Alkaloid-enriched Extracts Research Articles

Evaluation of the toxicological effects of Neltuma alpataco (Prosopis alpataco) pod alkaloid extract

The pods of Neltuma spp. have shown potential as a source of protein and energy in livestock. However, prolonged consumption of some of these species can lead to neurological symptoms in ruminants. This study aimed to determine the alkaloid content, as well as the in vitro and in vivo effects of an alkaloid-enriched extract (AEE) from N. alpataco pods. High performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) identified juliprosine and juliprosopine as primary alkaloids, with juliprosine being most abundant. AEE from N. alpataco demonstrated dose-dependent cytotoxicity on glioma cells after 48 h, with a 50% cytotoxic concentration (CC50) of 24.69 μg/mL. However, the release of LDH was observed only at the highest tested concentration, indicating cellular damage. Further examination through phase-contrast microscopy and dual acridine orange/ethidium bromide fluorescence staining revealed morphological changes consistent with an apoptotic mechanism of cell death, ultimately leading to secondary necrosis. Finally, the LD50 after intraperitoneal injection in mice was determined to be 12.98 mg/kg. Taken together, these findings demonstrated for the first time the in vivo and in vitro toxicity of the AEE from N. alpataco pods.

Phytochemical characterization and biological activities of Stenomesson miniatum bulb extract, a medicinal plant of the Andes

Fresh bulbs of Stenomesson miniatum, a plant belonging to the Amaryllidaceae family with a poorly investigated phytochemical profile, were traditionally employed by Andean healers to treat tumors and abscesses. The aims of this study were to characterize the extract from the bulbs of S. miniatum and to test its cytotoxic and antibacterial potential. A previous structural study of the major extract constituents was extended to include the minor components by means of 13C-NMR-based dereplication. Cytotoxic activities were evaluated on A431 human epidermoid carcinoma cells through a metabolic assay and on Jurkat human acute T-leukemia cells through a cell-impermeant fluorescent nuclear probe. Antibacterial assays were carried out against Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes by using a standardized broth microdilution method. Eleven known Amaryllidaceae alkaloids were identified together with another compound determined as being an extraction artefact. The alkaloid-enriched extract showed good cytotoxic activity against both tumor cell lines, reaching an IC50 of 3.3 µg/mL against A431 cells and of 10.9 µg/mL against Jurkat cells. Biological assays carried out on single fractions showed that activity can be attributed to the presence of pretazettine and haemanthamine. Conversely, no antibacterial activities were recorded for any of the samples.

Phytochemical Analysis and In Vitro Antileukemic Activity of Alkaloid-Enriched Extracts from Vinca sardoa (Stearn) Pignatti.

Vinca sardoa (Stearn) Pignatti, known as Sardinian periwinkle, is widely diffused in Sardinia (Italy). This species contains indole alkaloids, which are known to have a great variety of biological activities. This study investigated the antileukemic activity against a B lymphoblast cell line (SUP-B15) of V. sardoa alkaloid-rich extracts obtained from plants grown in Italy, in Iglesias (Sardinia) and Rome (Latium). All the extracts showed a good capacity to induce reductions in cell proliferation of up to 50% at the tested concentrations (1-15 µg/mL). Moreover, none of the extracts showed cytotoxicity on normal cells at all the studied concentrations.

Anti-neuroinflammatory effects of alkaloid-enriched extract from Huperzia serrata on lipopolysaccharide-stimulated BV-2 microglial cells

Context Alkaloid-enriched extract of Huperzia serrata (Thunb.) Trevis (Lycopodiaceae) (HsAE) can potentially be used to manage neuronal disorders. Objective This study determines the anti-neuroinflammatory effects of HsAE on lipopolysaccharide (LPS)-stimulated BV-2 microglial cells and the underlying mechanisms. Materials and methods BV-2 cells were pre- or post-treated with different concentrations of HsAE (25-150 µg/mL) for 30 min before or after LPS induction. Cell viability was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and no cytotoxicity was found. Nitric oxide (NO) concentration was determined using Griess reagent. The levels of prostaglandin E2 (PGE2), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 were determined using enzyme-linked immunosorbent assay. The levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 and the phosphorylation of mitogen-activated protein kinase (MAPK) were analyzed using western blotting. Results HsAE reduced LPS-induced NO production with half-maximal inhibitory concentration values of 99.79 and 92.40 µg/mL at pre- and post-treatment, respectively. Pre-treatment with HsAE at concentrations of 50, 100, and 150 µg/mL completely inhibited the secretion of PGE2, TNF-α, IL-6, and IL-1β compared to post-treatment with HsAE. This suggests that prophylactic treatment is better than post-inflammation treatment. HsAE decreased the expression levels of iNOS and COX-2 and attenuated the secretion of pro-inflammatory factors by downregulating the phosphorylation of p38 and extracellular signal-regulated protein kinase in the MAPK signaling pathway. Discussion and Conclusions HsAE exerts anti-neuroinflammatory effects on LPS-stimulated BV-2 cells, suggesting that it may be a potential candidate for the treatment of neuroinflammation in neurodegenerative diseases.

Anti-Acanthamoeba castellanii activity of alkaloid-enriched extracts and lycorine from the Amaryllidaceae species

Free-living amoebae of the genus Acanthamoeba are the causative agents of granulomatous encephalitis and keratitis, severe human infections. Bioactive compounds from plants are recognized as an alternative source for the development of new drugs. The Amaryllidaceae is a botanical family able to synthesize a very specific and consistent group of biologically active isoquinoline-like alkaloids. The alkaloidal fractions from the Brazilian species Hippeastrum canastrense, H. diniz-cruziae, H. puniceum, and Crinum x amabile, along with the alkaloid lycorine, were investigated against Acanthamoeba castellanii. The in vitro assays were performed with distinct concentrations of lycorine and alkaloidal fractions, while the cell viability was evaluated by the MTT method upon MDCK cells. Chlorhexidine 0.02% was used as the positive control. The effect of alkaloid fractions was concentration dependent, and 2000 μg mL-1 of H. canastrense and H. diniz-cruziae provided a 100% inhibition. At concentrations of 250, 500, and 1000 μg mL-1, the H. diniz-cruziae alkaloidal fraction showed the lowest cytotoxic effect (5%-7%) and remarkable anti-amoebic activity, demonstrating values of IC50 285.61 μg mL-1, low cytotoxicity (5%-7%), and selectivity index (7.0). Taken together, the results are indicative of the great potential that the alkaloids from H. diniz-cruziae have as new candidates for anti-amoebicidal compounds.

Amelioration of metabolic disorders by a mushroom-derived polyphenols correlates with the reduction of Ruminococcaceae in gut of DIO mice

A polyphenolic alkaloid-enriched extract (PAE) was prepared from the fruiting bodies of a wild edible mushroom Sarcodon leucopus. Oral administration of PAE reduced hyperglycemia, hyperlipidemia, hepatic steatosis, and LPS-related inflammation in high fat diet-induced obese (DIO) mice. Furthermore, we show that PAE produces taxonomic and predicted functional changes in the gut microbiome of DIO mice. A significant decrease in the family of Ruminococcaceae, especially the secondary bile acid-producing bacteria of Intestinimonas and Anaerotruncus, is detected in the gut microbiome of PAE-treate mice. Accordingly, reductions of deoxycholic acid and lithocholic acid are found in the feces of PAE-treated DIO mice, which benefits for the intestinal integrity and the reduction of inflammation. A gut microbiota related mechanism for the anti-metabolic syndrome effects of the PAE is proposed. We suppose the polyphenolic alkaloid extract from S. leucopus be a new and beneficial prebiotic regulating glucose and lipid metabolisms.

Characterization and cytotoxic activity on glial cells of alkaloid-enriched extracts from pods of the plants Prosopis flexuosa and Prosopis nigra (Fabaceae)

Introduction: Prosopis spp. pods have shown to be a potential source of protein and energy in livestock. However, prolonged ingestion of some of these species produces neurological symptoms in ruminants. Objective: In the present study, the alkaloid content and the in vitro neurotoxic activity of alkaloid enriched-extracts from P. flexuosa and P. nigra pods were determined in order to elucidate the mechanism of animal poisoning caused by these species. Methods: The main alkaloids present in both extracts were analyzed by high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS). The cytotoxic activity of Prosopis alkaloid enriched-extracts in primary mixed glial cell culture was assessed by phase contrast microscopy and using neutral red, and lactate dehydrogenase (LDH) activity assays. Results: Juliprosine and juliprosopine were identified in P. flexuosa pods, while the absence of these alkaloids in P. nigra was confirmed. Both extracts (5-30 μg/mL) induced in a dose dependent manner, morphological alterations, such as swelling, enlargement and detachment from the culture surface. Consistent with this, decrease in cell viability and release of LDH 48 hours after exposure, revealed that P. flexuosa pods was significantly more cytotoxic than P. nigra. Conclusions: The present study suggest that the cytotoxic effect displayed by both extracts are due to the alkaloid content. However, the presence of the alkaloids juliprosine and juliprosopine in P. flexuosa could explain the greater cytotoxicity on glial cells with respect to P. nigra that was not shown to contain these alkaloids.

In vitro and in vivo antiplasmodial activity of extracts and isolated constituents of Alstonia congensis root bark

Ethnopharmacological relevanceAn aqueous decoction of root bark of Alstonia congensis Engl. (Apocynaceae) is used in several African countries to treat various ailments including malaria. Materials and methodsExtracts of different polarity and isolated constituents were tested in vitro for their antiplasmodial activity against the chloroquine-resistant strain Plasmodium falciparum K1 and the chloroquine-sensitive strain P. falciparum NF54A19A, as well as for their cytotoxic effects againt MRC-5 cells (human lung fibroblasts). Extracts and fractions were evaluated in vivo against the chloroquine-resistant strain P. yoelii N67 and the chloroquine-sensitive strain P. berghei berghei ANKA. ResultsThe aqueous extract, the 80% methanol extract and the alkaloid-enriched extract exhibited strong antiplasmodial activity against P. falciparum K1 with IC50 values < 10 µg/ml and against P. falciparum NF54 A19A with IC50 values < 0.02 µg/ml. In vivo against P. yoelii N67, at the highest oral dose of 400 mg/kg body weight, all extracts produced 70–73% chemosuppression, while against P. berghei berghei, more than 75% chemosuppression was observed. With regard to the isolated constituents, boonein was inactive in vitro against P. falciparum K-1 (IC50 > 64 µM), while echitamine, 6,7-seco-angustilobine B and β-amyrin exhibited moderate activity (IC50 < 30 µM). Against P. falciparum NF54 A19A, boonein was inactive (IC50 > 64 µM), while echitamine, 6,7-secoangustilobine and β-amyrin showed moderate IC50 values of 11.07, 21.26 and 40.70 µM, respectively. ConclusionThese results demonstrated that all extracts from A. congensis root bark possessed antiplasmodial activity in vitro and in vivo. They can be used as raw materials for the preparation of ameliorated remedies for the treatment of uncomplicated malaria. The observed antiplasmodial activity may be due in part to the presence of indole alkaloids.

Anti-inflammatory effects of alkaloid enriched extract from roots of Eurycoma longifolia Jack

Objective: To examine the in vitro and in vivo anti-inflammatory effects of the alkaloid enriched extract (ELA) from the roots of Eurycoma longifolia. Methods: The in vitro antiinflammatory effects of ELA were evaluated by examining its inhibitory activities against nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) expressions in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The level of NO produced in the culture media was determined by Griess method. The iNOS and COX-2 protein expressions were analyzed by Western blot. The in vivo effect of ELA was evaluated on LPS-induced septic shock in mice model. Mice mortality was monitored for 5 days after injection of LPS. The chemical contents of the ELA were determined by using various chromatographic and spectroscopic techniques. Results: The ELA was found to exhibit a significant anti-inflammatory effect in both in vitro and in vivo models. The results demonstrated that ELA dose-dependently inhibited LPS-induced NO production as well as the protein iNOS and COX-2 expressions. In the septic shock model, ELA dose-dependently protected mice from LPS-induced mortality. Further study on the isolated components of ELA indicated that 9,10-dimethoxycanthin-6-one may contribute significantly to the anti-inflammatory effects of the extract. Conclusions: These results suggest that ELA exhibits the anti-inflammatory activity via suppression of pro-inflammatory mediators such as NO, iNOS, and COX-2 and protects mice from LPS-induced mortality in septic shock model.

In vivo antimalarial extracts and constituents of Prosopis juliflora (Fabaceae)

Prosopis juliflora (Fabaceae) is a small perennial tree used as human food and livestock feed for thousands of years in arid and semi-arid regions worldwide. This study was performed to investigate the in vivo antimalarial activity of alkaloid-enriched extracts and pure alkaloidal constituents of Prosopis juliflora in a murine model. Alkaloid-enriched extracts from leaves (FACB) and pods (BCE) of P. juliflora, as well as FACB pure constituents (as formate salts), were obtained and assayed against Plasmodium berghei NK65 infection in mice via oral administration. FACB and BCE exhibited a remarkable in vivo antimalarial activity with little parasitemia inhibition at the 2 mg/kg dose. Additionally, julifloridine was weakly active, but juliprosopine caused a parasitemia inhibition at the 2 mg/kg dose similar to that observed for chloroquine at 50 mg/kg. This study reports for the first time the in vivo antimalarial activity of julifloridine, juliprosopine and alkaloid-enriched extracts from P. juliflora (Fabaceae).

Mesquite (Prosopis juliflora) plant prevalence in different districts of Balochistan &amp; antibacterial activity of its pods

This study was conducted to evaluate in vivo multiple uses of mesquite plant, identification of selected areas in Balochistan and anti-bacterial activity of mesquite pods (alkaloid-enriched extracts). For this purpose a survey was conducted in areas where mesquite plant prevails. Pods of mesquite were collected from different trees standing at Yaro Pishin Roadside Plantation and were brought to the physiology laboratory of Centre for Advanced Studies in Vaccinology & Biotechnology (CASVAB) University of Balochistan Quetta. Pods were dried and extract was obtained which was subjected to check antibacterial activity through two different methods. The inhibition zones of bacteria were measured in mm. It was concluded that mesquite, which was once viewed as weed, its pods have antibacterial components. Furthermore, this study indicated that mesquite is a useful plant if properly managed. Keywords: Prosopis juliflora; Pods; Balochistan; Antibacterial activity http://dx.doi.org/10.19045/bspab.2017.600162

An experimental design approach to obtain canthinone alkaloid-enriched extracts from Simaba aff. paraensis

The species of the genus Simaba (Simaroubaceae) are found in almost all Brazil and they are used by local population for the treatment of ulcers and malaria. The genus is characterized by the presence of quassinoids and canthinone alkaloids. There is a great interest in canthinones due to important biological activities associated with this class of alkaloids. In this study, methods were developed for obtaining enriched fractions of canthinone alkaloids from Simaba aff. paraensis using experimental factorial design analyzed by gas chromatography. Three alkaloids were detected: canthin-6-one, 4,5-dimethoxycanthin-6-one and the major 9-methoxycanthin-6-one. Within the experimental domain, factorial designs 22 helped establish the minimum amount of solvent and minimum time necessary to obtain extracts enriched in canthinone alkaloids from S. aff. paraensis barks by two extraction methods. These results represent a reduction in costs for obtaining canthinone alkaloids described for the first time in S. aff. paraensis.

Identification of an aspidospermine derivative from borage extract as an anti-amyloid compound: A possible link between protein aggregation and antimalarial drugs

A number of human diseases, including Alzheimer's and Parkinson's have been linked to amyloid formation. To search for an anti-amyloidogenic product, alkaloid enriched extract from borage leaves was examined for anti-amyloidogenic activity using Hen Egg White Lysozyme (HEWL) as a model protein. After isolation of the plant extract using rHPLC, only one fraction indicated a significant bioactivity. TEM analysis confirmed a remarkable reduction of amyloid fibrils in the presence of the bioactive fraction. To identify the effective substance in the fraction, mass spectrometry, FTIR, and NMR were performed. Our analyses determined that the bioactive compound as 1-acetyl-19,21-epoxy-15,16-dimethoxyaspidospermidine-17-ol, a derivative of aspidospermine. To investigate the mechanism of the inhibition, ANS binding, intrinsic fluorescence, and amide I content were performed in the presence of the bioactive compound. All the results confirmed the role of the compound in assisting the proper folding of the protein. In addition, molecular docking indicated the aspidospermine derivative binds the amyloidogenic region of the protein. Our results show that the alkaloid extracted from borage leaves reduces protein aggregation mediating through structural elements of the protein, promoting the correct folding of lysozyme. Since a number of aspidospermine compounds have been shown to possess potent antimalarial activities, the action of compound identified in the present study suggests a possible link between protein aggregation and aspidospermine drugs.

Anxiolytic-like effect of ethanolic extract of Argemone mexicana and its alkaloids in Wistar rats.

Argemone mexicana is a Papaveracea plant; some reports have shown their antibacterial, anti-cancer, sedative and probably anti-anxiety properties. From their aerial parts, flavonoids and alkaloids have been isolated, which are intrinsically related to some actions on the central nervous system. The aim of this study was to evaluate the anxiolytic-like effects of the plant, using its ethanolic extract and alkaloid-enriched extract obtained from fresh leaves. Phytochemical screening was carried out together with evaluation of antioxidant capacity and the enrichment of alkaloids present in the extract. Subsequently, 100 and 200 mg/kg doses of ethanolic extract and alkaloid-enriched extract (200 µg/kg) were intraperitoneally administered to female Wistar rats, which were exposed to elevated plus maze (EPM) test. Picrotoxin (1 mg/kg), a non-competitive gamma-aminobutyric acid A (GABAA) chloride channel antagonist, was used in experimental procedures to evaluate if this receptor is involved in the anxiolytic-like effects of A. mexicana. To discard motor effects associated with the treatments, the rats were evaluated by the locomotor activity test. Only the ethanolic extract at 200 mg/kg and alkaloid-enriched extract (200 µg/kg) produced anxiolytic-like effects similarly to diazepam 2 mg/kg on EPM test, without affecting locomotor activity. Meanwhile, the administration of picrotoxin blocked anti-anxiety effect of alkaloid-enriched extract of the plant. These results showed that A. mexicana is a potential anxiolytic agent and we suggest that this effect is mediated by the GABAA receptor. These effects are related to the presence of alkaloids.

Antibacterial Activity of the Alkaloid-Enriched Extract from Prosopis juliflora Pods and Its Influence on in Vitro Ruminal Digestion

The purpose of this study was to assess the in vitro antimicrobial activity of alkaloid-enriched extracts from Prosopis juliflora (Fabaceae) pods in order to evaluate them as feed additives for ruminants. As only the basic chloroformic extract (BCE), whose main constituents were juliprosopine (juliflorine), prosoflorine and juliprosine, showed Gram-positive antibacterial activity against Micrococcus luteus (MIC = 25 μg/mL), Staphylococcus aureus (MIC = 50 μg/mL) and Streptococcus mutans (MIC = 50 μg/mL), its influence on ruminal digestion was evaluated using a semi-automated in vitro gas production technique, with monensin as the positive control. Results showed that BCE has decreased gas production as efficiently as monensin after 36 h of fermentation, revealing its positive influence on gas production during ruminal digestion. Since P. juliflora is a very affordable plant, this study points out this alkaloid enriched extract from the pods of Prosopis juliflora as a potential feed additive to decrease gas production during ruminal digestion.

In VitroPermeation of Mesembrine Alkaloids fromSceletium tortuosumacross Porcine Buccal, Sublingual, and Intestinal Mucosa

Sceletium tortuosum is an indigenous South African plant that has traditionally been used for its mood-enhancing properties. Recently, products containing S. tortuosum have become increasingly popular and are commonly administered as tablets, capsules, teas, decoctions, or tinctures, while traditionally the dried plant material has been masticated. This study evaluated the in vitro permeability of the four major S. tortuosum alkaloids (i.e., mesembrine, mesembrenone, mesembrenol, and mesembranol) across porcine intestinal, sublingual, and buccal tissues in their pure form and in the form of three different crude plant extracts, namely water, methanol, and an acid-base alkaloid-enriched extract. The permeability of mesembrine across intestinal tissue was higher than that of the highly permeable reference compound caffeine (which served as a positive control for membrane permeability) both in its pure form, as well as in the form of crude extracts. The intestinal permeability of mesembranol was similar to that of caffeine, while those of mesembrenol and mesembrenone were lower than that of caffeine, but much higher than that of the poorly permeable reference compound atenolol (which served as a negative control for membrane permeability). In general, the permeabilities of the alkaloids were lower across the sublingual and the buccal tissues than across the intestinal tissue. However, comparing the transport of the alkaloids with that of the reference compounds, there are indications that transport across the membranes of the oral cavity may contribute considerably to the overall bioavailability of the alkaloids, depending on pre-systemic metabolism, when the plant material is chewed and kept in the mouth for prolonged periods. The results from this study confirmed the ability of the alkaloids of S. tortuosum in purified or crude extract form to permeate across intestinal, buccal, and sublingual mucosal tissues.

Investigation of the in vitro and ex vivo acetylcholinesterase and antioxidant activities of traditionally used Lycopodium species from South America on alkaloid extracts

Ethnopharmacological relevanceThe study was aimed at evaluating medicinal and therapeutic potentials of two Lycopodiaceae species, Lycopodium clavatum (L.) and Lycopodium thyoides (Humb. & Bonpl. ex Willd), both used in South American folk medicine for central nervous system conditions. Alkaloid extracts were evaluated for chemical characterization, acetylcholinesterase and antioxidant activities. Materials and methodsThe alkaloid extracts obtained by alkaline extraction were determined for each species by GC/MS examination. The evaluation of the anticholinesterase and the antioxidant activities of the extracts were tested by determining in vitro and ex vivo models. Effects on acetylcholinesterase (AChE) were tested in vitro using rat brain homogenates and ex vivo after a single administration (25, 10 and 1mg/kg i.p.) of the alkaloid extracts in mice. The in vitro antioxidant effects were tested for the 2-deoxyribose degradation, nitric oxide (NO) interaction, 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activity and total reactive antioxidant potential (TRAP). After an acute administration (25 and 10mg/kg i.p.) of the extracts in middle-aged (12 months) mice, the antioxidant effects were estimated through the thiobarbituric acid reactive substances test (TBARS), and the antioxidant enzymes activities for catalase (CAT) and superoxide dismutase (SOD) were measured. ResultsAChE activity was inhibited in vitro by the alkaloid-enriched extracts of both Lycopodium species in a dose and time-dependent manner in rat cortex, striatum and hippocampus. A significant inhibition was also observed in areas of the brain after acute administration of extracts, as well as decreased lipid peroxidation and increased CAT activity in the cortex, hippocampus and cerebellum. A moderate antioxidant activity was observed in vitro for the extracts. Chemically, the main alkaloids found for the two species were lycopodine and acetyldihidrolycopodine. ConclusionThis study showed that the biological properties of the folk medicinal plants Lycopodium clavatum and Lycopodium thyoides include AChE inhibitory activity and antioxidant effects, two possible mechanisms of action in Alzheimer's related processes.

An investigation of the in vitro transport of Sceletium tortuosum alkaloids across porcine buccal, sublingual and intestinal membranes

Sceletium tortuosum (L.) N.E.Br. is indigenous to South Africa and has traditionally been used for its mood enhancing properties. Recently, products containing S. tortuosum have become increasingly popular and are commonly administered as tablets, capsules, teas, decoctions or tinctures, while the dried plant material has traditionally been masticated and the resulting extracts swallowed. In this study, the in vitro transport of four major S. tortuosum alkaloids across porcine intestinal, sublingual and buccal mucosa in their pure form as well as in the form of three different crude extracts; water, methanol and an acid-base alkaloid-enriched extract, was evaluated.

Inhibitory mechanisms of two Uncaria tomentosa extracts affecting the Wnt-signaling pathway

Uncaria tomentosa ("uña de gato"; "cat's claw"), a woody vine native to the Amazon rainforest, is commonly used in South American traditional medicine to treat a broad spectrum of diseases. Although recent studies have reported anti-inflammatory and anti-proliferative properties of different alkaloids extracted from this plant, the underlying molecular mechanisms of these effects have not been elucidated yet. Our study investigates the inhibitory mechanisms of Uncaria tomentosa extracts on the Wnt-signaling pathway, a central regulator of development and tissue homoeostasis. A modified cell-based luciferase assay for screening inhibitors of the Wnt-pathway was used for analysis. Three cancer cell lines displaying different levels of aberrant Wnt-signaling activity were transfected with Wnt-signaling responsive Tcf-reporter plasmids and treated with increasing concentrations of two Uncaria tomentosa bark extracts. Wnt-signaling activity was assessed by luciferase activity and by expression of Wnt-responsive target genes. We show that both, an aqueous and an alkaloid-enriched extract specifically inhibit Wnt-signaling activity in HeLa, HCT116 and SW480 cancer cells resulting in reduced expression of the Wnt-target gene: c-Myc. The alkaloid-enriched extract (B/S(rt)) was found to be more effective than the aqueous extract (B/W(37)). The strongest effect was observed in SW480 cells, displaying the highest endogenous Wnt-signaling activity. Downregulation of Wnt-signaling by a dominant negative-TCF-4 variant in non-cancer cells rendered the cells insensitive towards treatment with B/S(rt). B/Srt was less toxic in non-cancer cells than in cancer cells. Our data suggest that the broad spectrum of pharmacological action of Uncaria tomentosa involves inhibition of the Wnt-signaling pathway, downstream of beta-Catenin activity.

Isolation and characterization of a presumed biosynthetic precursor of camptothecin from extracts of Camptotheca acuminata

A biosynthetic precursor 4 of the antitumor alkaloid camptothecin ( 1) has been isolated from alkaloid enriched extracts of Camptotheca acuminata. The structure of 4, which was determined both in the solid state by x-ray diffraction and in solution by NMR analysis, provides strong evidence in support of the proposed biosynthetic scheme for camptothecin ( 1).