In vitro toxicity of latex, its terpenoidal fractions and isolated phorbol esters from Euphorbia umbellata (Pax) Bruyns on monocytic and melanoma cells.

In Brazil, latex from Euphorbia umbellata (African milk tree) has been increasingly used in folk medicine to treat several types of cancer, including melanoma. The effect of lyophilized latex (LL), its hydroethanolic extract (E80), triterpene (F-TRI)- and diterpene (F-DIT)-enriched fractions, along with six isolated phorbol esters from LL and phorbol 12-myristate 13-acetate (PMA) on J774A.1, THP-1, SK-MEL-28, and B16-F10 cell line viability were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method. The compounds were identified by 2D-NMR and HRESIMS. The effect of the LL, extract and fractions on cell viability was also assessed through a resazurin reduction assay. At 100 µg/ml, LL, and its fractions moderately inhibited J774A.1 (37.5-59.5%) and THP-1 (12.6-43.6%) metabolism. LL (IC50 70 µg/ml) and F-TRI (IC50 68 µg/ml) were barely more effective against B16-F10 cells, and only F-TRI exerted an inhibitory effect on SK-MEL-28 cells (IC50 66-75 µg/ml). The samples did not effectively inhibit THP-1 growth (IC50 69-87 µg/ml, assessed by MTT). B16-F10 was susceptible to PMA (IC50 53 µM) and two 12-phenylacetate esters (IC50 56-60 µM), while SK-MEL-28 growth was inhibited (IC50 58 µM) by one of these kinds of esters with an additional 4ß-deoxy structure. Synagrantol A (IC50 39 µM) was as effective as PMA (IC50 47 µM) in inhibiting J774A.1 growth in a dose-dependent manner. Furthermore, an in silico study with target receptors indicated a high interaction of the compounds with the PKC proteins. These results provide useful knowledge on the effect of tigliane-type diterpenes on tumor cell from the perspective of medicinal chemistry.

Natural heat shock protein 90 inhibitors in cancer and inflammation.

Heat shock protein (HSP)90 is the most abundant HSPs, which are chaperone molecules whose major roles are cell protection and maintenance by means of aiding the folding, the stabilization and the remodeling of a wide range of proteins. A few hundreds of proteins depend on HSP90 chaperone activity, including kinases and transcriptional factors that play essential roles in cancer and inflammation, so that HSP90-targeted therapies have been considered as a potential strategy for the treatment of cancer and inflammatory-associated diseases. HSP90 inhibition by natural, semi-synthetic and synthetic compounds have yield promising results in pre-clinical studies and clinical trials for different types of cancers and inflammation. Natural products are a huge source of biologically active compounds widely used in drug development due to the great diversity of their metabolites which are capable to modulate several protein functions. HSP90 inhibitors have been isolated from bacteria, fungi and vegetal species. These natural compounds have a noteworthy ability to modulate HSP90 activity as well as serve as scaffolds for the development of novel synthetic or semi-synthetic inhibitors. Over a hundred clinical trials have evaluated the effect of HSP90 inhibitors as adjuvant treatment against different types of tumors and, currently, new studies are being developed to gain sight on novel promising and more effective approaches for cancer treatment. In this review, we present the naturally occurring HSP90 inhibitors and analogues, discussing their anti-cancer and anti-inflammatory effects.

Development of Thiophene Compounds as Potent Chemotherapies for the Treatment of Cutaneous Leishmaniasis Caused by Leishmania major.

Leishmania major (L. major) is a protozoan parasite that causes cutaneous leishmaniasis. About 12 million people are currently infected with an annual incidence of 1.3 million cases. The purpose of this study was to synthesize a small library of novel thiophene derivatives, and evaluate its parasitic activity, and potential mechanism of action (MOA). We developed a structure⁻activity relationship (SAR) study of the thiophene molecule 5A. Overall, eight thiophene derivatives of 5A were synthesized and purified by silica gel column chromatography. Of these eight analogs, the molecule 5D showed the highest in vitro activity against Leishmania major promastigotes (EC50 0.09 ± 0.02 µM), with an inhibition of the proliferation of intracellular amastigotes higher than 75% at only 0.63 µM and an excellent selective index. Moreover, the effect of 5D on L. major promastigotes was associated with generation of reactive oxygen species (ROS), and in silico docking studies suggested that 5D may play a role in inhibiting trypanothione reductase. In summary, the combined SAR study and the in vitro evaluation of 5A derivatives allowed the identification of the novel molecule 5D, which exhibited potent in vitro anti-leishmanial activity resulting in ROS production leading to cell death with no significant cytotoxicity towards mammalian cells.

Drug Design, Synthesis and In Vitro Evaluation of Substituted Benzofurans as Hsp90 Inhibitors.

BACKGROUND: Heat shock protein 90 is a molecular chaperone required for the stability and function of several client proteins that promote cancer cell growth and/or survival. Discovery of Hsp90 inhibitors has emerged as an attractive target of research in cancer therapeutics. Natural products like geldanamycin and radicicol are established Hsp90 inhibitors, but face limitations with toxicity and inactivity, by in vivo studies respectively. However, they lay the logical starting point for the design of novel synthetic or semi-synthetic congeners as Hsp90 inhibitors. OBJECTIVE: In this article, the structure based drug design of substituted 2-aryl/heteroarylidene-6- hydroxybenzofuran-3(2H)-one analogues to optimize and mimic the pharmacophoric interactions of the valid Hsp90 inhibitor radicicolis focused. METHOD: In silico docking study was performed by Surflex dock-Geom (SYBYL- X 1.2 drug discovery suite) and the designed ligands were chemically synthesized by conventional method using resorcinol and chlororesorcinol as starting materials. Two dimensional chemical similarity search was carried out to identify the chemical space of 'SY' series in comparison with reported Hsp90 inhibitors. The in vitro cell proliferation assay (resazurin reduction method) and proteomic investigation (DARTS) was carried out on whole cell lysate to evaluate anticancer activity. RESULTS: The chemical structures of all the synthesized compounds were confirmed by IR, 1H-NMR and Mass spectral analysis. The results of chemical similarity search show that SY series fit it in the chemical space defined by existing Hsp90 inhibitors. In vitro cell proliferation assay, against human melanoma and breast cancer cell lines, identified 'SY3' as the promising anticancer agent amongst the series. CONCLUSION: Docking studies, 2D chemical similarity search, resazurin reduction assay and qualitative proteomic analysis identify 'SY3'as a promising Hsp90 inhibitor amongst the series.

Effect of gedunin on acute articular inflammation and hypernociception in mice.

Gedunin, a natural limonoid from Meliaceae species, has been previously described as an antiinflammatory compound in experimental models of allergic inflammation. Here, we report the antiinflammatory and antinociceptive effects of gedunin in an acute model of articular inflammation induced by zymosan (500 µg/cavity; intra-articular) in C57BL/6 mice. Intraperitoneal (i.p.) pretreatment with gedunin (0.005-5 mg/kg) impaired zymosan-induced edema formation, neutrophil accumulation and hypernociception in mouse knee joints, due to decreased expression of preproET-1 mRNA and production of LTB4, PGE2, TNF-α and IL-6. Mouse post-treatment with gedunin (0.05 mg/kg; i.p.) 1 and 6 h after stimulation also impaired articular inflammation, by reverting edema formation, neutrophil accumulation and the production of lipid mediators, cytokines and endothelin. In addition, gedunin directly modulated the functions of neutrophils and macrophages in vitro. The pre-incubation of neutrophil with gedunin (100 µM) impaired shape change, adhesion to endothelial cells, chemotaxis and lipid body formation triggered by different stimuli. Macrophage pretreatment with gedunin impaired intracellular calcium mobilization, nitric oxide production, inducible nitric oxide synthase expression and induced the expression of the antiinflammatory chaperone heat shock protein 70. Our results demonstrate that gedunin presents remarkable antiinflammatory and anti-nociceptive effects on zymosan-induced inflamed knee joints, modulating different cell populations.

Anti-inflammatory effects of methyl ursolate obtained from a chemically derived crude extract of apple peels: potential use in rheumatoid arthritis.

Ursolic acid (UA), a pentacyclic triterpene acid found in apple peels (Malus domestica, Borkh, Rosaceae), has a large spectrum of pharmacological effects. However, the vegetal matrix usually produces highly viscous and poorly soluble extracts that hamper the isolation of this compound. To overcome this problem, the crude EtOH-AcOEt extract of commercial apple peels was exhaustively treated with diazomethane, after which methyl ursolate (MU) was purified by column chromatography and characterized spectrometrically. The anti-inflammatory effects of UA and MU (50 mg/kg) were analyzed by zymosan-induced paw edema, pleurisy and in an experimental arthritis model. After 4 h of treatment with UA and MU, paw edema was reduced by 46 and 44 %, respectively. Both UA and MU inhibited protein extravasation into the thoracic cavity; tibio-femoral edema by 40 and 48 %, respectively; and leukocyte influx into the synovial cavity after 6 h by 52 and 73 %, respectively. Additionally, both UA and MU decreased the levels of mediators related to synovial inflammation, such as KC/CXCL-1 levels by 95 and 90 %, TNF-α levels by 76 and 71 %, and IL-1ß levels by 57 and 53 %, respectively. Both the compounds were equally effective when assayed in different inflammatory models, including experimental arthritis. Hence, MU may be considered to be a useful anti-inflammatory derivative to overcome the inherent poor solubility of UA for formulating pharmaceutical products.

Design and synthesis of new (E)-cinnamic N-acylhydrazones as potent antitrypanosomal agents.

We report herein the synthesis and trypanocidal profile of new (E)-cinnamic N-acylhydrazones (NAHs) designed by exploiting molecular hybridization between the potent cruzain inhibitors (E)-1-(benzo[d][1,3]dioxol-5-yl)-3-(4-bromophenyl)prop-2-en-1-one and (E)-3-hydroxy-N'-((2-hydroxynaphthalen-1-yl)methylene)-7-methoxy-2-naphthohydrazide. These derivatives were evaluated against both amastigote and trypomastigote forms of Trypanosoma cruzi and lead us to identify two compounds that were approximately two times more active than the reference drug, benznidazole, and with good cytotoxic index. Although designed as cruzain inhibitors, the weak potency displayed by the best cinnamyl NAH derivatives indicated that another mechanism of action was likely responsible for their trypanocide action.