In vitro activity of alpha-mangostin in killing and eradicating Staphylococcus epidermidis RP62A biofilms

Thymol as a Novel Plant-Derived Antibacterial Agent for Suppressing Xanthomonas citri pv. malvacearum in Cotton

Xanthomonas citri pv. malvacearum (Xcm) associated with bacterial blight disease is a significant and widespread pathogen affecting cotton worldwide. The excessive use of harmful chemicals to control plant pathogens has exerted a negative impact on environmental safety. Thymol is a monoterpene phenol present in the essential oils of plants belonging to Lamiaceae family. In this study the antimicrobial activity of thymol was evaluated against Xcm. The minimum inhibitory concentration (MIC) and 99.9% bactericidal concentration (MBC) of thymol against Xcm were 2 and 4 mg/mL, respectively. The effect of MIC and MBC of thymol against Xcm was assessed on the Luria-Bertani medium. The effect of thymol on intercellular ATP levels, membrane potential, and motility in Xcm was assessed using fluorescence spectrometry for membrane potential and firefly luciferase-based assay for ATP levels. Thymol ruptured the cellular membrane of Xcm, resulting in decreased intracellular ATP concentrations, intracellular leakage of genetic material, and changes in membrane potential. Scanning electron microscopy images supported the impact of thymol on the cell membrane of Xcm. Moreover, thymol inhibited the swimming motility and biofilm formation of Xcm at concentrations equal to or above the MIC and MBC. In contrast, sub-MIC concentrations of thymol had little to no impact on the virulence of Xcm. In conclusion, thymol demonstrated the potential as a strong bactericidal compound against Xcm.

Can α-Mangostin and Photodynamic Therapy Support Ciprofloxacin in the Inactivation of Uropathogenic Escherichia coli and Staphylococcus aureus Strains?

Multidrug-resistant bacteria represent a significant challenge in the treatment of bacterial infections, often leading to therapeutic failures. This issue underlines the need to develop strategies that improve the efficacy of conventional antibiotic therapies. In this study, we aimed to assess whether a plant-derived compound, α-mangostin, and photodynamic therapy (PDT) could enhance the antibacterial activity of ciprofloxacin against uropathogenic strains of Escherichia coli and Staphylococcus aureus. Using nanopore sequencing technology, we confirmed that the clinical strains tested were classified as multidrug-resistant. Digital holotomography (DHT) was used to examine α-mangostin-induced changes in the bacterial cells' penetration by a photosensitizer. A scanning confocal fluorescence microscope was used to visualize photosensitizer penetration into bacterial cells and validate DHT results. A synergistic effect between α-mangostin and ciprofloxacin was observed exclusively in S. aureus strains, while no enhancement of ciprofloxacin's antibacterial activity was detected in E. coli strains when combined with α-mangostin. Notably, photodynamic therapy significantly potentiated the antibacterial effects of ciprofloxacin and its combination with α-mangostin compared to untreated controls. In addition, morphological changes were observed in bacterial cells exposed to these antimicrobials. In conclusion, our findings suggest that α-mangostin and PDT may serve as valuable adjuncts to ciprofloxacin, improving the eradication of uropathogens.

Screening novel antiviral compounds to treat Clostridioides difficile infections

Clostridioides difficile is a major cause of nosocomial infections, often associated with individuals who have gut dysbiosis from previous antibiotic therapies. C. difficile infections (CDI) have a high recurrence rate and impose significant financial and mortality burdens on the healthcare system. Therefore, novel anti-C. difficile drugs are urgently needed to treat and reduce the severity and recurrence of infection. In this study, we screened a library of 618 antiviral drugs to identify a potential candidate for repurposing as novel anti-C. difficile therapeutics. Following our preliminary screening, we identified 9 novel compounds that inhibited C. difficile at a concentration of 16 μM or lower. Among these, 4 antiviral compounds demonstrated the most potent anti-C. difficile activity against a panel of 15 C. difficile isolates, with minimum inhibitory concentrations (MICs) comparable to the drug of choice, vancomycin. These include rottlerin (MIC50 = 0.25 μg/mL), α-mangostin (MIC50 = 1 μg/mL), dryocrassin ABBA (MIC50 = 1 μg/mL), and obefazimod (MIC50 = 4 μg/mL). All exhibited minimal to no activity against representative members of the human gut microbiota. Interestingly, α-mangostin, a natural xanthone derived from the mangosteen fruit, exhibited strong bactericidal action, clearing a high inoculum of C. difficile in less than an hour. All other drugs exhibited bacteriostatic activity. Given their characteristics, these compounds show great promise as novel treatments for CDI.

Naturally Occurring Xanthones; Biological Activities, Chemical Profiles and In Silico Drug Discovery

Xanthones are widely distributed polyphenols, present commonly in higher plants; Garcinia, Calophyllum, Hypericum, Platonia, Mangifera, Gentiana and Swertia. Xanthone tricyclic scaffold is able to interact with different biological targets, showing antibacterial and cytotoxic effects, as well as potent effects against osteoarthritis, malaria, and cardiovascular diseases. Thus, in this article we focused on pharmacological effects, applications and preclinical studies with the recent updates of xanthon´s isolated compounds from 2017-2020. We found that only α-mangostin, gambogic acid, and mangiferin, have been subjected to preclinical studies with particular emphasis on the development of anticancer, diabetes, antimicrobial and hepatoprotective therapeutics. Molecular docking calculations were performed to predict the binding affinities of xanthone-derived compounds against SARS-CoV-2 M^pro. According to the results, cratoxanthone E and morellic acid demonstrated promising binding affinities towards SARS-CoV-2 M^pro with docking scores of -11.2 and -11.0 kcal/mol, respectively. Binding features manifested the capability of cratoxanthone E and morellic acid to exhibit nine and five hydrogen bonds, respectively, with the key amino acids of the M^pro active site. In conclusion, cratoxanthone E and morellic acid are promising anti-COVID-19 drug candidates that warrant further detailed in vivo experimental estimation and clinical assessment.

Attenuation of biofilm and quorum sensing regulated virulence factors of an opportunistic pathogen Pseudomonas aeruginosa by phytofabricated silver nanoparticles

Green-synthesized nanoparticles provide an effective strategy for inhibiting microbial pathogenesis by affecting biofilm formation, quorum sensing (QS), and other surface properties of microorganisms. QS is a density-dependent communication signaling cascade that regulates biofilm formation and other pathogenic factors of Pseudomonas aeruginosa. In this context, the effect of phytofabricated silver nanoparticles (CC-AgNPs) synthesized using Cuphea carthagenensis extract on biofilm, QS, and QS-dependent virulence factors of P. aeruginosa were evaluated in this study. CC-AgNPs demonstrated significant attenuation of biofilm, QS, and QS-dependent virulence factors at sub-MICs. A significant inhibition of 88.39 ± 4.32 %, 79.64 ± 3.31 %, 73.07 ± 3.0 %, and 61.67 ± 1.5 % of biofilm formation, quorum sensing, pyocyanin, and LasB elastase, respectively was reported in the study at 20 μg/mL. The study also demonstrated a significant reduction of LasA Staphylolytic activity and 91.37 ± 1.05 % exoprotease production in comparison to untreated control. The lower concentrations of CC-AgNPs also demonstrated significant attenuation of biofilm and other virulence factors suggesting the strong potency of NPs against P. aeruginosa. XTT analysis reported the effect of CC-AgNPs on sessile cells of P. aeruginosa without impacting growth of planktonic cells at sub-MICs. Cell-proliferation study in human cell lines (HEK 293 and Caco-2 cells) demonstrated the safe nature of CC-AgNPs at tested concentrations. This study is novel in a way that environmentally friendly CC-AgNPs were used to inhibit QS at sub-MICs without killing the tested strains, therefore, could be developed as an anti-virulent drug to overcome biofilm and antimicrobial resistance problems.

Antibacterial activity of 2-hydroxy-4-methoxybenzaldehyde and its possible mechanism against Staphylococcus aureus

AIM

Staphylococcus aureus causes several complicated infections. Despite decades of research on developing new antimicrobials, methicillin-resistant S. aureus (MRSA) remains a global health problem. Hence, there is a dire need to identify potent natural antibacterial compounds as an alternative to antimicrobials. In this light, the present work divulges the antibacterial efficacy and the action mechanism of 2-hydroxy-4-methoxybenzaldehyde (HMB) isolated from Hemidesmus indicus against S. aureus.

METHODS AND RESULTS

Antimicrobial activity of HMB was assessed. HMB exhibited 1024 µg ml-1 as the minimum inhibitory concentration (MIC) and 2 × MIC as the minimum bactericidal concentration against S. aureus. The results were validated by spot assay, time kill, and growth curve analysis. In addition, HMB treatment increased the release of intracellular proteins and nucleic acid contents from MRSA. Additional experiments assessing the structural morphology of bacterial cells using SEM analysis, β-galactosidase enzyme activity, and the fluorescence intensities of propidium iodide and rhodamine123 dye divulged that the cell membrane as one of the targets of HMB to hinder S. aureus growth. Moreover, the mature biofilm eradication assay revealed that HMB dislodged nearly 80% of the preformed biofilms of MRSA at the tested concentrations. Further, HMB treatment was found to sensitize MRSA cells upon combining tetracycline treatment.

CONCLUSIONS

The present study suggests that HMB is a promising compound with antibacterial and antibiofilm activities and could act as a lead structure for developing new antibacterial drugs against MRSA.

Antimicrobial activity of α-mangostin against Staphylococcus species from companion animals in vitro and therapeutic potential of α-mangostin in skin diseases caused by S. pseudintermedius

Antimicrobial resistance in Staphylococcus species from companion animals is becoming increasingly prevalent worldwide. S. pseudintermedius is a leading cause of skin infections in companion animals. α-mangostin (α-MG) exhibits various pharmacological activities, including antimicrobial activity against G (+) bacteria. This study investigated the antimicrobial activity of α-MG against clinical isolates of Staphylococcus species from companion animals and assessed the therapeutic potential of α-MG in skin diseases induced by S. pseudintermedius in a murine model. Furthermore, the action mechanisms of α-MG against S. pseudintermedius were investigated. α-MG exhibited antimicrobial activity against clinical isolates of five different Staphylococcus species from skin diseases of companion animals in vitro, but not G (-) bacteria. α-MG specifically interacted with the major histocompatibility complex II analogous protein (MAP) domain-containing protein located in the cytoplasmic membrane of S. pseudintermedius via hydroxyl groups at C-3 and C-6. Pretreatment of S. pseudintermedius with anti-MAP domain-containing protein polyclonal serum significantly reduced the antimicrobial activity of α-MG. The sub-minimum inhibitory concentration of α-MG differentially regulated 194 genes, especially metabolic pathway and virulence determinants, in S. pseudintermedius. α-MG in pluronic lecithin organogel significantly reduced the bacterial number, partially restored the epidermal barrier, and suppressed the expression of cytokine genes associated with pro-inflammatory, Th1, Th2, and Th17 in skin lesions induced by S. pseudintermedius in a murine model. Thus, α-MG is a potential therapeutic candidate for treating skin diseases caused by Staphylococcus species in companion animals.

Antibacterial and Antibiofilm Activity of Different Species of Fabiana sp. Extract Obtained via Maceration and Ultrasound-Assisted Extraction against Staphylococcus epidermidis

Staphylococcus epidermidis is an opportunistic pathogen that, under certain conditions, can induce aggravated infectious processes, mainly in immunosuppressed patients. Moreover, S. epidermidis is one of the leading causes of medical device- and implant-associated infections and is also recognized as a canonical biofilm producer. Fabiana punensis, F. densa and F. patagonica are three medicinal plants that grow in arid environments in Argentina (Altoandina, Puna, Prepuna and Monte regions). In this work, we studied the antimicrobial activity of alcoholic extracts of these plant species obtained via maceration (M) and ultrasound-assisted extraction (UAE) against S. epidermidis. In addition, the antibiofilm activity of the F. densa extract was also evaluated. It was found that the extracts obtained via M did not present differences with those obtained via UAE regarding the chemical profile. F. densa showed the lowest minimum inhibitory concentration (MIC) value (75 µg GAE/mL). At concentrations higher than the MIC, the extract induced the release of cellular constituents. At the concentration of 1/8× MIC, the extract inhibited biofilm formation by 78%, reducing metabolic activity by 67%. On the other hand, it presented a low percentage of preformed biofilm removal. In all assays, gallic acid (GA) has been used as a reference antimicrobial compound. Finally, it was shown via microscopy visualization that the extract reduces adhesion to hydrophobic and hydrophilic surfaces. Thus, F. densa extracts could potentially be used for the antibiotic treatment of infections produced by S. epidermidis or as an inhibitor agent of production biofilm, avoiding infections caused by medical devices.

The action of phytochemicals in biofilm control

Covering: 2009 to 2021Antimicrobial resistance is now rising to dangerously high levels in all parts of the world, threatening the treatment of an ever-increasing range of infectious diseases. This has becoming a serious public health problem, especially due to the emergence of multidrug-resistance among clinically important bacterial species and their ability to form biofilms. In addition, current anti-infective therapies have low efficacy in the treatment of biofilm-related infections, leading to recurrence, chronicity, and increased morbidity and mortality. Therefore, it is necessary to search for innovative strategies/antibacterial agents capable of overcoming the limitations of conventional antibiotics. Natural compounds, in particular those obtained from plants, have been exhibiting promising properties in this field. Plant secondary metabolites (phytochemicals) can act as antibiofilm agents through different mechanisms of action from the available antibiotics (inhibition of quorum-sensing, motility, adhesion, and reactive oxygen species production, among others). The combination of different phytochemicals and antibiotics have revealed synergistic or additive effects in biofilm control. This review aims to bring together the most relevant reports on the antibiofilm properties of phytochemicals, as well as insights into their structure and mechanistic action against bacterial pathogens, spanning December 2008 to December 2021.

Formulation and Characterization of a Novel Palm-Oil-Based α-Mangostin Nano-Emulsion (PO-AMNE) as an Antimicrobial Endodontic Irrigant: An In Vitro Study

Aim: To formulate and characterize a palm-oil-in-water-based α-Mangostin nano-emulsion (PO-AMNE) endodontic irrigant, in order to evaluate its antibacterial efficacy against Enterococcus faecalis, Staphylococcus epidermidis, and Candida albicans biofilms, as well as its capacity to remove smear layer. Methods: The solubility of α-Mangostin in various oils was determined and selected, surfactants and co-surfactants were used for the nano-emulsion trial. PO-AMNE was prepared and optimized. The MIC was performed, and the antimicrobial efficacy was estimated against biofilms. The optimized 0.2% PO-AMNE irrigant antimicrobial efficacy in a tooth model was done using colony-forming units. The treated teeth were processed by scanning electron microscopic examination for debris and smear layer removal. An Alamar Blue assay was used to evaluate cell viability. The optimization of the PO-AMNE irrigant was performed using Box–Behnken statistical design. Results: The optimized 0.2% PO-AMNE irrigant was found to have a particle size of 340.9 nm with 0.246 PDI of the dispersed droplets, and a zeta potential (mV) of −27.2 ± 0.7 mV. The MIC values showed that 0.2% PO-AMNE (1.22 ± 0.02) were comparable to 2% CHX (1.33 ± 0.01), and 3.25% NaOCl (2.2 ± 0.09) had the least inhibition for E. faecalis. NaOCl (3.25%) showed the maximum inhibition of S. epidermidis (0.26 ± 0.05), whereas 0.2% PO-AMNE (1.25 ± 0.0) was comparable to 2% CHX (1.86 ± 0.07). For C. albicans, 2% CHX (8.12 ± 0.12) showed the least inhibition as compared to 0.2% PO-AMNE (1.23 ± 0.02) and 3.25% NaOCl (0.59 ± 0.02). The 0.2% PO-AMNE irrigant was then evaluated for its antimicrobial efficacy against the three biofilms, using colony-forming units. The 0.2% PO-AMNE was comparable to both 3.25% NaOCl and 2% CHX in inhibiting the growth of biofilms. The 0.2% PO-AMNE and 17% EDTA eliminated the smear layer with the lowest mean scores (p < 0.001). Finally, 0.2% PO-AMNE was shown to be biocompatible when compared to 17% EDTA, 3.25% NaOCl, and 2% CHX in immortalized oral keratinocyte cells. Conclusion: Overall, the formulated 0.2% PO-AMNE irrigant was an effective antimicrobial and biocompatible which could combat endodontic-infection-related polymicrobial biofilms.

Formulation optimization of sterilized xanthones-loaded nanoemulgels and evaluation of their wound healing activities

Xanthones (XTs) are bioactive compounds found in mangosteen trees (Garcinia mangostana Linn.). They are used as an active ingredient in various health products. However, there is a lack of data of their application in wound healing. In particular, the topical products of XTs for wound healing; they should be sterilized to minimize the risks of wound infection from contaminated microorganisms. This study thus aimed to optimize the formulation of sterilized XTs-loaded nanoemulgel (XTs-NE-G) and to investigate their wound healing activities. The XTs-NE-Gs were prepared by mixing various gels containing sodium alginate (Alg) and Pluronic F127 (F127) into a XTs-nanoemulsion (NE) concentrate according to the face-centered central composite design. The results showed that the optimized XTs-NE-G was A5-F3 containing 5% w/w Alg and 3% w/w F127. It enhanced the proliferation-, migration rates of skin fibroblasts (HFF-1 cells) with an optimal viscosity. After blending the XTs-NE concentrate and the gel that was previously sterilized by a membrane filtration and an autoclaving technique, respectively, the sterilized A5-F3 was obtained. The sterilized A5-F3 still had effective bioactivities towards the HFF-1 cells. It promoted re-epithelialization, collagen deposition and inflammation suppression in the mice' wounds. It could thus be accepted for further investigation in clinical studies.

N-Containing α-Mangostin Analogs via Smiles Rearrangement as the Promising Cytotoxic, Antitrypanosomal, and SARS-CoV-2 Main Protease Inhibitory Agents

New N-containing xanthone analogs of α-mangostin were synthesized via one-pot Smiles rearrangement. Using cesium carbonate in the presence of 2-chloroacetamide and catalytic potassium iodide, α-mangostin (1) was subsequently transformed in three steps to provide ether 2, amide 3, and amine 4 in good yields at an optimum ratio of 1:3:3, respectively. The evaluation of the biological activities of α-mangostin and analogs 2-4 was described. Amine 4 showed promising cytotoxicity against the non-small-cell lung cancer H460 cell line fourfold more potent than that of cisplatin. Both compounds 3 and 4 possessed antitrypanosomal properties against Trypanosoma brucei rhodesiense at a potency threefold stronger than that of α-mangostin. Furthermore, ether 2 gave potent SARS-CoV-2 main protease inhibition by suppressing 3-chymotrypsinlike protease (3CL^pro) activity approximately threefold better than that of 1. Fragment molecular orbital method (FMO-RIMP2/PCM) indicated the improved binding interaction of 2 in the 3CL^pro active site regarding an additional ether moiety. Thus, the series of N-containing α-mangostin analogs prospectively enhance druglike properties based on isosteric replacement and would be further studied as potential biotically active chemical entries, particularly for anti-lung-cancer, antitrypanosomal, and anti-SARS-CoV-2 main protease applications.

A review of stingless bees' bioactivity in different parts of the world

Stingless bees, also known as meliponines, live in beehives. However, reports on the distribution of stingless bees are scattered, resulting in a lack of precision. Honey and propolis are the main components that can be harvested from their beehive, with a great commercial value of up to 610 million USD. Despite the enormous potential profits, discrepancies in their bioactivities have been observed worldwide, leading to a lack of confidence. Therefore, this review provided oversight on the potential of stingless bee products and highlighted the differences between stingless bees in Asia, Australia, Africa, and America. The bioactivity of stingless bee products is diverse and exhibits great potential as an antimicrobial agent or in various diseases such as diabetes, cardiovascular disease, cancers, and oral problems.

Anti-biofilm activity of caffeine against uropathogenic E. coli is mediated by curli biogenesis

Biofilms are assemblages of sessile microorganisms that form an extracellular matrix around themselves and mediate attachment to surfaces. The major component of the extracellular matrix of Uropathogenic E. coli and other Enterobacteriaceae are curli fibers, making biofilms robust and resistant to antimicrobials. It is therefore imperative to screen antibiofilm compounds that can impair biofilm formation. In the present study, we investigated the curli-dependent antibiofilm activity of caffeine against UPEC strain CFT073 and commensal strain E. coli K-12MG1655.Caffeine significantly reduced the biofilm formation of both UPEC and E. coli K-12 by 86.58% and 91.80% respectively at 48 mM caffeine as determined by Crystal Violet assay. These results were further confirmed by fluorescence microscopy and Scanning Electron Microscope (SEM). Caffeine significantly reduced the cytotoxicity and survivability of UPEC. Molecular docking analysis revealed a strong interaction between caffeine and curli regulator protein (Csg D) of E. coli. The qRT-PCR data also showed significant downregulation in the expression of CsgBA and the CsgDEFG operon at both 24 mM and 48 mM caffeine. The findings revealed that caffeine could inhibit E. coli biofilm formation by regulating curli assembly and thus may be used as an alternative therapeutic strategy for the treatment of chronic E. coli biofilm-related infections.

Nanogels as Potential Delivery Vehicles in Improving the Therapeutic Efficacy of Phytopharmaceuticals

Nanogel is a promising drug delivery approach to improve the pharmacokinetics and pharmacodynamic prospect of phytopharmaceuticals. In the present review, phytopharmaceuticals with astonishing therapeutic utilities are being explored. However, their in vivo delivery is challenging, owing to poor biopharmaceutical attributes that impact their drug release profile, skin penetration, and the reach of optimal therapeutic concentrations to the target site. Nanogel and its advanced version in the form of nanoemulgel (oil-in-water nanoemulsion integrated gel matrix) offer better therapeutic prospects than other conventional counterparts for improving the biopharmaceutical attributes and thus therapeutic efficacy of phytopharmaceuticals. Nanoemulgel-loaded phytopharmaceuticals could substantially improve permeation behavior across skin barriers, subsequently enhancing the delivery and therapeutic effectiveness of the bioactive compound. Furthermore, the thixotropic characteristics of polymeric hydrogel utilized in the fabrication of nanogel/nanoemulgel-based drug delivery systems have also imparted improvements in the biopharmaceutical attributes of loaded phytopharmaceuticals. This formulation approach is about to be rife in the coming decades. Thus, the current review throws light on the recent studies demonstrating the role of nanogels in enhancing the delivery of bioactive compounds for treating various disease conditions and the challenges faced in their clinical translation.

The metabolic and molecular mechanisms of α‑mangostin in cardiometabolic disorders (Review)

α‑mangostin is a xanthone predominantly encountered in Garcinia mangostana. Extensive research has been carried out concerning the effects of this compound on various diseases, including obesity, cancer and metabolic disorders. The present review suggests that α‑mangostin exerts promising anti‑obesity, hepatoprotective, antidiabetic, cardioprotective, antioxidant and anti‑inflammatory effects on various pathways in cardiometabolic diseases. The anti‑obesity effects of α‑mangostin include the reduction of body weight and adipose tissue size, the increase in fatty acid oxidation, the activation of hepatic AMP‑activated protein kinase and Sirtuin‑1, and the reduction of peroxisome proliferator‑activated receptor γ expression. Hepatoprotective effects have been revealed, due to reduced fibrosis through transforming growth factor‑β 1 pathways, reduced apoptosis and steatosis through reduced sterol regulatory‑element binding proteins expression. The antidiabetic effects include decreased fasting blood glucose levels, improved insulin sensitivity and the increased expression of GLUT transporters in various tissues. Cardioprotection is exhibited through the restoration of cardiac functions and structure, improved mitochondrial functions, the promotion of M2 macrophage populations, reduced endothelial and cardiomyocyte apoptosis and fibrosis, and reduced acid sphingomyelinase activity and ceramide depositions. The antioxidant effects of α‑mangostin are mainly related to the modulation of antioxidant enzymes, the reduction of oxidative stress markers, the reduction of oxidative damage through a reduction in Sirtuin 3 expression mediated by phosphoinositide 3‑kinase/protein kinase B/peroxisome proliferator‑activated receptor‑γ coactivator‑1α signaling pathways, and to the increase in Nuclear factor‑erythroid factor 2‑related factor 2 and heme oxygenase‑1 expression levels. The anti‑inflammatory effects of α‑mangostin include its modulation of nuclear factor‑κB related pathways, the suppression of mitogen‑activated protein kinase activation, increased macrophage polarization to M2, reduced inflammasome occurrence, increased Sirtuin 1 and 3 expression, the reduced expression of inducible nitric oxide synthase, the production of nitric oxide and prostaglandin E2, the reduced expression of Toll‑like receptors and reduced proinflammatory cytokine levels. These effects demonstrate that α‑mangostin may possess the properties required for a suitable candidate compound for the management of cardiometabolic diseases.

The Potential of α-Mangostin from Garcinia mangostana as an Effective Antimicrobial Agent-A Systematic Review and Meta-Analysis

This systematic review aims to evaluate the antimicrobial activity of α-mangostin derived from Garcinia mangostana against different microbes. A literature search was performed using PubMed and Science Direct until March 2022. The research question was developed based on a PICO (Population, Intervention, Control and Outcomes) model. In this study, the population of interest was microbes, α-mangostin extracted from Garcinia mangostana was used as exposure while antibiotics were used as control, followed by the outcome which is determined by the antimicrobial activity of α-mangostin against studied microbes. Two reviewers independently performed the comprehensive literature search following the predetermined inclusion and exclusion criteria. A methodological quality assessment was carried out using a scoring protocol and the risk of bias in the studies was analyzed. Reward screening was performed among the selected articles to perform a meta-analysis based on the pre-determined criteria. Case groups where α-mangostin extracted from Garcinia mangostana was incorporated were compared to groups using different antibiotics or antiseptic agents (control) to evaluate their effectiveness. A total of 30 studies were included; they were heterogeneous in their study design and the risk of bias was moderate. The results showed a reduction in microbial counts after the incorporation of α-mangostin, which resulted in better disinfection and effectiveness against multiple microbes. Additionally, the meta-analysis result revealed no significant difference (p > 0.05) in their effectiveness when α-mangostin was compared to commercially available antibiotics. α-mangostin worked effectively against the tested microbes and was shown to have inhibitory effects on microbes with antibiotic resistance.

Effect of alpha-mangostin in the prevention of behavioural and neurochemical defects in methylmercury-induced neurotoxicity in experimental rats

Methylmercury (MeHg+) is a known neurotoxin that causes progressive motor neuron degeneration in the central nervous system. Axonal degeneration, oligodendrocyte degeneration, and myelin basic protein (MBP) deficits are among the neuropathological abnormalities caused by MeHg+ in amyotrophic lateral sclerosis (ALS). This results in demyelination and motor neuron death in both humans and animals. Previous experimental studies have confirmed that overexpression of the extracellular signalling regulated kinase (ERK1/2) signalling contributes to glutamate excitotoxicity, inflammatory response of microglial cells, and oligodendrocyte (OL) dysfunction that promotes myelin loss. Alpha-mangostin (AMG), an active ingredient obtained from the tree "Garcinia mangostana Linn," has been used in experimental animals to treat a variety of brain disorders, including Parkinson's and Huntington's disease memory impairment, Alzheimer's disease, and schizophrenia, including Parkinson's disease and Huntington's disease memory impairment, Alzheimer's disease, and schizophrenia. AMG has traditionally been used as an antioxidant, anti-inflammatory, and neuroprotective agent.Accordingly, we investigated the therapeutic potential of AMG (100 and 200 mg/kg) in experimental rats with methylmercury (MeHg+)-induced neurotoxicity. The neuroprotective effect of AMG on behavioural, cellular, molecular, and other gross pathological changes, such as histopathological alterations in MeHg+ -treated rat brains, is presented. The neurological behaviour of experimental rats was evaluated using a Morris water maze (MWM), open field test (OFT), grip strength test (GST), and force swim test (FST). In addition, we investigate AMG's neuroprotective effect by restoring MBP levels in cerebral spinal fluid and whole rat brain homogenate. The apoptotic, pro-inflammatory, and oxidative stress markers were measured in rat blood plasma samples and brain homogenate. According to the findings of this study, AMG decreases ERK-1/2 levels and modulates neurochemical alterations in rat brains, minimising MeHg+ -induced neurotoxicity.

Modulatory Effects of Alpha-Mangostin Mediated by SIRT1/3-FOXO3a Pathway in Oxidative Stress-Induced Neuronal Cells

Background

alpha-Mangostin, a polyphenolic xanthone, is primarily found in the pericarp of mangosteen throughout Southeast Asia and is considered as the “Queen of Fruit” in Thailand. Nonetheless, it is not clarified how alpha-mangostin protects neuronal cells against oxidative stress.

Objective

In this study, molecular mechanisms underlying the neuroprotective effect of alpha-mangostin in defending hydrogen peroxide (H2O2)-induced neurotoxicity was explored.

Methods

cytotoxicity, reactive oxygen species (ROS) generation, apoptotic cascades, and protein expression profiles were performed incorporation of molecular docking.

Results

Human SH-SY5Y cells were pretreated with 1 μM alpha-mangostin for 3 h prior to exposure to 400 μM H2O2. alpha-Mangostin significantly inhibited oxidative stress-induced cell death in neuronal cells by reducing BAX protein, decreasing caspase-3/7 activation, and increasing anti-apoptotic BCL-2 protein. Collectively, alpha-mangostin was demonstrated to be a prominent ROS suppressor which reversed the reduction of antioxidant enzymes (CAT and SOD2). Surprisingly, alpha-mangostin significantly promoted the expression of the sirtuin family and the FOXO3a transcription factor exerting beneficial effects on cell survival and longevity. A molecular docking study predicted that alpha-mangostin is directly bound to the active site of SIRT1.

Conclusion

Findings from this study suggest that alpha-mangostin potentially serves as a promising therapeutic compound against oxidative stress by activation of the SIRT1/3-FOXO3a pathway comparable to the effect of memantine, an anti-AD drug used for the treatment of moderate to severe dementia.

Plant-derived nanotherapeutic systems to counter the overgrowing threat of resistant microbes and biofilms

Since antiquity, the survival of human civilization has always been threatened by the microbial infections. An alarming surge in the resistant microbial strains against the conventional drugs is quite evident in the preceding years. Furthermore, failure of currently available regimens of antibiotics has been highlighted by the emerging threat of biofilms in the community and hospital settings. Biofilms are complex dynamic composites rich in extracellular polysaccharides and DNA, supporting plethora of symbiotic microbial life forms, that can grow on both living and non-living surfaces. These enforced structures are impervious to the drugs and lead to spread of recurrent and non-treatable infections. There is a strong realization among the scientists and healthcare providers to work out alternative strategies to combat the issue of drug resistance and biofilms. Plants are a traditional but rich source of effective antimicrobials with wider spectrum due to presence of multiple constituents in perfect synergy. Other than the biocompatibility and the safety profile, these phytochemicals have been repeatedly proven to overcome the non-responsiveness of resistant microbes and films via multiple pathways such as blocking the efflux pumps, better penetration across the cell membranes or biofilms, and anti-adhesive properties. However, the unfavorable physicochemical attributes and stability issues of these phytochemicals have hampered their commercialization. These issues of the phytochemicals can be solved by designing suitably constructed nanoscaled structures. Nanosized systems can not only improve the physicochemical features of the encapsulated payloads but can also enhance their pharmacokinetic and therapeutic profile. This review encompasses why and how various types of phytochemicals and their nanosized preparations counter the microbial resistance and the biofouling. We believe that phytochemical in tandem with nanotechnological innovations can be employed to defeat the microbial resistance and biofilms. This review will help in better understanding of the challenges associated with developing such platforms and their future prospects.

The Protective Effects of α-Mangostin Attenuate Sodium Iodate-Induced Cytotoxicity and Oxidative Injury via Mediating SIRT-3 Inactivation via the PI3K/AKT/PGC-1α Pathway

It is well known that age-related macular degeneration (AMD) is an irreversible neurodegenerative disease that can cause blindness in the elderly. Oxidative stress-induced retinal pigment epithelial (RPE) cell damage is a part of the pathogenesis of AMD. In this study, we evaluated the protective effect and mechanisms of alpha-mangostin (α-mangostin, α-MG) against NaIO3-induced reactive oxygen species (ROS)-dependent toxicity, which activates apoptosis in vivo and in vitro. MTT assay and flow cytometry demonstrated that the pretreatment of ARPE-19 cells with α-MG (0, 3.75, 7.5, and 15 μM) significantly increased cell viability and reduced apoptosis from NaIO3-induced oxidative stress in a concentration-dependent manner, which was achieved by the inhibition of Bax, cleaved PARP-1, cleaved caspase-3 protein expression, and enhancement of Bcl-2 protein. Furthermore, pre-incubation of ARPE-19 cells with α-MG markedly inhibited the intracellular ROS and extracellular H2O2 generation via blocking of the abnormal enzyme activities of superoxide dismutase (SOD), the downregulated levels of catalase (CAT), and the endogenous antioxidant, glutathione (GSH), which were regulated by decreasing PI3K-AKT-PGC-1α-STRT-3 signaling in ARPE-19 cells. In addition, our in vivo results indicated that α-MG improved retinal deformation and increased the thickness of both the outer nuclear layer and inner nuclear layer by inhibiting the expression of cleaved caspase-3 protein. Taken together, our results suggest that α-MG effectively protects human ARPE-19 cells from NaIO3-induced oxidative damage via antiapoptotic and antioxidant effects.

Bacitracin-Ag Nanoclusters as a Novel Antibacterial Agent Combats Shigella flexneri by Disrupting Cell Membrane and Inhibiting Biofilm Formation

A novel nanomaterial Bacitracin-Ag Nanoclusters (Bacitracin-AgNCs) was formed to achieve a better antibacterial effect on Shigella flexneri which poses a serious threat to human health. In the current study, X-ray photoelectron spectrometer (XPS), Fourier transform infrared (FTIR), field-emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HR-TEM) and thermal gravimetric analysis (TGA) were used to characterize the properties of composited Bacitracin-AgNCs. Furthermore, the inhibitory effects of Bacitracin-AgNCs against S. flexneri were explored, and the inhibition mechanism was discussed in terms of its aspects of cell membrane ravage, ATPase activity decline and biofilm inhibition. The results reveal that the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Bacitracin-AgNCs against S. flexneri were 0.03 mg/mL and 4 mg/mL. Bacitracin-AgNCs may cause irreversible impairment to cells and greatly change the cell morphology. The cell membrane integrity of S. flexneri was destroyed with changes in the characteristics of membrane permeability and intracellular substances leakage. Moreover, our study further proved that Bacitracin-AgNCs significantly inhibited the formation of S. flexneri biofilms and reduced the number of viable bacteria in biofilm. These findings provide a potential method for the exploitation of organic composite nanomaterials as a novel antimicrobial agent and its application in the food industry.

The diverse bioactivity of α-mangostin and its therapeutic implications

α-Mangostin is a xanthone natural product isolated as a secondary metabolite from the mangosteen tree. It has attracted a great deal of attention due to its wide-ranging effects on certain biological activity, such as apoptosis, tumorigenesis, proliferation, metastasis, inflammation, oxidation, bacterial growth and metabolism. This review focuses on the key pathways directly affected by α-mangostin and how this varies between disease states. Insight is also provided, where investigated, into the key structural features of α-mangostin that produce these biological effects. The review then sheds light on the utility of α-mangostin as a investigational tool for certain diseases and demonstrate how future derivatives may increase selectivity and potency for specific disease states.

Inhibition of biofilm formation by alpha-mangostin loaded nanoparticles against Staphylococcus aureus

This study aimed to investigate the antibiofilm activity of alpha-mangostin (AMG) loaded nanoparticles (nanoAMG) against Staphylococcus aureus, including the methicillin-resistant strain MRSA252. The results indicated that treatment with 24 μmol/L nanoAMG inhibited the formation of biofilm biomass by 53-62%, compared to 40-44% for free AMG (p < 0.05). At 48 μmol/L, biofilms in all nanoAMG treated samples were nearly fully disrupted for the two tested strains, MRSA252 and the methicillin-sensitive strain NCTC6571. That concentration resulted in killing of biofilm cells. A lower concentration of 12 µmol/L nanoAMG inhibited initial adherence of the two bacterial strains by > 50%. In contrast, activity of nanoAMG was limited on preformed mature biofilms, which at a concentration of 48 µmol/L were reduced only by 27% and 22% for NCTC6571 and MRSA252, respectively. The effects of AMG or nanoAMG on the expression of biofilm-related genes showed some noticeable differences between the two strains. For instance, the expression level of ebpS was downregulated in MRSA252 and upregulated in NCTC6571 when those strains were treated with either AMG or nanoAMG. In contrast, the expression of fnbB was down regulated in NCTC6571, while it was up-regulated in the MRSA252. The expression of other biofilm-related genes (icaC, clfB and fnbA) was down regulated in both strains. In conclusion, our results suggest that AMG coated nanoparticles had enhanced biological activity as compared to free AMG, indicating that nanoAMG could be a new and promising inhibitor of biofilm formation to tackle S. aureus, including strains that are resistant to multiple antibiotics.

Neuroprotective Effect of α-Mangostin in the Ameliorating Propionic Acid-Induced Experimental Model of Autism in Wistar Rats

Several studies have documented the role of hyper-activation of extracellular signal-regulated kinases (ERK) in Autism pathogenesis. Alpha-mangostin (AMG) is a phytoconstituents with anti-oxidants, anti-inflammatory, and ERK inhibition properties in many diseases. Our research aims to investigate the neuroprotective effect of AMG in the rat model of intracerebroventricular-propionic acid (ICV-PPA) induced autism with a confirmation of its effect on the ERK signaling. Autism was induced in Wistar rats (total 36 rats; 18 male/18 female) by multiple doses of PPA through ICV injection for 11 days. Actophotometer and beam walking tasks were used to evaluate animals' motor abilities, and the Morris water maze task was utilized to confirm the cognition and memory in animals. Long term administration of AMG 100 mg/kg and AMG 200mg/kg continued from day 12 to day 44 of the experiment. Before that, animals were sacrificed, brains isolated, morphological, gross pathological studies were performed, and neurochemical analysis was performed in the brain homogenates. Cellular and molecular markers, including ERK, myelin basic protein, apoptotic markers including caspase-3, Bax, Bcl-2, neuroinflammatory markers, neurotransmitters, and oxidative stress markers, have been tested throughout the brain. Thus, AMG reduces the overactivation of the ERK signaling and also restored autism-like behavioral and neurochemical alterations.

Liposome encapsulated surfactant abetted copper nanoparticles alleviates biofilm mediated virulence in pathogenic Pseudomonas aeruginosa and MRSA

In the present study lipopeptide biosurfactant with high emulsification capacity produced by human skin bacterium Paenibacillus thiaminolyticus was purified and subjected to FTIR and NMR spectral analysis which gave evidence of the active characteristics of the surfactant. To augment the antivirulent potential further, the mixer of copper and copper oxide nanoparticles (CuNPs) was synthesized, and characterized by UV–Visible spectroscopy, SEM-EDAX, TEM, and Zeta analysis. Here, we attempted to enhance the antimicrobial and antibiofilm activity with the assistance of encapsulated preparation of lipopeptide and CuNPs in multilamellar liposomes. The proposed mechanism of action of lipopeptide and CuNPs liposomal preparation negatively influences the cell metabolism, secreted virulence such as staphyloxanthin, pyocyanin, and extracellular polysaccharides. The significant decline in the growth of MRSA and P. aeruginosa in both planktonic form and biofilm by lipopeptide and CuNPs treatment were visualized using scanning electron microscopy and High content screening imaging system. In vivo studies revealed that treatment with lipopeptide and CuNPs in multilamellar liposomes extended the lifespan of infected Caenorhabditis elegans by about 75%. Therefore, this study typifies lipopeptide and CuNPs could credibly be a substantial substitute over conventional antibiotics in averting the biofilm associated pathogenesis of MRSA and P. aeruginosa.

Natural Xanthones and Skin Inflammatory Diseases: Multitargeting Mechanisms of Action and Potential Application

The pathogenesis of skin inflammatory diseases such as atopic dermatitis, acne, psoriasis, and skin cancers generally involve the generation of oxidative stress and chronic inflammation. Exposure of the skin to external aggressors such as ultraviolet (UV) radiation and xenobiotics induces the generation of reactive oxygen species (ROS) which subsequently activates immune responses and causes immunological aberrations. Hence, antioxidant and anti-inflammatory agents were considered to be potential compounds to treat skin inflammatory diseases. A prime example of such compounds is xanthone (xanthene-9-one), a class of natural compounds that possess a wide range of biological activities including antioxidant, anti-inflammatory, antimicrobial, cytotoxic, and chemotherapeutic effects. Many studies reported various mechanisms of action by xanthones for the treatment of skin inflammatory diseases. These mechanisms of action commonly involve the modulation of various pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor α (TNF-α), as well as anti-inflammatory cytokines such as IL-10. Other mechanisms of action include the regulation of NF-κB and MAPK signaling pathways, besides immune cell recruitment via modulation of chemokines, activation, and infiltration. Moreover, disease-specific activity contributed by xanthones, such as antibacterial action against Propionibacterium acnes and Staphylococcus epidermidis for acne treatment, and numerous cytotoxic mechanisms involving pro-apoptotic and anti-metastatic effects for skin cancer treatment have been extensively elucidated. Furthermore, xanthones have been reported to modulate pathways responsible for mediating oxidative stress and inflammation such as PPAR, nuclear factor erythroid 2-related factor and prostaglandin cascades. These pathways were also implicated in skin inflammatory diseases. Xanthones including the prenylated α-mangostin (2) and γ-mangostin (3), glucosylated mangiferin (4) and the caged xanthone gambogic acid (8) are potential lead compounds to be further developed into pharmaceutical agents for the treatment of skin inflammatory diseases. Future studies on the structure-activity relationships, molecular mechanisms, and applications of xanthones for the treatment of skin inflammatory diseases are thus highly recommended.

Synergistic antimicrobial combination of carvacrol and thymol impairs single and mixed-species biofilms of Candida albicans and Staphylococcus epidermidis

Candida albicans and Staphylococcus epidermidis are important opportunistic human pathogens, which form mixed-species biofilms and cause recalcitrant device associated infections in clinical settings. Further to many reports suggesting the therapeutic potential of plant-derived monoterpenoids, this study investigated the interaction of the monoterpenoids carvacrol (C) and thymol (T) against mono- and mixed-species growth of C. albicans and S. epidermidis. C and T exhibited synergistic antimicrobial activity. The time-kill study and post-antimicrobial effect results revealed the effective microbicidal action of the C + T combination. Filamentation, surface coating assays and live-dead staining of biofilms determined the anti-hyphal, antiadhesion, and anti-biofilm activities of the C + T combination, respectively. Notably, this combination killed highly tolerant persister cells of mono-species and mixed-species biofilms and demonstrated less risk of resistance development. The collective data suggest that the C + T combination could act as an effective therapeutic agent against biofilm associated mono-species and mixed-species infections of C. albicans and S. epidermidis.

Design, synthesis and activity against Staphylococcus epidermidis of 5-chloro-2- or 5-chloro-4-methyl-9H-xanthen-9-one and some of its derivatives

Ten new xanthone derivatives have been designed and synthesized for their potential antibacterial activity. All compounds have been screened against Staphylococcus epidermidis strains ATCC 12228 and clinical K/12/8915. The highest antibacterial activity was observed for compound 3: 5-chloro-2-((4-(2-hydroxyethyl)piperazin-1-yl)methyl)-9H-xanthen-9-one dihydrochloride, exhibiting MIC of 0.8 µg/ml against ATCC 12228 strain, compared to linezolid (0.8 µg/ml), ciprofloxacin (0.2 µg/ml) or trimethoprim and sulfamethoxazole (0.8 µg/ml). For the most active compound 3, genotoxicity assay with use of Salmonella enterica serovar Typhimurium revealed safety in terms of genotoxicity at concentration 75 µg/ml and antibacterial activity against Salmonella at all higher concentrations. A final in silico prediction of skin metabolism of compound 3 seems promising, indicating stability of the xanthone moiety in the metabolism process.

Synergistic effect on anti-methicillin-resistant Staphylococcus aureus among combinations of α-mangostin-rich extract, lawsone methyl ether and ampicillin

α-Mangostin-rich extract (AME) exhibited satisfactory inhibitory activities against all tested MRSA strains, with minimum inhibitory concentrations (MICs) of 7·8-31·25 µg ml^-1 , whereas lawsone methyl ether (LME) and ampicillin revealed weak antibacterial activity with MICs of 62·5-125 µg ml^-1 . However, the combination of AME and LME showed synergistic effects against all tested MRSA strains with fractional inhibitory concentration index (FICI) values of 0·008-0·009, while the combination of AME and ampicillin, as well as LME and ampicillin produced synergistic effects with FICIs of 0·016-0·257. A time-kill assay against MRSA (DMST 20654 strain) revealed a 6-log reduction in CFU per ml, which completely inhibited bacterial growth for the combinations of AME and LME, AME and ampicillin, and LME and ampicillin at a 8-h incubation, while those against MRSA (2468 strain) were at 10-h incubation. The combination of α-mangostin and LME as well as the combinations of each compound with ampicillin synergized the alteration of membrane permeability. In addition, α-mangostin, LME and ampicillin inhibited the biofilm formation of MRSA. These findings indicated that the combinations of AME and LME or each of them in combination with ampicillin had enhanced antibacterial activity against MRSA. Therefore, these compounds might be used as the antibacterial cocktails for treatment of MRSA.

Lessons from Exploring Chemical Space and Chemical Diversity of Propolis Components

Propolis is a natural resinous material produced by bees and has been used in folk medicines since ancient times. Due to it possessing a broad spectrum of biological activities, it has gained significant scientific and commercial interest over the last two decades. As a result of searching 122 publications reported up to the end of 2019, we assembled a unique compound database consisting of 578 components isolated from both honey bee propolis and stingless bee propolis, and analyzed the chemical space and chemical diversity of these compounds. The results demonstrated that both honey bee propolis and stingless bee propolis are valuable sources for pharmaceutical and nutraceutical development.

Rosemary and Tea Tree Essential Oils Exert Antibiofilm Activities In Vitro against Staphylococcus aureus and Escherichia coli

ABSTRACT

The purpose of the present study was to determine the bioactive compounds in rosemary essential oil (REO) and tea tree essential oil (TEO) and to investigate their antibacterial and antibiofilm activities against Staphylococcus aureus and Escherichia coli in vitro. The MIC and MBC assays were performed to assess the antibacterial activity of these two EOs against S. aureus and E. coli with the broth microdilution method. A crystal violet assay was used to ascertain the effects of EOs on the biofilm formation of the test strains, and a tetrazolium bromide (MTT) assay was used to measure the level of inactivation of mature biofilms by EOs. Gas chromatography-mass spectrometry revealed 15 compounds in REO and 27 compounds in TEO, representing 97.78 and 98.13% of the total EO, respectively. Eucalyptol and α-pinene were found in high concentrations in REO, and the two major compounds in TEO were 4-terpineol and terpinolene. The MICs of REO for the two S. aureus and E. coli test strains were both 0.5 mg/mL, and the MICs of TEO for the two strains were both 0.25 mg/mL. Therefore, these EOs can significantly inhibit the formation of biofilms and induced morphological biofilm changes, as verified by scanning electron microscopy. Both EOs had destructive effects on the mature biofilm of the two test strains. TEO was more inhibitory than REO for biofilm formation by the two test strains.

HIGHLIGHTS

2-Hydroxy-4-methoxybenzaldehyde from Hemidesmus indicus is antagonistic to Staphylococcus epidermidis biofilm formation

Staphylococcus epidermidis (SE) is an opportunistic nosocomial pathogen that accounts for recalcitrant device-related infections worldwide. Owing to the growing interest in plants and their secondary metabolites targeting bacterial adhesion, this study was intended to uncover the anti-biofilm potential of Hemidesmus indicus and its major constituent 2-hydroxy-4-methoxybenzaldehyde (HMB) against SE. The minimum biofilm inhibitory concentration (MBIC) of H. indicus root extract and HMB were found to be 500 and 250 µg ml^-1, respectively. The results of time-dependent biofilm inhibition and mature biofilm disruption assays confirmed that HMB targets initial cell adhesion. Furthermore, interference by HMB in the expression of adhesin genes (icaA, aap and bhp) and biofilm components was associated with an increased susceptibility of SE to oxidative stress and antibiotics. To conclude, this study reports for the first time HMB as a potential drug against SE biofilms.

In vitro antibacterial activity of mangosteen (Garcinia mangostana Linn.) crude extract against Staphylococcus pseudintermedius isolates from canine pyoderma

BACKGROUND

Staphylococcus pseudintermedius, commonly involved in canine pyoderma, can be classified as meticillin-susceptible S. pseudintermedius (MSSP) or meticillin-resistant S. pseudintermedius (MRSP). MRSP infections may be difficult to treat due to broad β-lactam resistance of MRSP and typically additional multidrug-resistance. Topical antibacterial treatment is the preferred treatment modality for surface and superficial skin infections. HYPOTHESIS⁄OBJECTIVES: Mangosteen crude extract containing the antibacterial compound α-mangostin will have in vitro activity against MSSP and MRSP isolated from canine pyoderma.

BACTERIAL ISOLATES

Twenty-three samples, MSSP (n = 12) and MRSP (n = 11), isolated from canine pyoderma.

METHODS AND MATERIALS

Minimum inhibitory concentrations (MICs) were determined for mangosteen crude extract by broth microdilution. High-performance liquid chromatography (HPLC) analysis was used to determine the amount of α-mangostin in mangosteen crude extract. A time-kill assay was performed at 30 min and 2 h after exposure to a high concentration of crude extract (100× MIC). Antibacterial activity for α-mangostin was calculated according to HPLC results.

RESULTS

The concentration of α-mangostin was 17.72 ± 1.42% w/w. The mean MIC of α-mangostin towards MSSP was 0.53 ± 0.35 μg/mL, whereas the mean value for MRSP was 0.47 ± 0.27 μg/mL. There was no difference between the mean MIC of MRSP and MSSP (P = 0.84). After a 30 min exposure to 100× MIC of the crude extract, a 95% reduction in colony forming units was found.

CONCLUSIONS AND CLINICAL IMPORTANCE

The results showed that α-mangostin in mangosteen crude extract was effective in inhibiting S. pseudintermedius (both MRSP and MSSP). Clinical studies are needed to investigate this effectiveness further in vivo.

α-Mangostin suppresses NLRP3 inflammasome activation via promoting autophagy in LPS-stimulated murine macrophages and protects against CLP-induced sepsis in mice

BACKGROUND

The major mechanism of sepsis is immunosuppression caused by host response dysfunction. It has been found that α-Mangostin (α-M) is a potential candidate as a treatment for multiple inflammatory and immune disorders. To date, the role of α-M in host response during sepsis remains unexplored.

METHODS AND RESULTS

Herein, we examined the effect of α-M on macrophages-mediated host response in the presence of lipopolysaccharide (LPS), and the vital organ function, inflammatory response, and survival rate in septic mice. In murine peritoneal macrophages, α-M induced autophagy and then inhibited LPS-stimulated NLRP3 inflammasome activation, as well as interleukin-1β (IL-1β) production. Moreover, α-M improved phagocytosis and killing of macrophages, and increased M2 macrophages numbers after LPS stimulation. Furthermore, in vivo experiment suggested that α-M reduced serum levels of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), IL-1β, alanine transaminase (ALT), aspartate transaminase (AST), and creatinine (Cr), whilst increased that of interleukin-10 (IL-10) in caecal ligation and puncture (CLP) mice.

CONCLUSION

Taken together, these findings showed that α-M-mediated macrophages autophagy contributed to NLRP3 inflammasome inactivation and α-M exerted organ protection in septic mice.

Synthesis of chitosan biocomposites loaded with pyrrole-2-carboxylic acid and assessment of their antifungal activity against Aspergillus niger

A wide variety of chitosan (CS) biomaterials have been loaded with different antimicrobial agents to improve the activity of CS against phytopathogenic fungi. Recently, the antimicrobial activity of 1H-pyrrole-2-carboxylic acid (PCA) has been reported as a secondary metabolite of Streptomyces griseus, which was identified as the main bioactive compound in the biological control. However, it is sensitive to light and its activity against filamentous fungi has not yet been reported. The aim of the present research work was to evaluate the biological activity of CS-PCA biocomposites for the control of Aspergillus niger. CS-PCA biocomposites were obtained through nanoprecipitation. In vitro antifungal activity was determined by viability assay, spore germination, morphometric analysis of spores and hyphae, and the analysis of cellular components by fluorescence microscopy. CS-PCA showed an average size and Z potential of 502 ± 72 nm and + 54.7 ± 15 mV, respectively. Micrographs demonstrated well-distributed biocomposites with an apparently spherical shape. A new signal at 1473 cm^-1 in the FT-IR spectrum of the CS-PCA biocomposite was observed, confirming the presence of PCA in the composition of the CS-PCA nanosystem. CS-PCA biocomposites reduced the spores' viability by up to 58%. Effects on fungi morphometry, observed as an increase in the spores' average diameter, swelling, distortion, and an increase in the branching of hyphae, were observed. Fluorescence analysis showed oxidative stress and membrane and cell wall damage, mainly at early growth stages. The inhibitory effect against CS-resistant fungi, such as A. niger, opens a door for the control of CS-sensitive fungi.

Deciphering the Antibacterial Mode of Action of Alpha-Mangostin on Staphylococcus epidermidis RP62A Through an Integrated Transcriptomic and Proteomic Approach

Background: Alpha-mangostin (α-MG) is a natural xanthone reported to exhibit rapid bactericidal activity against Gram-positive bacteria, and may therefore have potential clinical application in healthcare sectors. This study sought to identify the impact of α-MG on Staphylococcus epidermidis RP62A through integrated advanced omic technologies. Methods: S. epidermidis was challenged with sub-MIC (0.875 μg/ml) of α-MG at various time points and the differential expression pattern of genes/proteins were analyzed in the absence and presence of α-MG using RNA sequencing and LC-MS/MS experiments. Bioinformatic tools were used to categorize the biological processes, molecular functions and KEGG pathways of differentially expressed genes/proteins. qRT-PCR was employed to validate the results obtained from these analyses. Results: Transcriptomic and proteomic profiling of α-MG treated cells indicated that genes/proteins affected by α-MG treatment were associated with diverse cellular functions. The greatest reduction in expression was observed in transcription of genes conferring cytoplasmic membrane integrity (yidC2, secA and mscL), cell division (ftsY and divlB), teichoic acid biosynthesis (tagG and dltA), fatty-acid biosynthesis (accB, accC, fabD, fabH, fabI, and fabZ), biofilm formation (icaA) and DNA replication and repair machinery (polA, polC, dnaE, and uvrA). Those with increased expression were involved in oxidative (katA and sodA) and cellular stress response (clpB, clpC, groEL, and asp23). The qRT-PCR analysis substantiated the results obtained from transcriptomic and proteomic profiling studies. Conclusion: Combining transcriptomic and proteomic methods provided comprehensive information about the antibacterial mode of action of α-MG. The obtained results suggest that α-MG targets S. epidermidis through multifarious mechanisms, and especially prompts that loss of cytoplasmic membrane integrity leads to rapid onset of bactericidal activity.

Decrease of growth, biofilm and secreted virulence in opportunistic nosocomial Pseudomonas aeruginosa ATCC 25619 by glycyrrhetinic acid

The present study elucidates the antibiofilm and antivirulent capability of glycyrrhetinic acid (GRA) against Pseudomonas aeruginosa ATCC 25619. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of GRA against P. aeruginosa were found to be 160 μg/mL and 420 μg/mL respectively. In an acclimatization resistance analysis using P. aeruginosa, no resistance towards GRA was observed during the habituation period. Adequate penetration of GRA over the biofilm matrix was proposed with the membrane penetration model assembly constructed with the preformed biofilm exhibited the prospective penetration of GRA above the mature biofilm. Furthermore, GRA resulted in the attenuation of virulence factors such as motility, biofilm formation, pyocyanin secretion, secreted proteases with its sub MIC concentrations. The antibiofilm property of GRA was assessed with the light microscopy and high content screening fluorescent imaging system, which clearly demonstrates, the thickness of P. aeruginosa biofilm was reduced to 11.33 ± 2.08 μm from 39 ± 2.51 μm. Transmission Electron Microscopy (TEM) images depicted the morphological changes in cells such as disaggregation of colonies, cell disruption with loss of intracellular material, cytolytic damage, the process of morphological transformation, bacteriolysis indicating the potential effect of GRA.

Antibacterial Effects of Phage Lysin LysGH15 on Planktonic Cells and Biofilms of Diverse Staphylococci

Treatment of infections caused by staphylococci has become more difficult because of the emergence of multidrug-resistant strains as well as biofilm formation. In this study, we observed the ability of the phage lysin LysGH15 to eliminate staphylococcal planktonic cells and biofilms formed by Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus haemolyticus, and Staphylococcus hominis All these strains were sensitive to LysGH15, showing reductions in bacterial counts of approximately 4 log units within 30 min after treatment with 20 μg/ml of LysGH15, and the MICs ranged from 8 μg/ml to 32 μg/ml. LysGH15 efficiently prevented biofilm formation by the four staphylococcal species at a dose of 50 μg/ml. At a higher dose (100 μg/ml), LysGH15 also showed notable disrupting activity against 24-h and 72-h biofilms formed by S. aureus and coagulase-negative species. In the in vivo experiments, a single intraperitoneal injection of LysGH15 (20 μg/mouse) administered 1 h after the injection of S. epidermidis at double the minimum lethal dose was sufficient to protect the mice. The S. epidermidis cell counts were 4 log units lower in the blood and 3 log units lower in the organs of mice 24 h after treatment with LysGH15 than in the untreated control mice. LysGH15 reduced cytokine levels in the blood and improved pathological changes in the organs. The broad antistaphylococcal activity exerted by LysGH15 on planktonic cells and biofilms makes LysGH15 a valuable treatment option for biofilm-related or non-biofilm-related staphylococcal infections.IMPORTANCE Most staphylococcal species are major causes of health care- and community-associated infections. In particular, Staphylococcus aureus is a common and dangerous pathogen, and Staphylococcus epidermidis is a ubiquitous skin commensal and opportunistic pathogen. Treatment of infections caused by staphylococci has become more difficult because of the emergence of multidrug-resistant strains as well as biofilm formation. In this study, we found that all tested S. aureus, S. epidermidis, Staphylococcus haemolyticus, and Staphylococcus hominis strains were sensitive to the phage lysin LysGH15 (MICs ranging from 8 to 32 μg/ml). More importantly, LysGH15 not only prevented biofilm formation by these staphylococci but also disrupted 24-h and 72-h biofilms. Furthermore, the in vivo efficacy of LysGH15 was demonstrated in a mouse model of S. epidermidis bacteremia. Thus, LysGH15 exhibits therapeutic potential for treating biofilm-related or non-biofilm-related infections caused by diverse staphylococci.

Inhibitory effect of α-mangostin on Acinetobacter baumannii biofilms - an in vitro study

The present study was designed to investigate the anti-biofilm potential of alpha-mangostin (α-MG) against Acinetobacter baumannii (AB). The biofilm inhibitory concentration (BIC) of α-MG against AB was found to be 2 μg ml^-1. α-MG (0.5, 1 and 2 μg ml^-1) exhibited non-bactericidal concentration-dependent anti-biofilm activities against AB. However, α-MG failed to disintegrate the mature biofilms of AB even at a 10-fold increased concentration from its BIC. Results from qRT-PCR and in vitro bioassays further demonstrated that α-MG downregulated the expression of bfmR, pgaA, pgaC, csuA/B, ompA, bap, katE, and sodB genes, which correspondingly affects biofilm formation and its associated virulence traits. The present study suggests that α-MG exerts its anti-biofilm property by interrupting initial biofilm formation and the cell-to-cell signaling mechanism of AB. Additional studies are required to understand the mode of action responsible for the anti-biofilm property.

Bioactivity and pharmacological properties of α-mangostin from the mangosteen fruit: a review

INTRODUCTION

α-Mangostin (α-MG) is the most representative xanthone isolated from the pericarp of mangosteen, possessing extensive biological activities and pharmacological properties, considered as an antineoplastic agent, antioxidant, anti-proliferation and induces apoptosis.

AREAS COVERED

The bioactivity and pharmacological properties of α-MG are being actively investigated by various industrial and academic institutions. The bioactivities of α-MG have been summarized in several previous reviews, which were worthy of high compliment. However, recently, many new literatures about the bioactivities of α-MG have been further reported from 2016 to 2017. Herein, the activities of α-MG are supplemented and summarized in this text.

EXPERT OPINION

As previously said, α-MG possesses good bioactivities pharmacological properties. More recently, it found that α-MG has the effect of maintaining cardiovascular system and gastrointestinal health and controlling free radical oxidation. Furthermore, α-MG has more applications in cosmetics, with the effects of anti-aging, anti-wrinkle, acne treatment, maintenance of skin lubrication. The application of α-MG in treating rheumatoid arthritis has been disclosed and the MG-loaded self-micro emulsion (MG-SME) was designed to improve its pharmacokinetic deficiencies. As mentioned above, α-MG can be a promising drug, also worthy of developing, and further research is crucial for the future application of α-MG.

Antibiofilm activity of α-mangostin extracted from Garcinia mangostana L. against Staphylococcus aureus

OBJECTIVE

To isolate α-mangostin (AMG) from the peels of mangosteen (Garcinia mangostana L.), grown in Vietnam, and to investigate antibiofilm activity of this compound against three Staphylococcus aureus (S. aureus) strains, one of which was methicillin-resistant S. aureus (MRSA) and the other two strains were methicillin-sensitive S. aureus (MSSA).

METHODS

AMG in n-hexane fraction was isolated on a silica gel column and chemically analyzed by HPLC and NMR. The antibiofilm activity of this compound was investigated by using a 96-well plate model for the formation of biofilms. Biofilm biomass was quantified using crystal violet. The viability of cells was observed under confocal microscopy using LIVE/DEAD BacLight stains. Biofilm composition was determined using specific chemical and enzyme tests for polysaccharide, protein and DNA. Membrane-damaging activity was assayed by measuring the hemolysis of human red blood cells in presence of AMG.

RESULTS

The results indicated that the isolated AMG, with a purity that exceeded 98%, had minimal inhibitory concentrations in the range of 4.6-9.2 μmol/L for the three strains tested. Interestingly, the MSSA strains were more sensitive to AMG than the MRSA strain. Minimal bactericidal concentrations were 2-fold higher than the minimal inhibitory concentration values for the three strains, indicating that AMG was a bactericidal compound. AMG also prevented biofilm formation effectively, albeit that again the MRSA strain was the most resistant. Interestingly, biofilms of the MRSA strain contained protein as a main component of the extracellular matrix, whereas this was polysaccharide in the MSSA strains. This might relate to the resistance of the MRSA 252 strain to AMG. Assays using human red blood cells indicated that AMG caused significant membrane damage with 50% of cell lysis occurred at concentration of about 36 μmol/L.

CONCLUSIONS

Our results provide evidence that the isolated AMG has inhibitory activity against biofilm formation by S. aureus, including MRSA. Thus, isolated AMG proposes a high potential to develop a novel phytopharmaceutical for the treatment of MRSA.