Latex proteins from Plumeria pudica reduce ligature-induced periodontitis in rats.

BACKGROUND: Previous studies have shown that latex proteins from Plumeria pudica (LPPp) have anti-inflammatory and antioxidant activity. Therefore, the aim of this study was to evaluate the effects in rats of LPPp on ligature-induced periodontitis, an inflammatory disease. METHODS: The animals were divided into groups: saline (animals without induction of periodontitis), periodontitis (induced periodontitis and untreated) and LPPp (induced periodontitis and treated with 40 mg/kg). The following parameters were evaluated after 20 consecutive days of treatment: gingival bleeding index (GBI), probing pocket depth (PPD), alveolar bone height (ABH) and gingival myeloperoxidase (MPO) activity. In the hepatic tissue, malondialdehyde (MDA), glutathione (GSH) and histopathological alterations were evaluated. Blood levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured. RESULTS: Significant reduction in GBI, PPD and gingival MPO activity and ABH was seen in animals treated with LPPp compared with periodontitis. Values of GSH, MDA, ALT and histopathological evaluation were preserved in animals treated with LPPp. CONCLUSIONS: Treatment with LPPp improved clinical aspects of periodontitis, reduced the blood and hepatic alterations and prevented alveolar bone loss. Data suggest that LPPp have potential for treatment of periodontitis.

Anti-inflammatory latex proteins of the medicinal plant Calotropis procera: a promising alternative for oral mucositis treatment.

OBJECTIVE AND DESIGN: Oral mucositis (OM) is an intense inflammatory reaction progressing to tissue damage and ulceration. The medicinal uses of Calotropis procera are supported by anti-inflammatory capacity. PII-IAA, a highly homogenous cocktail of laticifer proteins (LP) prepared from the latex of C. procera, with recognized pharmacological properties was tested to treat OM. MATERIALS AND SUBJECTS: Male Golden Sirius hamsters were used in all treatments. TREATMENT: The latex protein samples were injected i.p. (5 mg/Kg) 24 h before mucositis induction (mechanical trauma) and 24 h later. METHODS: Histology, cytokine measurements [ELISA], and macroscopic evaluation [scores] were performed. RESULTS: PII-IAA eliminated OM, accompanied by total disappearance of myeloperoxidase activity and release of IL-1b, as well as reduced TNF-a. Oxidative stress was relieved by PII-IAA treatment, as revealed by MDA and GSH measurements. PII-IAA also reduced the expression of adhesion molecules (ICAM-1) and Iba-1, two important markers of inflammation, indicating modulatory effects. Histological analyses of the cheek epithelium revealed greater deposition of type I collagen fibers in animals given PII-IAA compared with the control group. This performance was only reached when LPPII was treated with iodoacetamide (IAA), an irreversible inhibitor of proteolytic activity of cysteine proteases. The endogenous proteolytic activity of LPPII induced adverse effects in animals. Candidate proteins involved in the phytomodulatory activity are proposed. CONCLUSIONS: Therapy was successful in treating OM with the laticifer protein fraction, containing peptidases and osmotin, from Calotropis procera. The effective candidate from the latex proteins for therapeutic use is PII-IAA.

Erythrocytes morphology and hemorheology in severe bacterial infection.

BACKGROUND: Severe bacterial infections initiate inadequate inflammation that leads to disseminated intravascular coagulation and death. OBJECTIVES: To evaluate the influence of bacterial infection on blood viscosity and red blood cells (RBCs) morphology, and the ability of Calotropis procera proteins (CpLP) to prevent the patho-hemorheology in infected animals. METHODS: Rheology of blood, atomic force microscopy measurements on specific blood elements and blood count were performed to examine changes in blood viscosity, RBCs morphology, platelets activation, and RBCs indices. FINDINGS: Infected mice hold their blood rheological behaviour as compared to that of the control group. However, they presented hyperactivated platelets, RBCs at different stages of eryptosis, and variation on RBCs indices. CpLP administration in healthy animals altered blood behaviour from pseudoplastic to Bingham-like fluid. Such effect disappeared over time and by inhibiting its proteases. No alterations were observed in RBCs morphology or platelets. Treatment of infected animals with CpLP prevented the changes in RBCs indices and morphology. MAIN CONCLUSIONS: The inflammatory process triggered by bacterial infection induced pathological changes in RBCs and platelets activation. Treatment of infected animals with CpLP prevented the emergence of RBCs abnormal morphology and this may have implications in the protective effect of CpLP, avoiding animal death.

Proteomic identification and purification of seed proteins from native Amazonian species displaying antifungal activity.

MAIN CONCLUSION: Seeds of native species from the rain forest (Amazon) are source of chitinases and their protein extracts exhibited strong and broad antifungal activity. Numerous plant species native to the Amazon have not yet been chemically studied. Studies of seeds are scarcer, since adversities in accessing study areas and seasonality pose constant hurdles to systematic research. In this study, proteins were extracted from seeds belonging to endemic Amazon species and were investigated for the first time. Proteolytic activity, peptidase inhibitors, and chitinases were identified, but chitinolytic activity predominated. Four proteins were purified through chromatography and identified as lectin and chitinases by MS/MS analyses. The proteins were examined for inhibition of a phytopathogen (Fusarium oxysporum). Analyses by fluorescence microscopy suggested binding of propidium iodide to DNA of fungal spores, revealing that spore integrity was lost when accessed by the proteins. Further structural and functional analyses of defensive proteins belonging to species facing highly complex ecosystems such as Amazonia should be conducted, since these could provide new insights into specificity and synergism involving defense proteins of plants submitted to a very complex ecosystem.

A phytomodulatory hydrogel with enhanced healing effects.

The healing performance of a hydrogel composed of hemicelluloses extracted from seeds of Caesalpinia pulcherrima (Fabaceae) and mixed with phytomodulatory proteins obtained from the latex of Calotropis procera was characterized on excisional wounds. The hydrogel did not induce dermal irritability. When topically used on excisional wounds, the hydrogel enhanced healing by wound contraction. Histology and the measurement of inflammatory mediators (myeloperoxidase, interleukin-1ß, and interleukin-6) suggested that the inflammatory phase of the healing process was intensified, stimulating fibroplasia and neovascularization (proliferative phase) and tissue remodeling by increasing new collagen fiber deposition. In addition, reduction on levels of malondialdehyde in the groups that the hydrogel was applied suggested that the oxidative stress was reduced. The hydrogel performed better than the reference drug used, as revealed by the extended thickness of the remodeled epithelium.

Latex peptidases of Calotropis procera for dehairing of leather as an alternative to environmentally toxic sodium sulfide treatment.

Dehairing of crude leather is a critical stage performed at the beginning of its processing to obtain industrially useful pieces. Tanneries traditionally apply a chemical process based on sodium sulfide. Since this chemical reactive is environmentally toxic and inefficiently recycled, innovative protocols for reducing or eliminating its use in leather depilation are welcomed. Therefore, latex peptidases from Calotropis procera (CpLP) and Cryptostegia grandiflora (CgLP) were assayed for this purpose. Enzyme activity on substrates representative of skin such as hide powder azure (UHPA), elastin (UE), azocollagen (UAZOCOL), keratin (UK), and epidermis (UEP) was determined, while depilation activity was assayed on cow hide. Only CpLP was active against keratin (13.4 UK) and only CgLP was active against elastin (0.12 UE). CpLP (93.0 UHPA, 403.6 UAZOCOL, 36.3 UEP) showed higher activity against the other substrates than CgLP (47.6 UHPA, 261.5 UAZOCOL, 8.5 UEP). In pilot assays, CpLP (0.05% w/v with sodium sulfite 0.6% w/v as activator) released hairs from cow hide pieces. Macroscopic and microscopic analyses of the hide revealed that the dehairing process was complete and the leather structure was preserved. The proteolytic system of C. procera is a suitable bioresources to be exploited by tanneries.

Proteomic analysis and purification of an unusual germin-like protein with proteolytic activity in the latex of Thevetia peruviana.

MAIN CONCLUSION: The latex from Thevetia peruviana is rich in plant defense proteins, including a 120 kDa cysteine peptidase with structural characteristics similar to germin-like proteins. More than 20,000 plant species produce latex, including Apocynaceae, Sapotaceae, Papaveraceae and Euphorbiaceae. To better understand the physiological role played by latex fluids, a proteomic analysis of Thevetia peruviana (Pers.) Schum latex was performed using two-dimensional gel electrophoresis and mass spectrometry. A total of 33 proteins (86 %) were identified, including storage proteins, a peptidase inhibitor, cysteine peptidases, peroxidases and osmotins. An unusual cysteine peptidase, termed peruvianin-I, was purified from the latex by a single chromatographic step involving gel filtration. The enzyme (glycoprotein) was inhibited by E-64 and iodoacetamide and exhibited high specific activity towards azocasein (K m 17.6 µM), with an optimal pH and temperature of 5.0-6.0 and 25-37 °C, respectively. Gel filtration chromatography, two-dimensional gel electrophoresis, and mass spectrometry revealed that peruvianin-I possesses 120 kDa, pI 4.0, and six subunits (20 kDa). A unique N-terminal amino acid sequence was obtained to oligomer and monomers of peruvianin-I (1ADPGPLQDFCLADLNSPLFINGYPCRNPALAISDDF36). High-resolution images from atomic force microscopy showed the homohexameric structure of peruvianin-I may be organized as a trimer of dimers that form a central channel similar to germin-like proteins. Peruvianin-I exhibited no oxalate oxidase and superoxide dismutase activity or antifungal effects. Peruvianin-I represents the first germin-like protein (GLP) with cysteine peptidase activity, an activity unknown in the GLP family so far.

Peptidases and peptidase inhibitors in gut of caterpillars and in the latex of their host plants.

Studies investigating the resistance-susceptibility of crop insects to proteins found in latex fluids have been reported. However, latex-bearing plants also host insects. In this study, the gut proteolytic system of Pseudosphinx tetrio, which feeds on Plumeria rubra leaves, was characterized and further challenged against the latex proteolytic system of its own host plant and those of other latex-bearing plants. The gut proteolytic system of Danaus plexippus (monarch) and the latex proteolytic system of its host plant (Calotropis procera) were also studied. The latex proteins underwent extensive hydrolysis when mixed with the corresponding gut homogenates of the hosted insects. The gut homogenates partially digested the latex proteins of foreign plants. The fifth instar of D. plexippus that were fed diets containing foreign latex developed as well as those individuals who were fed diets containing latex proteins from their host plant. In vitro assays detected serine and cysteine peptidase inhibitors in both the gut homogenates and the latex fluids. Curiously, the peptidase inhibitors of caterpillars did not inhibit the latex peptidases of their host plants. However, the peptidase inhibitors of laticifer origin inhibited the proteolysis of gut homogenates. In vivo analyses of the peritrophic membrane proteins of D. plexippus demonstrate resistance against latex peptidases. Only discrete changes were observed when the peritrophic membrane was directly treated with purified latex peptidases in vitro. This study concludes that peptidase inhibitors are involved in the defensive systems of both caterpillars and their host plants. Although latex peptidase inhibitors inhibit gut peptidases (in vitro), the ability of gut peptidases to digest latex proteins (in vivo) regardless of their origin seems to be important in governing the resistance-susceptibility of caterpillars.

Review: Laticifer as a plant defense mechanism.

Laticifers have been utilized as paradigms to enhance comprehension of specific facets of plant ecology and evolution. From the beginning of seedling growth, autonomous laticifer networks are formed throughout the plant structure, extending across all tissues and organs. The vast majority of identified products resulting from laticifer chemistry and metabolism are linked to plant defense. The latex, which is the fluid contained within laticifers, is maintained under pressure and has evolved to serve as a defense mechanism against both aggressors and invaders, irrespective of their capabilities or tactics. Remarkably, the latex composition varies among different species. The current goal is to understand the specific functions of various latex components in combating plant enemies. Therefore, the study of latex's chemical composition and proteome plays a critical role in advancing our understanding about plant defense mechanisms. Here, we will discuss some of these aspects.

Class III plant peroxidases: From classification to physiological functions.

Peroxidases (EC 1.11.1.7) are involved in a wide range of physiological processes, hence their broad distribution across biological systems. These proteins can be classified as haem or non-haem enzymes. According to the RedOxiBase database, haem peroxidases are approximately 84 % of all known peroxidase enzymes. Class III plant peroxidases are haem-enzymes that share similar three-dimensional structures and a common catalytic mechanism for hydrogen peroxide degradation. They exist as large multigene families and are involved in metabolizing Reactive Oxygen Species (ROS), hormone synthesis and decomposition, fruit growth, defense, and cell wall synthesis and maintenance. As a result, plant peroxidases gained attention in research and became one of the most extensively studied groups of enzymes. This review provides an update on the database, classification, phylogeny, mechanism of action, structure, and physiological functions of class III plant peroxidases.

Proteomic analysis of Cryptostegia grandiflora latex, purification, characterization, and biological activity of two osmotin isoforms.

Although latex fluids are found in >20,000 plant species, the biochemical composition and biological function of their proteins are still poorly explored. Thus, this work aimed to conduct a proteomic analysis of Cryptostegia grandiflora latex (CgLP) for subsequent purification and characterization of an antifungal protein. After 2D-SDS-PAGE and mass spectrometry, 27 proteins were identified in CgLP, including a polygalacturonase inhibitor, cysteine peptidases, pathogenesis-related proteins (PR-4), and osmotins. Then, two osmotin isoforms (CgOsm) were purified, and a unique N-terminal sequence was determined (1ATFDIRSNCPYTVWAAAVPGGGRRLDRGQTWTINVAPGTA40). The PCR products revealed a cDNA sequence of 609 nucleotides for CgOsm, which encoded a polypeptide with 203 amino acid residues. The structure of CgOsm has features of typical osmotin or thaumatin-like proteins (TLPs), such as 16 conserved Cys residues, REDDD and FF motifs, an acidic cleft, and three main domains. Atomic force microscopy (AFM) and bioinformatics suggested that CgOsm is associated with three chain units. This result was interesting since the literature describes osmotins and TLPs as monomers. AFM also showed that Fusarium falciforme spores treated with CgOsm were drastically damaged. Therefore, it is speculated that CgOsm forms pores in the membrane of these cells, causing the leakage of cytoplasmic content.

Wound tissue remodeling by latex exudate of Himatanthus drasticus: A plant species used in Brazilian folk medicine.

This work investigated the healing properties of proteins extracted of latex (HdLP) on excisional wounds. Cell toxicity of HdLP was investigated carried out in murine fibroblasts after incubation with HdLP (12.5-100 µg/ml). The dermal irritability test was performed to evaluate dermal reactions. The wounds were performed and treated with vehicle or HdLP (0.5 %, 1.0 %, and 2.0 %). The macroscopic parameters, histological analysis and measurement of inflammatory markers and mediators were evaluated. HdLP did not exhibit cytotoxicity and did not induce skin irritation. HdLP stimulated the release of IL-1ß at the beginning of the inflammatory phase. This effect probably favored the earlier release of IL-10 by macrophages, during the proliferative phase. The shortening and completeness of healing were characterized by fibroblast proliferation and the presence of newly synthesized collagen fibers. This was accompanied by well-organized re-epithelialization. The involvement of latex proteins in this activity is reported for the first time.

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.

Inflammation induced by phytomodulatory proteins from the latex of Calotropis procera (Asclepiadaceae) protects against Salmonella infection in a murine model of typhoid fever.

OBJECTIVE AND DESIGN: Laticifer proteins (LP) of Calotropis procera were fractionated by ion-exchange chromatography, and the influence of a sub-fraction (LP(PI)) on the inflammatory response of Swiss mice challenged by Salmonella enterica Ser. Typhimurium was investigated. METHODS: Mice (n = 10) received LP(PI) (30 or 60 mg/kg) in a single inoculum by the intraperitoneal route 24 h before infection. To investigate the relevance of the proteolytic activity, three additional groups were included: the first one received heat-treated LP (30 mg/kg-30 min at 100 °C), the second received LP (30 mg/kg) inactivated by iodoacetamide, and a control group received only phosphate-buffered saline (PBS). RESULTS: The survival rate reached 100 % in mice treated with LP(PI) and was also observed with the other treatment, whereas the PBS group died 1-3 days after infection. The neutrophil infiltration into the peritoneal cavity of pretreated mice was enhanced and accompanied by high bacterial clearance from the bloodstream. Tumor necrosis factor-alpha mRNA transcripts, but not interferon-gamma, were detected early in spleen cells of pretreated mice after infection; however, the nitric oxide contents in the bloodstream were decreased in comparison to the PBS group. CONCLUSIONS: The inflammatory stimulus of C. procera proteins increased phagocytosis and balanced the nitric oxide release in the bloodstream, preventing septic shock induced by Salmonella infection.

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.

Serine carboxypeptidases from the carnivorous plant Nepenthes mirabilis: Partial characterization and heterologous expression.

This study aimed to partially characterize the three main serine carboxypeptidases (SCP3, SCP20, and SCP47) from Nepenthes mirabilis. Furthermore, one peptidase (SCP3) was chosen for further heterologous expression in Escherichia coli Shuffle®T7. SCP3 also was characterized in terms of its allergenic potential using bioinformatics tools. SCP3, SCP20, and SCP47 showed very similar 3D structures and mechanistic features to other plant serine peptidases belonging to clan SC and family S10. Although SCP3 was obtained in its soluble form, using 1% ethanol during induction with 0.5 mM IPTG at 16 °C for 18 h, it did not show proteolytic activity by zymography or in vitro analysis. SCP3 presented a few allergenic peptides and several cleavage sites for digestive enzymes. This work describes additional features of these enzymes, opening new perspectives for further studies for characterization and analysis of heterologous expression, as well as their potential biotechnological applications.

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.

Successful Pre-Clinical Management of Irinotecan-Debilitated Animals: A Protein- Based Accessory Phytomedicine.

BACKGROUND: Calotropis procera is a laticiferous plant (Apocynaceae) found in tropical regions all over the world. The ultrastructural characteristics of laticifers, their restricted distribution among different taxonomic groups, and in some species in each clade, as peptidases from latex, make them very attractive for biological analysis. OBJECTIVE: The study aims to investigate the effects of LP-PII-IAA (laticifer protein (LP) sub-fraction II (PII) of C. procera presenting an iodoacetamide-inhibited cysteine proteinase activity) on irinotecan-induced intestinal mucositis, a serious adverse effect of this medicine for the treatment of cancer. METHODS: LP-PII-IAA is composed of closely related isoforms (90%) of peptidases derived from catalysis and an osmotin protein (5%). Animals receiving co-administration of LP-PII-IAA presented a significant decrease in mortality, absence of diarrhea, histological preservation, and normalization of intestinal functions. RESULTS: Clinical homeostasis was accompanied by a reduction in MPO activity and declined levels of IL-1ß, IL-6 and KC, while the IL-10 level increased in LP-PII-IAA-treated animals. COX-2 and NF-kB immunostaining was reduced and the levels of oxidative markers (GSH, MDA) were normalized in animals that received LP-PII-IAA. CONCLUSION: We suggest that peptidases from the latex of Calotropis procera were instrumental in the suppression of the adverse clinical and physiological effects of irinotecan.

Laticifer proteins play a defensive role against hemibiotrophic and necrotrophic phytopathogens.

Proteins from latex of Calotropis procera (CpLP), Plumeria rubra (PrLP), Carica candamarcensis (P1G10) and Euphorbia tirucalli (EtLP) were tested for antifungal activity against phytopathogens. CpLP and P1G10 inhibited each fungi analyzed. PrLP and EtLP did not exert inhibition. CpLP and P1G10 exhibited preferential inhibitory activity towards R. solani (IC50 = 20.7 and 25.3 µg/ml, respectively). The inhibitory activity was lost after heat treatment or proteolysis, providing evidence for the involvement of proteins in the inhibitory effect. Treatment of CpLP or P1G10 with Dithiothreitol improved both, the endogenous proteolytic activity and the antifungal properties. Conversely, pre-treatment of CpLP or P1G10 with iodoacetamide drastically reduced endogenous proteolytic activities and partially abrogated antifungal activity. Similar results were observed when spores were challenged to germinate in the presence of laticifer proteins. The purified cysteine proteinase CMS2MS2 from Carica candamarcensis latex or papain (E.C. 3.4.22.2), a cysteine proteinase from latex of Carica papaya L., but not trypsin (EC 3.4.21.4) or chymotrypsin (EC 3.4.21.1), two serine proteases, replicated the results obtained with CpLP or P1G10, thus restricting the antifungal property to latex plant cysteine proteinases. CpLP, CMS2MS2 and papain induced production of reactive oxygen species in spores of F. solani, suggesting that inhibition could be linked to oxidative stress. Proteome analysis of CpLP by 2-D electrophoresis and MALDI-TOF-TOF confirmed the existence of various pathogenic-related proteins such as chitinases, peroxidases and osmotins. The results support that laticifer proteins are part of plant defense repertoire against phytopathogenic fungi.

Protective effect of proteins derived from the latex of Calotropis procera against inflammatory hyperalgesia in monoarthritic rats.

Calotropis procera (family: Apocynaceae) is a plant growing in the wild and has been used in the traditional medicinal system for the treatment of various diseases. The plant produces milky latex that possesses potent antiinflammatory and analgesic properties. In present study the non-dialysable protein fraction isolated from the latex (LP) of this plant was evaluated for its efficacy against inflammation in rats where paw edema was induced by sub-plantar injection of carrageenin or monoarthritis was induced by intra-articular injection of Freund's complete adjuvant (FCA). The effect of LP was evaluated on edema volume in the paw model and on joint diameter, stair climbing ability, motility, dorsal flexion pain, levels of oxidative stress markers and joint histology in arthritis model. The protection afforded by LP was compared with that of standard antiinflammatory drug, diclofenac (5 mg/kg). LP exhibited a dose-dependent antiinflammatory effect and produced 32% and 60% inhibition of paw edema at 10 and 25 mg/kg doses and 12% and 36% inhibition of joint inflammation at 50 and 150 mg/kg doses. The protective effect of LP was associated with normalization of joint functions, histology and levels of oxidative stress markers in joint tissue. The findings of this study suggest that the protein fraction of latex of Calotropis procera has the potential to relieve inflammation and pain associated with various arthritic conditions.