Toxic profile of marinobufagin from poisonous Amazon toads and antitumoral effects on human colorectal carcinomas.

ETHNOPHARMACOLOGICAL RELEVANCE: South Americans natives have extensively used the toad "kururu" to reduce/treat skin infections, cutaneous lesions and sores. They release secretions rich in bufadienolides, polyhydroxy steroids with well-documented cardiotonic and antiproliferative actions, but in vivo antitumoral evaluations in mammals are rare, and toxicological safety has been left in second place. AIMS OF THE STUDY: This investigation used in silico, in vitro and in vivo tools to evaluate acute and subacute toxic effects of marinobufagin and the anticancer action in tumor-bearing mice models. MATERIALS AND METHODS: Initially, in silico toxic predictions were performed, followed by in vitro assays using human and murine normal and tumor lines. Next, acute and subacute studies on mice investigated the behavior, hematological and intestinal transit profile and antitumoral activity of marinobufagin in sarcoma 180- and HCT-116 colorectal carcinoma-transplanted mice for 7 and 15 days, respectively. Ex vivo and in vivo cytogenetic assays in Sarcoma 180 and bone marrow cells and histopathological examinations were also executed. RESULTS: In silico studies revealed ecotoxicological effects on crustaceans (Daphnia sp.), fishes (Pimephales promelas and Oryzias latipes), and algae. A 24-h marinobufagin-induced acute toxicity included signals of central activity, mainly (vocal frenzy, absence of body tonus, increased ventilation, ataxia, and equilibrium loss), and convulsions and death at 10 mg/kg. The bufadienolide presented effective in vitro cytotoxic action on human lines of colorectal carcinomas in a similar way to ouabain and tumor reduction in marinobufagin-treated SCID-bearing HCT-116 heterotopic xenografts. Animals under subacute nonlethal doses exhibited a decrease in creatinine clearance with normal levels of blood urea, probably as a result of a marinobufagin-induced renal perfusion fall. Nevertheless, only minor morphological side effects were identified in kidneys, livers, hearts and lungs. CONCLUSIONS: Marinobufagin has in vitro and in vivo anticancer action on colorectal carcinoma and mild and reversible alterations in key metabolic organs without direct chemotherapy-induced gastrointestinal effects at subacute exposure, but it causes acute ataxia, equilibrium loss, convulsions and death at higher acute exposure.

Natural Dibenzo[b,f]oxepines, Pacharin and Bauhiniastatin-1, Isolated from Bauhinia acuruana Induce Apoptosis on Breast Cancer Cells via MCL-1 Protein Reduction.

Herein, we describe the antiproliferative effects of two natural dibenzo [b,f]oxepines, pacharin and bauhiniastatin-1, isolated from Bauhinia acuruana on a breast cancer cell line and the mode of action underlying the cytotoxicity. Both compounds were cytotoxic in a panel of six tumor lines analyzed by the MTT assay, and IC50 values ranged from 7.8 to 45.1 µM, including human breast adenocarcinoma (MCF-7) cells. In contrast, none of the compounds were cytotoxic on normal human peripheral blood mononuclear cells (IC50 > 100 µM). Human breast adenocarcinoma (MCF-7) cells treated with pacharin or bauhiniastatin-1 20 µM for 24 h presented a reduction in cell volume and intensification of chromatin condensation, DNA fragmentation, and apoptotic cells. These findings became more evident after 48 h of exposure. Antiapoptotic B-cell lymphoma-2 family members, such as myeloid cell leukemia-1 and B-cell lymphoma-extra large, are important targets in cancer cells since their overexpression confers resistance to cancer treatments. A significant reduction of the myeloid cell leukemia-1 protein levels in human breast adenocarcinoma (MCF-7) cells after 24 h of treatment with pacharin or bauhiniastatin-1 at 20 µM was observed, while the B-cell lymphoma-extra large protein content was reduced in bauhiniastatin-1-treated cells at 40 µM only. The cytotoxic effects of pacharin and bauhiniastatin-1 are likely linked to myeloid cell leukemia-1 inhibition, which leads to the apoptosis of breast adenocarcinoma cells.

Chemical composition, larvicidal and cytotoxic activity of Annona salzmannii (Annonaceae) seed oil

The seed oil of Annona salzmannii A. DC. was analyzed by GC-MS and 1H qNMR, revealing a mixture of unsaturated (80.5%) and saturated (18.7%) fatty acids. Linoleic (45.3%) and oleic (33.5%) acid were the major unsaturated fatty acids identified, while palmitic acid (14.3%) was the major saturated fatty acid. The larvicidal effects of A. salzmannii seed oil were evaluated against third-instar larvae of Aedes aegypti (Linn.). The oil exhibited moderate larvicidal activity, with a LC50 of 569.77 ppm (95% CI = 408.11 to 825.88 ppm). However, when the cytotoxic effects of the oil were evaluated, no expressive antiproliferative effects were observed in tumor cell lines B16-F10 (mouse melanoma), HepG2 (human hepatocellular carcinoma), K562 (human chronic myelocytic leukemia), HL-60 (human promyelocytic leukemia), and non-tumor cell line PBMC (peripheral blood mononuclear cells), with IC50 values > 50 µg·mL-1. This is the first study to evaluate the chemical composition, larvicidal and cytotoxic activity of A. salzmannii seed oil

The Dual Antioxidant/Prooxidant Effect of Eugenol and Its Action in Cancer Development and Treatment.

The formation of reactive oxygen species (ROS) during metabolism is a normal process usually compensated for by the antioxidant defense system of an organism. However, ROS can cause oxidative damage and have been proposed to be the main cause of age-related clinical complications and diseases such as cancer. In recent decades, the relationship between diet and cancer has been more studied, especially with foods containing antioxidant compounds. Eugenol is a natural compound widely found in many aromatic plant species, spices and foods and is used in cosmetics and pharmaceutical products. Eugenol has a dual effect on oxidative stress, which can action as an antioxidant or prooxidant agent. In addition, it has anti-carcinogenic, cytotoxic and antitumor properties. Considering the importance of eugenol in the area of food and human health, in this review, we discuss the role of eugenol on redox status and its potential use in the treatment and prevention of cancer.

Chemical Composition of the Essential Oil from the Fresh Fruits of Xylopia laevigata and its Cytotoxic Evaluation.

The essential oil obtained by hydrodistillation from the fresh fruits of Xylopia laevigata was analyzed by gas chromatography using a flame ionization detector (GC-FID) coupled to a mass spectrometer (GC-MS). Monoterpenes predominated, forming 95.0% of the total essential oil. The major constituents identified were limonene (56.2%), α-pinene (28.0%), and ß-pinene (5.5%). Cytotoxic activity against tumor cell lines and non-tumor cells was also investigated; however, neither the essential oil nor its major constituents evaluated presented any cytotoxic activity (IC50 > 25.0 µg mL⁻¹).

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.

In vivo growth-inhibition of Sarcoma 180 by an alpha-(1-->4)-glucan-beta-(1-->6)-glucan-protein complex polysaccharide obtained from Agaricus blazei Murill.

Agaricus blazei Murrill, a native mushroom of Brazil, has been widely consumed in different parts of the world due to its anticancer potential. This effect is generally attributed to its polysaccharides; however, the precise structure of these has not been fully characterized. To better understand the relationship between polysaccharide structures and antitumor activity, we investigated the effect of the intraperitoneally (i.p.) or orally (p.o.) administered alpha-(1-->4)-glucan-beta-(1-->6)-glucan-protein complex polysaccharide from A. blazei alone or in association with 5-fluorouracil (5-FU) in tumor growth using Sarcoma 180 transplanted mice. Hematological, biochemical, and histopathological analyses were performed in order to evaluate the toxicological aspects of the polysaccharide treatment. The polysaccharide had no direct cytotoxic action on tumor cells in vitro. However, the polysaccharide showed strong in vivo antitumor effect. Thus, the tumor growth-inhibitory effect of the polysaccharide is apparently due to host-mediated mechanisms. The histopathological analysis suggests that the liver and the kidney were not affected by polysaccharide treatment. Neither enzymatic activity of transaminases (AST and ALT) nor urea levels were significantly altered. In hematological analysis, leucopeny was observed after 5-FU treatment, but this effect was prevented when the treatment was associated with the polysaccharide. In conclusion, this polysaccharide probably could explain the ethnopharmacological use of this mushroom in the treatment of cancer.

Antitumor activity of biflorin, an o-naphthoquinone isolated from Capraria biflora.

Pharmacological studies with an aqueous extract obtained from leaves of Capraria biflora showed potent cytotoxic, analgesic, antimicrobial and anti-inflammatory activities. It has been demonstrated that biflorin possesses an in vitro cytotoxic activity against tumor cells. The in vivo antitumor activity of biflorin was evaluated on two mouse models, sarcoma 180 and Ehrlich carcinoma. Biflorin was active against both tumors with a very similar profile. In addition, biflorin was also able to increase the response elicited by 5-FU in mice inoculated with both tumors. The results showed a decrease in Ki67 staining in tumor cells from treated-animals when compared with non-treated groups, which suggests an inhibition of tumor proliferation rate. Histopathological analysis from kidneys and liver showed that biflorin possessed weak and reversible toxic effects. It was also demonstrated that biflorin acts as an immunoadjuvant agent, rising the production of ovalbumin-specific antibodies and inducing a discreet increase of the white pulp and nest of megakaryocytic in spleen of treated mice, which can be related to its antitumor properties.