Combating Staphylococcus aureus biofilm formation: the inhibitory potential of tormentic acid and 23-hydroxycorosolic acid.

Plant extracts have been used to treat microbiological diseases for centuries. This study examined plant triterpenoids tormentic acid (TA) and 23-hydroxycorosolic acid (HCA) for their antibiofilm effects on Staphylococcus aureus strains (MTCC-96 and MTCC-7405). Biofilms are bacterial colonies bound by a matrix of polysaccharides, proteins, and DNA, primarily impacting healthcare. As a result, ongoing research is being conducted worldwide to control and prevent biofilm formation. Our research showed that TA and HCA inhibit S. aureus planktonic growth by depolarizing the bacterial membrane. In addition, zone of inhibition studies confirmed their effectiveness, and crystal violet staining and biofilm protein quantification confirmed their ability to prevent biofilm formation. TA and HCA exhibited substantial reductions in biofilm formation for S. aureus (MTCC-96) by 54.85% and 48.6% and for S. aureus (MTCC-7405) by 47.07% and 56.01%, respectively. Exopolysaccharide levels in S. aureus biofilm reduced significantly by TA (25 µg/mL) and HCA (20 µg/mL). Microscopy, bacterial motility, and protease quantification studies revealed their ability to reduce motility and pathogenicity. Furthermore, TA and HCA treatment reduced the mRNA expression of S. aureus virulence genes. In silico analysis depicted a high binding affinity of triterpenoids for biofilm and quorum-sensing associated proteins in S. aureus, with TA having the strongest affinity for TarO (- 7.8 kcal/mol) and HCA for AgrA (- 7.6 kcal/mol). TA and HCA treatment reduced bacterial load in S. aureus-infected peritoneal macrophages and RAW264.7 cells. Our research indicates that TA and HCA can effectively combat S. aureus by inhibiting its growth and suppressing biofilm formation.

Interdependencies between Toll-like receptors in Leishmania infection.

Multiple pathogen-associated molecular patterns (PAMPs) on a pathogen's surface imply their simultaneous recognition by the host cell membrane-located multiple PAMP-specific Toll-like receptors (TLRs). The TLRs on endosomes recognize internalized pathogen-derived nucleic acids and trigger anti-pathogen immune responses aimed at eliminating the intracellular pathogen. Whether the TLRs influence each other's expression and effector responses-termed TLR interdependency-remains unknown. Herein, we first probed the existence of TLR interdependencies and next determined how targeting TLR interdependencies might determine the outcome of Leishmania infection. We observed that TLRs selectively altered expression of their own and of other TLRs revealing novel TLR interdependencies. Leishmania major-an intra-macrophage parasite inflicting the disease cutaneous leishmaniasis in 88 countries-altered this TLR interdependency unfolding a unique immune evasion mechanism. We targeted this TLR interdependency by selective silencing of rationally chosen TLRs and by stimulation with selective TLR ligands working out a novel phase-specific treatment regimen. Targeting the TLR interdependency elicited a host-protective anti-leishmanial immune response and reduced parasite burden. To test whether this observation could be used as a scientific rationale for treating a potentially fatal L. donovani infection, which causes visceral leishmaniasis, we targeted the inter-TLR dependency adopting the same treatment regimen. We observed reduced splenic Leishman-Donovan units accompanied by host-protective immune response in susceptible BALB/c mice. The TLR interdependency optimizes TLR-induced immune response by a novel immunoregulatory framework and scientifically rationalizes targeting TLRs in tandem and in sequence for redirecting immune responses against an intracellular pathogen.

Central and local controls of monocytopoiesis influence the outcome of Leishmania infection.

Leishmaniases represent a complex of tropical and subtropical diseases caused by an intracellular protozoon of the genus Leishmania. The principal cells controlling the interaction between the host and the parasite Leishmania are monocytes and macrophages, as these cells play a decisive role in establishing the pathogenesis or cure. These cells are involved in controlling the growth of Leishmania and in modulating the adaptive immune responses. The heterogeneity and extensive plasticity of monocytes allow these cells to adjust their functional phenotypes in response to the pathogen-directed immunological cues. In Leishmania-infected host, the rate of myelopoiesis is augmented by enhanced monocytic lineage commitment and proliferation of myeloid progenitor cells both in the BM and at the site of infection. These newly generated monocytes play as "safe haven" for the parasite and also as the antigen-presenting cells for T cells to cause deregulated cytokine production. This altered monocytopoiesis is characterized by tissue-specific immune responses, spatiotemporal dynamics of immunoregulation and functional heterogeneity. In the presence of Th1 cytokines, monocytes exhibit a pro-inflammatory phenotype that protects the host from Leishmania. By contrast, in an environment of Th2 cytokines, monocytes display anti-inflammatory phenotype with pro-parasitic functions. In this review, we summarize the involvement of cytokines in the regulation of monocytopoiesis and differentiation of macrophages during leishmanial infection. Understanding the role of cytokines in regulating interactions between Leishmania and the host monocytes is key to developing new therapeutic interventions against leishmaniases.

Conundrums in leishmaniasis.

Parasites of the genus Leishmania cause the disease leishmaniasis. As the sandfly vector transfers the promastigotes into the skin of the human host, the infection is either cured or exacerbated. In the process, there emerge several unsolved paradoxes of leishmaniasis. Chronologically, as the infections starts in skin, the role of the salivary proteins in supporting the infection or the host response to these proteins influencing the induction of immunological memory becomes a conundrum. As the parasite invokes inflammation, the infiltrating neutrophils may act as "Trojan Horse" to transfer parasites to macrophages that, along with dendritic cells, carry the parasite to lymphoid organs to start visceralization. As the visceralized infection becomes chronic, the acutely enhanced monocytopoiesis takes a downturn while neutropenia and thrombocytopenia ensue with concomitant rise in splenic colony-forming-units. These responses are accompanied by splenic and hepatic granulomas, polyclonal activation of B cells and deviation of T cell responses. The granuloma formation is both a containment process and a form of immunopathogenesis. The heterogeneity in neutrophils and macrophages contribute to both cure and progression of the disease. The differentiation of T-helper subsets presents another paradox of visceral leishmaniasis, as the counteractive T cell subsets influence the curing or non-curing outcome. Once the parasites are killed by chemotherapy, in some patients the cured visceral disease recurs as a cutaneous manifestation post-kala azar dermal leishmaniasis (PKDL). As no experimental model exists, the natural history of PKDL remains almost a black box at the end of the visceral disease.

Lupeol and amphotericin B mediate synergistic anti-leishmanial immunomodulatory effects in Leishmania donovani-infected BALB/c mice.

Leishmania donovani, a protozoan parasite, inflicts the disease Visceral leishmaniasis (VL) Worldwide. The only orally bioavailable drug miltefosine is toxic, whereas liposomal amphotericin B (AmpB) is expensive. Lupeol, a triterpenoid from Sterculia villosa bark, was exhibited immunomodulatory and anti-leishmanial activity in experimental VL. Herein, we evaluated synergism between sub-optimum dose of AmpB and lupeol in anti-leishmanial and immunomodulatory effects in L. donovani-infected BALB/c mice. We observed that a combination of sub-optimum dose of lupeol and AmpB significantly reduced the hepatic and splenic parasitic burden accompanied by enhanced nitric oxide production, robust induction of Th1 cytokines (IL-12 and IFN-γ) but suppressed Th2 cytokine (IL-10 and TGF- ß) production. The treatment with the lupeol-AmpB combination enhanced p38mitogen-activated protein kinase (p38MAPK), but reduced extracellular signal-related kinase (ERK-1/2), phosphorylation and up-regulated pro-inflammatory response. The present work thus indicates a lupeol-AmpB-mediated immunotherapeutic approach for eliminating the parasite-induced immunosuppression.

The anti-biofilm potential of triterpenoids isolated from Sarcochlamys pulcherrima (Roxb.) Gaud.

Formation of biofilm is the major cause of Pseudomonas aeruginosa associated pathological manifestations in the urinary tract, respiratory system, gastrointestinal tract, skin, soft tissues etc. Triterpenoid group of compounds have shown their potential in reducing planktonic and biofilm form of bacteria. Sarcochlamys pulcherrima (Roxb.) Gaud. is an ethnomedicinal plant traditionally used for its anti-microbial and anti-inflammatory property. In the present study two triterpenoids, have been isolated from this plant, characterised and evaluated for their antibacterial and antibiofilm potential against P. aeruginosa. Compounds were characterised as 2α, 3ß, 19α-trihydroxy-urs-12-ene-28-oic acid (Tormentic acid) and 2α, 3ß, 23-trihydroxyurs-12-ene-28-oic acid (23-hydroxycorosolic acid) through spectroscopic studies viz. infrared (IR), nuclear magnetic resonance (NMR) and mass spectroscopy (MS). Depolarization of bacterial membrane and zone of inhibition studies revealed that both the compounds inhibited the growth of planktonic bacteria. Compounds were also found to inhibit the formation of P. aeruginosa biofilm. Inhibition of biofilm found to be mediated through suppressed secretion of pyoverdin, protease and swarming motility of P. aeruginosa. Gene expression study, in silico binding analysis, in vivo bacterial load and tissue histology observations also supported the antibiofilm activity of both the compounds. In vitro and in vivo study showed that both compounds were non-toxic. The study has explored the antibacterial and antibiofilm effect of two triterpenes isolated for the first time from S. pulcherrima.

Barley beta-Glucan and Zymosan induce Dectin-1 and Toll-like receptor 2 co-localization and anti-leishmanial immune response in Leishmania donovani-infected BALB/c mice.

Toll-like receptors (TLRs), TLR2 in particular, are shown to recognize various glycans and glycolipid ligands resulting in various immune effector functions. As barley ß-glucan and zymosan are the glycans implicated in immunomodulation, we examined whether these ligands interact with Dectin-1, a lectin-type receptor for glycans, and TLR2 and induce immune responses that can be used against Leishmania infection in a susceptible host. The binding affinity of barley ß-glucan and zymosan with Dectin-1 and TLR2 was studied in silico. Barley ß-glucan- and zymosan-induced dectin-1 and TLR2 co-localization was studied by confocal microscopy and co-immunoprecipitation. These ligands-induced signalling and effector functions were assessed by Western blot analyses and various immunological assays. Finally, the anti-leishmanial potential of barley ß-glucan and zymosan was tested in Leishmania donovani -infected macrophages and in L. donovani-infected BALB/c mice. Both barley ß-glucan and zymosan interacted with TLR2 and dectin-1, but with a much stronger binding affinity for the latter, and therefore induced co-localization of these two receptors on BALB/c-derived macrophages. Both ligandsactivated MyD88- and Syk-mediated downstream pathways for heightened inflammatory responses in L. donovani-infected macrophages. These two ligands induced T cell-dependent host protection in L. donovani-infected BALB/c mice. These results establish a novel modus operandi of ß-glucans through dectin-1 and TLR2 and suggest an immuno-modulatory potential against infectious diseases.

Free radical stress induces DNA damage response in RAW264.7 macrophages during Mycobacterium smegmatis infection.

Genomic instability resulting from oxidative stress responses may be traced to chromosomal aberration. Oxidative stress suggests an imbalance between the systemic manifestation of reactive free radicals and biological system's ability to repair resulting DNA damage and chromosomal aberration. Bacterial infection associated insult is considered as one of the major factors leading to such stress conditions. To study free radical responses by host cells, RAW 264.7 macrophages were infected with non-pathogenic M. smegmatis mc2155 at different time points. The infection process was followed up with an assessment of free radical stress, cytokine, toll-like receptors (TLRs) and the resulting DNA damage profiles. Results of CFU count showed that maximum infection in macrophages was achieved after 9 h of infection. Host responses to the infection across different time periods were validated from nitric oxide quantification and expression of iNOS and were plotted at regular intervals. IL-10 and TNF-α expression profile at protein and mRNA level showed a heightened pro-inflammatory response by host macrophages to combat M. smegmatis infection. The expression of TLR4, a receptor for recognition of mycobacteria, in infected macrophages reached the highest level at 9 h of infection. Furthermore, comet tail length, micronuclei and γ-H2AX foci recorded the highest level at 9 h of infection, pointing to the fact that breakage in DNA double strands in macrophage reaches its peak at 9 h of infection. In contrast, treatment with ROS inhibitor N-acetyl-L-cysteine (NAC) prevented host cell death through reduction in oxidative stress and DNA damage response during M. smegmatis infection. Therefore, it can be concluded that enhanced oxidative stress response in M. smegmatis infected macrophages might be correlated with DNA damage response.

Free tryptophan residues inhibit quorum sensing of Pseudomonas aeruginosa: a potential approach to inhibit the development of microbial biofilm.

Microbial biofilm reveals a cluster of microbial population aggregated on a surface. Pseudomonas aeruginosa, a strong biofilm forming organism, often causes several human diseases. Microorganism-based diseases become more difficult to manage when the causative organism develops biofilm during the course of disease progression as the organism attains alarming drug resistance in biofilm form. Agents inhibiting microbial biofilm formation could be considered as a potential tool to weaken the extent of microbial pathogenesis. Tryptophan has already been reported as a promising agent against the biofilm development by P. aeruginosa. In the current study, we had focused on the underlying mechanism of microbial biofilm inhibition of P. aeruginosa under the influence of tryptophan. The expression level of the mRNA of the genes (lasR, lasB and lasI) associated with quorum sensing was compared between tryptophan treated and untreated cells under similar conditions using real time polymerase chain reaction (RT-PCR). The results showed that the tested concentrations of tryptophan considerably reduced the expression of those genes (lasR, lasB and lasI) that are required during the occurrence of quorum sensing in P. aeruginosa. Molecular docking also revealed that tryptophan can interact with the proteins responsible for the occurrence of quorum sensing in P. aeruginosa. The cytotoxicity assay was carried out wherein we observed that the tested concentration of tryptophan did not show any considerable cytotoxicity against the RAW 264.7 macrophage cell line. From this study, it may be concluded that the tryptophan-mediated inhibition of biofilm formation is associated with interference of quorum sensing in P. aeruginosa. Hence, tryptophan could be used as a potential agent against the microbial biofilm mediated pathogenesis.

Modulation of S. aureus and P. aeruginosa biofilm: an in vitro study with new coumarin derivatives.

Coumarin is an important heterocyclic molecular framework of bioactive molecules against broad spectrum pathological manifestations. In the present study 18 new coumarin derivatives (CDs) were synthesized and characterized for antibiofilm activity against two model bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa. It was observed that all the CDs executed significant effect in moderating activities against both planktonic and biofilm forms of these selected bacteria. Hence, to interpret the underlying probable reason of such antibiofilm effect, in-silico binding study of CDs with biofilm and motility associated proteins of these organisms were performed. All CDs have shown their propensity for occupying the native substrate binding pocket of each protein with moderate to strong binding affinities. One of the CDs such as CAMN1 showed highest binding affinity with these proteins. Interestingly, the findings of in-silico studies coincides the experimental results of antibiofilm and motility affect of CDs against both S. aureus and P. aeruginosa. Moreover, in-silico studies suggested that the antibiofilm activity of test CDs may be due to the interference of biofilm and motility associated proteins of the selected model organisms (PilT from P. aeruginosa and TarK, TarO from S. aureus). The detailed synthesis, characterization, methodology and results of biological screening along with computational studies have been reported. This study could be of greater interest in the context of the development of new anti-bacterial agent in the future.

Prolonged inflammatory microenvironment is crucial for pro-neoplastic growth and genome instability: a detailed review.

INTRODUCTION: Chronic inflammation can affect the normal cell homeostasis and metabolism by rendering the cells susceptible to genomic instability that may lead to uncontrolled cellular growth and proliferation ensuing tumorigenesis. The causal agents for inflammation may be pathogenic infections like microbial agents ranging from viruses to bacteria. These infections lead to DNA damage or disruption of normal cell metabolism and alter the genome integrity. FINDINGS: In this review, we have highlighted the role of recurrent infections in tumor microenvironment can lead to recruitment of pro-inflammatory cells, cytokines and growth factors to the site of inflammation. This makes the environment rich in cytokines, chemokines, DNA-damaging agents (ROS, RNS) and growth factors which activate DNA damage response pathway and help in sustained proliferation of the tumor cells. In any inflammatory response, the production of cytokines and related signaling molecules is self-regulating and limiting. But in case of neoplastic risk, deregulation of these factors may lead to abnormalities and related pathogenesis. CONCLUSION: The scope of the present review is to explore the probable mechanistic link and factors responsible for chronic inflammation. The relation between chronic inflammation and DNA damage response was further elucidated to understand the mechanism by which it makes the cells susceptible to carcinogenesis.

Exploration of Phytoconstituents from Mussaenda roxburghii and Studies of Their Antibiofilm Effect.

In the context of ethno botanical importance with no phytochemical investigations, Mussaenda roxburghii have been investigated to explore it's phytoconstituents and studies of their antibiofilm activity. Four compounds have been isolated from the aerial parts of this plant and were characterized as 2α,3ß,19α,23-tetrahydroxyurs-12-en-28-oic acid (1), ß-sitosterol glucoside (4), lupeol palmitate (5), and myoinositol (6). All these compounds were tested for antibacterial and antibiofilm activity against Pseudomonas aeruginosa. Compound 1 exhibited three times more antibiofilm activity with minimum inhibitory concentration (MIC) at 0.74 mm compared to that of streptomycin. Molecular docking studies exhibited a very high binding affinity of 1 with P. aeruginosa quorum sensing proteins and motility associated proteins viz. LasR and PilB, PilY1, PilT, respectively. Compound 1 was also found to be non-cytotoxic against sheep RBC and murine peritoneal macrophages at selected sub-MIC doses.

Evaluation of the antileishmanial potency, toxicity and phytochemical constituents of methanol bark extract of Sterculia villosa.

CONTEXT: Visceral leishmaniasis is a protozoan disease caused by Leishmania donovani parasite. The genus Sterculia (Malvaceae) possesses ethnobotanical potential against this protozoan infection. OBJECTIVE: Determining the potential role of methanol bark extracts from Sterculia villosa Roxb (SVE) and its phytoconstituents against Leishmania donovani promastigotes. MATERIALS AND METHODS: SVE was analysed by TLC, UV-Vis, IR spectroscopy and biochemical assays. Antileishmanial potential of SVE (0.5-130 µg/mL for 72 h) was characterized by MTT assay. Fluorescent microscopy was performed to validate the IC50 dose. To determine the effect of SVE on promastigotes, reactive oxygen species (ROS) and superoxide generation, lipid peroxidation and DNA fragmentation assays were performed. Molecular aggregation of compounds was determined by atomic force microscopy (AFM). Extent of cytotoxicity of SVE at IC50 dose was determined against RAW 264.7 macrophages, peritoneal macrophages and murine RBCs. In vivo cytotoxicity of SVE was evaluated in BALB/c mice. RESULT: SVE exhibited reverse dose dependent antileishmanial activity when 130-0 µg/mL doses were tested against promastigotes. The IC50 and IC70 values were found to be 17.5 and 10 µg/mL, respectively. SVE at IC50 dose demonstrated elevated level of ROS, superoxide, lipid peroxidation and DNA fragmentation against promastigotes with no cytotoxicity. AFM analysis suggested increasing size of molecular aggregation (31.3 nm < 35.2 nm < 2.93 µm) with increase in concentration (10 µg < 17.5 µg < 130 µg). DISCUSSION AND CONCLUSIONS: The study elucidates the antileishmanial potential of SVE against Leishmania donovani promastigotes by exerting oxidative stress and DNA damage. In sum, SVE can be explored as an immunotherapeutic candidate against leishmaniasis and other infectious diseases.

Biofilm, pathogenesis and prevention--a journey to break the wall: a review.

Biofilms contain group(s) of microorganisms that are found to be associated with the biotic and abiotic surfaces. Biofilms contain either homogenous or heterogeneous populations of bacteria which remain in the matrix made up of extracellular polymeric substances secreted by constituent population of the biofilm. Biofilms can be either single or multilayered. Biofilms are an increasing issue of concern that is gaining importance with each passing day. Due to the ubiquitous nature of biofilms, it is difficult to eradicate them. It has been seen that many infectious diseases harbour biofilms of bacterial pathogens as the reservoir of persisting infections which can prove fatal at times. The presence of biofilms can be seen in diseases like endocarditis, cystic fibrosis, periodontitis, rhinosinusitis and osteomyelitis. The presence of biofilms has been mostly seen in medical implants and urinary catheters. Various signalling events including two-component signalling, extra cytoplasmic function and quorum sensing are involved in the formation of biofilms. The presence of an extracellular polymeric matrix in biofilms makes it difficult for the antimicrobials to act on them and make the bacteria tolerant to antibiotics and other drugs. The aim of this review was to discuss about the basic formation of a biofilm, various signalling cascades involved in biofilm formation, possible mechanisms of drug resistance in biofilms and recent therapeutic approaches involved in successful eradication of biofilms.

Optimization of the sublethal dose of silver nanoparticle through evaluating its effect on intestinal physiology of Nile tilapia (Oreochromis niloticus L.).

Silver nanoparticles (SNPs) are widely used in a variety of biomedical and consumer products as an antimicrobial additive. The present study was conducted to evaluate the impacts of low-dose SNPs on intestinal physiology of tilapia (Oreochromis niloticus L.) for assessing its apparent environmental risk due to extensive commercial use. SNPs were synthesized by a chemical reduction method yielding 1-27 nm oval shaped particles. Early fingerlings of tilapia were exposed with two sublethal concentrations (0.8 and 0.4 mg L(-1)) of SNPs for twenty one days period and its impact on the intestinal physiology was evaluated by histochemistry, catalase expression, glutamate dehydrogenase activity, SDS-PAGE and gut micro flora count. Histological analysis showed thinning of intestinal wall, swelling on mucosal layer and immunohistochemical assay exhibited an enhanced catalase expression in SNPs treated fishes. Gut microflora count elicited a dose-dependent depletion and a variable SDS-PAGE profile followed by significant (P < 0.05) elevations in glutamate dehydrogenase activity in SNPs-treated fishes. This study was designed to provide a better understanding of environmentally acceptable, dose-dependent SNPs delivery in fishes and to formulate guidelines in aquatic toxicology.

Toll like receptor 2 and CC chemokine receptor 5 cluster in the lipid raft enhances the susceptibility of Leishmania donovani infection in macrophages.

In experimental visceral leishmaniasis the causative obligate protozoan parasite, L. donovani invades and multiplies inside of macrophages, one of the sentries of the mammalian immune system. The initial host-parasite interaction between the Leishmania promastigote and the macrophage takes place at the plasma membrane interface. To trace any possible interaction between Toll-like receptor 2 (TLR2) and CC chemokine receptor 5 (CCR5) during early Leishmania-macrophage interactions, it was observed that the expression of both TLR2 and CCR5 were significantly increased, along with their recruitment to the lipid raft. TLR2 silencing attenuates CCR5 expression and restricts L. donovani infection, indicating a regulatory role of TLR2 and CCR5 during infection. Silencing of CCR5 and TLR2 markedly reduced the number of intracellular parasites in macrophages by host protective cytokine responses, while raft disruption using beta-MCD affected TLR2/CCR5 cross-talk and resulted in a significant reduction in parasite invasion. In vivo RNA interference of TLR2 and CCR5 using shRNA plasmids rendered protection in Leishmania donovani-infected mice. Thus, this study for the first time demonstrates the importance of TLR2/CCR5 crosstalk as a significant determinant of Leishmania donovani entry in host macrophages.

Sulfonium-Cross-Linked Hyaluronic Acid-Based Self-Healing Hydrogel: Stimuli-Responsive Drug Carrier with Inherent Antibacterial Activity to Counteract Antibiotic-Resistant Bacteria.

Augmentation of the activity of Food and Drug Administration-approved antibiotics by an adjuvant or antibiotic carrier is considered one of the promising strategies to fight against antibiotic-resistant bacteria. This study reports the development of sulfonium-cross-linked hyaluronic acid (HA)-based polymer (HA-SS-HA) as an inherent antimicrobial agent and antibiotic carrier. The HA-SS-HA polymer offers the potential for encapsulating various classes of antibiotics and accomplishing a stimuli-responsive release profile in the presence of hyaluronidase produced by bacterial cells within their extracellular environment. Systematic antibacterial studies reveal that the HA-SS-HA-encapsulated antibiotics (vancomycin, amoxicillin, and tetracycline) restore its activity against the antibiotic-resistant bacterial cells methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE), and Pseudomonas aeruginosa. The HA-SS-HA gel shows robust efficacy in eradicating the mature biofilm of Staphylococcus aureus (S. aureus). The membrane-disrupting activity reveals that HA-SS-HA can also counteract the antibiotic resistance mechanism of the bacterial cells. The in vivo studies reveal excellent wound-healing activity of HA-SS-HA in albino laboratory-bred (BALB/c) mice. The outcome of additional antibacterial studies reveals that antibiotics-encapsulated HA-SS-HA hydrogel can effectively combat Gram-negative, Gram-positive, and antibiotic-resistant bacterial strains. Therefore, revitalizing the activity of commercial antibiotics by HA-SS-HA can be considered a valuable and economically effective strategy to fight against antibiotic-resistant bacteria.

Leishmania-induced biphasic ceramide generation in macrophages is crucial for uptake and survival of the parasite.

The initial macrophage-Leishmania donovani interaction results in the formation of membrane platforms, termed lipid rafts, that help in the entry of the parasite. Therefore, it is imperative that the parasite designs a strategy to modulate its uptake and survival within the macrophages. Herein, we report Leishmania-triggered biphasic ceramide generation. In the first phase, L. donovani promastigotes induce activation of acid sphingomyelinase (ASMase), which catalyzes the formation of ceramide from sphingomyelin. Inhibition of ASMase resulted in reduced uptake and infection with the parasite. In the second phase, de novo synthesis generates ceramide that reduces the cellular cholesterol level and displaces the cholesterol from the membrane, leading to enhanced membrane fluidity, disruption of rafts, and impaired antigen-presentation to the T cells. The results reveal a novel role for ceramide in the perspective of L. donovani infection and help formulate an antileishmanial strategy that can possibly be applied to other intracellular infections as well.

Novel Insight into the Cellular and Molecular Signalling Pathways on Cancer Preventing Effects of Hibiscus sabdariffa: A Review.

A category of diseases known as cancer includes abnormal cell development and the ability to infiltrate or spread to other regions of the body, making them a major cause of mortality worldwide. Chemotherapy, radiation, the use of cytotoxic medicines, and surgery are the mainstays of cancer treatment today. Plants or products produced from them hold promise as a source of anti-cancer medications that have fewer adverse effects. Due to the presence of numerous phytochemicals that have been isolated from various parts of the Hibiscus sabdariffa (HS) plant, including anthocyanin, flavonoids, saponins, tannins, polyphenols, organic acids, caffeic acids, citric acids, protocatechuic acid, and others, extracts of this plant have been reported to have anti-cancer effects. These compounds have been shown to reduce cancer cell proliferation, induce apoptosis, and cause cell cycle arrest. They also increase the expression levels of the cell cycle inhibitors (p53, p21, and p27) and the pro-apoptotic proteins (BAD, Bax, caspase 3, caspase 7, caspase 8, and caspase 9). This review highlights various intracellular signalling pathways involved in cancer preventive potential of HS.

Quinoline Thiourea-Based Zinc Ionophores with Antibacterial Activity.

The increasing resistance of bacteria to commercially available antibiotics threatens patient safety in healthcare settings. Perturbation of ion homeostasis has emerged as a potential therapeutic strategy to fight against antibacterial resistance and other channelopathies. This study reports the development of 8-aminoquinoline (QN) derivatives and their transmembrane Zn2+ transport activities. Our findings showed that a potent QN-based Zn2+ transporter exhibits promising antibacterial properties against Gram-positive bacteria with reduced hemolytic activity and cytotoxicity to mammalian cells. Furthermore, this combination showed excellent in vivo efficacy against Staphylococcus aureus. Interestingly, this combination prevented bacterial resistance and restored susceptibility of gentamicin and methicillin-resistant S. aureus to commercially available ß-lactam and other antibiotics that had lost their activity against the drug-resistant bacterial strain. Our findings suggest that the transmembrane transport of Zn2+ by QN derivatives could be a promising strategy to combat bacterial infections and restore the activity of other antibiotics.