A Shortcut from Genome to Drug: The Employment of Bioinformatic Tools to Find New Targets for Gastric Cancer Treatment.

Gastric cancer (GC) is a highly heterogeneous, complex disease and the fifth most common cancer worldwide (about 1 million cases and 784,000 deaths worldwide in 2018). GC has a poor prognosis (the 5-year survival rate is less than 20%), but there is an effort to find genes highly expressed during tumor establishment and use the related proteins as targets to find new anticancer molecules. Data were collected from the Gene Expression Omnibus (GEO) bank to obtain three dataset matrices analyzing gastric tumor tissue versus normal gastric tissue and involving microarray analysis performed using the GPL570 platform and different sources. The data were analyzed using the GEPIA tool for differential expression and KMPlot for survival analysis. For more robustness, GC data from the TCGA database were used to corroborate the analysis of data from GEO. The genes found in in silico analysis in both GEO and TCGA were confirmed in several lines of GC cells by RT-qPCR. The AlphaFold Protein Structure Database was used to find the corresponding proteins. Then, a structure-based virtual screening was performed to find molecules, and docking analysis was performed using the DockThor server. Our in silico and RT-qPCR analysis results confirmed the high expression of the AJUBA, CD80 and NOLC1 genes in GC lines. Thus, the corresponding proteins were used in SBVS analysis. There were three molecules, one molecule for each target, MCULE-2386589557-0-6, MCULE-9178344200-0-1 and MCULE-5881513100-0-29. All molecules had favorable pharmacokinetic, pharmacodynamic and toxicological properties. Molecular docking analysis revealed that the molecules interact with proteins in critical sites for their activity. Using a virtual screening approach, a molecular docking study was performed for proteins encoded by genes that play important roles in cellular functions for carcinogenesis. Combining a systematic collection of public microarray data with a comparative meta-profiling, RT-qPCR, SBVS and molecular docking analysis provided a suitable approach for finding genes involved in GC and working with the corresponding proteins to search for new molecules with anticancer properties.

Antimicrobial Activity the Essential Oil from Croton pluriglandulosus Carn. Leaves against Microorganisms of Clinical Interest.

Multiresistant pathogens pose a serious threat to human health. The genus Candida is one class of human pathogenic yeasts responsible for infections affecting healthy and immunocompromised patients. In this context, plant essential oils emerged as a future natural alternative to control the diseases caused by these pathogens. Based on that, the present study aimed to evaluate the antimicrobial potential of essential oil from C. pluriglandulosus and understand the mechanism of action. Here, it highlighted antimicrobial activity and the mechanisms of action of the essential oil extracted from C. pluriglandulosus Carn.-Torres & Riina (CpEO) leaves on human pathogenic microorganisms in planktonic and biofilm lifestyles. In addition, for the first time, the oil composition was revealed by GC-MS analysis and the toxicity to human red blood cells (HRBC). Twenty-six chemical compounds were identified in CpEO, elemicin, bicyclogermacrene, caryophyllene, brevifolin, and 2,4,6-trimethoxy-styrene. Through hemolytic assay, it was shown that CpEO has no toxicity to human RBCs. At the concentration of 50 µg mL-1, CpEO did not show great antibacterial potential. However, promising data were found for C. krusei and C. parapsilosis inhibiting by 89.3% and 80.7% of planktonic cell growth and 83.5% and 77.9% the biofilm formation, respectively. Furthermore, the mechanisms of action CpEO were elucidated by fluorescence. Scanning electron microscopy revealed damage to the cell membrane and pore formation, ROS overproduction, and induction of apoptosis in candida cells. Our results reinforce the potential of CpEO as an effective alternative molecule of pharmaceutical interest.

Natural and Synthetic Peptides to Control Drug-resistant Pathogens.

Due to the excessive and inappropriate use of antibiotics in farming and clinic, pathogens developed resistance mechanisms to currently used drugs. Thus, because of this resistance, drugs become ineffective, leading to public health problems worldwide. According to the World Health Organization (WHO), microbial resistance to drugs is one of the most threats that humanity must face. Therefore, it is imperative to seek alternative methods to overcome microbial resistance. Here, the potential of natural or synthetic antimicrobial peptides to overcome microbial resistance will be discussed, and how peptides could be a source for new therapeutics molecules. In this context, antimicrobial peptides (natural or synthetic) are considered promising molecules based on their antifungal, antiviral, and antibacterial properties, making them eligible for developing new drugs. In addition, they can act synergistically with existing drugs on the market, revealing a broad spectrum of applications.

A historical, economic, and technical-scientific approach to the current crisis in the development of antibacterial drugs: Promising role of antibacterial peptides in this scenario.

The emergence of antibiotic resistance (AMR) is a global public health problem. According to estimates, drug-resistant bacteria infect 2 million patients and perish 23,000 annually. To overcome this problem, antimicrobial peptides became a potential solution based on a new mechanism of action against bacteria. This article addresses the phenomenon of antibacterial resistance in most of its nuances, responding to historical, technical-scientific, and economic aspects. Likewise, it explores new therapeutic approaches to combat multi-resistant pathogens, specifically concerning antibacterial peptides, as a potential therapeutic tool to mitigate the current crisis of antibacterial drugs. It is expected that, with technological advances, especially with the advent and adoption of artificial intelligence, there will be an increase in diversified synthetic peptide production, which can face the challenges that we have in terms of antibacterial drugs.

Use of Calotropis procera cysteine peptidases (CpCPs) immobilized on glyoxyl-agarose for cheesemaking.

Calotropis procera cysteine peptidases (CpCPs) have presented several potential biotechnological applications. Here, these enzymes were immobilized on glyoxyl-agarose (glyoxyl-CpCPs) with yields of 90-95 % and the recovered activities ranged from 10 % to 15 %, according to enzyme loadings (5, 10, 20, 40, and 50 mgBSAeq/g). Spectrophotometric assays and SDS-PAGE showed that the casein hydrolysis by glyoxyl-CpCPs was similar to soluble CpCPs. In addition, glyoxyl-CpCPs exhibited similar ratio of milk-clotting activity to proteolytic activity in comparison with soluble CpCPs and chymosin. Even after being stored for six months at 8 °C, the residual proteolytic activity of glyoxyl-CpCPs remained close to 100 %. Atomic force microscopy and dynamic light scattering techniques showed that the process of casein micelle aggregation after treatment with glyoxyl-CpCPs was very similar to its soluble form and chymosin. Glyoxyl-CpCPs performed well after five reaction cycles, producing cheeses with yield, moisture, protein, and fat similar to those produced with chymosin.

Essential Oil from Croton blanchetianus Leaves: Anticandidal Potential and Mechanisms of Action.

Antimicrobial drugs are becoming ineffective given the resistance acquired by microorganisms. As such, it is imperative to seek new antimicrobial molecules that could provide a basis for the development of new drugs. Therefore, this work aimed to evaluate the antimicrobial potential and the mechanisms of action of the essential oil extracted from leaves of Croton blanchetianus (named CbEO) on different fungi and bacteria of clinical importance in both planktonic and biofilm lifestyles. GC-MS/MS analysis revealed the presence of twenty-two different compounds in the CbEO, which were identified using the Kovats retention index. Among these, the most abundant were amorphene (20.03%), spathulenol (5%), bicyclogermacrene (1.49%), caryophyllene oxide (4.55%), and eucalyptol (5.62%). CbOE (50 µg mL-1) barely inhibited the growth of Bacillus subtilis (23%), Pseudomonas aeruginosa (27%), and Salmonella enterica (28%), and no inhibition was obtained against Enterobacter aerogenes and Klebsiella pneumoniae. Additionally, no activity against bacterial biofilm was detected. In contrast, CbEO was active against Candida species. C. albicans and C. parapsilosis were inhibited by 78 and 75%, respectively. The antibiofilm potential also was favorable against C. albicans and C. parapsilosis, inhibiting 44 and 74% of biofilm formation and reducing around 41 and 27% of the preformed biofilm, respectively. CbOE caused membrane damage and pore formation, overproduction of ROS, and apoptosis on C. albicans and C. parapsilosis cells, as well as not inducing hemolysis in human red cells. The results obtained in this work raise the possibility of using the essential oil of C. blanchetianus leaves as an alternative to fight infections caused by C. albicans and C. parapsilosis.

Systematic review of antiprotozoal potential of antimicrobial peptides.

Protozoa is a group of microorganisms that cause neglected tropical diseases, such as malaria, Chagas disease, and Leishmaniasis. Due to the growing demand for new therapeutic agents, antimicrobial peptides (AMPs) have gained attention for antiprotozoal action. A systematic literature review described the current scenario of plant and animal AMPs with action antiprotozoal. The terms "antimicrobial peptides", "plant", and "animal" combined with the names of the etiological agents were used in the search. Boolean and Operator were used to connect the terms. The search found 4,825 articles. However, 79 articles were excluded because they were duplicates, and 4,627 were excluded based on title and abstract. Therefore, 119 were evaluated and included here. Of these, the use of antimicrobial peptides of animal origin was predominant. Still, the works with plant peptides focused on the genus Leishmania. Only antimicrobial peptides of animal origin were described for the other genera of protozoa (Toxoplasma spp, Trypanosoma spp, Plasmodium spp). Antimicrobial peptides are an excellent option as a pharmacological tool to fight these infections due to their aggregation and extravasation of cellular content through the formation of pores in the cell membrane of these microorganisms.

Luffa operculata seed proteins: Identification by LC-ESI-MS/MS and biotechnological potential against Candida albicans and C. krusei.

L: operculata is a plant commonly found in the North and Northeast of Brazil. Although the regional population knows its medicinal potential, there are few scientific studies about its antimicrobial potential. Thus, this study aimed to characterize the proteins from L. operculata seeds extracted using different solutions and evaluate their antimicrobial potentials. The protein extracts obtained with NaCl and sodium acetate buffer presented the best inhibitory activities against Candida albicans and C. krusei. The study of the mechanism of action revealed proteins from L. operculata seeds induced pore formation on the membrane and ROS overaccumulation. Scanning Electron Microscopy images also showed severe morphological changes in Candida albicans and C. krusei. Proteins from L.operculata seeds did not show antibacterial activity. The enzymatic assays revealed the presence of proteolytic enzymes, serine and cysteine protease inhibitors, and chitinases in both protein extracts. Proteomic analysis by LC-ESI-MS/MS identified 57 proteins related to many biological processes, such as defense to (a)biotic stress, energetic metabolism, protein folding, and nucleotide metabolism. In conclusion, the L. operculata seed proteins have biotechnological potential against the human pathogenic yeasts Candida albicans and C. krusei.

Ornamental tobacco floral nectar is a rich source of antimicrobial peptides.

Although floral nectar is a rich source of nutrients, it is rarely infected by microorganisms. Defense molecules such as proteins have been identified in this fluid, but defense peptides have been largely overlooked. Thus, the aim of this study was to perform an extensive peptidomic analysis of the ornamental tobacco floral nectar to seek peptides involved in nectar defense. Using LC-MS/MS, 793 peptides were sequenced and characterized. After extensive bioinformatics analysis, six peptides were selected for further characterization, synthesis, and evaluation of their antimicrobial properties against phytopathogenic fungi and bacteria. All six peptides had antimicrobial activity to some extent. However, the activity varied by peptide concentration and microorganism tested. An analysis of the action mechanism revealed damage in the cell membrane induced by peptides. The results show that floral nectar is rich in peptides and that, together with proteins and hydrogen peroxide, they contribute to plant defense against microorganisms during pollination.

Plant antimicrobial peptides: An overview about classification, toxicity and clinical applications.

Antimicrobial peptides, also known as AMPs, are cationic and amphipathic molecules found in all living organisms, composing part of the defense mechanisms against various pathogens, including fungi, viruses, bacteria, and nematodes. AMPs derived from plants are the focus of this review because they have gained attention as alternative molecules to overcome pathogen resistance as well as new drugs to combat cancer. Plant AMPs are generally classified based on their sequences and structures, as thionins, defensins, hevein-like peptides, knottins, stable-like peptides, lipid transfer proteins, snakins, and cyclotides. Although there are studies reporting the toxicity of plant AMPs to nontarget cells or limitations of oral administration, synthetic AMPs with reduced toxicity or allergenicity, or greater resistance to peptidases can be designed by using different bioinformatics tools. Thus, this review provides information about the classification of plant AMPs, their characteristics, mechanisms of action, hemolytic and cytotoxic potential, possible applications in the medical field, and finally, the use of bioinformatics to help design synthetic AMPs with improved features.

ACE2-derived peptides interact with the RBD domain of SARS-CoV-2 spike glycoprotein, disrupting the interaction with the human ACE2 receptor.

Vaccines could be the solution to the current SARS-CoV-2 outbreak. However, some studies have shown that the immunological memory only lasts three months. Thus, it is imperative to develop pharmacological treatments to cope with COVID-19. Here, the in silico approach by molecular docking, dynamic simulations and quantum biochemistry revealed that ACE2-derived peptides strongly interact with the SARS-CoV-2 RBD domain of spike glycoprotein (S-RBD). ACE2-Dev-PepI, ACE2-Dev-PepII, ACE2-Dev-PepIII and ACE2-Dev-PepIV complexed with S-RBD provoked alterations in the 3D structure of S-RBD, leading to disruption of the correct interaction with the ACE2 receptor, a pivotal step for SARS-CoV-2 infection. This wrong interaction between S-RBD and ACE2 could inhibit the entry of SARS-CoV-2 in cells, and thus virus replication and the establishment of COVID-19 disease. Therefore, we suggest that ACE2-derived peptides can interfere with recognition of ACE2 in human cells by SARS-CoV-2 in vivo. Bioinformatic prediction showed that these peptides have no toxicity or allergenic potential. By using ACE2-derived peptides against SARS-CoV-2, this study points to opportunities for further in vivo research on these peptides, seeking to discover new drugs and entirely new perspectives to treat COVID-19.Communicated by Ramaswamy H. Sarma.

Quantum biochemistry, molecular docking, and dynamics simulation revealed synthetic peptides induced conformational changes affecting the topology of the catalytic site of SARS-CoV-2 main protease.

The recent outbreak caused by SARS-CoV-2 continues to threat and take many lives all over the world. The lack of an efficient pharmacological treatments are serious problems to be faced by scientists and medical staffs worldwide. In this work, an in silico approach based on the combination of molecular docking, dynamics simulations, and quantum biochemistry revealed that the synthetic peptides RcAlb-PepI, PepGAT, and PepKAA, strongly interact with the main protease (Mpro) a pivotal protein for SARS-CoV-2 replication. Although not binding to the proteolytic site of SARS-CoV-2 Mpro, RcAlb-PepI, PepGAT, and PepKAA interact with other protein domain and allosterically altered the protease topology. Indeed, such peptide-SARS-CoV-2 Mpro complexes provoked dramatic alterations in the three-dimensional structure of Mpro leading to area and volume shrinkage of the proteolytic site, which could affect the protease activity and thus the virus replication. Based on these findings, it is suggested that RcAlb-PepI, PepGAT, and PepKAA could interfere with SARS-CoV-2 Mpro role in vivo. Also, unlike other antiviral drugs, these peptides have no toxicity to human cells. This pioneering in silico investigation opens up opportunity for further in vivo research on these peptides, towards discovering new drugs and entirely new perspectives to treat COVID-19.Communicated by Ramaswamy H. Sarma.

Latex peptidases produce peptides capable of delaying fungal growth in bread.

Antimicrobial peptides (AMPs) have been reported to be promising alternatives to chemical preservatives. Thus, this study aimed to characterise AMPs generated from the hydrolysis of wheat gluten proteins using latex peptidases of Calotropis procera, Cryptostegia grandiflora, and Carica papaya. The three hydrolysates (obtained after 16 h at 37 °C, using a 1: 25 enzyme:  substrate ratio) inhibited the growth of Aspergillus niger, A. chevalieri, Trichoderma reesei, Pythium oligandrum, Penicillium sp., and Lasiodiplodia sp. by 60-90%, and delayed fungal growth on bread by 3 days when used at 0.3 g/kg. Moreover, the specific volume and expansion factor of bread were not affected by the hydrolysates. Of 28 peptides identified, four were synthesised and exhibited activity against Penicillium sp. Fluorescence and scanning electron microscopy suggested that the peptides damaged the fungal plasma membrane. Bioinformatics analysis showed that no peptide was toxic and that the antigenic ones had cleavage sites for trypsin or pepsin.

Structural Analysis Revealed the Interaction of Cardenolides from Calotropis procera with Na+/K+ ATPases from Herbivores.

BACKGROUND: The herbivores Danaus plexippus (Lepidoptera), Oncopeltus fasciatus, and Aphis nerii (Hemiptera) are special insects that feed on Calotropis procera (Apocynaceae) (Sodom Apple). At least 35 chemically distinct cardenolides have been reported in C. procera. OBJECTIVE: We aimed to evaluate the interaction between cardenolides and Na+/K+ ATPases from herbivores. METHODS: The Na+/K+ ATPases from these insects were modeled, and docking studies were performed involving cardenolides from C. procera. RESULTS: The replacement of serine in sensitive Na+/K+ ATPase by histidine, phenylalanine, and tyrosine in the structures examined suggested spatial impairment caused by interaction, probably making the herbivorous insects resistant against the cardenolides of C. procera. In addition, the ability of the insects to avoid cardenolide toxicity was not correlated with cardenolide polarity. Therefore, the plant fights predation through molecular diversity, and the insects, regardless of their taxonomy, face this molecular diversity through amino acid replacements at key positions of the enzyme targeted by the cardenolides. CONCLUSION: The results show the arsenal of chemically distinct cardenolides synthesized by the C. procera.

Anticancer potential of limonoids from Swietenia macrophylla: Genotoxic, antiproliferative and proapoptotic effects towards human colorectal cancer.

AIMS: Swietenia macrophylla have been considered for the treatment of various diseases, including anticancer activity. This study aimed to investigate the anticancer activity of S. macrophylla leaves extract and its isolated compound towards human colorectal cancer cell line. MAIN METHODS: Hexanic extract of S. macrophylla leaves demonstrated relevant cytotoxicity only against colon cancer cell line HCT116. KEY FINDINGS: Our results showed significant DNA damage and apoptosis after treatment with the hexanic extract of S. macrophylla. Moreover, no toxicity was noticed for the animal model. The isolated compound limonoid L1 showed potent cytotoxicity against cancer cell lines with IC50 at 55.87 µg mL-1. Limonoid L1 did not trigger any cell membrane rupture in the mice erythrocytes suggesting no toxicity. The antiproliferative effect of L1 was confirmed in colorectal cancer cells by clonogenic assay, inducing G2/M arrest, apoptosis, and DNA damage in cancer-type cells. SIGNIFICANCE: L1 reduced BCL2 and increased ATM, CHK2, TP53, ARF, CDK1, CDKN1A, and CASP3 in the colorectal cancer cell line. These findings suggest that limonoid L1 isolated from S. macrophylla can be a promising anticancer agent in managing colorectal cancer.

Kinase inhibitor screening reveals aurora-a kinase is a potential therapeutic and prognostic biomarker of gastric cancer.

Gastric cancer is one of the most common and deadly types of cancer in the world, and poor prognosis with treatment failure is widely reported in the literature. In this context, kinases have been considered a relevant choice for targeted therapy in gastric cancer. Here, we explore the antiproliferative and antimigratory effects of the AURKA inhibitor and the prognostic and therapeutic value as a biomarker of gastric cancer. A total of 145 kinase inhibitors were screened to evaluate the cytotoxic or cytostatic effects in the gastric cancer cell line. Using the Alamar Blue assay, flow cytometry, quantitative polymerase chain reaction, and observation of caspase 3/7 activity and cell migration, we investigated the antiproliferative, proapoptotic, and antimigratory effects of the AURKA inhibitor. Moreover, AURKA overexpression was evaluated in the gastric cell lines and the gastric tumor tissue. Out of the 145 inhibitors, two presented the highest antiproliferative effect. Both molecules can induce apoptosis by the caspases 3/7 pathway in addition to inhibiting cancer cell migration, mainly the AURKA inhibitor. Moreover, molecular docking analysis revealed that GW779439X interacts in the active site of the AURKA enzyme with similar energy as a well-described inhibitor. Our study identified AURKA overexpression in the gastric cancer cell line and gastric tumor tissue, revealing that its overexpression in patients with cancer is correlated with low survival. Therefore, it is feasible to suggest AURKA as a potential marker of gastric cancer, besides providing robust information for diagnosis and estimated survival of patients. AURKA can be considered a new molecular target used in the prognosis and therapy of gastric cancer.

Computational approach, scanning electron and fluorescence microscopies revealed insights into the action mechanisms of anticandidal peptide Mo-CBP3-PepIII.

AIMS: The Candida genus is composed of opportunistic pathogens that threaten public health. Given the increase in resistance to current drugs, it is necessary to develop new drugs to treat infections by these pathogens. Antimicrobial peptides are promising alternative molecules with low cost, broad action spectrum and low resistance induction. This study aimed to clarify the action mechanisms of synthetic peptides against Candida albicans. MAIN METHODS: The mode of action of the anticandidal peptides Mo-CBP3-PepIII were analyzed through molecular dynamics and quantum biochemistry methods against Exo-ß-1,3-glucanase (EXG), vital to cell wall metabolism. Furthermore, scanning electron (SEM) and fluorescence (FM) microscopies were employed to corroborate the in silico data. KEY FINDINGS: Mo-CBP3-PepIII strongly interacted with EXG (-122.2 kcal mol-1) at the active site, higher than the commercial inhibitor pepstatin. Also, molecular dynamics revealed the insertion of Mo-CBP3-PepIII into the yeast membrane. SEM analyses revealed that Mo-CBP3-PepIII induced cracks and scars of the cell wall and FM analyses confirmed the pore formation on the Candida membrane. SIGNIFICANCE: Mo-CBP3-PepIII has strong potential as a new drug with a broad spectrum of action, given its different mode of action compared to conventional drugs.

Quantum biochemistry in cancer immunotherapy: New insights about CTLA-4/ipilimumab and design of ipilimumab-derived peptides with high potential in cancer treatment.

Cancer is a group of diseases involving disordered growth of abnormal cells with the potential to invade and spread to other parts of the body. Today, immunotherapy is the most efficient treatment, with fewer side effects. Notably, the employment of monoclonal antibodies to inhibit checkpoint proteins, such as CTLA-4, has caused much excitement among cancer immunotherapy researchers. Thus, in-depth analysis through quantum biochemistry and molecular dynamics simulations was performed to understand the complex formed by ipilimumab and its target CTLA-4. Our computational results provide a better understanding of the binding mechanisms and new insights about the CTLA-4: ipilimumab interaction, identifying essential amino acid residues to support the complex. Additionally, we report new interactions such as aromatic-aromatic, aromatic-sulfur, and cation-pi interactions to stabilize the CTLA-4:ipilimumab complex. Finally, quantum biochemistry analyses reveal the most important amino acid residues involved in the CTLA-4:ipilimumab interface, which were used to design synthetic peptides to inhibit CTLA-4. The computational results presented here provide a better understanding of the CTLA-4:ipilimumab binding mechanisms, and can support the development of alternative antibody-based drugs with high relevance in cancer immunotherapy.

The forgotten 2S albumin proteins: Importance, structure, and biotechnological application in agriculture and human health.

2S albumin proteins are a group of important seed storage proteins (SSPs) essential to seeds at early and late developmental stages, by providing amino acids and other nutrients during germination and for seed defense. 2S albumins possess a well-conserved cysteine supporting the stability of temperature, pH, and proteolysis. The 3D structure rich in alpha-helices and positively charged is particularly suited for antibacterial and antifungal activity, which is presented by many 2S albumins. However, the hypervariable region present in 2S albumins induces allergenic reactions. Because of that, 2S albumins have never been recognized for their biotechnological potential. However, the development of servers used for the rational design of antimicrobial molecules has now brought a new application to 2S albumins, acting as a model to design antimicrobial molecules without the toxic or allergenic effects of 2S albumins. Therefore, this review is focused on discussing the importance of 2S albumins to seed development and defense and the biochemical, structural and functional properties of these proteins thought to play a role in their antimicrobial activity. Additionally, the application of 2S albumins to design synthetic antimicrobial peptides is discussed, potentially bringing new functions to these forgotten proteins.

Crystal structure and specific location of a germin-like protein with proteolytic activity from Thevetia peruviana.

Peruvianin-I is a cysteine peptidase (EC 3.4.22) purified from Thevetia peruviana. Previous studies have shown that it is the only germin-like protein (GLP) with proteolytic activity described so far. In this work, the X-ray crystal structure of peruvianin-I was determined to a resolution of 2.15 Å (PDB accession number: 6ORM) and its specific location was evaluated by different assays. Its overall structure shows an arrangement composed of a homohexamer (a trimer of dimers) where each monomer exhibits a typical ß-barrel fold and two glycosylation sites (Asn55 and Asn144). Analysis of its active site confirmed the absence of essential amino acids for typical oxalate oxidase activity of GLPs. Details of the active site and molecular docking results, using a specific cysteine peptidase inhibitor (iodoacetamide), were used to discuss a plausible mechanism for proteolytic activity of peruvianin-I. Histological analyses showed that T. peruviana has articulated anastomosing laticifers, i.e., rows of cells which merge to form continuous tubes throughout its green organs. Moreover, peruvianin-I was detected exclusively in the latex. Because latex peptidases have been described as defensive molecules against insects, we hypothesize that peruvianin-I contributes to protect T. peruviana plants against herbivory.