studies showed that the extract and active compounds of A. indica killed Gram-negative and -positive bacteria via destruction of the bacterial membrane. Finally, in vivo data demonstrated that A. indica protected against bacterial infection in mice as evidenced by survival rate, bacterial load in organs, gut pathology, diarrhea, body weight, food consumption, stool weight, and pathology score. A. indica and its active compounds have potential for use as food supplements for food-borne bacterial diseases and thus improve human health.

The Koala (Phascolarctos cinereus) faecal microbiome differs with diet in a wild population

Background

The diet of the koala (Phascolarctos cinereus) is comprised almost exclusively of foliage from the genus Eucalyptus (family Myrtaceae). Eucalyptus produces a wide variety of potentially toxic plant secondary metabolites which have evolved as chemical defences against herbivory. The koala is classified as an obligate dietary specialist, and although dietary specialisation is rare in mammalian herbivores, it has been found elsewhere to promote a highly-conserved but low-diversity gut microbiome. The gut microbes of dietary specialists have been found sometimes to enhance tolerance of dietary PSMs, facilitating competition-free access to food. Although the koala and its gut microbes have evolved together to utilise a low nutrient, potentially toxic diet, their gut microbiome has not previously been assessed in conjunction with diet quality. Thus, linking the two may provide new insights in to the ability of the koala to extract nutrients and detoxify their potentially toxic diet.

Method

The 16S rRNA gene was used to characterise the composition and diversity of faecal bacterial communities from a wild koala population (n = 32) comprising individuals that predominately eat either one of two different food species, one the strongly preferred and relatively nutritious species Eucalyptus viminalis, the other comprising the less preferred and less digestible species Eucalyptus obliqua.

Results

Alpha diversity indices indicated consistently and significantly lower diversity and richness in koalas eating E. viminalis. Assessment of beta diversity using both weighted and unweighted UniFrac matrices indicated that diet was a strong driver of both microbial community structure, and of microbial presence/absence across the combined koala population and when assessed independently. Further, principal coordinates analysis based on both the weighted and unweighted UniFrac matrices for the combined and separated populations, also revealed a separation linked to diet. During our analysis of the OTU tables we also detected a strong association between microbial community composition and host diet. We found that the phyla Bacteroidetes and Firmicutes were co-dominant in all faecal microbiomes, with Cyanobacteria also co-dominant in some individuals; however, the E. viminalis diet produced communities dominated by the genera Parabacteroides and/or Bacteroides, whereas the E. obliqua-associated diets were dominated by unidentified genera from the family Ruminococcaceae.

Discussion

We show that diet differences, even those caused by differential consumption of the foliage of two species from the same plant genus, can profoundly affect the gut microbiome of a specialist folivorous mammal, even amongst individuals in the same population. We identify key microbiota associated with each diet type and predict functions within the microbial community based on 80 previously identified Parabacteroides and Ruminococcaceae genomes.