UNBS1450 from Calotropis procera as a regulator of signaling pathways involved in proliferation and cell death

Cardiac glycosides with cytotoxic activity from the seeds of Thevetia peruviana

Phytochemical investigation on the extract of the seeds of Thevetia peruviana resulted in the isolation of six new cardiac glycosides, namely theveperosides A-F (1-6), including a rare 19-nor-cardenolide (1), together with seven known analogues (7-13). The chemical structures of these compounds were determined based on detailed spectroscopic analysis. The cytotoxic activities of 1-13 were evaluated against MCF-7, HCT-116, HeLa, and HepG2 cancer cell lines, and their structure-activity relationships (SARs) were investigated. Compound 3 exhibited the significant cytotoxic effects with IC50 values ranging from 0.032 to 0.055 μΜ, which could induce HepG2 cells apoptosis in a dose-dependent manner.

Calotropis procera extract inhibits prostate cancer through regulation of autophagy

Current treatment options available for prostate cancer (PCa) patients have many adverse side effects and hence, new alternative therapies need to be explored. Anticancer potential of various phytochemicals derived from Calotropis procera has been studied in many cancers but no study has investigated the effect of leaf extract of C. procera on PCa cells. Hence, we investigated the effect of C. procera leaf extract (CPE) on cellular properties of androgen-independent PC-3 and androgen-sensitive 22Rv1 cells. A hydroalcoholic extract of C. procera was prepared and MTT assay was performed to study the effect of CPE on viability of PCa cells. The effect of CPE on cell division ability, migration capability and reactive oxygen species (ROS) production was studied using colony formation assay, wound-healing assay and 2',7'-dichlorodihydrofluorescein diacetate assay, respectively. Caspase activity assay and LDH assay were performed to study the involvement of apoptosis and necrosis in CPE-mediated cell death. Protein levels of cell cycle, antioxidant, autophagy and apoptosis markers were measured by western blot. The composition of CPE was identified using untargeted LC-MS analysis. Results showed that CPE decreased the viability of both the PCa cells, PC-3 and 22Rv1, in a dose- and time-dependent manner. Also, CPE significantly inhibited the colony-forming ability, migration and endogenous ROS production in both the cell lines. Furthermore, CPE significantly decreased NF-κB protein levels and increased the protein levels of the cell cycle inhibitor p27. A significant increase in expression of autophagy markers was observed in CPE-treated PC-3 cells while autophagy markers were downregulated in 22Rv1 cells after CPE exposure. Hence, it can be concluded that CPE inhibits PCa cell viability possibly by regulating the autophagy pathway and/or altering the ROS levels. Thus, CPE can be explored as a possible alternative therapeutic agent for PCa.

Anti-Leishmania major activity of Calotropis procera extract by increasing ROS production and upregulating TNF-α, IFN-γ and iNOS mRNA expression under in vitro conditions

BACKGROUND

Leishmaniasis, caused by protozoan parasites of the genus Leishmania, is a neglected tropical disease with 700,000 to 1,000,000 global new cases annually. Adverse effects associated with expense, long-term treatment and drug resistance have made conventional therapies unfavorable, encouraging the search for alternative drugs based on plant products. In this study, the effect of Calotropis procera (Asclepiadaceae) extract against viability of promastigotes and amastigotes of Leishmania major was evaluated in vitro.

METHODS

The extract from the leaves of C. procera seedlings was prepared using a methanol maceration method. The colorimetric cell viability 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the growth-inhibitory effect of the extract on promastigotes. The level of reactive oxygen species (ROS) in promastigote cultures was determined after treatment with the extract using the 2',7'-dichlorofluorescein diacetate (DCFH-DA) method and compared with untreated cultures (control). After exposure to the extract the expression levels of tumor necrosis factor-α (TNF-α), interferon gamma (IFN-γ) and inducible nitric oxide synthase (iNOS) genes were determined and compared to control in peripheral blood mononuclear cells (PBMCs) infected with L. major.

RESULTS

Based on the MTT assay, the C. procera extract significantly reduced the proliferation of L. major promastigotes with IC50 values of 377.28 and 222.44 μg/mL for 24 and 72 h, respectively (p < 0.01). After treatment with 222.44 and 377.28 μg/mL of C. procera extract, ROS production in L. major promastigote cultures increased 1.2- to 1.65-fold and 2- to 4-fold compared to the control, respectively (p < 0.05). C. procera extract induced significant increases in gene expression of TNF-α (2.76-14.83 fold), IFN-γ (25.63-threefold) and iNOS (16.32-3.97 fold) in infected PBMCs compared to control (p < 0.01).

CONCLUSIONS

On the basis of its anti-leishmanial activity, C. procera can be considered as a promising new plant source for the potential treatment of leishmaniasis.

Promiscuous CYP87A enzyme activity initiates cardenolide biosynthesis in plants

Cardenolides are specialized, steroidal metabolites produced in a wide array of plant families1,2. Cardenolides play protective roles in plants, but these molecules, including digoxin from foxglove (Digitalis spp.), are better known for treatment of congenital heart failure, atrial arrhythmia, various cancers and other chronic diseases3-9. However, it is still unknown how plants synthesize 'high-value', complex cardenolide structures from, presumably, a sterol precursor. Here we identify two cytochrome P450, family 87, subfamily A (CYP87A) enzymes that act on both cholesterol and phytosterols (campesterol and β-sitosterol) to form pregnenolone, the first committed step in cardenolide biosynthesis in the two phylogenetically distant plants Digitalis purpurea and Calotropis procera. Arabidopsis plants overexpressing these CYP87A enzymes ectopically accumulated pregnenolone, whereas silencing of CYP87A in D. purpurea leaves by RNA interference resulted in substantial reduction of pregnenolone and cardenolides. Our work uncovers the key entry point to the cardenolide pathway, and expands the toolbox for sustainable production of high-value plant steroids via synthetic biology.

Cytotoxic steroids from the stems of Strophanthus divaricatus

Phytochemical investigation on the stems of Strophanthus divaricatus led to the isolation of four undescribed cardiac glycosides and one undescribed C₂₁ pregnane, together with eleven known steroids. Their structures were elucidated by a comprehensive analysis of HRESIMS, 1D and 2D NMR spectra. The absolute configuration of 16 was determined by comparison of the experimental and computed ECD spectra. Compounds 1-13 and 15 displayed potent to significant cytotoxicity against human cancer cell lines K562, SGC-7901, A549 and HeLa with IC₅₀ values of 0.02-16.08, 0.04-23.13, 0.06-22.31 and 0.06-15.13 μM, respectively.

Tap the sap - investigation of latex-bearing plants in the search of potential anticancer biopharmaceuticals

Latex-bearing plants have been in the research spotlight for the past couple of decades. Since ancient times their extracts have been used in folk medicine to treat various illnesses. Currently they serve as promising candidates for cancer treatment. Up to date there have been several in vitro and in vivo studies related to the topic of cytotoxicity and anticancer activity of extracts from latex-bearing plants towards various cell types. The number of clinical studies still remains scarce, however, over the years the number is systematically increasing. To the best of our knowledge, the scientific community is still lacking in a recent review summarizing the research on the topic of cytotoxicity and anticancer activity of latex-bearing plant extracts. Therefore, the aim of this paper is to review the current knowledge on in vitro and in vivo studies, which focus on the cytotoxicity and anticancer activities of latex-bearing plants. The vast majority of the studies are in vitro, however, the interest in this topic has resulted in the substantial growth of the number of in vivo studies, leading to a promising number of plant species whose latex can potentially be tested in clinical trials. The paper is divided into sections, each of them focuses on specific latex-bearing plant family representatives and their potential anticancer activity, which in some instances is comparable to that induced by commonly used therapeutics currently available on the market. The cytotoxic effect of the plant's crude latex, its fractions or isolated compounds, is analyzed, along with a study of cell apoptosis, chromatin condensation, DNA damage, changes in gene regulation and morphology changes, which can be observed in cell post plant extract addition. The in vivo studies go beyond the molecular level by showing significant reduction of the tumor growth and volume in animal models. Additionally, we present data regarding plant-mediated biosynthesis of nanoparticles, which is regarded as a new branch in plant latex research. It is solely based on the green-synthesis approach, which presents an interesting alternative to chemical-based nanoparticle synthesis. We have analyzed the cytotoxic effect of these particles on cells. Data regarding the cytotoxicity of such particles raises their potential to be involved in the design of novel cancer therapies, which further underlines the significance of latex-bearing plants in biotechnology. Throughout the course of this review, we concluded that plant latex is a rich source of many compounds, which can be further investigated and applied in the design of anticancer pharmaceuticals. The molecules, to which this cytotoxic effect can be attributed, include alkaloids, flavonoids, tannins, terpenoids, proteases, nucleases and many novel compounds, which still remain to be characterized. They have been studied extensively in both in vitro and in vivo studies, which provide an excellent starting point for their rapid transfer to clinical studies in the near future. The comprehensive study of molecules from latex-bearing plants can result in finding a promising alternative to several pharmaceuticals on the market and help unravel the molecular mode of action of latex-based preparations.

Chemistry and the Potential Antiviral, Anticancer, and Anti-Inflammatory Activities of Cardiotonic Steroids Derived from Toads

Cardiotonic steroids (CTS) were first documented by ancient Egyptians more than 3000 years ago. Cardiotonic steroids are a group of steroid hormones that circulate in the blood of amphibians and toads and can also be extracted from natural products such as plants, herbs, and marines. It is well known that cardiotonic steroids reveal effects against congestive heart failure and atrial fibrillation; therefore, the term "cardiotonic" has been coined. Cardiotonic steroids are divided into two distinct groups: cardenolides (plant-derived) and bufadienolides (mainly of animal origin). Cardenolides have an unsaturated five-membered lactone ring attached to the steroid nucleus at position 17; bufadienolides have a doubly unsaturated six-membered lactone ring. Cancer is a leading cause of mortality in humans all over the world. In 2040, the global cancer load is expected to be 28.4 million cases, which would be a 47% increase from 2020. Moreover, viruses and inflammations also have a very nebative impact on human health and lead to mortality. In the current review, we focus on the chemistry, antiviral and anti-cancer activities of cardiotonic steroids from the naturally derived (toads) venom to combat these chronic devastating health problems. The databases of different research engines (Google Scholar, PubMed, Science Direct, and Sci-Finder) were screened using different combinations of the following terms: “cardiotonic steroids”, “anti-inflammatory”, “antiviral”, “anticancer”, “toad venom”, “bufadienolides”, and “poison chemical composition”. Various cardiotonic steroids were isolated from diverse toad species and exhibited superior anti-inflammatory, anticancer, and antiviral activities in in vivo and in vitro models such as marinobufagenin, gammabufotalin, resibufogenin, and bufalin. These steroids are especially difficult to identify. However, several compounds and their bioactivities were identified by using different molecular and biotechnological techniques. Biotechnology is a new tool to fully or partially generate upscaled quantities of natural products, which are otherwise only available at trace amounts in organisms.

A review on phytochemical constituents and pharmacological potential of Calotropis procera

Calotropis procera is locally known as Aak or Madar in Hindi, milk weed in English and belongs to the family Apocynaceae and subfamily Asclepiadoideae. Although a wasteland plant, it is of sacred use as its flowers are offered for worshipping Lord Shiva, a Hindu God. Tribes all over the world use the plant in treatment of various diseases like snake bite, body pain, asthma, epilepsy, cancer, sexual disorders, skin diseases and many more. This plant contains various phytoconstituents such as flavonoids, terpenoids, cardenolides, steroids oxypregnanes etc. Though literature searches reveal many reviews about ethnomedicinal uses, chemical composition and pharmacological activities, no recent papers are available that provide an overview of the therapeutic potential and toxicity of Calotropis procera. Hence, the insight of this review is to provide a systemic summary of phytochemistry, pharmacology, toxicology and therapeutic potential of Calotropis procera and to highlight the gaps in the knowledge so as to offer inspiration for future research.

Calotropis procera is also known as Aak or Madar. The present review provides a systematic outline of phytochemistry, toxicology, pharmacology and therapeutic potential of Calotropis procera.

Bcl2-dependent antineoplastic effects of Calotropis procera root extract against canine mammary tumor cells

There has been a prevailing trend in the application of herbal medicine as cancer therapeutics. Calotropis procera is an ayurvedic plant applied to ameliorate various illnesses. There is no report on the anti-tumor effects of the root of the plant on canine tumors, although it has been used for the treatment of various diseases in human medicine. The objective of the present study was to investigate the antitumor potential of ethanolic root extract of C. procera against canine mammary tumor cell line (CF41-Mg). MTT, western blot, and flow cytometry assays were carried out to evaluate the possible cytotoxicity and apoptosis induction of the extract. MTT results showed that the extract had a potent cytotoxic activity in a dose-dependent manner with an IC₅₀ of 9.00 μg mL^-1. Based on the results of flow cytometry and western blotting, IC₅₀ concentration of the extract induced significant apoptosis in the studied cell line, possibly through down-regulation of Bcl-2 expression. The results of the present study clearly indicated that the root extract of C. procera had promising anti-cancer activity and could be considered as a candidate for the treatment of mammary tumors.

Antioxidant and anticancer potentials of edible flowers: where do we stand?

Edible flowers are attracting special therapeutic attention and their administration is on the rise. Edible flowers play pivotal modulatory roles on oxidative stress and related interconnected apoptotic/inflammatory pathways toward the treatment of cancer. In this review, we highlighted the phytochemical content and therapeutic applications of edible flowers, as well as their modulatory potential on the oxidative stress pathways and apoptotic/inflammatory mediators, resulting in anticancer effects. Edible flowers are promising sources of phytochemicals (e.g., phenolic compounds, carotenoids, terpenoids) with several therapeutic effects. They possess anti-inflammatory, anti-diabetic, anti-microbial, anti-depressant, anxiolytic, anti-obesity, cardioprotective, and neuroprotective effects. Edible flowers potentially modulate oxidative stress by targeting erythroid nuclear transcription factor-2/extracellular signal-regulated kinase/mitogen-activated protein kinase (Nrf2/ERK/MAPK), reactive oxygen species (ROS), nitric oxide (NO), malondialdehyde (MDA) and antioxidant response elements (AREs). As the interconnected pathways to oxidative stress, inflammatory mediators, including tumor necrosis factor (TNF)-α, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), interleukins (ILs) as well as apoptotic pathways such as Bcl-2-associated X protein (Bax), Bcl-2, caspase and cytochrome C are critical targets of edible flowers in combating cancer. In this regard, edible flowers could play promising anticancer effects by targeting oxidative stress and downstream dysregulated pathways.

Calotropis procera (Aiton) Dryand (Apocynaceae) as an anti-cancer agent against canine mammary tumor and osteosarcoma cells

Our goal was to evaluate phytochemical characterization and the antitumor potential of Calotropis procera. The phytochemical constitution of the crude extract (CE) revealed the presence of flavonoids, glycosides and cardenolide. The MTT assay was used to evaluate the cytotoxicity of CE, methanolic (MF) and ethyl acetate fractions (EAF) of C. procera in canine osteosarcoma cells (OST), canine mammary tumor (CMT), and canine skin fibroblasts (non-tumor cell). Doxorubicin was also used as a positive control. Results showed that CE, MF and EAF promoted a decrease in the viability of OST and CMT cells and did not alter the fibroblasts viability. C. procera also decreased the number of cells, corroborating to the decrease in proliferation and the cell cycle arrest in the G0/G1 phase. It was also evaluated the cell morphology by light and fluorescence microscopy, being demonstrated a reduction in cytoplasmic and cell rounding characteristic of programmed cell death. Moreover, flow cytometry data demonstrated that CE treatment promoted increase of caspase-3 and p53, showing that the cell death was activated in OST cells. In addition, there was a decrease in CD31, VEGF, osteopontin and TGF-β after CE treatment, suggesting that CE exerts its antitumor effect by reducing angiogenesis and tumor progression in OST cells. Moreover, CMT cells showed a reduction in PCNA after treatment with MF and CE. Analyzing the data together, C. procera, especially CE, showed an antitumor potential in both OST and CMT cells, encouraging us to continue investigating its use in cancer therapy.

Cardiac glycosides inhibit cancer through Na/K-ATPase-dependent cell death induction

Successful drug repurposing relies on the understanding of molecular mechanisms of the target compound. Cardiac glycosides have demonstrated potent anticancer activities; however, the pharmacological mechanisms underlying their anticancer effects remained elusive, which has restricted their further development in cancer treatment. A bottleneck is the lack of comprehensive understanding about genes and signaling pathways that are altered at the early stage of drug treatment, which is key to understand how they inhibit cancer. To address this issue, we first investigated the anticancer effects of a panel of 68 naturally isolated cardiac glycosides. Our results illustrate critical structure activity relationship of these compounds on cancer cell survival. We confirmed the anticancer effect of cardiac glycoside in mouse tumor xenografts. Through RNA sequencing, quantitative PCR and immunoblotting, we show that cardiac glycoside first activated autophagy and then induced apoptosis. Further activating autophagy by rapamycin or inhibiting apoptosis by caspase inhibitor mitigated cardiac glycoside-induced cell death, whereas inhibiting autophagy by RNA interference-mediated depletion of critical autophagy genes enhanced cell death. While depletion of Na/K-ATPase, the protein target of cardiac glycosides, by RNA interference inhibited both autophagy activation and apoptosis induction by cardiac glycoside, expression of human, but not rodent Na/K-ATPase, increased cell sensitivity to cardiac glycoside. In conclusion, our analyses reveal sequential activation of autophagy and apoptosis during early stages of cardiac glycoside treatment and indicate the importance of Na/K-ATPase in their anticancer effects.

Chemical Constituents and Uses of Calotropis Procera and Calotropis Gigantea – A Review (Part I – The Plants as Material and Energy Resources)

The traditional and current use of Calotropis procera and C. gigantea, two soft-wooded, xerophytic shrubs of the family Apocynaceae, are reviewed against the background of the plants' chemical constituents and their biological properties. The focus is on the usage of the plants for building materials, natural pesticides, animal feed and bioremediative purposes.

Natural modulators of the hallmarks of immunogenic cell death

Natural compounds act as immunoadjuvants as their therapeutic effects trigger cancer stress response and release of damage-associated molecular patterns (DAMPs). These reactions occur through an increase in the immunogenicity of cancer cells that undergo stress followed by immunogenic cell death (ICD). These processes result in a chemotherapeutic response with a potent immune-mediating reaction. Natural compounds that induce ICD may function as an interesting approach in converting cancer into its own vaccine. However, multiple parameters determine whether a compound can act as an ICD inducer, including the nature of the inducer, the premortem stress pathways, the cell death pathways, the intrinsic antigenicity of the cell, and the potency and availability of an immune cell response. Thus, the identification of hallmarks of ICD is important in determining the prognostic biomarkers for new therapeutic approaches and combination treatments.

Calotroposid A: a Glycosides Terpenoids from Calotropis gigantea Induces Apoptosis of Colon Cancer WiDr Cells through Cell Cycle Arrest G2/M and Caspase 8 Expression

Objective:

This study aims to isolate the active anticancer compound from ethyl acetate fraction extracted from the roots of Calotropis gigantea and to determine the operating mechanism of the isolates towards WiDr colon cancer cells.

Methods:

the isolation was conducted by using bioassay guided isolation approach method. The cytotoxic potential was determined by using MTT method. The chemical structure was identified by using UPLCMS/MS and NMR-1H spectroscopy. The cell cycle arrest and apoptosis induction were determined by flow cytometry method. The expression of caspase-8 was determined by immunocytochemistry method.

Results:

The results showed that the active compounds are obtained calotroposid A compound which is glycosides terpenoids. Calotroposide A is capable of inhibiting the growth of WiDr colon cancer cells at IC₅₀ 17.23µg/ml. Cell apoptosis induction took place and was indicated by cell apoptosis increase, S and G2/M accumulation and by caspase-8 expression.

Conclusion:

Calotroposide A induces anticancer activity against WiDr colon cancer cells by means of apoptosis induction mechanism through extrinsic pathway with increased expression of caspase-8.

Anticancer and Immunogenic Properties of Cardiac Glycosides

Cardiac glycosides (CGs) are natural compounds widely used in the treatment of several cardiac conditions and more recently have been recognized as potential antitumor compounds. They are known to be ligands for Na/K-ATPase, which is a promising drug target in cancer. More recently, in addition to their antitumor effects, it has been suggested that CGs activate tumor-specific immune responses. This review summarizes the anticancer aspects of CGs as new strategies for immunotherapy and drug repositioning (new horizons for old players), and the possible new targets for CGs in cancer cells.

Natural Compounds As Modulators of Non-apoptotic Cell Death in Cancer Cells

Cell death is an innate capability of cells to be removed from microenvironment, if and when they are damaged by multiple stresses. Cell death is often regulated by multiple molecular pathways and mechanism, including apoptosis, autophagy, and necroptosis. The molecular network underlying these processes is often intertwined and one pathway can dynamically shift to another one acquiring certain protein components, in particular upon treatment with various drugs. The strategy to treat human cancer ultimately relies on the ability of anticancer therapeutics to induce tumor-specific cell death, while leaving normal adjacent cells undamaged. However, tumor cells often develop the resistance to the drug-induced cell death, thus representing a great challenge for the anticancer approaches. Numerous compounds originated from the natural sources and biopharmaceutical industries are applied today in clinics showing advantageous results. However, some exhibit serious toxic side effects. Thus, novel effective therapeutic approaches in treating cancers are continued to be developed. Natural compounds with anticancer activity have gained a great interest among researchers and clinicians alike since they have shown more favorable safety and efficacy then the synthetic marketed drugs. Numerous studies in vitro and in vivo have found that several natural compounds display promising anticancer potentials. This review underlines certain information regarding the role of natural compounds from plants, microorganisms and sea life forms, which are able to induce non-apoptotic cell death in tumor cells, namely autophagy and necroptosis.

Non-canonical programmed cell death mechanisms triggered by natural compounds

Natural compounds are the fundament of pharmacological treatments and more than 50% of all anticancer drugs are of natural origins or at least derived from scaffolds present in Nature. Over the last 25 years, molecular mechanisms triggered by natural anticancer compounds were investigated. Emerging research showed that molecules of natural origins are useful for both preventive and therapeutic purposes by targeting essential hallmarks and enabling characteristics described by Hanahan and Weinberg. Moreover, natural compounds were able to change the differentiation status of selected cell types. One of the earliest response of cells treated by pharmacologically active compounds is the change of its morphology leading to ultra-structural perturbations: changes in membrane composition, cytoskeleton integrity, alterations of the endoplasmic reticulum, mitochondria and of the nucleus lead to formation of morphological alterations that are a characteristic of both compound and cancer type preceding cell death. Apoptosis and autophagy were traditionally considered as the most prominent cell death or cell death-related mechanisms. By now multiple other cell death modalities were described and most likely involved in response to chemotherapeutic treatment. It can be hypothesized that especially necrosis-related phenotypes triggered by various treatments or evolving from apoptotic or autophagic mechanisms, provide a more efficient therapeutic outcome depending on cancer type and genetic phenotype of the patient. In fact, the recent discovery of multiple regulated forms of necrosis and the initial elucidation of the corresponding cell signaling pathways appear nowadays as important tools to clarify the immunogenic potential of non-canonical forms of cell death induction.

Finding New Tricks for Old Drugs: Tumoricidal Activity of Non-Traditional Antitumor Drugs

Chemotherapy, a traditional method, plays an important role in tumor therapy. Currently, common clinical antitumor drugs have several defects like poor efficacy, side effects, etc. Furthermore, developing new antitumor drugs takes a long time and requires many resources. Recent studies have found that oldies are newbies for the oncologist, such as flavonoid, metformin, aspirin, etc. These non-traditional antitumor drugs (NTADs) are widely used in management of non-cancer diseases, which gained FDA approval for treatment of patients. Increasingly, studies about antitumor action of NTADs have attracted many researchers' interests. A giant amount of studies showed a decrease in cancer incidence in NTAD-treated patients. Several reports outlined a direct inhibitory effect of NTADs on cancer cell growth and antitumoral actions. This review summarized the research progress on antitumor effects of ten NTADs. Retrospective and meta-analyses of trials also showed that these NTADs had preventive effects against cancer in vitro and in vivo. These drugs represent a promising option for cancer treatment, which have clear benefits including clinical safety, obvious curative effect, and saving medical and health resources. Judged from previous reports, future studies will yield valuable data about the profitable effects of these drugs. With a better understanding of its mechanisms of antitumor activity, NTADs may become available for combination with chemotherapy or targeted therapy in clinic.

Cytotoxic, Antiproliferative and Pro-Apoptotic Effects of 5-Hydroxyl-6,7,3',4',5'-Pentamethoxyflavone Isolated from Lantana ukambensis

Lantana ukambensis (Vatke) Verdc. is an African food and medicinal plant. Its red fruits are eaten and highly appreciated by the rural population. This plant was extensively used in African folk medicinal traditions to treat chronic wounds but also as anti-leishmanial or cytotoxic remedies, especially in Burkina Faso, Tanzania, Kenya, or Ethiopia. This study investigates the in vitro bioactivity of polymethoxyflavones extracted from a L. ukambensis as anti-proliferative and pro-apoptotic agents. We isolated two known polymethoxyflavones, 5,6,7,3′,4′,5′-hexamethoxyflavone (1) and 5-hydroxy-6,7,3′,4′,5′-pentamethoxyflavone (2) from the whole plant of L. ukambensis. Their chemical structures were determined by spectroscopic analysis and comparison with published data. These molecules were tested for the anti-proliferative, cytotoxic and pro-apoptotic effects on human cancer cells. Among them, 5-hydroxy-6,7,3′,4′,5′-pentamethoxyflavone (2) was selectively cytotoxic against monocytic lymphoma (U937), acute T cell leukemia (Jurkat), and chronic myelogenous leukemia (K562) cell lines, but not against peripheral blood mononuclear cells (PBMCs) from healthy donors, at all tested concentrations. Moreover, this compound exhibited significant anti-proliferative and pro-apoptotic effects against U937 acute myelogenous leukemia cells. This study highlights the anti-proliferative and pro-apoptotic effects of 5-hydroxy-6,7,3′,4′,5′-pentamethoxyflavone (2) and provides a scientific basis of traditional use of L. ukambensis.

Cell type-dependent ROS and mitophagy response leads to apoptosis or necroptosis in neuroblastoma

A limiting factor in the therapeutic outcome of children with high-risk neuroblastoma is the intrinsic and acquired resistance to common chemotherapeutic treatments. Here we investigated the molecular mechanisms by which the hemisynthetic cardiac glycoside UNBS1450 overcomes this limitation and induces differential cell death modalities in both neuroblastic and stromal neuroblastoma through stimulation of a cell-type-specific autophagic response eventually leading to apoptosis or necroptosis. In neuroblastic SH-SY5Y cells, we observed a time-dependent production of reactive oxygen species that affects lysosomal integrity inducing lysosome-associated membrane protein 2 degradation and cathepsin B and L activation. Subsequent mitochondrial membrane depolarization and accumulation of mitochondria in phagophores occurred after 8h of UNBS1450 treatment. Results were confirmed by mitochondrial mass analysis, electron microscopy and co-localization of mitochondria with GFP-LC3, suggesting the impaired clearance of damaged mitochondria. Thus, a stress-induced defective autophagic flux and the subsequent lack of clearance of damaged mitochondria sensitized SH-SY5Y cells to UNBS1450-induced apoptosis. Inhibition of autophagy with small inhibitory RNAs against ATG5, ATG7 and Beclin-1 protected SH-SY5Y cells against the cytotoxic effect of UNBS1450 by inhibiting apoptosis. In contrast, autophagy progression towards the catabolic state was observed in stromal SK-N-AS cells: here reactive oxygen species (ROS) generation remained undetectable preserving intact lysosomes and engulfing damaged mitochondria after UNBS1450 treatment. Moreover, autophagy inhibition determined sensitization of SK-N-AS to apoptosis. We identified efficient mitophagy as the key mechanism leading to failure of activation of the apoptotic pathway that increased resistance of SK-N-AS to UNBS1450, triggering rather necroptosis at higher doses. Altogether we characterize here the differential modulation of ROS and mitophagy as a main determinant of neuroblastoma resistance with potential relevance for personalized anticancer therapeutic approaches.

Early downregulation of Mcl-1 regulates apoptosis triggered by cardiac glycoside UNBS1450

Cardiac glycosides (CGs), prescribed to treat cardiovascular alterations, display potent anti-cancer activities. Despite their well-established target, the sodium/potassium (Na⁺/K⁺)-ATPase, downstream mechanisms remain poorly elucidated. UNBS1450 is a hemi-synthetic cardenolide derived from 2″-oxovorusharin extracted from the plant Calotropis procera, which is effective against various cancer cell types with an excellent differential toxicity. By comparing adherent and non-adherent cancer cell types, we validated Mcl-1 as a general and early target of UNBS1450. A panel of CGs including cardenolides ouabain, digitoxin and digoxin as well as bufadienolides cinobufagin and proscillaridin A allowed us to generalize our findings. Our results show that Mcl-1, but not Bcl-xL nor Bcl-2, is rapidly downregulated prior to induction of apoptosis. From a mechanistic point of view, we exclude an effect on transcription and demonstrate involvement of a pathway affecting protein stability and requiring the proteasome in the early CG-induced Mcl-1 downregulation, without the involvement of caspases or the BH3-only protein NOXA. Strategies aiming at preventing UNBS1450-induced Mcl-1 downregulation by overexpression of a mutated, non-ubiquitinable form of the protein or the use of the proteasome inhibitor MG132 inhibited the compound's ability to induce apoptosis. Altogether our results point at Mcl-1 as a ubiquitous factor, downregulated by CGs, whose modulation is essential to achieve cell death.

Strophalloside induces apoptosis of SGC-7901 cells through the mitochondrion-dependent caspase-3 pathway

Cardenolides with special chemical structures have been considered as effective anti-cancer drugs in clinic trials. Strophalloside is a cardenolide we recently isolated from Antiaris toxicaria obtained from Hainan, China. The aim of this study was to investigate the possible anticancer effects induced by strophalloside and the underlying molecular mechanism. Gastric carcinoma SGC-7901 cells were treated with strophalloside at various concentrations for different times, and resulting cell viability was determined by the MTT assay, and the motility and invasion of tumor cells were assessed by the Transwell chamber assay. Apoptosis were measured by Annexin V-FITC/PI and Hoechst staining. The changes of mitochondrial transmembrane potential were examined by a JC-1 kit. The expressions of pro-apoptotic protein cytochrome c, caspase-3 and caspase-9 were detected by western blotting analysis. The results showed that strophalloside was capable of reducing cell viability, inhibiting cell growth, and suppressing cell migration and invasion in a time- and dose-dependent manner. Mitochondrial membrane potential declined and the concentration of cytochrome c increased in cytoplasm and caspase-3 and caspase-9 were cleaved into activated states, suggesting that cytochrome c was released from the mitochondrion to cytoplasm and finally activated the caspase-dependent apoptosis pathway. Our results indicate that strophalloside is a potential anticancer drug.

Calotropis procera extract induces apoptosis and cell cycle arrest at G2/M phase in human skin melanoma (SK-MEL-2) cells

Calotropis procera (family: Asclepiadaceae) contains cardiac glycosides which are cytotoxic to cancer cells. The extracts of C. procera have been reported to be cytotoxic to many cancer cell lines and this is the first report against the human skin melanoma cells (SK-MEL-2). The SK-MEL-2 cells treated with C. procera methanolic extract (CPME) were analysed for growth inhibition and apoptosis. The exposure of phosphatidylserine in apoptotic SK-MEL-2 was analysed by using the Annexin-V FITC flow cytometry method. In CPME-treated SK-MEL-2 cells, 19.6% of apoptotic and 58.3% dead cells were observed. The 15.97% and 15.85% of early apoptotic cells were found at 20 μg/mL of the ouabain and paclitaxel, respectively. Active caspases, nuclear degradation confirmed apoptotic SK-MEL-2 cells in time- and dose-dependent manner. The cell cycle analysis shows that CPME treated cells halt at G2/M phase. Significant cytotoxic activity of CPME against SK-MEL-2 may be attributed to its high cardenolide content.

The use of plants in the traditional management of diabetes in Nigeria: pharmacological and toxicological considerations

ETHNOPHARMACOLOGICAL RELEVANCE

The prevalence of diabetes is on a steady increase worldwide and it is now identified as one of the main threats to human health in the 21st century. In Nigeria, the use of herbal medicine alone or alongside prescription drugs for its management is quite common. We hereby carry out a review of medicinal plants traditionally used for diabetes management in Nigeria. Based on the available evidence on the species׳ pharmacology and safety, we highlight ways in which their therapeutic potential can be properly harnessed for possible integration into the country׳s healthcare system.

MATERIALS AND METHODS

Ethnobotanical information was obtained from a literature search of electronic databases such as Google Scholar, Pubmed and Scopus up to 2013 for publications on medicinal plants used in diabetes management, in which the place of use and/or sample collection was identified as Nigeria. 'Diabetes' and 'Nigeria' were used as keywords for the primary searches; and then 'Plant name - accepted or synonyms', 'Constituents', 'Drug interaction' and/or 'Toxicity' for the secondary searches.

RESULTS

The hypoglycemic effect of over a hundred out of the 115 plants reviewed in this paper is backed by preclinical experimental evidence, either in vivo or in vitro. One-third of the plants have been studied for their mechanism of action, while isolation of the bioactive constituent(s) has been accomplished for twenty three plants. Some plants showed specific organ toxicity, mostly nephrotoxic or hepatotoxic, with direct effects on the levels of some liver function enzymes. Twenty eight plants have been identified as in vitro modulators of P-glycoprotein and/or one or more of the cytochrome P450 enzymes, while eleven plants altered the levels of phase 2 metabolic enzymes, chiefly glutathione, with the potential to alter the pharmacokinetics of co-administered drugs.

CONCLUSION

This review, therefore, provides a useful resource to enable a thorough assessment of the profile of plants used in diabetes management so as to ensure a more rational use. By anticipating potential toxicities or possible herb-drug interactions, significant risks which would otherwise represent a burden on the country׳s healthcare system can be avoided.

The cytotoxic activities of cardiac glycosides from Streptocaulon juventas and the structure-activity relationships

A series of cardiac glycosides were isolated and identified from the anti-tumor fraction of the root of Streptocaulon juventas in previous studies. In the present research, the cytotoxic activities of the 43 cardiac glycosides on three cell lines, human lung A549 adenocarcinoma cell, large cell lung cancer NCI-H460 cell and normal human fetal lung fibroblast MRC-5 cell, were evaluated in vitro. Most of the tested compounds showed potent inhibitory activities toward the three cell lines. Then, the structure-activity relationships were discussed in detail. It was indicated that hydroxyl and acetyl groups at C-16 increased the activity, whereas hydroxyl group at C-1 and C-5 can both increase and decrease the activity. Two glucosyl groups which were connected by C1'→C6' showed better inhibitory activity against cancer cell lines, while the C1'→C4' connection showed stronger inhibitory activity against the normal cell line. Also, this is the first report that the activities of these compounds exhibited different variation trends between A549 and NCI-H460 cell lines, which indicated that these compounds could selectively inhibit the cell growth. The results would lay a foundation for further research on new anti-tumor drug development.

Antagonistic role of natural compounds in mTOR-mediated metabolic reprogramming

Cells reprogram their metabolism very early during carcinogenesis; this event is critical for the establishment of other cancer hallmarks. Many oncogenes and tumor suppressor genes control metabolism by interplaying with the existing nutrient-sensing intracellular pathways. Mammalian target of rapamycin, mTOR, is emerging as a collector and sorter of a metabolic network controlling upstream and downstream modulation of these same genes. Natural compounds represent a source of anti-cancer molecules with chemopreventive and therapeutic properties. This review describes selected pathways and genes orchestrating the metabolic reprogramming and discusses the potential of natural compounds to target oncogenic metabolic aberrations.

Anti-inflammatory and anticancer drugs from nature

Over the centuries, plant extracts have been used to treat various diseases. Until now, natural products have played an important role in anticancer therapy as there are more than 500 compounds from terrestrial and marine plants or microorganisms, which have antioxidant, antiproliferative, or antiangiogenic properties and are therefore able to reduce tumor growth. The recent discovery of new natural products has been accelerated by novel technologies (high throughput screening of natural products in plants, animals, marine organisms, and microorganisms). Vincristine, irinotecan, etoposide, and paclitaxel are examples of compounds derived from plants that are used in cancer treatment. Similarly, actinomycin D, mitomycin C, bleomycin, doxorubicin, and L-asparaginase are drugs derived from microorganisms. In this review, we describe the molecular mechanisms of natural compounds with anti-inflammatory and anticancer activities.

Insights on the phytochemical profile (cyclopeptides) and biological activities of Calotropis procera latex organic fractions

Calotropis procera is a medicinal plant whose pharmacological properties are associated with its latex. Here, the Calotropis procera latex fractions were investigated in an attempt to trace its phytochemical profile and measure its anti-inflammatory and toxicity activity. The crude latex was partitioned, yielding five fractions (49.4% hexane, 5.2% dichloromethane, 2.0% ethyl acetate, 2.1% n-butanol, and 41.1% aqueous). Phytochemical screening and spectroscopy analysis revealed that dichloromethane is the most chemically diverse fraction. Triterpenes were detected in both the hexane and dichloromethane fractions, while flavonoids were detected in the dichloromethane and ethyl acetate fractions. These fractions were cytotoxic to cancer cell lines (LD₅₀ 0.05 to 3.9 μg/mL) and lethal to brine shrimp (LD₅₀ 10.9 to 65.7 μg/mL). Reduced neutrophil migration in rats was observed in carrageenan-induced peritonitis for the dichloromethane (67%), ethyl acetate (56%), and aqueous (72%) fractions. A positive reaction with tolidine and ninhydrin suggested that cyclopeptides are in the ethyl acetate fraction. It is therefore concluded that Calotropis procera latex dichloromethane and ethyl acetate fractions exhibit both in vitro and in vivo activities as well as anti-inflammatory properties. Cyclopeptide detection is especially interesting because previous attempts to investigate these low-molecular cyclic amino acid sequences in C. procera have failed.

Anticancer attributes of desert plants: a review

The ever-increasing emergence of the resistance of mammalian tumor cells to chemotherapy and its severe side effects reduces the clinical efficacy of a large variety of anticancer agents that are currently in use. Thus, despite the significant progress in cancer therapeutics in the last decades, the need to discover and to develop new, alternative, or synergistic anticancer agents remains. Cancer prevention or chemotherapy based on bioactive fractions or pure components derived from desert plants with known cancer-inhibiting properties suggests promising alternatives to current cancer therapy. Plants growing on low nutrient soils and/or under harsh climatic conditions, such as extreme temperatures, intense solar radiation, and water scarcity, are particularly susceptible to attack from reactive oxygen species and have evolved efficient antioxidation defense systems. The many examples of desert plants displaying anticancer effects as presented here indicates that the same defensive secondary metabolites protecting them against the harsh environment may also play a protective or a curative role against cancer, as they also do against diabetes, neurodegenerative, and other acute and chronic diseases. The present review highlights a plethora of studies focused on the antineoplastic properties of desert plants and their prinicipal phytochemicals, such as saponins, flavonoids, tannins, and terpenes. Although many desert plants have been investigated for their antitumor properties, there are many that still remain to be explored - a challenge for the prospective cancer therapy of the future.

Anti-cancer potential of South Asian plants

Phyto-chemicals are increasingly being used in the treatment of cancer because of their availability, potential anti-cancer activity with less adverse effects when compared with chemotherapy. The variation of climate and geography in South Asian countries provides a nursing environment for the growth of versatile plant species, that are repeatedly drawing attention of the scientific community. In this review, we have focused on the anti-cancer potential of thirty plants, which are commonly found in Bangladesh, India, Nepal, Pakistan and Sri Lanka, with their mechanisms of action. In particular, we have discussed the bio-active components that display anti-cancer activity, which have been identified in these plants. This review may help researchers to profile plants with known anti-cancer effect of this region and further investigations of anti-cancer agents in medicinal plants from South Asia.

Anticancer steroids: linking natural and semi-synthetic compounds

Steroids, a widespread class of natural organic compounds occurring in animals, plants and fungi, have shown great therapeutic value for a broad array of pathologies. The present overview is focused on the anticancer activity of steroids, which is very representative of a rich structural molecular diversity and ability to interact with various biological targets and pathways. This review encompasses the most relevant discoveries on steroid anticancer drugs and leads through the last decade and comprises 668 references.

Traditional West African pharmacopeia, plants and derived compounds for cancer therapy

Traditional pharmacopeia is strongly involved in the continuous search for the well being of African populations. The World Health Organization (WHO) estimates that 80% of the population of developing countries relies on traditional medicine for their primary care needs. Medicinal plants are the major resource of this folk medicine where several species are used for the treatment of diseases with an inflammatory and/or infectious component as it is the case of old wounds, skin diseases and malfunctions affecting internal organs such as liver, lung, prostate and kidney. Many of these pathologies described by practitioners of traditional medicine have similarities with certain cancers, but the lack of training of many of these healers does not allow them to establish a link with cancer. However, ethnobotanical and ethnopharmacological surveys conducted by several researchers allowed to identify plants of interest for cancer treatment. Most scientific investigations on these plants demonstrated an anti-inflammatory or antioxidant effect, and sometimes, antiproliferative and cytotoxic activities against cancer cells were reported as well. The emergence of resistance to cancer chemotherapy has forced researchers to turn to natural products of plant and marine origin. In the West African sub-region, research on natural anti-cancer molecules is still in its infancy stage because of very limited financial resources and the scarcity of adequate technical facilities. However, several plants were investigated for their anticancer properties through north-south or south-south partnerships. In this review, we will review the role of West African traditional pharmacopeia in cancer treatment as well as medicinal plants with anti-cancer properties.

Cardiac glycosides induce autophagy in human non-small cell lung cancer cells through regulation of dual signaling pathways

Na(+)/K(+)-ATPase targeted cancer therapy has attracted increasing interests of oncologists in lung cancer field. Although multiple anti-cancer mechanisms of cardiac glycosides as Na(+)/K(+)-ATPase inhibitors are revealed, the role of autophagy and related molecular signaling pathway for the class of compounds in human non-small cell lung cancer (NSCLC) cells has not been systematically examined. We herein investigated the anti-cancer effects of two representative cardiac glycosides, digoxin and ouabain, in A549 and H460 cell lines. Both agents caused significant growth inhibition at nanomolar level. The cardiac glycosides were found to induce moderate G(2)/M arrest but not apoptosis at IC(50) level in the NSCLC cell lines. Moreover, autophagy was markedly induced by both agents, as evidenced by the time- and dose-dependent increase of LC3-II, up-regulation of Atg5 and Beclin1, as well as by the observations through acridine orange staining, transmission electron microscopy and quantification of GFP-LC3 fluorescence. Importantly, AMP-activated protein kinase (AMPK) pathway was activated, resulting in mammalian target of rapamycin (mTOR) deactivation during autophagy induction. Moreover, extracellular-signal-regulated kinase 1/2 (ERK1/2) activation was simultaneously found to be involved in the autophagy regulation. Co-treatment with respective inhibitors or siRNAs could either block the autophagic phenotypes and signals, or significantly increase the cellular viability, indicating the drugs-induced autophagy plays tumor-suppressing role. This work provides first evidence showing that the cardiac glycosides induce autophagy in human NSCLC cells through regulation of both mTOR and ERK1/2 signaling pathways. The autophagy may at least partially account for the growth inhibitory effects of the compounds in human NSCLC cells.

Rapid identification of calotropagenin glycosides using high-performance liquid chromatography electrospray ionisation tandem mass spectrometry

INTRODUCTION

Cardiac glycosides in Calotropis procera have therapeutic use as inhibitors of Na⁺/K⁺-ATPase to regulate heart contractions. A large amount of research attention has been received by these compounds towards their identification and structural characterisation. In order to achieve rapid identification of cardiac glycosides in phytochemical extracts a liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed involving metal cationisation by post-column addition of alkali salts for the unambiguous determination of their molecular weights.

OBJECTIVE

Identification of cardiac glycosides in Calotropis procera leaf extract.

RESULTS

Calotropagenin and its 10 glycosides were unambiguously identified. The daughter ions at m/z 387, 369, 359, 351, 341 and 323 in their MS/MS spectra were attributed to the calotropagenin aglycone unit.

CONCLUSION

High performance liquid chromatography in combination with electrospray ionization tandem mass spectrometry involving metal cationisation by post column addition of alkali salts was successfully utilised for the rapid identification of calotropagenin glycosides/derivatives in Calotropis procera extract.

Discovery of new anticancer agents from higher plants

Small organic molecules derived from higher plants have been one of the mainstays of cancer chemotherapy for approximately the past half a century. In the present review, selected single chemical entity natural products of plant origin and their semi-synthetic derivatives currently in clinical trials are featured as examples of new cancer chemotherapeutic drug candidates. Several more recently isolated compounds obtained from plants showing promising in vivo biological activity are also discussed in terms of their potential as anticancer agents, with many of these obtained from species that grow in tropical regions. Since extracts of only a relatively small proportion of the ca. 300,000 higher plants on earth have been screened biologically to date, bioactive compounds from plants should play an important role in future anticancer drug discovery efforts.

Discovery of new anticancer agents from higher plants

Small organic molecules derived from higher plants have been one of the mainstays of cancer chemotherapy for approximately the past half a century. In the present review, selected single chemical entity natural products of plant origin and their semi-synthetic derivatives currently in clinical trials are featured as examples of new cancer chemotherapeutic drug candidates. Several more recently isolated compounds obtained from plants showing promising in vivo biological activity are also discussed in terms of their potential as anticancer agents, with many of these obtained from species that grow in tropical regions. Since extracts of only a relatively small proportion of the ca. 300,000 higher plants on earth have been screened biologically to date, bioactive compounds from plants should play an important role in future anticancer drug discovery efforts.

Targeting the Na(+)/K(+)-ATPase alpha1 subunit of hepatoma HepG2 cell line to induce apoptosis and cell cycle arresting

Recent research has shown that the Na(+)/K(+)-ATPase alpha1 subunit is a novel anti-cancer target, which plays pivotal roles in malignant cell ion transport, metabolism, migration and signal transduction. The purpose of the present study was to investigate the anti-cancer effects of ouabain and Na(+)/K(+)-ATPase alpha1 small interfering ribonucleic acid (siRNA) on HepG2 cell proliferation, apoptosis and cell cycle, and to explore the molecular mechanisms. The expression of Na(+)/K(+)-ATPase alpha1 subunit in human hepatocellular carcinoma (HCC), normal liver tissues and human HCC line (HepG2, SMMC-7721 and Bel-7402) has been investigated. Using the ouabain and Na(+)/K(+)-ATPase alpha1 subunit siRNA, which target the Na(+)/K(+)-ATPase, we have evaluated the effects of inhibiting Na(+)/K(+)-ATPase alpha1 in human HepG2 cells with respect to cell proliferation, morphology, cell cycle, impact on intracellular Ca2++, reactive oxygen species (ROS) concentration, and correlated gene expression level on messenger ribonucleic acid (mRNA) and protein. Our data showed that the expression Na(+)/K(+)-ATPase alpha1 subunit in HCC tissues is higher than that in normal liver tissues. Ouabain and Na(+)/K(+)-ATPase alpha1 siRNA could inhibit HepG2 cell proliferation. Ouabain could induce HepG2 cell apoptosis and generate S phase arrest, and siRNA could enhance the anti-cancer effect of ouabain that induced HepG2 cells apoptosis via an intracellular Ca(2+) and ROS increase-mediated, and generated cell cycle S phase arresting by decreasing the CyclinA1/cyclin-dependent kinase 2 (CDK2)/proliferating cell nuclear antigen (PCNA) complex product and increasing the expression of cyclin-dependent kinase inhibitor 1A (P21(CIP1)). We believe that targeting of the Na(+)/K(+)-ATPase alpha1 subunit in human HCC cells could provide new sight into the treatment of HCC.

UNBS1450, a steroid cardiac glycoside inducing apoptotic cell death in human leukemia cells

Cardiac steroids are used to treat various diseases including congestive heart failure and cancer. The aim of this study was to investigate the anti-leukemic activity of UNBS1450, a hemi-synthetic cardenolide belonging to the cardiac steroid glycoside family. Here, we report that, at low nanomolar concentrations, UNBS1450 induces apoptotic cell death. Subsequently, we have investigated the molecular mechanisms leading to apoptosis activation. Our results show that UNBS1450 inhibits NF-κB transactivation and triggers apoptosis by cleavage of pro-caspases 8, 9 and 3/7, by decreasing expression of anti-apoptotic Mcl-1 and by recruitment of pro-apoptotic Bak and Bax protein eventually resulting in cell death.

In vivo growth inhibition of sarcoma 180 by latex proteins from Calotropis procera

Latex of Calotropis procera has been described as a relevant source of pharmacologically active proteins, including proteins with anticancer activity. A previous in vitro study of laticifer proteins (LP) from C. procera reported that they had selective cytotoxic effects on human cancer cell lines. The aim of this study was to determine the effects of LP in vivo using mice transplanted with sarcoma 180. Biochemical, hematological, histopathological, and morphological analyses were performed in animals given LP by oral or intraperitoneal routes. LP significantly reduced tumor growth (51.83%) and augmented the survival time of animals for up to 4 days. Tumor growth inhibitory activity was lost when LP fraction was submitted to proteolysis, acidic treatment, or pretreated with iodoacetamide. However, LP retained its inhibitory activities on sarcoma 180 growth after heat treatment. Thus, it seems that heat-stable proteins are involved in tumor suppression. Biochemical parameters, such as the enzymatic activity of aspartate aminotransferase and alanine aminotransferase and urea content in serum were not affected in treated mice. It is worth noting that LP completely eliminated the 5-FU-induced depletion of leukocytes in mice even when given orally. The active proteins were recovered in a single fraction by ion exchange chromatography and still exhibited anticancer activity. This study confirms the pharmacological potential of proteins from the latex of C. procera to control sarcoma cell proliferation.