Phospholipase A2 Inhibitor Research Articles

"Synthesis and Characterization of New Secretory Phospholipase A2-Inhibitor N-P-Substituted-1- ((5-P-Substituted-1, 3, 4-Oxadiazol-2-Yl) Methyl)- 1h-1, 2, 3-Triazole-4-Carboxamides and Their Anti- Inflammatory and Anticancer Activities"

"Synthesis and Characterization of New Secretory Phospholipase A2-Inhibitor N-P-Substituted-1- ((5-P-Substituted-1, 3, 4-Oxadiazol-2-Yl) Methyl)- 1h-1, 2, 3-Triazole-4-Carboxamides and Their Anti- Inflammatory and Anticancer Activities"

In silico screening of the phytochemicals present in Clitoria ternatea L. as the inhibitors of snake venom phospholipase A2 (PLA2)

Millions of people suffer from snake bite envenomation, and its management is a challenge, even today. Medicinal plants have attracted the researcher’s attention for their outstanding advantages in treating many diseases, including snake venom poisoning. Clitoria ternatea L, is a plant popularly known for its various pharmacological effects especially, anti-snake venom property. However, the molecular mechanism behind this is poorly understood. It is reported that snake venom PLA2 is an extensively studied toxic factor. This study is meant to screen the compound’s capability to act as inhibitors of the Daboia russelli snake venom PLA2 through molecular docking and dynamics studies. Our results show that among the 27 compounds taken for the study, only Kaempferol showed good interaction profile with the conserved catalytic active site residues, His48 and Asp49. The pharmacophore features of the compound also demonstrate its exact fitting at the binding pocket. Further RMSD, RMSF, Rg, and hydrogen bond analysis confirmed the stable binding of Kaempferol with PLA2 through molecular dynamic simulations for 100 ns. In addition, the MM/PBSA binding free energy calculation of the complex was also affirming the docking results. The binding free energy (BFE) of Kaempferolis better than the reference compound. ADME and Lipinski’s rule of five reveals its drug like properties. Communicated by Ramaswamy H. Sarma

Resolvin D2 uses multiple Ca2+ -dependent signaling pathways to stimulate mucin secretion in rat and human conjunctival goblet cells.

The mucin layer of the tear film is produced by goblet cells in the conjunctiva to protect the ocular surface and maintain homeostasis. The pro-resolving lipid mediator resolvin D2 (RvD2) biosynthesized from an omega 3 fatty acid actively terminates inflammation and regulates mucin secretion from conjunctival goblet cells. Our objective was to determine which Ca2+ -dependent signaling pathways RvD2 uses to stimulate conjunctival goblet cell function (CGC). We hypothesize that RvD2 activates multiple intracellular Ca2+ signaling pathways to stimulate CGC secretion. Rat and human CGCs were cultured from conjunctival explants. The amount of RvD2 receptor GPR18/DRV2 message and protein were determined. The intracellular concentration of Ca2+ ([Ca2+ ]i ) was measured in CGCs using a fluorescent Ca2+ dye and mucin secretion was determined by measuring protein secretion enzymatically with a lectin. Goblet cells were incubated with signaling pathway inhibitors before stimulation with RvD2 and [Ca2+ ]i or secretion was measured. In rat and human CGCs RvD2 receptor and in rat CGCs IP3 (a molecule that releases Ca2+ from intracellular organelles) receptors 1-3 were detected. In both species of CGC RvD2 increased [Ca2+ ]i similarly to RvD1. In rat CGCs, the increase in [Ca2+ ]i and secretion stimulated by RvD2 was significantly blocked by inhibitors to phospholipase (PL-) C and IP3 -receptor, but not protein kinase C. Increase in [Ca2+ ]i was blocked by the PLD inhibitor, but not the PLA2 inhibitor. Secretion was blocked by PLA2 inhibitor, but not the PLD inhibitor. An inhibitor of the epidermal growth factor receptor blocked the increase in [Ca2+ ]i by RvD2 in both species of CGCs. In CGCs RvD2 activates multiple intracellular signaling pathways that are Ca2+ -dependent, along with one Ca2+ -independent and one cAMP/protein kinase A-dependent pathway. Activation of these pathways stimulate mucin secretion from rat and human CGCs into the tear film contributing to ocular surface homeostasis and health.

Thrombin Induced Apoptosis through Calcium-Mediated Activation of Cytosolic Phospholipase A2 in Intestinal Myofibroblasts.

Thrombin is a serine protease that participates in a variety of biological signaling through protease-activated receptors. Intestinal myofibroblasts play central roles in maintaining intestinal homeostasis. In this study, we found that thrombin-induced apoptosis is mediated by the calcium-mediated activation of cytosolic phospholipase A2 in the CCD-18Co cell. Thrombin reduced cell viability by inducing apoptosis and proteinase-activated receptor-1 antagonist attenuated thrombin-induced cell death. Endogenous ceramide did not affect the cell viability itself, but a ceramide-mediated pathway was involved in thrombin-induced cell death. Thrombin increased intracellular calcium levels and cytosolic phospholipase A2 activity. The ceramide synthase inhibitor Fumonisin B1, intracellular calcium chelator BAPTA-AM, and cytosolic phospholipase A2 inhibitor AACOCF3 inhibited thrombin-induced cell death. Thrombin stimulated arachidonic acid release and reactive oxygen species generation, which was blocked by AACOCF3, BAPTA-AM, and the antioxidant reagent Trolox. Taken together, thrombin triggered apoptosis through calcium-mediated activation of cytosolic phospholipase A2 in intestinal myofibroblasts.

Cervical sympathetic trunk transection alleviates acute lung injury caused by intestinal obstruction via inhibition of phospholipase A2 in rats

BackgroundIntestinal obstruction can result in inflammatory injury to distant organs, especially the lungs. Stellate ganglion block (SGB) provides sympathetic nervous homeostasis and inhibits the systemic inflammatory response. This study aimed to investigate whether SGB can alleviate acute lung injury by inhibiting phospholipase A2 expression in rats.MethodsThirty healthy male Sprague–Dawley rats were divided into three groups: C group (sham-operated); CLP group (cecal ligation and puncture with intestinal obstruction), and cervical sympathetic trunk transection (CSTT) group (transection of the cervical sympathetic trunk following CLP).Arterial blood samples were obtained to determine the ratio of partial arterial pressure of oxygen (PaO2) to fraction of oxygen in inspired air (FiO2). Venous blood samples were used to evaluate the serum concentrations of chemokines, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 using enzyme-linked immunosorbent assays. Following euthanasia, the lungs were isolated to estimate the wet/dry lung weight (W/D) ratio, evaluate the pathological damage to lung tissues on microscopy, and determine secretory-type phospholipase A2 (sPLA2) expression using western blotting.ResultsRats in the CLP group showed increased fatigue, decreased activity levels, and coarse, gray hair. The levels of chemokines, TNF-α, and IL-6 in the CLP and CSTT groups were higher than those in the C group. However, the levels were lower in the CSTT group than those in the CLP group. IL-10 levels in the CLP group were higher and lower than those in the C and CSTT groups, respectively. W/D ratios and PaO2/FiO2 in the CLP and CSTT groups were higher than those in the C group, whereas these ratios in the CSTT group were lower than those in the CLP group. No lung injury was noted in group C, and the lung injury scores were lower in the CSTT group than those in the CLP group. sPLA2 expression levels in the CLP group were higher than those in the C group, whereas these levels in the CSTT group were lower than those in the CLP group.ConclusionssPLA2 overexpression in the lungs may be a pathogenic factor in acute lung injury. CSTT alleviated acute lung injury by inhibiting sPLA2 expression.

Binding of rosmarinic acid curcumin and capsaicin with PLA2: A comparative study

Phospholipase A2 (PLA2) is a key enzyme involved in the formation of pro-inflammatory mediators like eicosanoids. Inhibition of PLA2 is regarded as one of the effective methods of controlling inflammation. The present study investigated the binding potentials of three natural compounds, rosmarinic acid (RA), capsaicin (CAP), and curcumin (CUR) by means of in silico and in vitro methods. Our study revealed that RA has relatively better binding affinity and inhibition potentials when compared to the other two molecules. Our ITC experiments were also suggested a slightly better binding energy for the RA. The stoichiometry of the protein ligand complex obtained from one of the ITC experiments suggested the possibilities of binding of a small molecule MCW (degraded product of CUR) on PLA2. Overall study demonstrated that the anti-inflammatory activity of RA, CUR and CAP may be partly due to the inhibition of PLA2.

Identification of a Dual Inhibitor of Secreted Phospholipase A2 (GIIA sPLA2) and SARS-CoV-2 Main Protease.

The development of novel agents to combat COVID-19 is of high importance. SARS-CoV-2 main protease (Mpro) is a highly attractive target for the development of novel antivirals and a variety of inhibitors have already been developed. Accumulating evidence on the pathobiology of COVID-19 has shown that lipids and lipid metabolizing enzymes are critically involved in the severity of the infection. The purpose of the present study was to identify an inhibitor able to simultaneously inhibit both SARS-CoV-2 Mpro and phospholipase A2 (PLA2), an enzyme which plays a significant role in inflammatory diseases. Evaluating several PLA2 inhibitors, we demonstrate that the previously known potent inhibitor of Group IIA secretory PLA2, GK241, may also weakly inhibit SARS-CoV-2 Mpro. Molecular mechanics docking and molecular dynamics calculations shed light on the interactions between GK241 and SARS-CoV-2 Mpro. 2-Oxoamide GK241 may represent a lead molecular structure for the development of dual PLA2 and SARS-CoV-2 Mpro inhibitors.

The relative efficacy of chemically diverse small-molecule enzyme-inhibitors against anticoagulant activities of Black Snake (Pseudechis spp.) venoms

Snakebite remains a worldwide public health burden and a severely neglected tropical disease. Recent research has begun to focus on the potential use of repurposed small-molecule enzyme-inhibitors as early treatments to neutralise the effects of snake venoms. Black snakes (Pseudechis spp.) are a widespread and dangerously venomous group found throughout Australia and New Guinea. Utilising validated coagulation assays, our study assessed the efficacy of two chemically different small molecule inhibitors, a phospholipase A2 inhibitor (varespladib) and a metalloproteinase inhibitor (prinomastat), in vitro neutralisation of the anticoagulant prothrombinase-inhibiting activity of venom from seven species within the Pseudechis genus (P. australis, P. butleri, P. coletti, P. guttatus, P. papuanus, P.rossignolii, P. sp (NT).). Varespladib was shown to be highly effective at neutralising this anticoagulant activity for all seven species, but with P. coletti notably less so than the others. In contrast, prinomastat showed strong neutralisation for five out of the seven species, but was ineffective at neutralising the activity of P. coletti or P. rossignolii venoms. This suggests that varespladib binds to a highly conserved site but that prinomastat binds to a more variable site. These results build upon recent literature indicating that metalloproteinase inhibitors have cross-neutralising potential towards snake venom phospholipase A2 toxins, but with higher degrees of variability that PLA2-specific inhibitors. An important caveat is that these are in vitro tests and while suggestive of potential clinical utility, in vivo animal testing and clinical trials are required as future work.

The Short-Term Opening of Cyclosporin A-Independent Palmitate/Sr2+-Induced Pore Can Underlie Ion Efflux in the Oscillatory Mode of Functioning of Rat Liver Mitochondria.

Mitochondria are capable of synchronized oscillations in many variables, but the underlying mechanisms are still unclear. In this study, we demonstrated that rat liver mitochondria, when exposed to a pulse of Sr2+ ions in the presence of valinomycin (a potassium ionophore) and cyclosporin A (a specific inhibitor of the permeability transition pore complex) under hypotonia, showed prolonged oscillations in K+ and Sr2+ fluxes, membrane potential, pH, matrix volume, rates of oxygen consumption and H2O2 formation. The dynamic changes in the rate of H2O2 production were in a reciprocal relationship with the respiration rate and in a direct relationship with the mitochondrial membrane potential and other indicators studied. The pre-incubation of mitochondria with Ca2+(Sr2+)-dependent phospholipase A2 inhibitors considerably suppressed the accumulation of free fatty acids, including palmitic and stearic acids, and all spontaneous Sr2+-induced cyclic changes. These data suggest that the mechanism of ion efflux from mitochondria is related to the opening of short-living pores, which can be caused by the formation of complexes between Sr2+(Ca2+) and endogenous long-chain saturated fatty acids (mainly, palmitic acid) that accumulate due to the activation of phospholipase A2 by the ions. A possible role for transient palmitate/Ca2+(Sr2+)-induced pores in the maintenance of ion homeostasis and the prevention of calcium overload in mitochondria under pathophysiological conditions is discussed.

Phospholipase A2 inhibitor varespladib prevents wasp sting-induced nephrotoxicity in rats

This study aimed to clarify whether varespladib, a phospholipase A2 (PLA2) inhibitor, can be used as a therapeutic agent for wasp sting-induced acute kidney injury (AKI). Rats were divided into control, AKI, and AKI + varespladib groups. The AKI model was established by subcutaneously injecting wasp venom at five different sites in rats. Varespladib treatment showed a significant inhibitory effect on wasp venom PLA2in vitro and in vivo. Moreover, we observed that varespladib decreased the levels of rhabdomyolysis and hemolysis markers compared with that in the AKI group. Histopathological changes in the kidney decreased significantly, and rat serum creatinine levels were reduced after varespladib administration. The significantly regulated genes in the kidney of the AKI group were mostly involved in inflammatory response pathway, and the administration of varespladib remarkably attenuated the expression of these genes. Therefore, varespladib inhibited wasp sting-induced functional and pathological damage to the kidneys. We propose that the PLA2 inhibitor varespladib protects the kidney tissue in a wasp sting-induced AKI model by inhibiting PLA2 activity.

Human peroxiredoxin 6 is essential for malaria parasites and provides a host-based drug target.

The uptake and digestion of host hemoglobin by malaria parasites during blood-stage growth leads to significant oxidative damage of membrane lipids. Repair of lipid peroxidation damage is crucial for parasite survival. Here, we demonstrate that Plasmodium falciparum imports a host antioxidant enzyme, peroxiredoxin 6 (PRDX6), during hemoglobin uptake from the red blood cell cytosol. PRDX6 is a lipid-peroxidation repair enzyme with phospholipase A2 (PLA2) activity. Inhibition of PRDX6 with a PLA2 inhibitor, Darapladib, increases lipid-peroxidation damage in the parasite and disrupts transport of hemoglobin-containing vesicles to the food vacuole, causing parasite death. Furthermore, inhibition of PRDX6 synergistically reduces the survival of artemisinin-resistant parasites following co-treatment of parasite cultures with artemisinin and Darapladib. Thus, PRDX6 is a host-derived drug target for development of antimalarial drugs that could help overcome artemisinin resistance.

PENGGUNAAN KORTIKOSTEROID PADA SINDROM HELLP

Background: Hypertension in pregnancy is one of the main causes of maternal morbidity and mortality. HELLP syndrome is potentially life-threatening to the mother. Currently the main treatment for HELLP syndrome is symptomatic. Corticosteroids can be used to treat the patient's condition and promote fetal lung maturation. Methods: The research method used is a literature review, namely literature collected from various sources related to the use of corticosteroids in the HELLP syndrome. Results: The typical clinical symptoms of HELLP syndrome were right upper quadrant abdominal pain, nausea, and vomiting. At less than 27 weeks of gestation, conservative therapy is considered. Corticosteroids are important therapeutic agents used to treat allergic and inflammatory disorders or to suppress unwanted immune systems. Steroid molecules diffuse across cell membranes and bind to glucocorticoid receptors, causing a conformational change in the receptor thereby inhibiting transcription factors that control the synthesis of proinflammatory mediators. Another important effect is the inhibition of phospholipase A2, which is responsible for the production of many inflammatory mediators. Several studies showed that there was no difference in outcome between the treatment group and the control group. Other references say the use of corticosteroids in preterm pregnancy has shown beneficial results. Conclusion: The use of corticosteroids in the HELLP syndrome of preterm pregnancy has been shown to be beneficial.Keyword: Corticosteroid, HELLP syndrome, Pregnancy

Effect of the phospholipase A2 inhibitor Varespladib, and its synergism with crotalic antivenom, on the neuromuscular blockade induced by Crotalus durissus terrificus venom (with and without crotamine) in mouse neuromuscular preparations

The venom of the South American rattlesnake Crotalus durissus terrificus causes an irreversible neuromuscular blockade in isolated preparations due to action of the presynaptically-acting heterodimeric phospholipase A2 (PLA2) crotoxin. Some populations of this subspecies contain, in addition to crotoxin, the toxin crotamine, which acts directly on muscle fibers. In this study we used C. d. terrificus venoms with (crot+) or without (crot-) crotamine to test whether Varespladib, a PLA2 inhibitor, is able to abrogate the neuromuscular blockade induced by these venoms comparatively with crotalic antivenom. Mouse phrenic nerve-diaphragm preparations were exposed to venoms previously incubated with two different concentrations of Varepladib or antivenom, or with a mixture of these two agents, before addition to the bath. In another experimental setting, venoms were initially added to the system, followed by the addition of Varespladib or antivenom 10, 30, or 60 min after venom. At the highest concentrations tested, Varespladib and antivenom inhibited the action of the venom >80% and >70%, respectively. With lower concentrations the inhibition of neuromuscular blockade decreased, but when low doses of the two agents were incubated together with the venom, the inhibitory effect improved, underscoring a synergistic phenomenon. When added after venom, Varespladib was able to halt the progression of the neuromuscular blockade even when added at 60 min. Antivenom exhibited a lower ability to inhibit the toxic effect of the venoms in these conditions. In conclusion, the PLA2 inhibitor Varespladib is highly effective at abrogating the neuromuscular blocking activity of crotamine-positive and crotamine-negative C. d. terrificus venoms and seems to act synergistically with antivenom.

Group IIA secreted phospholipase A2 inhibition by elemolic acid as a function of anti-inflammatory activity

Human group IIA secreted phospholipase A2 (GIIA) is a key enzyme in inflammatory reactions, worsening the condition of several chronic inflammatory diseases. The natural inhibitors of GIIA potentially block the production of inflammatory mediators. In the present study, elemolic acid, a triterpenoid from Boswellia serrata inhibited the GIIA enzyme in a concentration-dependent manner with IC50 value of 5.70 ± 0.02 µM. The mode of GIIA inhibition was studied by increasing the concentration of the substrate from 30 to 120 nM, and calcium from 2.5 to 15 mM, the level of inhibition was not changed. The inhibitor-enzyme interaction was examined by fluorimetry and Circular Dichroism (CD) studies; elemolic acid altered intrinsic fluorescence intensity and shifted far UV- CD spectra of GIIA enzyme, suggesting the direct interaction with GIIA. Elemolic acid neutralized the GIIA mediated indirect hemolytic activity from 94.5 to 9.8% and reduced GIIA induced mouse paw edema from 171.75 to 113.68%. Elemolic acid also reduced the hemorrhagic effect of GIIA along with Vipera russelii neurotoxic non-enzymatic peptide -VNTx-II (VR-HC-I). Thus, the elemolic acid has been proven as a potent inhibitor of GIIA enzyme and modulated the GIIA induced inflammatory response by in situ and in vivo methods.

Partial efficacy of a Brazilian coralsnake antivenom and varespladib in neutralizing distinct toxic effects induced by sublethal Micrurus dumerilii carinicauda envenoming in rats

In this work, we reported the efficacy of a combination of Brazilian therapeutic coralsnake antivenom (CAV) and varespladib (phospholipase A2 inhibitor – VPL) in partially neutralizing selected toxic effects of Micrurus dumerilii carinicauda coralsnake venom in rats. Venom caused local myonecrosis and systemic neurotoxicity, nephrotoxicity, and hepatotoxicity within 2 h of injection. CAV and VPL administered separately failed to prevent most of these alterations. However, a combination of CAV plus VPL offered variable protection against venom-induced coagulation disturbances, leukocytosis, and renal-hepatic morphological alterations.

A comparative study of endogenous phospholipase A2 inhibitors in the serum of Brazilian pit vipers

This work compared the presence of phospholipase A2 inhibitors (PLIs) in the serum of 19 snake species maintained at Instituto Butantan to better understand the mechanisms of venom resistance in snakes and improve the treatment of snakebite. PLI was isolated from blood of 19 snake species by one-step chromatography and identified in all samples, besides its identity was confirmed through the interaction with both phospholipase A2 and anti-γPLI. These findings highlight the diversity of snake serum PLIs and emphasize the importance of structure-function studies.

In silico Exploration of Phospholipase A2 Inhibitor Compounds from Lufariella variabilis as Antivenom of Ophiophagus hannah

The King Cobra (Ophiophagus hannah) is a venomous snake found in Southeast Asia and South Asia. Globally, it is estimated that there are 81,000 to 138,000 cases of snakebite deaths from 1.8 million to 2 million snakebite cases. The limited availability of antivenom is a problem in handling snake venom poisoning. Exploration of natural ingredients is needed as a preventive measurement from the spread of toxins when they are inside the body. Exploration could be carried out by utilizing natural metabolite compounds that can be inhibitors of the phospholipase A2 (PLA2) enzyme. Luffariella variabilis is known as a marine organism that can produce sesterterpenoid compounds and has the potential as an inhibitor of the phospholipase A2 enzyme. This study aims to explore the potential of sesterterpenoid compounds produced by Luffariella variabilis as an in silico inhibitor of phospholipase A2. Several methods used in this research are molecular docking simulation, toxicity test using pkCSM and Toxtree, and chemical bond analysis using Discovery Studio. The results showed that the manoalide compound was the most potent compound of the other sesterterpenoid compounds in its ability to become a snake antivenom candidate.

Allosteric regulation by membranes and hydrophobic subsites in phospholipase A2 enzymes determine their substrate specificity

Lipids play critical roles in several major chronic diseases of our times, including those that involve inflammatory sequelae such as metabolic syndrome including obesity, insulin sensitivity, and cardiovascular diseases. However, defining the substrate specificity of enzymes of lipid metabolism is a challenging task. For example, phospholipase A2 (PLA2) enzymes constitute a superfamily of degradative, biosynthetic, and signaling enzymes that all act stereospecifically to hydrolyze and release the fatty acids of membrane phospholipids. This review focuses on how membranes interact allosterically with enzymes to regulate cell signaling and metabolic pathways leading to inflammation and other diseases. Our group has developed “substrate lipidomics” to quantify the substrate phospholipid specificity of each PLA2 and coupled this with molecular dynamics simulations to reveal that enzyme specificity is linked to specific hydrophobic binding subsites for membrane phospholipid substrates. We have also defined unexpected headgroup and acyl chain specificity for each of the major human PLA2 enzymes, which explains the observed specificity at a structural level. Finally, we discovered that a unique hydrophobic binding site—and not each enzyme’s catalytic residues or polar headgroup binding site—predominantly determines enzyme specificity. We also discuss how PLA2s release specific fatty acids after allosteric enzyme association with membranes and extraction of the phospholipid substrate, which can be blocked by stereospecific inhibitors. After decades of work, we can now correlate PLA2 specificity and inhibition potency with molecular structure and physiological function.

Identification of integrative hepatotoxicity induced by lysosomal phospholipase A2 inhibition of cationic amphiphilic drugs via metabolomics

Drug-induced liver injury (DILI) is a condition caused by drugs that leads to abnormal hepatic function. Hepatotoxicity caused by DILI has been shown to be due to cellular stress, mitochondrial dysfunction, cell necrosis and apoptosis and many types of hepatotoxicity, such as phospholipidosis, steatosis and hepatitis, commonly share intracellular molecular mechanisms. Metabolomics can be useful for mechanism-based toxicity evaluations and has been recently utilized as a scientific technique that can effectively predict the risk factors for chemical substances. To evaluate the key events in hepatotoxicity associated with lysosomal phospholipase A2 (LPLA2) inhibition by cationic amphiphilic drugs (CADs), LPLA2 inhibition assays and phospholipid accumulation assays were performed in HepG2 cells. Additionally, to suggest the integrative molecular mechanisms of hepatotoxicity by CADs, we profiled intracellular metabolites. Cell-based metabolomics was performed using an UPLC-Orbitrap-MS instrument equipped with heated electrospray ionization in positive and negative ion modes. As a result, CADs such as amiodarone, fluoxetine, chlorpromazine and tamoxifen significantly inhibited LPLA2 and accumulated phospholipids. In metabolomics, a total of 17 significant metabolites were identified, and the changed metabolite types were as follows: nucleotide sugars, conjugated bile acids, branched-chain amino acids, polyamine biosynthesis, and long-chain fatty acid and glycerophospholipid metabolism. From these data, it was suggested that the integrative mechanism of DILI could be verified and that a toxicological approach is possible using metabolomics.

New Insights into the Toxin Diversity and Antimicrobial Activity of the "Fire Coral" Millepora complanata.

To date, few studies have been carried out aimed at characterizing the toxins synthesized by hydrocorals of the genus Millepora. The purpose of this study was to explore the toxin diversity and antibacterial activity of the “fire coral” M. complanata using a transcriptomic data mining approach. In addition, the cytolytic and antibacterial activities of the M. complanata nematocyst proteome were experimentally confirmed. Cytolysins were predicted from the transcriptome by comparing against the Animal Toxin Annotation Project database, resulting in 190 putative toxins, including metalloproteases, hemostasis-impairing toxins, phospholipases, among others. The M. complanata nematocyst proteome was analyzed by 1D and 2D electrophoresis and zymography. The zymograms showed different zones of cytolytic activity: two zones of hemolysis at ~25 and ~205 kDa, two regions corresponding to phospholipase A2 (PLA2) activity around 6 and 25 kDa, and a proteolytic zone was observed between 50 and 205 kDa. The hemolytic activity of the proteome was inhibited in the presence of PLA2 and proteases inhibitors, suggesting that PLA2s, trypsin, chymotrypsin, serine-proteases, and matrix metalloproteases are responsible for the hemolysis. On the other hand, antimicrobial peptide sequences were retrieved from their transcripts with the amPEPpy software. This analysis revealed the presence of homologs to SK84, cgUbiquitin, Ubiquicidin, TroTbeta4, SPINK9-v1, and Histone-related antimicrobials in the transcriptome of this cnidarian. Finally, by employing disk diffusion and microdilution assays, we found that the nematocyst peptidome of M. complanata showed inhibitory activity against both Gram-positive and Gram-negative bacteria including S. enteritidis, P. perfectomarina, E. coli, and C. xerosis, among others. This is the first transcriptomic data mining analysis to explore the diversity of the toxins synthesized by an organism of the genus Millepora. Undoubtedly, this work provides information that will broaden our general understanding of the structural richness of cnidarian toxins.