Effects of aqueous extract of Casearia sylvestris (Flacourtiaceae) on actions of snake and bee venoms and on activity of phospholipases A2

Casearia sylvestris var. lingua (Càmbess.) Eichler leaves aqueous extract improves colon inflammation through mucogenic, antioxidant and anti-inflammatory actions in TNBS- induced IBD rats

ETHNOPHARMACOLOGICAL RELEVANCE

Casearia sylvestris var. lingua (Cambess.) Eichler, a member of the Salicaceae family, holds a prominent place in traditional medicine across various cultures due to its versatile therapeutic properties. Historically, indigenous communities have utilized different parts of the plant, including leaves, bark, and roots, to address a wide array of health conditions. Traditional uses of C. sylvestris var. lingua encompasses the treatment of gastrointestinal disorders, respiratory infections, wound healing, inflammation, and stomach ulcers. Pharmacological studies have demonstrated the plant's antimicrobial, anti-inflammatory, antioxidant, analgesic, gastroprotective, and immunomodulatory effects. This signifies the first scientific validation report for C. sylvestris var. lingua regarding its effectiveness against ulcerative colitis. The report aims to affirm the traditional use of this plant through pre-clinical experiments.

AIM OF THE RESEARCH

This work uses an aqueous extract from C. sylvestris var. lingua leaves (AECs) to evaluate the acute anti-ulcerative colitis efficacy in rat and HT-29 (human colorectal cancer cell line) models.

METHODS

To determine the secondary metabolites of AECs, liquid chromatography with a diode array detector (LC-DAD) study was carried out. 2,4,6-trinitrobenzenesulfonic acid (TNBS, 30 mg/0.25 mL EtOH 30% v/v) was used as an enema to cause acute colitis. Three days were spent giving the C. sylvestris var. lingua extract orally by gavage at dosages of 3, 30, and 300 mg/kg. The same route was used to deliver distilled water to the vehicle and naïve groups. After the animals were sacrificed on the fourth day, intestinal tissues were taken for histological examination and evaluation of biochemical tests such as those measuring superoxide dismutase (SOD), reduced glutathione (GSH), catalase (CAT), malondialdehyde (MDA), nitrite/nitrate, myeloperoxidase (MPO) activity. Additionally, interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and interleukin 10 (IL-10), were conducted on the intestinal tissues. Additionally, an MTT assay was used to evaluate the effect of AECs on the viability of HT-29 cells. Additionally, a molecular docking study was carried out to compare some potential target proteins with identified chemicals found in AECs.

RESULTS

LC-DAD analysis identified five compounds (caffeic acid, ellagic acid, ferulic acid, gallic acid, and quercetin) in AECs. Pre-administration of AECs (3; 30; 300 mg/kg) and mesalazine (500 mg/kg) reduced macroscopic scores (55%, 47%, 45%, and 52%, p < 0.001) and ulcerated areas (70.3%, 70.5%, 57%, and 56%, p < 0.001), respectively. It also increased SOD, GSH, and CAT activities (p < 0.01), while decreasing MDA (p < 0.001), nitrite/nitrate (p < 0.05), and MPO (p < 0.001) activities compared to the colitis group. Concerning inflammatory markers, significant modulations were observed: AECs (3, 30, and 300 mg/kg) lowered levels of IL-1β and TNF-α (p < 0.001) and increased IL-10 levels (p < 0.001) compared to the colitis groups. The viability of HT-29 cells was suppressed by AECs with an IC50 of 195.90 ± 0.01 μg/mL (48 h). During the molecular docking analysis, quercetin, gallic acid, ferulic acid, caffeic acid, and ellagic acid demonstrated consistent binding affinities, forming stable interactions with the 3w3l (TLR8) and the 3ds6 (MAPK14) complexes.

CONCLUSION

These results imply that the intestinal mucogenic, anti-inflammatory, and antioxidant properties of the C. sylvestris var. lingua leaf extract may be involved in its therapeutic actions for ulcerative colitis. The results of the in silico study point to the possibility of quercetin and ellagic acid interacting with P38 and TLR8, respectively, in a beneficial way.

Promising Effects of Casearins in Tumor-Bearing Mice and Antinociceptive Action against Oncologic Pain: Molecular Docking and In Vivo Findings

Safer analgesic drugs remain a hard challenge because of cardiovascular and/or gastrointestinal toxicity, mainly. So, this study evaluated in vivo the antiproliferative actions of a fraction with casearins (FC) from Casearia sylvestris leaves against human colorectal carcinomas and antihyperalgesic effects on inflammatory- or opiate-based pain relief and oncologic pain in Sarcoma 180 (S180)-bearing mice. Moreover, docking investigations evaluated the binding among Casearin X and NMDA(N-methyl-D-aspartate)-type glutamate receptors. HCT-116 colorectal carcinoma-xenografted mice were treated with FC for 15 days. Antinociceptive assays included chemically induced algesia and investigated mechanisms by pharmacological blockade. Intraplantar region S180-bearing animals received a single dose of FC and were examined for mechanical allodynia and behavior alterations. AutoDock Vina determined molecular interactions among Cas X and NMDA receptor subunits. FC reduced tumor growth at i.p. (5 and 10 mg/kg) and oral (25 mg/kg/day) doses (31.12-39.27%). FC reduced abdominal pain, as confirmed by formalin and glutamate protocols, whose antinociception activity was blocked by naloxone and L-NAME (neurogenic phase) and naloxone, atropine, and flumazenil (inflammatory phase). Meanwhile, glibenclamide potentiated the FC analgesic effects. FC increased the paw withdrawal threshold without producing changes in exploratory parameters or motor coordination. Cas X generated a more stable complex with active sites of the NMDA receptor GluN2B subunits. FC is a promising antitumor agent against colorectal carcinomas, has peripheral analgesic effects by desensitizing secondary afferent neurons, and inhibits glutamate release from presynaptic neurons and/or their action on cognate receptors. These findings emphasize the use of clerodane diterpenes against cancer-related pain conditions.

The potential of Brazilian native plant species used in the therapy for snakebites: A literature review

Snakebite envenoming is a potentially fatal disease categorized as a neglected public health issue for not receiving the appropriate attention from national and international health authorities. The most affected people by this problem usually live in poor rural communities, where medical resources are often sparse and, in some instances, there is even a scarcity of serum therapy. The administration of the appropriate antivenom is the only specific treatment available, however it has limited efficacy against venom-induced local effects. In this scenario, various plant species are used as local first aid for the treatment of snakebite accidents in Brazil, and some of them can effectively inhibit lethality, neurotoxicity, hemorrhage, and venom enzymes activities. This review compiles a list of plants used in the treatment of snakebites in Brazil, focusing on the native Brazilian species registered in the databases Pubmed, Scielo, Scopus and Google Scholar. All these searches were limited to peer-reviewed journals written in English, with the exception of a few articles written in Portuguese. The most cited native plant species were Casearia sylvestris Sw., Eclipta prostrata (L.) L., Mikania glomerata Spreng., Schizolobium parahyba (Vell.) S.F.Blake and Dipteryx alata Vogel, all used to decrease the severity of toxic signs, inhibit proteolytic and hemorrhagic activities, thus increasing survival time and neutralizing myotoxicity effects. Different active compounds showing important activity against the snake venoms and their toxins include flavonoids, alkaloids and tannins. Although some limitations to the experimental studies with medicinal plants were observed, including lack of comparison with control drugs and unknown active extracts compounds, species with anti-venom characteristics are effective and considered as candidates for the development of adjuvants in the treatment of snake envenomation. Further studies on the chemistry and pharmacology of traditionally used plant species will help to understand the role that snakebite herbal remedies may display in local medical health systems. It might also contribute to the development of alternative or complementary treatments to reduce the number of severe disabilities and deaths.

The synthetic varespladib molecule is a multi-functional inhibitor for PLA2 and PLA2-like ophidic toxins

BACKGROUND

The treatment for snakebites is early administration of antivenom, which can be highly effective in inhibiting the systemic effects of snake venoms, but is less effective in the treatment of extra-circulatory and local effects. To complement standard-of-care treatments such as antibody-based antivenoms, natural and synthetic small molecules have been proposed for the inhibition of key venom components such as phospholipase A₂ (PLA₂) and PLA₂-like toxins. Varespladib (compound LY315920) is a synthetic molecule developed and clinically tested aiming to block inflammatory cascades of several diseases associated with high PLA₂s. Recent studies have demonstrated this molecule is able to potently inhibit snake venom catalytic PLA₂ and PLA₂-like toxins.

METHODS

In vivo and in vitro techniques were used to evaluate the inhibitory effect of varespladib against MjTX-I. X-ray crystallography was used to reveal details of the interaction between these molecules. A new methodology that combines crystallography, mass spectroscopy and phylogenetic data was used to review its primary sequence.

RESULTS

Varespladib was able to inhibit the myotoxic and cytotoxic effects of MjTX-I. Structural analysis revealed a particular inhibitory mechanism of MjTX-I when compared to other PLA₂-like myotoxin, presenting an oligomeric-independent function.

CONCLUSION

Results suggest the effectiveness of varespladib for the inhibition of MjTX-I, in similarity with other PLA₂ and PLA₂-like toxins.

GENERAL SIGNIFICANCE

Varespladib appears to be a promissory molecule in the treatment of local effects led by PLA₂ and PLA₂-like toxins (oligomeric dependent and independent), indicating that this is a multifunctional or broadly specific inhibitor for different toxins within this superfamily.

Macroscopic, biochemical and hystological evaluation of topical anti-inflammatory activity of Casearia sylvestris (Flacourtiaceae) in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Inflammatory skin diseases presents high prevalence and lack of alternatives that can be used for self-care by the population. Casearia sylvestris is a plant used topically in different communities in Brazil, to treat wounds or promote cutaneous healing. To evaluate the topical anti-inflammatory activity for the crude hydroalcoholic extract of Casearia sylvestris (HCE-CS) in the models of single or multiple administration of chroton oil to induce ear edema in mice.

MATERIALS AND METHODS

Experimental study using male Swiss mice (25-35g) kept under constant conditions in the Laboratory of Experimental Neuroscience (LaNEx)-UNISUL. Edema was induced in both models, respectively, by the single or multiple application of croton oil (CO, 2.5%, in 20 μl) on the external surface of the ear. The different groups of animals (n = 8) received different treatments: vehicle, dexamethasone (DEXA) or different doses of HCE-CS. Edema was evaluated macroscopically for 6 h (early edema) or 8 days (late edema) after the first application of the CO and immediately after the animals were submitted to euthanasia for the collection of the samples (treated ears). For early edema, the tissue was biochemically evaluated for myeloperoxidase activity (MPO) and levels of nitrite/nitrate. In the late edema model, the ears were histologically evaluated for general morphometry, degranulated and non-degranulated mast cells, as well as acanthosis.

RESULTS

Topic treatment with HCE-CS significantly reduced the early and late edema, as well as MPO activity and tissue levels of nitrite/nitrate. Finally, in the late edema model there was a lower density of degranulated mast cells in relation to the vehicle treated group and decreased thickness of the epidermis (acanthosis).

CONCLUSION

These results suggest a possible benefit of topical treatment with HCE-CS in inflammatory conditions of the skin.

Using the plants of Brazilian Cerrado for wound healing: From traditional use to scientific approach

ETHNOPHARMACOLOGICAL RELEVANCE

The Brazilian Cerrado is a biome with a remarkable diversity of plant species, many of which are used mainly by local communities as a source of treatment to several pathologic processes, especially for the treatment of wounds. However, no systematic review exists focusing on the plants used in this respect and on the appropriate pharmacological investigations that substantiate the actions that are reported. This study revisits the traditional use of medicinal plants from the Brazilian Cerrado in the treatment of wounds and the pharmacological characteristics of the reported plant species.

METHOD

ology: For the present article, previous studies on plants of the Brazilian Cerrado used for wound healing carried out between 1996 and 2018 were researched on various academic databases (PubMed, Elsevier, Springer, Lilacs, Google Escolar, and Scielo).

RESULTS

A total of 33 studies were carried out on 29 plant species distributed into 18 families, mainly Fabaceae or Leguminosae (9), Bignoniaceae (2), Asteraceae (2), Euphorbiaceae (2). Considering the great diversity of Cerrado plants, only a small number of wound healing studies were carried out between 1996 and 2018. It was observed that there is a large gap between experimentation assay and traditional use. There are only few connections between the form of use by the population and the experiments conducted in the laboratory. We found that only about 12% of these studies considered to use the methodologies, or at least in parts, to obtain extracts such as those used in folk medicine. Approximately 37% of the experiments were performed using the bark as well as the same ratio for leaves, 6% using the fruits, and 9% using the seeds, roots or flowers. In several studies, there are reports of chemical constituents such as flavonoids and tannins, followed by steroid terpenes, saponins, and fatty acids, and alkaloids. However, approximately 35% of the studies did not supply information about compounds present in the preparation or the effect which could be attributed to these agents in respect to wound healing. Regarding treatment, most of the studies employed a topical treatment, though intraperitoneal and oral treatment were also described using either topical, oil-based formulations, but also gel- or saline-based formulations.

CONCLUSIONS

Although, there has been an increase in knowledge about the biological actions of plants from Cerrado biome, the scientific basis for the traditional use of these local medicinal plants in wound healing does not provide sufficient information on the efficacy of the treatment, the molecular mechanisms, or, in particular, the effective doses used and the drug interactions. Thus, focused research investigating these hypotheses from traditional knowledge is necessary to prove the evidence of the potential pharmacological action.

Vanillic acid as phospholipase A2 and proteases inhibitor: In vitro and computational analyses

Enzymatic inhibition by natural compounds may represent a valuable adjuvant in snakebite serum therapy. The objective in this work was to evaluate possible in vitro interactions between vanillic acid and enzymes from Bothrops spp. and Crotalus durissus terrificus venoms, and also suggest a theory as how they interact based on molecular docking. Vanillic acid inhibited the phospholipase activity induced by Bothrops alternatus (∼25% inhibition); the caseinolytic activity induced by Bothrops atrox (∼30%), Bothrops jararacussu (∼44%), and C. d. terrificus (∼33%); the fibrinogenolysis induced by B. jararacussu, B. atrox, and C. d. terrificus (100%); the serine protease activity induced by Bothrops moojeni (∼45%) and Bothrops jararaca (∼66%); the hemolytic activity induced by B. moojeni (∼26%); the thrombolysis activity induced by B. atrox (∼30%) and B. jararacussu (∼20%); and the thrombotic activity induced by C. d. terrificus (∼8%). The compound was also capable of delaying the coagulation time in citrated plasma by 60, 35, and 75 Sec, when incubated with B. moojeni, B. atrox, and B. jararaca, respectively. The results obtained expand the possibilities for future pharmaceutical use of vanillic acid, considering the high homology degree among human and snake venom phospholipases A₂ and proteases (involved in chronic inflammatory diseases). Also, this compound can be used as adjuvant to improve currently available treatments for ophidism victims.

Antimicrobial and antibiofilm activities of Casearia sylvestris extracts from distinct Brazilian biomes against Streptococcus mutans and Candida albicans

Background

Dental caries is a biofilm-diet-dependent worldwide public health problem, and approaches against microorganisms in cariogenic biofilms are necessary.

Methods

The antimicrobial and antibiofilm activities of 12 Casearia sylvestris extracts (0.50 mg/mL) from different Brazilian biomes (Atlantic Forest, Cerrado, Caatinga, Pampa, and Pantanal) and varieties (sylvestris, lingua, and intermediate) were tested against two species found in cariogenic biofilms (Streptococcus mutans and Candida albicans). The extracts effective against S. mutans were used to evaluate the "adhesion strength" of this bacterium to the salivary pellicle and initial glucan matrix and the S. mutans-GtfB activity. Also, the antimicrobial activity against S. mutans of three fractions (methanol, ethyl acetate, and hexane; 0.25 mg/mL) from the extracts was evaluated.

Results

Three extracts from the Atlantic Forest variety sylvestris (FLO/SC, GUA/CE, PRE/SP) reduced ≥50% (> 3 logs) S. mutans viable population (p < 0.0001 vs. vehicle), while two extracts from the same biome and variety (PAC/CE, PRE/SP) decreased ≥50% of the viable counts of C. albicans (p < 0.0001 vs. vehicle). For S. mutans biofilms, three extracts (GUA/CE, PAC/CE, PRE/SP) reduced the biomass by ≥91% (p > 0.0001 vs. vehicle) and 100% of the microbial population (p < 0.0001 vs. vehicle). However, for the fungal biofilm, two extracts (PAC/CE, PRE/SP) reduced the viable counts by ≥52% (p < 0.0001 vs. vehicle), but none reduced biomass. The extracts with higher antimicrobial and antibiofilm activities presented higher content of clerodane-type diterpenes and lower content of glycosylated flavonoids than the less active extracts. The extracts had no effect on the removal of cells adhered to the pellicle (p > 0.05 vs. vehicle) while promoted the detachment of a larger number of S. mutans cells from GtfB-glucan matrix (p < 0.0031 vs. vehicle), and FLO/SC, GUA/CE and PRE/SP reduced the quantity of glucans (p < 0.0136 vs. vehicle). Only the ethyl acetate fractions reduced the microbial population of S. mutans (p < 0.0001 vs. vehicle), except for one (PAC/CE). Among the ethyl acetate fractions, three from var. lingua (two from Cerrado, and one from Cerrado/Caatinga) reduced ≥83% of the microbial population.

Conclusions

C. sylvestris extracts from Atlantic Forest var. sylvestris and ethyl acetate fractions from Cerrado and Cerrado/Caatinga var. lingua may be used as a strategy against cariogenic microorganisms.

Plants and Phytocompounds Active Against Bothrops Venoms

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Snakebite envenomation is an important health problem in tropical countries, with severe human and social consequences. In Latin America, the Bothrops species constitute the main threat to humans, and the envenomation caused by these species quickly develops into severe local tissue damage, including swelling, hemorrhaging, myonecrosis, skin ulceration, and pain. The systemic effects of envenomation are usually neutralized by antivenom serum therapy, despite its intrinsic risks. However, neutralization of local tissue damage remains a challenge. To improve actual therapy, two major alternatives are proposed: the rational design of new specific antibodies for most of the tissue damaging/ poor immunogenic toxins, or the search for new synthetic or natural compounds which are able to inhibit these toxins and complement the serum therapy. Natural compounds isolated from plants, mainly from those used in folk medicine to treat snakebite, are a good choice for finding new lead compounds to improve snakebite treatment and minimize its consequences for the victims. In this article, we reviewed the most promising plants and phytocompounds active against bothropic venoms.

Utilization of the Plant Clusia Fluminensis Planch & Triana Against Some Toxic Activities of the Venom of Bothrops jararaca and B. jararacussu Snake Venom Toxic Activities

BACKGROUND

In Brazil, the Bothrops genus accounts for 87% of registered snakebites, which are characterized by hemorrhage, tissue necrosis, hemostatic disturbances, and death. The treatment recommended by governments is the administration of specific antivenoms. Although antivenom efficiently prevents venom-induced lethality, it has limited efficacy in terms of preventing local tissue damage. Thus, researchers are seeking alternative therapies able to inhibit the main toxic effects of venoms, without compromising safety.

OBJECTIVE

The study aimed to test the ability of aqueous extracts of leaves, stems, and fruits of the plant Clusia fluminensis to neutralize some toxic effects induced by the venoms of Bothrops jararaca and Bothrops jararacussu.

METHODS

The plant extracts were incubated with venoms for 30 min. at 25 °C, and then in vitro (coagulant and proteolytic) and in vivo (hemorrhagic, myotoxic, and edematogenic) activities were evaluated. In addition, the extracts were administered to animals (by oral, intravenous or subcutaneous routes) before or after the injection of venom samples, and then hemorrhage and edema assays were performed. In addition, a gel solution of the fruit extract was produced and tested in terms of reducing hemorrhage effects. A chemical prospection was performed to identify the main classes of compounds present in the extracts.

RESULTS

All the extracts inhibited the activities of the two venoms, regardless of the experimental protocol or route of administration of the extracts. Moreover, the gel of the fruit extract inhibited the venom-induced-hemorrhage. The extracts comprised of tannins, flavonoids, saponins, steroids, and terpenoids.

CONCLUSION

Antivenom properties of C. fluminensis extracts deserve further investigation in order to gain detailed knowledge regarding the neutralization profile of these extracts.

Snake Venom PLA2, a Promising Target for Broad-Spectrum Antivenom Drug Development

Snakebite envenomation is a neglected global health problem, causing substantial mortality, disability, and psychological morbidity, especially in rural tropical and subtropical zones. Antivenin is currently the only specific medicine for envenomation. However, it is restricted by cold storage, snakebite diagnosis, and high price. Snake venom phospholipase A₂s (svPLA₂s) are found in all kinds of venomous snake families (e.g., Viperidae, Elapidae, and Colubridae). Along with their catalytic activity, svPLA₂s elicit a wide variety of pharmacological effects that play a pivotal role in envenomation damage. Hence, neutralization of the svPLA₂s could weaken or inhibit toxic damage. Here we overviewed the latest knowledge on the distribution, pathophysiological effects, and inhibitors of svPLA₂s to elucidate the potential for a novel, wide spectrum antivenom drug targeting svPLA₂s.

Evaluation of Rhamnetin as an Inhibitor of the Pharmacological Effect of Secretory Phospholipase A2

Rhamnetin (Rhm), 3-O-methylquercetin (3MQ), and Rhamnazin (Rhz) are methylated derivatives of quercetin commonly found in fruits and vegetables that possess antioxidant and anti-inflammatory properties. Phospholipase A2 (PLA2) displays several important roles during acute inflammation; therefore, this study aimed at investigating new compounds able to inhibit this enzyme, besides evaluating creatine kinase (CK) levels and citotoxicity. Methylated quercetins were compared with quercetin (Q) and were incubated with secretory PLA2 (sPLA2) from Bothrops jararacussu to determine their inhibitory activity. Cytotoxic studies were performed by using the J774 cell lineage incubated with quercertins. In vivo tests were performed with Swiss female mice to evaluate decreasing paw edema potential and compounds’ CK levels. Structural modifications on sPLA2 were made with circular dichroism (CD). Despite Q and Rhz showing greater enzymatic inhibitory potential, high CK was observed. Rhm exhibited sPLA2 inhibitory potential, no toxicity and, remarkably, it decreased CK levels. The presence of 3OH on the C-ring of Rhm may contribute to both its anti-inflammatory and enzymatic inhibition of sPLA2, and the methylation of ring A may provide the increase in cell viability and low CK level induced by sPLA2. These results showed that Rhm can be a candidate as a natural compound for the development of new anti-inflammatory drugs.

Hydroalcoholic crude extract of Casearia sylvestris Sw. reduces chronic post-ischemic pain by activation of pro-resolving pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Casearia sylvestris Sw. is widely used in popular medicine to treat conditions associated with pain.

AIM OF THE STUDY

The present study investigated the influence of hydroalcoholic crude extract of Casearia sylvestris (HCE-CS) and contribution of pro-resolving mediators on mechanical hyperalgesia in a mouse model of chronic post-ischemia pain (CPIP).

METHODS AND RESULTS

Male Swiss mice were subjected to ischemia of the right hind paw (3h), then reperfusion was allowed. At 10min, 24h or 48h post-ischemia/reperfusion (I/R), different groups of animals were treated with HCE-CS (30mg/Kg, orally [p.o]), selected agonists at the pro-resolving receptor ALX/FPR2 (natural molecules like resolvin D1 and lipoxin A4 or the synthetic compound BML-111; 0.1-1µg/animal) or vehicle (saline, 10mL/Kg, s.c.), in the absence or presence of the antagonist WRW4 (10µg, s.c.). Mechanical hyperalgesia (paw withdrawal to von Frey filament) was asseseed together with histological and immunostainning analyses. In these settings, pro-resolving mediators reduced mechanical hyperalgesia and HCE-CS or BML-111 displayed anti-hyperalgesic effects which was markedly attenuated in animals treated with WRW4. ALX/FPR2 expression was raised in skeletal muscle or neutrophils after treatment with HCE-CS or BML-111.

CONCLUSION

These results reveal significant antihyperalgesic effect of HCE-CS on CPIP, mediated at least in part, by the pathway of resolution of inflammation centred on the axis modulated by ALX/FPR2.

Behavioral effects induced by antitumor cleronade diterpenes from Casearia sylvestris and in silico interactions with neuron receptors

ETHNOPHARMACOLOGICAL RELEVANCE

Casearia sylvestris is a medicinal plant traditionally used to treat snakebites, wounds, inflammation and gastric ulcers and scientific supports for have demonstrated its antitumor, antihyperlipidemic and antiparasitic properties.

AIM OF THE STUDY

To assess the effects of a fraction with casearins (FC) on adult mice using classical experimental models of animal behavior and theoretical calculations to verify the interaction of Casearin X (Cas X) with neuron receptors.

MATERIALS AND METHODS

Animals divided in 6 groups (n=9/group) were intraperitoneally treated with vehicle (DMSO 4%), FC (2.5, 5, 10 and 25mg/kg/day) and diazepam (2mg/kg) for 7 days. Thirty minutes after the last dose of treatment, acute toxicity and behavioral experiments were performed.

RESULTS

The highest dose of FC (25mg/kg/day) caused diarrhea, weight loss and death of one animal. Elevated plus maze test showed that lower doses [2.5mg/kg/day (36.4±5.1s) and 5mg/kg/day (43.9±6.2s)] increased the time spent in open arms (TSOA). Open field test revealed reduction in the number of crossings (54.9%, 51.1%, 48% and 67.7% for 2.5, 5, 10 and 25mg/kg/day, respectively) in all doses of FC studied and decrease of rearings at 25mg/kg/day (p<0.05). Computational calculations showed that the inhibition constant (Ki) for the Cas X-D₁ complex is up to 1000-fold more favourable than the Cas X-GABA_A complex. All ∆G° values obtained for Cas X-D₁ complexes were more negative than those seen with Cas X-GABA_A complexes.

CONCLUSIONS

Findings indicate a probable anxiolytic action of the FC since it reduces the number of crossings and rearings and prolonged the time spent in open arms, without sedative and myorelaxant effects, probably due to the interaction of Cas X with dopaminergic system.

Preclinical anticancer effectiveness of a fraction from Casearia sylvestris and its component Casearin X: in vivo and ex vivo methods and microscopy examinations

ETHNOPHARMACOLOGICAL RELEVANCE

Casearia sylvestris (Salicaceae) is found in South America and presents antiulcerogenic, cytotoxic, antimicrobial, anti-inflammatory and antihypertensive activities.

AIM OF THE STUDY

To assess the in vivo and ex vivo antitumor action of a fraction with casearins (FC) and its main component - Casearin X-isolated from C. sylvestris leaves.

MATERIALS AND METHODS

Firstly, Sarcoma 180 bearing Swiss mice were treated with FC and Cas X for 7 days. Secondly, BALB/c nude animals received hollow fibers with colon carcinoma (HCT-116) or glioblastoma (SF-295) cells and were treated with FC for 4 days. On 5th day, proliferation was determined by MTT assay.

RESULTS

FC 10 and 25mg/kg/day i.p. and 50mg/kg/day oral and Cas X 25mg/kg/day i.p. and 50mg/kg/day oral revealed tumor growth inhibition rates of 35.8, 86.2, 53.7, 90.0 and 65.5% and such tumors demonstrated rare mitoses and coagulation necrosis areas. Similarly, FC reduced multiplying of HCT-116 and SF-295 cells when evaluated by the Hollow Fiber Assay (2.5 and 5mg/kg/day i.p. and 25 and 50mg/kg/day oral), with cell growth inhibition rates ranging from 33.3 to 67.4% (p<0.05). Flow cytometry experiments revealed that FC reduced membrane integrity and induced DNA fragmentation and mitochondrial depolarization (p<0.05).

CONCLUSIONS

FC and Cas X were efficient antitumor substances against murine and human cancer cells and caused reversible morphological changes in liver, kidneys and spleens, emphasizing clerodane diterpenes as an emerging class of anticancer molecules.

The standard aqueous stem bark extract of Mangifera indica L. inhibits toxic PLA2 - NN-XIb-PLA2 of Indian cobra venom

The aqueous extract of Mangifera indica is known to possess diverse medicinal properties, which also includes anti-snake venom activities. However, its inhibitory potency and mechanism of action on multi-toxic snake venom phospholipases A₂s are still unknown. Therefore, the objective of this study was to evaluate the modulatory effect of standard aqueous bark extract of M. indica on NN-XIb-PLA₂ of Indian cobra venom. The in vitro sPLA₂, in situ hemolytic and in vivo edema inhibition effect were carried out as described. Also the effect of substrate and calcium concentration was carried out. M. indica extract dose dependently inhibited the GIA sPLA₂ (NN-XIb-PLA₂) activity with an IC₅₀ value of 7.6 μg/ml. M. indica extract effectively inhibited the indirect hemolytic activity up to 98% at ∼40 μg/ml concentration. Further, M. indica extract (0–50 μg/ml) inhibited the edema formed in a dose dependent manner. When examined as a function of increased substrate and calcium concentration, there was no relieve of inhibitory effect of M. indica extract on the NN-XIb-PLA₂. Further, the inhibition was irreversible as evident from binding studies. The in vitro inhibition is well correlated with in situ and in vivo edema inhibiting activities of M. indica. As the inhibition is independent of substrate and calcium and was irreversible, it can be concluded that M. indica extract mode of inhibition could be due to direct interaction of components present in the extract with the PLA₂ enzyme. The aqueous extract of M. indica effectively inhibits svPLA₂ enzymatic and its associated toxic activities, which substantiate their anti-snake venom properties. Further in-depth studies on the role and mechanism of the principal constituents present in the extract, responsible for the anti-PLA₂ activity will be interesting to develop them into potent antisnake component and also as an anti-inflammatory agent.

Evaluation of the Intestinal Absorption Mechanism of Casearin X in Caco-2 Cells with Modified Carboxylesterase Activity

The clerodane diterpene casearin X (1), isolated from the leaves of Casearia sylvestris, is a potential new drug candidate due to its potent in vitro cytotoxic activity. In this work, the intestinal absorption mechanism of 1 was evaluated using Caco-2 cells with and without active carboxylesterases (CES). An LC-MS method was developed and validated for the quantification of 1. The estimation of permeability coefficients was possible only under CES-inhibited conditions in which 1 is able to cross the Caco-2 cell monolayer. The mechanism is probably by active transport, with no significant efflux, but with a high retention of the compound inside the cells. The enzymatic hydrolysis assay demonstrates the susceptibility of 1 to first-pass metabolism as substrate for specific CES expressed in human intestine.

The anti-inflammatory activity of standard aqueous stem bark extract of Mangifera indica L. as evident in inhibition of Group IA sPLA2

ABSTRACT The standard aqueous stem bark extract is consumed as herbal drink and used in the pharmaceutical formulations to treat patients suffering from various disease conditions in Cuba. This study was carried out to evaluate the modulatory effect of standard aqueous bark extract of M. indica on Group IA sPLA2. M. indica extract, dose dependently inhibited the GIA sPLA2 (NN-XIa-PLA2) activity with an IC50 value 8.1 µg/ml. M. indica extract effectively inhibited the indirect hemolytic activity up to 98% at ~40 µg/ml concentration and at various concentrations (0-50 µg/ml), it dose dependently inhibited the edema formation. When examined as a function of increased substrate and calcium concentration, there was no relieve of inhibitory effect on the GIA sPLA2. Furthermore, the inhibition was irreversible as evidenced from binding studies. It is observed that the aqueous extract ofM. indica effectively inhibits sPLA2 and it is associated inflammatory activities, which substantiate their anti-inflammatory properties. The mode of inhibition could be due to direct interaction of components present in the extract, with sPLA2 enzyme. Further studies on understanding the principal constituents, responsible for the anti-inflammatory activity would be interesting to develop this into potent anti-inflammatory agent.

Counteracting effects on free radicals and histological alterations induced by a fraction with casearins

ABSTRACTCasearia sylvestris Swartz is a medicinal plant widely distributed in Brazil. It has anti-inflammatory, antiulcer and antitumor activities and is popularly used to treat snakebites, wounds, diarrhea, flu and chest colds. Its leaves are rich in oxygenated tricyclic cis-clerodane diterpenes, particulary casearins. Herein, we evaluated the antioxidant activities of a fraction with casearins (FC) isolated from C. sylvestrisand histological changes on the central nervous system and livers of Mus musculus mice. Firstly, in vitro studies (0.9, 1.8, 3.6, 5.4 and 7.2 μg/mL) revealed EC50 values of 3.7, 6.4 and 0.16 µg/mL for nitrite, hydroxyl radical and TBARS levels, respectively. Secondly, FC (2.5, 5, 10 and 25 mg/kg/day) was intraperitoneally administered to Swiss mice for 7 consecutive days. Nitrite levels in the hippocampus (26.2, 27.3, 30.2 and 26.6 µM) and striatum (26.3, 25.4, 34.3 and 27.5 µM) increased in all treated animals (P < 0.05). Lower doses dropped reduced glutathione, catalase and TBARS levels in the hippocampus and striatum. With the exception of this reduction in TBARS formation, FC displayed only in vitro antioxidant activity. Animals exhibited histological alterations suggestive of neurotoxicity and hepatotoxicity, indicating the need for precaution regarding the consumption of medicinal formulations based on Casearia sylvestris.

Main plants used in traditional medicine for the treatment of snake bites n the regions of the department of Antioquia, Colombia

ETHNOPHARMACOLOGY RELEVANCE

In Colombia, more than 4.000 ophidian accidents occur per year and due to the scarce distribution and limited availability of antivenom, the use of traditional medicine has been perpetuated in some of its rural communities, in which initially, those affected are treated by healers and shamans using medicinal plants in different ways.

METHODS

Research was conducted with renowned healers or connoisseurs of plants on the ethnobotany of ophidian accidents in five different areas and their municipalities of Antioquia: Magdalena Medio (Caracolí, Puerto Berrío); Bajo Cauca (Caucasia, Zaragoza); Nordeste (San Roque, Yalí); Norte (Gómez Plata, Valdivia); Suroeste (Ciudad Bolívar, Salgar); collecting information related to experience and time of use of plants in the treatment of these poisonings, amounts used, ways of use (beverage, bathing, ointment, chupaderas, vapors), preparation types (maceration or decoction) and treatment duration.

RESULTS

71 plant species were identified and collected, 49.29% of them without previous reports as antiophidian and 38.0% employed for the same purpose in other geographical areas. The leaves (24.82%), stems (11.68%) and flowers (10.95%) were found to be the most frequently employed structures in the preparation of the extracts, which are usually prepared by decoction (83.94%), maceration (6.57%).

CONCLUSIONS

In this work, specimens lacking previous ethnobotanical reports have been found, plants used by ethnic groups from other regions of Antioquia and the world to treat snake bites; and herbaceous plants whose inhibitory activity of symptoms produced by some snake venoms, has been experimentally verified by in vivo and in vitro tests.

A randomized ethnomedicinal survey of snakebite treatment in southwestern parts of Bangladesh

Snakebite is the single most important toxin-related injury, causing substantial mortality in many parts of the Africa, Asia and the Americas. Incidence of snakebite is usually recorded in young people engaged in active physical work in rural areas. The various plant parts used to treat snakebite included whole plant, leaves, barks, roots and seeds. Most bites in Bangladesh are recorded between May and October with highest number in June. Lower and upper limbs are most common sites of snakebite, but it may happen in other sites as well. Snake venom (蛇毒 shé dú) has been the cause of innumerable deaths worldwide. However, antiserum does not provide enough protection against venom induced hemorrhage, necrosis, nephrotoxicity and hypersensitivity reactions. Informed consent was obtained from the practitioners prior to interviews. After the survey, it is concluded that the medicinal plants used by tribal medicinal practitioners in Bangladesh for treatment against snakebite are Acyranthes aspera L. (土牛膝 tǔ niú xī), Amaranthus Viridis L. (野莧菜 yě xiàng cài), Asparagus racemosus Willd (總序天冬 zǒng xù tiān dōng) and Emblica officinalis Gaertn (油柑 yóu gān), while the non-tribal communities used 35 plant species among them, most of the plants reported as new species used against snakebite in the belonging family. The plants present a considerable potential for discovery of novel compounds with fewer side effects for treatment of antisnake venom and can, at least in Bangladesh, become a source of affordable and more easily available drugs.

Anti-Streptococcal activity of Brazilian Amazon Rain Forest plant extracts presents potential for preventive strategies against dental caries

Caries is a global public health problem, whose control requires the introduction of low-cost treatments, such as strong prevention strategies, minimally invasive techniques and chemical prevention agents. Nature plays an important role as a source of new antibacterial substances that can be used in the prevention of caries, and Brazil is the richest country in terms of biodiversity.

Cardiovascular protective effects of Casearia sylvestris Swartz in Swiss and C57BL/6 LDLr-null mice undergoing high fat diet

ETHNOPHARMACOLOGICAL RELEVANCE

Although Casearia sylvestris Swartz is used in Brazilian folk medicine to treat obesity, no study has been conducted to evaluate the effects of this species in an experimental model of dyslipidemia and atherosclerosis. So, the aim of this study was to evaluate possible hypolipemiant and antiatherogenic activity of the methanolic extract obtained from Casearia sylvestris (MECS) using Swiss and C57BL/6 LDLr-null mice undergoing high fat diet (HFD).

MATERIAL AND METHODS

Dyslipidemia and atherogenesis were induced by the administration of commercial HFD for 4 weeks. The MECS was administered orally at doses of 250 and 500mg/kg, once a day, for two weeks, starting from the 2nd week of HFD. The gain in body weight and systolic blood pressure (SBP) were measured weekly over the four week study. At the end of the experiments the levels of triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and very low-density lipoprotein cholesterol (VLDL-C) were measured by colorimetric method. Aldosterone, vasopressin and angiotensin converting enzyme (ACE) activity were also evaluated in collected serum. The renal function, atherogenic index serum (AIS) and in vitro antiplatelet activity were investigated. Additionally, histopathological analyzes were performed to determine the intima-media thickness (IMT) and intima media ratio (IMR) in aorta samples.

RESULTS

The HFD induced dyslipidemia and major structural changes in the aortic wall, including raising of the systolic blood pressure in LDLr-null mice. In addition, we observed an increase in lipid peroxidation accompanied by a reduction of serum nitrite. The treatment with MECS was able to prevent the increase of SBP, TC, LDL-C, VLDL-C and triglycerides levels and increase HDL-C in Swiss and LDLr-null mice. These effects were accompanied by a significant reduction in oxidative stress. Moreover, AIS, IMT and IMR were significantly reduced in MECS-treated mice, and the extract was able to reduce platelet aggregation in vitro.

CONCLUSION

This study demonstrated that MECS reduces the serum lipids and oxidative stress when orally administered to Swiss and LDLr-null mice. In addition, it was able to prevent arterial thickening induced by HFD and to inhibit platelet aggregation in vitro.

Evaluation of morpho-anatomical and chemical differences between varieties of the medicinal plant Casearia sylvestris Swartz

Casearia sylvestris Swartz (Salicaceae) has been used in traditional medicine and its leaf extracts have been exhibited important pharmacological activities. The species presents morphological, chemical and genetic variation. Two varieties are considered due external morphological differences: C. sylvestris var. sylvestris and var. lingua. There are difficulties in definition of these varieties. The objective of this work is to evaluate chemical and morpho-anatomical differences between C. sylvestris varieties that can be applied in their distinction for pharmaceutical or botanical purposes. Transverse and paradermic sections of leaves were prepared for morpho-anatomical, histochemical and quantitative microscopy (stomatal and palisade index) analyses. Diterpene profiles of the specimens were obtained by HPLC-DAD and TLC. Morpho-anatomical analyses demonstrated significant differences between the varieties only in paradermic sections: var. sylvestris - polygonal epidermic cell walls and hypostomatic; var. lingua - rounded epidermic cell walls and amphistomatic. No differences were observed for stomatal index; palisade index was found 2.8 for var. lingua and 3.9 for var. sylvestris. Chromatographic analyses confirmed previous results demonstrating that diterpene profile in varieties differs, with predominance of these metabolites in var. sylvestris. In conclusion, this work indicates that chromatographic analysis besides morpho-anatomical analysis can be applied in distinction of C. sylvestris varieties.

Snake venom PLA2s inhibitors isolated from Brazilian plants: synthetic and natural molecules

Ophidian envenomation is an important health problem in Brazil and other South American countries. In folk medicine, especially in developing countries, several vegetal species are employed for the treatment of snakebites in communities that lack prompt access to serum therapy. However, the identification and characterization of the effects of several new plants or their isolated compounds, which are able to inhibit the activities of snake venom, are extremely important and such studies are imperative. Snake venom contains several organic and inorganic compounds; phospholipases A₂ (PLA₂s) are one of the principal toxic components of venom. PLA₂s display a wide variety of pharmacological activities, such as neurotoxicity, myotoxicity, cardiotoxicity, anticoagulant, hemorrhagic, and edema-inducing effects. PLA₂ inhibition is of pharmacological and therapeutic interests as these enzymes are involved in several inflammatory diseases. This review describes the results of several studies of plant extracts and their isolated active principles, when used against crude snake venoms or their toxic fractions. Isolated inhibitors, such as steroids, terpenoids, and phenolic compounds, are able to inhibit PLA₂s from different snake venoms. The design of specific inhibitors of PLA₂s might help in the development of new pharmaceutical drugs, more specific antivenom, or even as alternative approaches for treating snakebites.

Inhibition of venom serine proteinase and metalloproteinase activities by Renealmia alpinia (Zingiberaceae) extracts: comparison of wild and in vitro propagated plants

ETHNOPHARMACOLOGICAL RELEVANCE

The plant Renealmia alpinia has been used in folk medicine to treat snakebites in the northwest region of Colombia. In addition, it has been shown to neutralize edema-forming, hemorrhagic, lethal, and defibrin(ogen)ating activities of Bothrops asper venom. In this work, extracts of Renealmia alpinia obtained by micropropagation (in vitro) and from specimens collected in the wild were tested and compared in their capacity to inhibit enzymatic and toxic activities of a snake venom metalloproteinase isolated from Bothrops atrox (Batx-I) venom and a serine proteinase (Cdc SII) from Crotalus durissus cumanensis venom.

MATERIALS AND METHODS

We have investigated the inhibition capacity of Renealmia alpinia extracts on enzymatic and toxic actions of isolated toxins, a metalloproteinase and a serine proteinase. The protocols investigated included inhibition of proteolytic activity on azocasein, inhibition of proteolytic activity on fibrinogen, inhibition of pro-coagulant activity, inhibition of hemorrhagic activity and inhibition of edema-forming activity.

RESULTS

Colorimetric assays detected the presence of terpenoids, flavonoids, tannins and coumarins in Renealmia alpinia extracts. Renealmia alpinia extracts inhibited the enzymatic, hemorrhagic and fibrinogenolytic activities of Batx-I. Extracts also inhibited coagulant, defibrin(ogen)ating and edema-forming activities of Cdc SII. Results highlight that Renealmia alpinia in vitro extract displayed comparable inhibitory capacity on venom proteinases that Renealmia alpinia wild extract. No alteration was observed in the electrophoretic pattern of venom proteinases after incubation with Renealmia alpinia extracts, thus excluding proteolytic degradation or protein denaturation/precipitation as a mechanism of inhibition.

CONCLUSIONS

Our results showed that Renealmia alpinia wild and in vitro extracts contain compounds that neutralize metallo- and serine proteinases present in snake venoms. The mechanism of inhibition is not related to proteolytic degradation of the enzymes nor protein aggregation, but is likely to depend on molecular interactions of secondary metabolites in the plant with these venom proteinases.

Anti-inflammatory and antioxidant properties of hydroalcoholic crude extract from Casearia sylvestris Sw. (Salicaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Casearia sylvestris Sw. is widely used in popular medicine to treat inflammatory conditions.

AIM OF THE STUDY

To investigate the anti-inflammatory and antioxidant properties of hydroalcoholic crude extract (HCE) taken from Casearia sylvestris Sw. (Salicaceae).

METHODS AND RESULTS

The effect of the HCE from this plant (3-300 mg/kg) on the reduction of inflammatory response to carrageenan was investigated in pleurisy in rats (intrapleural, 2% in 0.2 mL) or paw edema in mice (intraplantar, 300 μg/20 μL, right hind paw). The plant anti-inflammatory action was assessed by its capability in inhibiting cell migration, enzymatic activity of myeloperoxidase (MPO) and production of nitrite/nitrate or edema. The in vitro antioxidant activity of this extract against lipid peroxidation and damage to proteins was assessed as possible pathways to contribute as anti-inflammatory mechanisms. Carrageenan-induced hind paw edema (739.3 ± 11.9 μm) was reduced by HCE (30 mg/kg: 462.8 ± 28.38 μm) to similar extents as dexametasone (365.1 ± 16.7). In pleurisy, treatment of the animals with HCE (100mg/kg: 0.010 ± 0.001 mU/mg of protein) also reduced MPO activity augmented by carrageenan (0.020 ± 0.001 mU/mg of protein) as well as leukocytes migration (carrageenan: 17.8890 ± 2.3900 leukocytes/mL, HCE 100mg/kg: 7.0880 ± 9631 leukocytes/mL). Significant effects were also observed in animals treated with different doses of HCE in biochemical tests for oxidative stress analysis.

CONCLUSION

The anti-inflammatory and antioxidant effects of HCE from Casearia sylvestris Sw. suggests a potential therapeutic benefit of this plant in treatment of inflammatory conditions.

Triacontyl p-coumarate: an inhibitor of snake venom metalloproteinases

Snake venom metalloproteinases (SVMPs) participate in a number of important biological, physiological and pathophysiological processes and are primarily responsible for the local tissue damage characteristic of viperid snake envenomations. The use of medicinal plant extracts as antidotes against animal venoms is an old practice, especially against snake envenomations. Such plants are sources of many pharmacologically active compounds and have been shown to antagonize the effects of some venoms and toxins. The present study explores the activity of triacontyl p-coumarate (PCT), an active compound isolated from root bark of Bombacopsis glabra vegetal extract (Bg), against harmful effects of Bothropoides pauloensis snake venom and isolated toxins (SVMPs or phospholipase A(2)). Before inhibition assays, Bg or PCT was incubated with venom or toxins at ratios of 1:1 and 1:5 (w/w; venom or isolated toxins/PCT) for 30 min at 37°C. Treatment conditions were also assayed to simulate snakebite with PCT inoculated at either the same venom or toxin site. PCT neutralized fibrinogenolytic activity and plasmatic fibrinogen depletion induced by B. pauloensis venom or isolated toxin. PCT also efficiently inhibited the hemorrhagic (3MDH - minimum hemorrhagic dose injected i.d into mice) and myotoxic activities induced by Jararhagin, a metalloproteinase from B. jararaca at 1:5 ratio (toxin: inhibitor, w/w) when it was previously incubated with PCT and injected into mice or when PCT was administered after toxin injection. Docking simulations using data on a metalloproteinase (Neuwiedase) structure suggest that the binding between the protein and the inhibitor occurs mainly in the active site region causing blockade of the enzymatic reaction by displacement of catalytic water. Steric hindrance may also play a role in the mechanism since the PCT hydrophobic tail was found to interact with the loop associated with substrate anchorage. Thus, PCT may provide a alternative to complement ophidian envenomation treatments.

Neutralisation of Local Haemorrhage Induced by the Saw-Scaled Viper Echis carinatus sochureki Venom Using Ethanolic Extract of Hibiscus aethiopicus L

The objective of the study is to investigate the anti-snake venom activities of a local plant, Hibiscus aethiopicus L. The H. aethiopicus was dried and extracted with ethanol. Different assays were performed according to standard techniques, to evaluate the plant's acute toxicity and its antivenom activities. The results of evaluating the systemic acute toxicity of the H. aethiopicus extract using “oral and intra-peritoneal” route were normal even at the highest dose (24 g/kg) tested. All guinea pigs (n = 3) when treated with venoms E. c. sochureki (75 μg) alone induced acute skin haemorrhage. In contrast, all guinea pigs (n = 18) treated with both venom and the plant extract at a concentration between 500 and 1000 mg/kg showed no signs of haemorrhage. Moreover, all guinea pigs (n = 18) treated with venom and the plant extract below 400 mg/kg showed acute skin haemorrhage. All guinea pigs treated with venom E. c. sochureki (75 μg) alone induced acute skin haemorrhage after both 24 and 32 hours. In contrast, all guinea pigs treated with both venom and the plant extract (administered independently) at concentrations between 500 and 1000 mg/kg showed no signs of haemorrhage after 32 hours. However, after 24 hours all tested guinea pigs showed less inhibition (<60%) compared to that obtained after 32 hours. The outcome of this study reflects that the extract of H. aethiopicus plant may contain an endogenous inhibitor of venom induced local haemorrhage.

Cross-cultural comparison of medicinal floras used against snakebites

ETHNOPHARMACOLOGICAL RELEVANCE

Envenomation causes an estimated 1.8-2.5 million incidences per year with a mortality level of 100-125,000 persons annually and more than 100,000 individuals suffer from severe complications, which may end in amputation of the attacked limb. The use of plants is a major part of the traditional practitioners' treatment of snakebites.

MATERIALS AND METHODS

A database was created for plants used to treat snakebites worldwide. From this database, we selected five countries with a high number of entries and representing different cultures, geography and floristic zones: Brazil, Nicaragua, Nepal, China and South Africa. The datasets were analysed by regression and binominal analysis to see if any family or genus used against snakebites was overrepresented in the respective traditional medicinal systems relative to the abundance in the local flora. The families from the different geographical areas were compared to ascertain whether the same plant families are preferred by different peoples.

RESULTS

Three 'hot' families (Apocynaceae, Lamiaceae and Rubiaceae) were recovered in at least two of the five compared countries in the regression analyses and one 'hot' family (Zingiberaceae) was recovered in two of the compared countries in the binomial analyses. Four out of five floras possess families identified as outliers in both regression and binomial analyses. Eight families were recovered by both the binomial and the regression analysis (40-62% of all highlighted families respectively). At the genus level, only Piper (Piperaceae) was recovered as a 'hot' genus in at least two floras. Seven genera were highlighted by both analyses (25-44% of the highlighted genera).

CONCLUSIONS

Cross-cultural comparison of medicinal floras used against snakebites appears to be useful for highlighting candidate families and genera for further studies.

Structural and functional studies of a bothropic myotoxin complexed to rosmarinic acid: new insights into Lys49-PLA₂ inhibition

Snakebite envenoming is an important public health problem in many tropical and subtropical countries, and is considered a neglected tropical disease by the World Health Organization. Most severe cases are inflicted by species of the families Elapidae and Viperidae, and lead to a number of systemic and local effects in the victim. One of the main problems regarding viperidic accidents is prominent local tissue damage whose pathogenesis is complex and involves the combined actions of a variety of venom components. Phospholipases A₂ (PLA₂s) are the most abundant muscle-damaging components of these venoms. Herein, we report functional and structural studies of PrTX-I, a Lys49-PLA₂ from Bothops pirajai snake venom, and the influence of rosmarinic acid (RA) upon this toxin's activities. RA is a known active component of some plant extracts and has been reported as presenting anti-myotoxic properties related to bothopic envenomation. The myotoxic activity of Lys49-PLA₂s is well established in the literature and although no in vivo neurotoxicity has been observed among these toxins, in vitro neuromuscular blockade has been reported for some of these proteins. Our in vitro studies show that RA drastically reduces both the muscle damage and the neuromuscular blockade exerted by PrTX-I on mice neuromuscular preparations (by ∼80% and ∼90%, respectively). These results support the hypothesis that the two effects are closely related and lead us to suggest that they are consequences of the muscle membrane-destabilizing activity of the Lys49-PLA₂. Although the C-terminal region of these proteins has been reported to comprise the myotoxic site, we demonstrate by X-ray crystallographic studies that RA interacts with PrTX-I in a different region. Consequently, a new mode of Lys49-PLA₂ inhibition is proposed. Comparison of our results with others in the literature suggests possible new ways to inhibit bothropic snake venom myotoxins and improve serum therapy.

Folk uses and pharmacological properties of Casearia sylvestris: a medicinal review

Folk uses and scientific investigations have highlighted the importance of Casearia sylvestris extracts and their relevant bioactive potential. The aim of this work was to review the pharmacological properties of C. sylvestris, emphasizing its anti-ulcer, anti-inflammatory, anti-ophidian and antitumor potentialities. Ethanolic extracts and essential oil of their leaves have antiulcerogenic activity and reduce gastric volume without altering the stomach pH, which corroborates their consumption on gastrointestinal disorders. Leaf water extracts show phospholipase A2 inhibitory activity that prevents damage effects on the muscular tissue after toxin inoculation. This antiphospholipasic action is probably related to the use as an anti-inflammatory, proposing a pharmacological blockage similar to that obtained with non-steroidal anti-inflammatory drugs on arachidonic acid and cyclooxygenase pathways. Bioguided-assay fractionations lead to the identification of secondary metabolites, especially the clerodane diterpenes casearins (A-X) and casearvestrins (A-C), compounds with a remarkable cytotoxic and antitumor action. Therefore, the C. sylvestris shrub holds a known worldwide pharmacological arsenal by its extensive folk utilization, exciting searches for new molecules and a better comprehension about biological properties.

Casearin X exhibits cytotoxic effects in leukemia cells triggered by apoptosis

Clerodane diterpenes have demonstrated cytotoxic, antiplasmodial and anti-ulcer properties. In the present work, we determined the cytotoxic effect of casearin L (Cas L), O (Cas O) and X (Cas X) and (-)-hardwickiic acid isolated from Casearia sylvestris leaves, and investigated the underlying mechanisms involved in in vitro cell death induced by Cas X in HL-60 leukemia cells (0.7, 1.5 and 3.0μM). Cytotoxicity tests demonstrated that Cas X was the most active compound studied, showing greater cytotoxic effects against CEM and HL-60 lines (IC(50) of 0.4μM) and human peripheral blood mononuclear cells (PBMC, IC(50) of 1.2μM). After 24h exposure, Cas X caused a decrease in 5-bromo-20-deoxyuridine (BrdU) incorporation (36.6 and 24.5% labeling at 0.7 and 1.5μM, respectively), reduction in viability, and increase in apoptotic and necrotic leukemia cells in a dose-dependent manner evidenced by the trypan blue and AO/EB (acridine orange/ethidium bromide) assays. Moreover, Cas X-treated cells exhibited nuclear fragmentation and cytoplasmic vacuolization depending on the concentration tested. These characteristics of apoptosis or secondary necrosis were confirmed by flow cytometry which revealed DNA fragmentation, phosphatidylserine externalization, activation of the effector caspases 3/7 and mitochondrial depolarization. We then found evidence that Cas X causes cell death via apoptotic pathways, corroborating the potential of casearins as compounds with promising antitumor-related properties.

WITHDRAWN: Antiophidian properties of a dolastane diterpene isolated from the marine brown alga Canistrocarpus cervicornis

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.bionut.2011.06.021. The duplicate article has therefore been withdrawn.

Structural and functional comparison of proteolytic enzymes from plant latex and snake venoms

This work describes classification, functions, location, inhibition, activation, and therapeutic applications of proteases from snake venoms and vegetables. Snake venoms and vegetables can present toxins that unchain necrosis or proteolysis due to the direct cytotoxic action of venom proteases. These proteases are potential tools in the development of drugs for the prevention and treatment of several illnesses. We report herein mainly fibrinogenolytic metallo proteases and serine proteases ("thrombin-like"). These enzymes are extensively used in the treatment and prevention of thrombotic disorders, since they serve as defibrinogenating agents. The therapeutic uses of fibrin(ogen)olytic metallo proteases hold promise for clinical application due to potential in reversing the effects of thrombosis; this has been shown to be an alternative approach to the prevention and treatment of cardiovascular disorders, which are among the most prominent causes of mortality around the world. Plant proteases can be utilized for many cellular and molecular activities, in antibacterial and anticancer therapies, and in the treatment of snakebites, inhibiting snake venom activities such as blood-clotting, defibrinogenation, and fibrin(ogen)olytic and hemorrhagic actions. These toxins also display potential for clinical use in the treatment of hemostatic disorders.

Antisnake Venom Activity of Hibiscus aethiopicus L. against Echis ocellatus and Naja n. nigricollis

The objective of the study is to investigate whether the Hibiscus aethiopicus L. plant has neutralization activity against venoms of two clinically important snakes. The H. aethiopicus was dried and extracted with water. Different assays were performed to evaluate the plant's acute toxicity and its anti-snake venom activities. The results showed that H. aethiopicus extract alone had no effect on the viability of C₂C₁₂ muscle cells, but significantly (P < .05) protected muscle cells against the toxic effects of E. ocellatus venom at 55, 150, and 300 μg/mL. The maximum protective effect of the extract was exhibited at 75 μg/mL. The extract significantly (P < .001) inhibited the cytotoxic effects of E. ocellatus venom at 300 μg/mL. All rabbits (n = 10) and guinea pigs (n = 10) were alive after the two weeks of given the lethal dosage 16 g/Kg of the H. aethiopicus extract herbal solution. No abnormal behaviour was observed of both groups of animals. All guinea pigs (n = 3) treated with venoms alone (5 mg/kg) died. However, all guinea pigs (n = 21) treated with venom (5 mg/kg) and the extract (400 to 1000 mg/kg) survived. Guinea pigs (n = 3) treated with Naja n. nigricollis venom alone (2.5 mg/kg) and guinea pigs (n = 21) venom with the extract (400 to 1000 mg/kg) died. The H. aethiopicus completely (100%) blocked the haemorrhagic activity of E. ocellatus in the egg embryo at 3.3 mg/mL of extract. These findings suggest that H. aethiopicus may contain an endogenous inhibitor of venom-induced haemorrhage.

Crystallization and preliminary X-ray crystallographic studies of a Lys49-phospholipase A2 homologue from Bothrops pirajai venom complexed with rosmarinic acid

PrTX-I, a noncatalytic and myotoxic Lys49-phospholipase A(2) from Bothrops pirajai venom, was crystallized in the presence of the inhibitor rosmarinic acid (RA). This is the active compound in the methanolic extract of Cordia verbenacea, a plant that is largely used in Brazilian folk medicine. The crystals diffracted X-rays to 1.8 A resolution and the structure was solved by molecular-replacement techniques, showing electron density that corresponds to RA molecules at the entrance to the hydrophobic channel. The crystals belong to space group P2(1)2(1)2(1), indicating conformational changes in the structure after ligand binding: the crystals of all apo Lys49-phospholipase A(2) structures belong to space group P3(1)21, while the crystals of complexed structures belong to space groups P2(1) or P2(1)2(1)2(1).