Antiplasmodial and cytotoxic effects of the methanol extract, canthinone alkaloids, squalene- and protolimonoid-type triterpenes from Homalolepis suffruticosa roots.

ETHNOPHARMACOLOGICAL RELEVANCE: Different species of the Simaroubaceae family are used in traditional medicine to treat malaria. Among these is Homalolepis suffruticosa (syn. Simaba suffruticosa and Quassia suffruticosa), which is native to Central Brazil and popularly known as calunga. However, there is a lack of investigation concerning its antimalarial effects. AIM OF THE STUDY: To investigate the antiplasmodial and cytotoxic effects of the isolated metabolites and methanol extract from H. suffruticosa roots as well as to conduct the dereplication of this extract aiming to characterize its metabolic profile by UPLC-DAD-ESI-MS/MS. MATERIALS AND METHODS: Methanol extract of the H. suffruticosa roots and six isolated compounds were evaluated against chloroquine-resistant Plasmodium falciparum W2 strain by the PfLDH method and cytotoxicity in HepG2 cells by the MTT assay. Dereplication of the extract was performed by UPLC-DAD-ESI-MS/MS. RESULTS: The six isolated compounds disclosed high to moderate antiplasmodial activity (IC50 0.0548 ± 0.0083 µg/mL to 26.65 ± 2.40 µg/mL) and cytotoxicity was in the range of CC50 0.62 ± 0.33 µg/mL to 56.43 ± 2.54 µg/mL, while 5-metoxycantin-6-one proved to be the most potent constituent of the six assayed ones. The methanol extract of the roots showed high in vitro antiplasmodial activity (IC50 1.88 ± 0.56 µg/mL), moderate cytotoxicity (CC50 41.93 ± 2.30 µg/mL), and good selectivity index (SI = 22.30). Finally, C20 quassinoids and canthin-6-one alkaloids were putatively identified in the H. suffruticosa methanol extract by LC-MS. CONCLUSIONS: Taken together, the isolated compounds, mainly the 5-metoxycantin-6-one and the methanol extract from H. suffruticosa roots, disclose good antiplasmodial activity, supporting the ethnopharmacological history of the Simaroubaceae species as traditional antimalarial drugs.

In vitro inhibition of protein glycation and advanced glycation end products formation by hydroethanolic extract and two fractions of Simaba trichilioides roots.

Long-term hyperglycemia maintenance is responsible for increased protein glycation and formation of advanced glycation end products (AGEs), both are associated with the onset of diabetes mellitus complications. Efforts have been made to discover new agents having antiglycation potential. The aim of this study was to investigate the effects of the hydroethanolic extract and the ethyl acetate and methanolic fractions of Simaba trichilioides roots on the formation of AGEs. In an in vitro model system of protein glycation, incubations with hydroethanolic extract, ethyl acetate or methanolic fractions of S. trichilioides decreased the fluorescent AGEs, and markers of tyrosine and tryptophan oxidation. Protein crosslinking was reduced in the presence of the ethyl acetate fraction of S. trichilioides. Simaba trichilioides roots seem to be a promising source of compounds having ability to prevent glycoxidation changes, with potential applications in complementary therapies for management of diabetic complications.

Fluorescent Canthin-6-one Alkaloids from Simaba bahiensis: Isolation, Identification, and Cell-Labeling Properties.

Canthin-6-one alkaloids, which are present in plants of the genus Simaba, are natural compounds that are capable of acting as fluorescent probes. However, the chemical composition and fluorescent properties of most species of this genus have not been analyzed. The objective of this study was to characterize the fluorescent properties of an extract of S. bahiensis and identify the chemical entities responsible for these properties. In addition, the cell-labeling properties of the fluorescent dye from A and of the isolated compounds were characterized by confocal fluorescence microscopy and flow cytometry. One quassinoid and three fluorescent alkaloids were isolated from S. bahiensis, all compounds were identified by using NMR spectroscopy and high-resolution mass spectrometry. Staining experiments and HPLC-FL analysis shown that canthin-6-one alkaloids are the main green fluorescent compounds in the analyzed dyes. All compounds evaluated showed a cytoplasmic marker with a residence time of 24 h. The present study is the first to describe the presence of canthin-6-one alkaloids in S. bahiensis, in addition to demonstrating promising cell-labeling properties of fluorescent compounds from S. bahiensis with broad emission wavelengths.

In vitro nematicidal effect of Chenopodium ambrosioides and Castela tortuosa n-hexane extracts against Haemonchus contortus (Nematoda) and their anthelmintic effect in gerbils.

The in vitro nematicidal effect of Chenopodium ambrosioides and Castela tortuosa n-hexane extracts (E-Cham and E-Cato, respectively) on Haemonchus contortus infective larvae (L3) and the anthelmintic effect of these extracts against the pre-adult stage of the parasite in gerbils were evaluated using both individual and combined extracts. The in vitro confrontation between larvae and extracts was performed in 24-well micro-titration plates. The results were considered 24 and 72 h post confrontation. The in vivo nematicidal effect was examined using gerbils as a study model. The extracts from the two assessed plants were obtained through maceration using n-hexane as an organic agent. Gerbils artificially infected with H. contortus L3 were treated intraperitoneally with the corresponding extract either individually or in combination. The results showed that the highest individual lethal in vitro effect (96.3%) was obtained with the E-Cham extract at 72 h post confrontation at 40 mg/ml, followed by E-Cato (78.9%) at 20 mg/ml after 72 h. The highest combined effect (98.7%) was obtained after 72 h at 40 mg/ml. The in vivo assay showed that the individual administration of the E-Cato and E-Cham extracts reduced the parasitic burden in gerbils by 27.1% and 45.8%, respectively. Furthermore, the anthelmintic efficacy increased to 57.3% when both extracts were administered in combination. The results of the present study show an important combined nematicidal effect of the two plant extracts assessed against L3 in gerbils.

Huberine, a New Canthin-6-One Alkaloid from the Bark of Picrolemma huberi.

A new alkaloid, Canthin-6-one, Huberine (1), together with three known compounds including 1-Hydroxy-canthin-6-one (2), Canthin-6-one (3) and stigma sterol (4), were isolated from the stem bark of Picrolemma huberi. The isolation was achieved by chromatographic techniques and the purification was performed on a C18 column using acetonitrile/water (90:10, v/v) with 0.1% formic acid as the mobile phase. The structural elucidation was performed via spectroscopic methods, notably 1D- and 2D-NMR, UV, IR, MS and HRMS. The antiplasmodial activity of the compounds was studied.

Anti-plasmodial effect of plant extracts from Picrolemma huberi and Picramnia latifolia.

BACKGROUND: Malaria is an infectious disease caused by parasites of the genus Plasmodium, of which Plasmodium vivax and Plasmodium falciparum are the major species that cause the disease in humans. As there are relatively few alternatives for malaria treatment, it is necessary to search for new chemotherapeutic options. Colombia possesses a great diversity of plants, which are potential sources of new compounds of medical interest. Thus, in this study the antiplasmodial effect of extracts from two species of plants from the families Simaroubaceae and Picramniaceae (Picramnia latifolia and Picrolemma huberi) was evaluated in vitro and in vivo. These plants were chosen because they contain secondary metabolites with interesting medicinal effects. RESULTS: The ethanolic extracts of both species were highly active with IC50: 1.2 ± 0.19 µg/mL for P. latifolia and IC50: 0.05 ± 0.005 µg/mL for P. huberi. The P. latifolia extract had a stage specific effect on trophozoites and inhibited parasite growth in vivo by 52.1 ± 3.4%, evaluated at 1000 mg/kg in Balb/c mice infected with Plasmodium berghei. On the other hand, evaluated at 150 mg/kg body weight in the same murine model, the ethanolic extract from P. huberi had an antiplasmodial effect in all the asexual intraerythrocytic stages of P. falciparum FCR3 and inhibited the parasitic growth in 93 ± 32.9%. CONCLUSIONS: This is the first report of anti-malarial activity for these two species of plants. Thus, P. latifolia and P. huberi are potential candidates for the development of new drugs for treating malaria.

Glaucarubulone glucoside from Castela macrophylla suppresses MCF-7 breast cancer cell growth and attenuates benzo[a]pyrene-mediated CYP1A gene induction.

Quassinoids often exhibit antioxidant and antiproliferative activity. Emerging evidence suggests that these natural metabolites also display chemopreventive actions. In this study, we investigated the potential for the quassinoid glaucarubulone glucoside (Gg), isolated from the endemic Jamaican plant Castela macrophylla (Simaroubaceae), to display potent cytotoxicity and inhibit human cytochrome P450s (CYPs), particularly CYP1A enzymes, known to convert polyaromatic hydrocarbons into carcinogenic metabolites. Gg reduced the viability of MCF-7 breast adenocarcinoma cells (IC50 = 121 nm) to a greater extent than standard of care anticancer agents 5-fluorouracil, tamoxifen (IC50 >10 µm) and the tamoxifen metabolite 4-hydroxytamoxifen (IC50 = 2.6 µm), yet was not cytotoxic to non-tumorigenic MCF-10A breast epithelial cells. Additionally, Gg induced MCF-7 breast cancer cell death. Gg blocked increases in reactive oxygen species in MCF-10A cells mediated by the polyaromatic hydrocarbon benzo[a]pyrene (B[a]P) metabolite B[a]P 1,6-quinone, yet downregulated the expression of genes that promote antioxidant activity in MCF-7 cells. This implies that Gg exhibits antioxidant and cytoprotective actions in non-tumorigenic breast epithelial cells and pro-oxidant, cytotoxic actions in breast cancer cells. Furthermore, Gg inhibited the activities of human CYP1A according to non-competitive kinetics and attenuated the ability of B[a]P to induce CYP1A gene expression in MCF-7 cells. These data indicate that Gg selectively suppresses MCF-7 breast cancer cell growth without impacting non-tumorigenic breast epithelial cells and blocks B[a]P-mediated CYP1A induction. Taken together, our data provide a rationale for further investigations of Gg and similar plant isolates as potential agents to treat and prevent breast cancer. Copyright © 2017 John Wiley & Sons, Ltd.

The quassinoid isobrucein B reduces inflammatory hyperalgesia and cytokine production by post-transcriptional modulation.

Isobrucein B (1) is a quassinoid isolated from the Amazonian medicinal plant Picrolemma sprucei. Herein we investigate the anti-inflammatory and antihyperalgesic effects of this quassinoid. Isobrucein B (1) (0.5-5 mg/kg) inhibited carrageenan-induced inflammatory hyperalgesia in mice in a dose-dependent manner. Reduced hyperalgesia was associated with reduction in both neutrophil migration and pronociceptive cytokine production. Pretreatment with 1 inhibited in vitro production/release of cytokines TNF, IL-1ß, and KC/CXCL1 by lipopolysaccharide-stimulated macrophages. To investigate its molecular mechanism, RAW 264.7 macrophages with a luciferase reporter gene controlled by the NF-κB promoter were used (RAW 264.7-Luc). Quassinoid 1 reduced the luminescence emission by RAW 264.7-Luc stimulated by different compounds. Unexpectedly, NF-κB translocation to macrophage nuclei was not inhibited by 1 when evaluated by Western blotting and immunofluorescence. Furthermore, quassinoid 1 did not change the levels of TNF mRNA transcription in stimulated macrophages, suggesting post-transcriptional modulation. In addition, constitutive expression of luciferase in RAW 264.7 cells transiently transfected with a plasmid containing a universal promoter was inhibited by 1. Thus, isobrucein B (1) displays anti-inflammatory and antihyperalgesic activities by nonselective post-transcriptional modulation, resulting in decreased production/release of pro-inflammatory cytokines and neutrophil migration.

Gastro-protective effects of isobrucein B, a quassinoid isolated from Picrolemma sprucei.

Infusions of Picrolemma sprucei roots, stems and leaves are used in traditional medicine throughout the Amazon region from the Guianas to Brazil and Peru in the treatment of gastritis, intestinal helminths and malaria. As there are no studies describing its mode of action in providing a gastroprotective effect, we determined herein that one of the main constituents found in P. sprucei infusions, the quassinoid isobrucein B (IsoB), reduces some of the pathophysiological effects in a mouse model of non-steroidal anti-inflammatory drug (NSAID)-induced gastritis and provides mechanisms of action. Then, IsoB (1.17 g) was isolated from the roots and stems (6.5 kg) of P. sprucei. Its structure was confirmed by 1D and 2D (1)H and (13)C NMR, ESI-tof-MS, IR and UV. C57BL/6 strain mice were subcutaneously injected with IsoB (0.5-5 mg kg(-1)) or vehicle before oral administration of indomethacin and sacrificed later at different time points. Gastric damage was assessed by measuring lesion length. Leukocyte migration was evaluated based on leukocyte rolling and adhesion using intravital microscopy in the mesenteric microcirculation and tissue MPO activity. Stomach extract cytokine (TNFα, IL-1ß and KC/CXCL1) and prostaglandin E2 (PGE2) levels were measured by ELISA and RIA, respectively. IsoB pre-treatment (0.5-5.0 mg kg(-1)) significantly reduced the formation of indomethacin-induced stomach lesions in a dose-dependent manner. The decrease in stomach lesions was associated with less observed leukocyte rolling, decreased leukocyte adhesion and less neutrophil infiltration (MPO activity). IsoB (1 mg kg(-1)) pre-treatment did not prevent indomethacin-induced decreases in stomach PGE2 levels. However, IL-1ß and KC/CXCL1 levels were inhibited by this same IsoB dosage, whereas TNF-α was unchanged. IsoB may be a prototypic compound to provide protective effects against NSAID-induced gastritis and possibly other gastropathies. Moreover, IsoB gastroprotective action may be due to a reduction in IL-1ß and KC/CXCL1 production/release and leukocyte rolling, adhesion and migration.

Tripanocide and antibacterial activity ofAlvaradoa subovata Cronquist extracts / Actividad tripanocida y antibacteriana de extractos de Alvaradoa subovata Cronquist

We studied antioxidant, antibacterial and tripanocide activities of Alvaradoa subovata extracts. The ethanolic extracts showed the greatest DPPH radical scavenging capacity, especially that of bark with an IC50 = 4.7 +/- 0.18 ug/mL. Wood dichloromethane extract displayed growth inhibition of the phytopathogenic bacteria Xanthomona axonopodis in the disk diffusion assay and showed a MIC value of 100 ug/ml. It also showed growth inhibition of Trypanosoma cruzi (IC50 = 0.063 +/- 0.003 mg/mL). A fraction of this extract, which has emodin as the main component, showed tripanocide activity (60 percent of growth inhibition at 100 ug/mL). The main compounds in wood dichloromethane extract were anthraquinones, identified as chrysophanol and emodin, and coumarins, of which scopoletin was identified. These three compound s could serve as analytical markers of the extract. The results of this study show that wood extract of A. subovata constitute a source of bioactive compounds such as antiparasitic and pesticides agents.

En el presente trabajo se estudió la actividad antioxidante, antibacteriana y tripanocida de extractos de Alvaradoa subovata. La mayor actividad depuradora de radicales libres se observó en el extracto etanólico de corteza (CI50 = 4.7 +/- 0.18 ug/mL). El extracto en diclorometano de madera inhibió el crecimiento de la bacteria fitopatógena Xanthomona axonopodis con una CIM = 100 ug/mL. El mismo extracto mostró inhibición del crecimiento de Trypanosoma cruzi (CI50 = 0.063 +/- 0.003 mg/mL). Una fracción de este extracto (100 ug/mL), cuyo componente mayoritario es emodina, inhibió en un 60 por ciento el crecimiento del parásito. Los compuestos mayoritarios detectados en el extracto de madera fueron antraquinonas, entre las cuales se identificaron emodina y crisofanol, y la cumarina escopoletina. Estos tres compuestos podrían servir como marcadores analíticos del extracto. Los resultados de este trabajo muestran que los extractos de A. subovata constituyen una fuente de compuestos bioactivos con potencial como antiparasitarios y plaguicidas.

Actividad antioxidante, análisis fitoquímico y micrografía analítica de hojas de Castela tweedii (Simaroubaceae) / Antioxidant activity, phytochemical analisys and micrographic characterization of Castela tweedii (Simaroubaceae) leaves

Castela tweedii is a small tree belonging to Simaroubaceae family. Infusions of its leaves are used in folk medicine to treat gastrointestinal disorders and diarrhea. In this work, we evaluated the antioxidant activity of ethanol and dicloromethane leaves extracts against DPPH radical (2,2-difenilpicrilhidrazil) in order to justify, at least in part, its popular use. Ethanol extract showed scavenging activity, with an IC50=0.1288 mg/mL. Responsible compounds for these activity were tannins, flavonoids and phenylcarboxilic acids, among them we identified rutine and chlorogenic acid. Microscopic and histochemical analysis of leaves was carry out to developed useful characterizations that will allow a future identification and authentication of raw material: such as, the presence of mucilaginous hypodermis, leaf of dorsiventral structure, 1 to 2 rows of empalisade parenchyma with tannin deposits, anomocytic stomata in low epidermis and simple, unicellular trichomes in both epidermis.

Castela tweedii es un árbol de bajo porte perteneciente a la Familia Simaroubaceae, las infusiones de sus hojas son utilizadas en la medicina popular Argentina para el tratamiento de desordenes gastrointestinales y diarreas. Con el objetivo de fundamentar el uso popular de esta especie se evaluó la actividad antioxidante de los extractos etanólicos y diclorometánicos de forma cuantitativa y cualitativa frente al radical 2,2-difenilpicrilhidrazilo (DPPH); el extracto etanólico demostró actividad obteniéndose una CI50= 0,1288 mg/mL. El análisis fitoquímico mostró que los compuestos responsables de esta actividad fueron taninos, flavonoides y ácidos fenilcarboxílicos, entre ellos se identificó rutina y ácido clorogénico. Además se realizó el estudio morfoanatómico e histoquímico de las hojas que aportó datos de valor diagnostico para el control de calidad de la droga vegetal: presencia de una hipodermis mucilaginosa, estructura dorsiventral con una a dos hileras de parénquima en empalizada conteniendo taninos, estomas anomocíticos solo en la epidermis abaxial y tricomas simples unicelulares en ambas epidermis.

Involvement of intrinsic mitochondrial pathway in neosergeolide-induced apoptosis of human HL-60 leukemia cells: the role of mitochondrial permeability transition pore and DNA damage.

CONTEXT: Quassinoids are biologically active secondary metabolites found exclusively in the Simaroubaceae family of plants. These compounds generally present important biological properties, including cytotoxic and antitumor properties. OBJECTIVE: In the present study, the cytotoxic effects of neosergeolide, a quassinoid isolated from Picrolemma sprucei Hook. f., were evaluated in human promyelocytic leukemia cells (HL-60). MATERIALS AND METHODS: Cytotoxicity and antiproliferative effects were evaluated by the MTT assay, May-Grünwald-Giemsa's staining, BrdU incorporation test, and flow cytometry procedures. The comet assay and micronuclei analysis were applied to determine the genotoxic and mutagenic potential of neosergeolide. RESULTS: After 24 h exposure, neosergeolide strongly inhibited cancer cell proliferation (IC50 0.1 µM), and its activity seemed to be selective to tumor cells because it had no antiproliferative effect on human peripheral blood mononuclear cells (PBMC) at tested concentrations. Apoptosis was induced at submicromolar concentrations (0.05, 0.1, and 0.2 µM) as evidenced by morphological changes, mitochondrial depolarization, phosphatidylserine externalization, caspases activation, and internucleosomal DNA fragmentation. Additionally, neosergeolide effects were prevented by cyclosporine A (CsA), an inhibitor of the mitochondrial permeability transition (MPT) pore, which reinforced the participation of intrinsic pathways in the apoptotic process induced by this natural quassinoid. Direct DNA damage was further confirmed by comet assay and cytokinesis-block micronucleus test. DISCUSSION AND CONCLUSION: The present study provided experimental evidence to support the underlying mechanism of action involved in the neosergeolide-mediated apoptosis. In addition, no antiproliferative effect or DNA damage effect of neosergeolide was evident in PBMC, highlighting its therapeutic potential.

Pharmacological mechanisms underlying the anti-ulcer activity of methanol extract and canthin-6-one of Simaba ferruginea A. St-Hil. in animal models.

RELEVANCE: Simaba ferruginea A. St-Hil. (Simaroubaceae) is a subshrub typical of the Brazilian Cerrado, whose rhizomes are popularly used as infusion or decoction for the treatment of gastric ulcers, diarrhea and fever. AIM OF THE STUDY: To evaluate the pharmacological mechanism(s) of action of the antiulcer effects of the methanol extract of Simaba ferruginea and its alkaloid canthin-6-one. MATERIALS AND METHODS: Rhizome of Simaba ferruginea was macerated with methanol to obtain the methanol extract (MESf) from which was obtained, the chloroform fraction. Canthin-6-one alkaloid (Cant) was purified and then isolated from the chloroform fraction (CFSf). The isolated Cant was identified by HPLC. Anti-ulcer assays were determined using ethanol and indomethacin-induced ulcer models in mice and rats respectively. In order to determine the probable mechanisms of actions of MESf and Cant animals were pretreated with l-NAME prior to anti-ulcer agent treatments and ulcer induction and nitric oxide (NO) level determined in order to assess NO involvement in the gastroprotective effects. Assays of malondialdehyde (MDA), myeloperoxidase (MPO), pro-inflammatory cytokines: interleukin 8 (IL-8) and tumor necrosis factor-alpha (TNF-α) and prostaglandin E(2) (PGE(2)) were also carried out according to previously described methods. RESULTS: The results indicate that the antiulcerogenic effects of MESf and Cant in ethanol-induced ulcer is mediated in part through increase in the production of protective endogenous NO as the antiulcerogenic activity of MESf and Cant was reduced in animals pre-treated with l-NAME. In indomethacin-induced ulcer pre-treatment with MESf and Cant showed reduction in the levels of MPO and MDA in the gastric tissue, thus indicating the participation of the antioxidant mechanisms on the gastroprotective effects. The plasma levels of IL-8 in ulcerated rats with indomethacin were also reduced by Cant, but not by MESf, indicating that inhibition of this cytokine contributes to the gastroprotective effect of Cant. However MESf and Cant had no effect on the mucosal membrane levels of PGE(2), indicating that the gastroprotective effects of these agents is independent of PGE(2) modulation. CONCLUSION: The results obtained in this study with MESf and Cant added insights into the pharmacological mechanisms involved in their mode of antiulcer action. The results indicate that Cant is one of the compounds responsible for these effects. Such findings are of extreme importance in the strive for future development of potent, safer and effective antiulcer agent. The efficacy of MESf and Cant in gastroprotection shows that Simaba ferruginea might be a promising antiulcer herbal medicine, in addition to confirming the popular use of this plant against gastric ulcer models utilised in this study.

Biological activity of neosergeolide and isobrucein B (and two semi-synthetic derivatives) isolated from the Amazonian medicinal plant Picrolemma sprucei (Simaroubaceae).

In the present study, in vitro techniques were used to investigate a range of biological activities of known natural quassinoids isobrucein B (1) and neosergeolide (2), known semi-synthetic derivative 1,12-diacetylisobrucein B (3), and a new semi-synthetic derivative, 12-acetylneosergeolide (4). These compounds were evaluated for general toxicity toward the brine shrimp species Artemia franciscana, cytotoxicity toward human tumour cells, larvicidal activity toward the dengue fever mosquito vector Aedes aegypti, haemolytic activity in mouse erythrocytes and antimalarial activity against the human malaria parasite Plasmodium falciparum. Compounds 1 and 2 exhibited the greatest cytotoxicity against all the tumor cells tested (IC50 = 5-27 microg/L) and against multidrug-resistant P. falciparum K1 strain (IC50 = 1.0-4.0 g/L) and 3 was only cytotoxic toward the leukaemia HL-60 strain (IC50 = 11.8 microg/L). Quassinoids 1 and 2 (LC50 = 3.2-4.4 mg/L) displayed greater lethality than derivative 4 (LC50 = 75.0 mg/L) toward A. aegypti larvae, while derivative 3 was inactive. These results suggest a novel application for these natural quassinoids as larvicides. The toxicity toward A. franciscana could be correlated with the activity in several biological models, a finding that is in agreement with the literature. Importantly, none of the studied compounds exhibited in vitro haemolytic activity, suggesting specificity of the observed cytotoxic effects. This study reveals the biological potential of quassinoids 1 and 2 and to a lesser extent their semi-synthetic derivatives for their in vitro antimalarial and cytotoxic activities.

Biological activity of neosergeolide and isobrucein B (and two semi-synthetic derivatives) isolated from the Amazonian medicinal plant Picrolemma sprucei (Simaroubaceae)

In the present study, in vitro techniques were used to investigate a range of biological activities of known natural quassinoids isobrucein B (1) and neosergeolide (2), known semi-synthetic derivative 1,12-diacetylisobrucein B (3), and a new semi-synthetic derivative, 12-acetylneosergeolide (4). These compounds were evaluated for general toxicity toward the brine shrimp species Artemia franciscana, cytotoxicity toward human tumour cells, larvicidal activity toward the dengue fever mosquito vector Aedes aegypti, haemolytic activity in mouse erythrocytes and antimalarial activity against the human malaria parasite Plasmodium falciparum. Compounds 1 and 2 exhibited the greatest cytotoxicity against all the tumor cells tested (IC50 = 5-27 µg/L) and against multidrug-resistant P. falciparum K1 strain (IC50 = 1.0-4.0 g/L) and 3 was only cytotoxic toward the leukaemia HL-60 strain (IC50 = 11.8 µg/L). Quassinoids 1 and 2 (LC50 = 3.2-4.4 mg/L) displayed greater lethality than derivative 4 (LC50 = 75.0 mg/L) toward A. aegypti larvae, while derivative 3 was inactive. These results suggest a novel application for these natural quassinoids as larvicides. The toxicity toward A. franciscana could be correlated with the activity in several biological models, a finding that is in agreement with the literature. Importantly, none of the studied compounds exhibited in vitro haemolytic activity, suggesting specificity of the observed cytotoxic effects. This study reveals the biological potential of quassinoids 1 and 2 and to a lesser extent their semi-synthetic derivatives for their in vitro antimalarial and cytotoxic activities.

Alvaradoins E-N, antitumor and cytotoxic anthracenone C-glycosides from the leaves of Alvaradoa haitiensis.

Bioactivity-directed fractionation of an extract of the leaves of Alvaradoa haitiensis, using the KB (human oral epidermoid carcinoma) cell line, led to the isolation and identification of 10 new anthracenone C-glycosides, alvaradoins E-N (1-10), along with the known compound chrysophanol (11). The cytotoxicity of all compounds was evaluated, and preliminary structure-activity relationships are suggested. The most potent compounds in the in vitro assays (1 and 2) were evaluated in vivo versus the P388 (murine lymphocytic leukemia) model, and alvaradoin E (1) showed antileukemic activity (125% T/C) at a dose of 0.2 mg kg-1 per injection when administered intraperitoneally.

In vitro inhibition of Plasmodium falciparum by substances isolated from Amazonian antimalarial plants.

In the present study, a quassinoid, neosergeolide, isolated from the roots and stems of Picrolemma sprucei (Simaroubaceae), the indole alkaloids ellipticine and aspidocarpine, isolated from the bark of Aspidosperma vargasii and A. desmanthum (Apocynaceae), respectively, and 4-nerolidylcatechol, isolated from the roots of Pothomorphe peltata (Piperaceae), all presented significant in vitro inhibition (more active than quinine and chloroquine) of the multi-drug resistant K1 strain of Plasmodium falciparum. Neosergeolide presented activity in the nanomolar range. This is the first report on the antimalarial activity of these known, natural compounds. This is also the first report on the isolation of aspidocarpine from A. desmanthum. These compounds are good candidates for pre-clinical tests as novel lead structures with the aim of finding new antimalarial prototypes and lend support to the traditional use of the plants from which these compounds are derived.

In vitro inhibition of Plasmodium falciparum by substances isolated from Amazonian antimalarial plants

In the present study, a quassinoid, neosergeolide, isolated from the roots and stems of Picrolemma sprucei (Simaroubaceae), the indole alkaloids ellipticine and aspidocarpine, isolated from the bark of Aspidosperma vargasii and A. desmanthum (Apocynaceae), respectively, and 4-nerolidylcatechol, isolated from the roots of Pothomorphe peltata (Piperaceae), all presented significant in vitro inhibition (more active than quinine and chloroquine) of the multi-drug resistant K1 strain of Plasmodium falciparum. Neosergeolide presented activity in the nanomolar range. This is the first report on the antimalarial activity of these known, natural compounds. This is also the first report on the isolation of aspidocarpine from A. desmanthum. These compounds are good candidates for pre-clinical tests as novel lead structures with the aim of finding new antimalarial prototypes and lend support to the traditional use of the plants from which these compounds are derived.

Phytochemical and antiulcerogenic properties of rhizomes from Simaba ferruginea St. Hill. (Simaroubaceae).

Simaba ferruginea (Simaroubaceae) is a Brazilian medicinal plant used in traditional medicine to treat several ailments, including gastric ulcers, fever, diarrhea, and dolorous and inflammatory processes. This study examines the chemical composition and antiulcerogenic effects of rhizomes from this plant. Bioassay-guided fractionation led to the isolation of two bioactive indole alkaloids called canthin-6-one (1) and 4-methoxycanthin-6-one (2). The alkaloid fraction and both alkaloids demonstrated potent antiulcerogenic effects when evaluated in gastric lesion-induced animals, as well as significant antinociceptive activity in mice. These results confirm and justify the popular use of S. ferruginea against gastric ulcers and dolorous processes.