Natural Compounds Purified from the Leaves of Aristotelia chilensis: Makomakinol, a New Alkaloid and the Effect of Aristoteline and Hobartine on NaV Channels.

Aristotelia chilensis or "maqui" is a tree native to Chile used in the folk medicine of the Mapuche people as an anti-inflammatory agent for the treatment of digestive ailments, fever, and skin lesions. Maqui fruits are black berries which are considered a "superfruit" with notable potential health benefits, promoted to be an antioxidant, cardioprotective, and anti-inflammatory. Maqui leaves contain non-iridoid monoterpene indole alkaloids which have previously been shown to act on nicotinic acetylcholine receptors, potassium channels, and calcium channels. Here, we isolated a new alkaloid from maqui leaves, now called makomakinol, together with the known alkaloids aristoteline, hobartine, and 3-formylindole. Moreover, the polyphenols quercetine, ethyl caffeate, and the terpenes, dihydro-ß-ionone and terpin hydrate, were also obtained. In light of the reported analgesic and anti-nociceptive properties of A. chilensis, in particular a crude mixture of alkaloids containing aristoteline and hobartinol (PMID 21585384), we therefore evaluated the activity of aristoteline and hobartine on NaV1.8, a key NaV isoform involved in nociception, using automated whole-cell patch-clamp electrophysiology. Aristoteline and hobartine both inhibited Nav1.8 with an IC50 of 68 ± 3 µM and 54 ± 1 µM, respectively. Hobartine caused a hyperpolarizing shift of the voltage-dependence of the activation, whereas aristoteline did not change the voltage-dependence of the activation or inactivation. The inhibitory activity of these alkaloids on NaV channels may contribute to the reported analgesic properties of Aristotelia chilensis used by the Mapuche people.

In Vitro Anti-Venom Potentials of Aqueous Extract and Oils of Toona ciliata M. Roem against Cobra Venom and Chemical Constituents of Oils.

There are high mortality and morbidity rates from poisonous snakebites globally. Many medicinal plants are locally used for snakebite treatment in Uganda. This study aimed to determine the in vitro anti-venom activities of aqueous extract and oils of Toona ciliata against Naja melanoleuca venom. A mixture of venom and extract was administered intramuscularly in rats. Anticoagulant, antiphospholipase A2 (PLA2) inhibition assay, and gel electrophoresis for anti-venom activities of oils were done. The chemical constituents of the oils of ciliata were identified using Gas chromatography-tandem mass spectroscopy (GC-MS/MS). The LD50 of the venom was 0.168 ± 0.21 µg/g. The venom and aqueous extract mixture (1.25 µg/g and 3.5 mg/g) did not cause any rat mortality, while the control with venom only (1.25 µg/g) caused death in 1 h. The aqueous extract of T. ciliata inhibited the anticoagulation activity of N. melanoleuca venom from 18.58 min. to 4.83 min and reduced the hemolytic halo diameter from 24 to 22 mm. SDS-PAGE gel electrophoresis showed that oils completely cleared venom proteins. GC-MS/MS analysis showed that the oils had sesquiterpene hydrocarbons (60%) in the volatile oil (VO) and oxygenated sesquiterpenes (48.89%) in the non-volatile oils (NVO). Some major compounds reported for the first time in T. ciliata NVOs were: Rutamarin (52.55%), ß-Himachalol (9.53%), Girinimbine (6.68%) and Oprea1 (6.24%). Most compounds in the VO were reported for the first time in T. ciliata, including the major ones Santalene (8.55%) and Himachal-7-ol (6.69%). The result showed that aqueous extract and oils of T. ciliata have anti-venom/procoagulant activities and completely neutralized the venom. We recommend a study on isolation and testing the pure compounds against the same venom.

A new C-C linked benzophenathridine-2-quinoline dimer, and the antiplasmodial activity of alkaloids from Zanthoxylum holstzianum.

The CH2Cl2/MeOH (1:1) extract of Zanthoxylum holstzianum stem bark showed good antiplasmodial activity (IC50 2.5 ± 0.3 and 2.6 ± 0.3 µg/mL against the W2 and D6 strains of Plasmodium falciparum, respectively). From the extract five benzophenanthridine alkaloids [8-acetonyldihydrochelerythrine (1), nitidine (2), dihydrochelerythine (3), norchelerythrine (5), arnottianamide (8)]; a 2-quinolone alkaloid [N-methylflindersine (4)]; a lignan [4,4'-dihydroxy-3,3'-dimethoxylignan-9,9'-diyl diacetate (7)] and a dimer of a benzophenanthridine and 2-quinoline [holstzianoquinoline (6)] were isolated. The CH2Cl2/MeOH (1:1) extract of the root bark afforded 1, 3-6, 8, chelerythridimerine (9) and 9-demethyloxychelerythrine (10). Holstzianoquinoline (6) is new, and is the second dimer linked by a C-C bond of a benzophenanthridine and a 2-quinoline reported thus far. The compounds were identified based on spectroscopic evidence. Amongst five compounds (1-5) tested against two strains of P. falciparum, nitidine (IC50 0.11 ± 0.01 µg/mL against W2 and D6 strains) and norchelerythrine (IC50 value of 0.15 ± 0.01 µg/mL against D6 strain) were the most active.

Safety evaluation and bioassay-guided isolation of antimycobacterial compounds from Morella salicifolia root ethanolic extract.

ETHNOPHARMACOLOGICAL RELEVANCE: Although the available medicines can cure almost all tuberculosis drug-susceptible patients some problems including the emergence of multi-drug resistant and extensively drug-resistant strains press for the need of new anti-TB medicines. Morella salicifolia is a common plant that is widely used in traditional medicine for managing HIV and AIDS-related conditions including tuberculosis but no studies have been done to evaluate its safety and efficacy. AIM OF THE STUDY: This study was designed to investigate the antimycobacterial activity and safety of M. salicifolia extract and its constituents. MATERIAL AND METHODS: Antimycobacterial activity of the crude extract was tested against non-pathogenic mycobacteria including Mycobacterium aurum (MA), Mycobacterium indicus pranii (MIP) and Mycobacterium madagascariense (MM) using the broth microdilution method. Bioassay-guided fractionation was employed to isolate the active compounds. Some of the isolated active compounds were tested for antimycobacterial activity against the standard and selected clinical isolates of M. tuberculosis. Safety of the crude extract was assessed using cytotoxicity assay and oral acute toxicity testing. RESULTS: The crude extract exhibited antimycobacterial activity against all the species used. The study led to isolation of six compounds; four pentacyclic triterpenoids; (3ß)-3-Hydroxyolean-12-en-28-oic acid (Oleanolic acid) (1), (2α,3ß)-2,3-Dihydroxyolean-12-en-28-oic acid (maslinic acid) (2), D-Friedoolean-14-ene-3ß,28-diol (taraxerol) (3), and D-Friedoolean-14-en-3ß-ol (myricadiol) (4), and two diarylheptanoids; (±)-myricanol (5) and myricanone (6). The six compounds exhibited activity against three nonpathogenic mycobacteria species. Compound 2, was the most active, with MICs of 17, 28 and 56 µg/ml against MM, standard a M. tuberculosis strain H37RV and rifampicin resistant M. tuberculosis clinical isolates, respectively. The crude extract did not show toxicity on peripheral blood mononuclear cells and it was safe in mice following acute oral toxicity test. CONCLUSION: The results from this study indicate that some isolated compounds in Morella salicifolia could form potential scaffolds for drug development efforts targeting M. tuberculosis. More studies are needed to further explore the potential of the plant extract and its secondary metabolites in the management of HIV and AIDS-related conditions using in-vivo models.

Two mosquito larvicidal arabinofuranosidetridecanol from Commiphora merkeri exudate.

Two new arabinofuranosidetridecanol, namely 1,2-tridecanediol-1-O-α-L-5'-acetylarabinofuranoside (1) and 1,2-tridecanediol-1-O-α-L-arabinofuranoside (2) together with known compound, 1,2-tridecanediol (3) were isolated from Commiphora merkeri exudate. Compound 1 showed larvicidal activity against Ae. aegypti (LC50 = 40.66 µg/mL), An. gambiae (LC50 = 22.86 µg/mL) and Cx. quinquefasciatus (LC50 = 15.88 µg/mL). Also, Compound 2 had larvicidal activity against Ae. aegypti (LC50 = 33.79 µg/mL), An. gambiae (LC50 = 31.99 µg/mL) and Cx. quinquefasciatus (LC50 = 17.70 µg/mL). There were no significant difference of larvae mortalities (≥ 95%) among the two compounds and among mosquito species except for compound 2 at 72 h for Cx. quinquefasciatus and An. gambiae. Compound 3 was not larvicidal active even after 72 h of exposure time. In addition, none of the compound was cytotoxic to brine shrimps. The two Arabinofuranosidetridecanol are potential against mosquito species and they could be safe in the environment.

Antibacterial secondary metabolites from Vernonia auriculifera Hiern (Asteraceae) against MDR phenotypes.

Purification of the aerial parts of Vernonia auriculifera Hiern afforded steroids (1-2), flavonoids (3-5), and polyalcohol (6). Their structures were determined using spectral evidences as well as by comparison with reported data. Iodonitrotetrazolium chloride (INT) colorimetric assay was used to assess the antibacterial activity of the extract and isolates against 13 pathogenic strains. The crude extract showed strong antibacterial activity (MIC < 100 µg/mL) against the tested bacterial strains. When combined with an efflux pump inhibitor phenylalanine beta naphthylamide (PAßN), the inhibition potency of the extract was substantially enhanced with the lowest MIC value at 4 µg/mL. Compounds 5 and 6 showed moderate activity (MIC < 100 µg/mL) against 12/13 (92.3%), and 8/13 (61.5%) bacterial strains, respectively. A minimal bactericidal concentration (MBC)/minimal inhibitory concentration (MIC) ratio ≤ 4 indicated their bactericidal effect against Escherichia coli, Enterbacter aerogenes, Klebsiella pneumoniae, Providencia stuartii, Pseudomonas aeruginosa, and Staphylococcus aureus.

A new benzophenone, and the antiplasmodial activities of the constituents of Securidaca longipedunculata fresen (Polygalaceae).

Extracts from Securidaca longipedunculata showed antiplasmodial activities against reference clones and clinical isolates using SYBR Green I method. A new benzophenone, 2,3,4,5-tetramethoxybenzophenone (1) was isolated and characterized along with seven known compounds: 4-hydroxy-2,3-dimethoxybenzophenone (2); 3-hydroxy-5-methoxybiphenyl (3), methyl-2-hydroxy-6-methoxybenzoate (4), benzyl-2-hydroxy-6-methoxybenzoate (5), 2-hydroxy-6-methoxybenzoic acid (6), 2,4,5-trimethoxybenzophenone (7) and 2-methoxy-3,4-methylenedioxybenzophenone (8). Compounds 1 and 2 showed ex vivo antiplasmodial activities (IC50 28.8 µM and 18.6 µM, respectively); while 5 and 8 showed in vivo activities (IC50 19.7 µM and 14.5 µM, respectively) against D6 strain. In a cytotoxicity assay, all the extracts (with an exception of the MeOH extract of the leaves) and pure compounds were not toxic to the normal LO2 and BEAS cell-lines, while the methanol roots extract (IC50 66.4 µg/mL against A549, and 77.4 µg/mL against HepG2), compounds 6 (IC50 22.2 µM against A549) and 7 (IC50 45.2 µM against HepG2) were weakly active against cancerous cell-lines.

Cytotoxicity of fagaramide derivative and canthin-6-one from Zanthoxylum (Rutaceae) species against multidrug resistant leukemia cells.

In our continuous search for cytotoxic compounds from the genus Zanthoxylum, chromatographic separation of the MeOH/CH2Cl2 (1:1) extract of Z. chalybeum yielded one new alkamide; 4-(isoprenyloxy)-3-methoxy-3,4-deoxymethylenedioxyfagaramide (1) and a known one; fagaramide (2). Similarly, from the MeOH/CH2Cl2 (1:1) extract of the stem bark of Z. parachanthum four known compounds; canthin-6-one (3), dihydrochelerythrine (4), lupeol (5) and sesamin (6) were isolated. Characterization of the structures of these compounds was achieved using spectroscopic techniques (NMR and MS). Using resazurin reduction assay 1, 3 and 6 displayed moderate cytotoxicity with IC50 values below 50 µM against the drug sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 leukemia cell lines. It is interesting to note that 3 was more active than the standard drug, doxorubicin against CEM/ADR5000 leukemia cells. Compounds 3 and 6 showed good selectivity on leukemia cells than normal cells. In future studies 3 should be tested against a panel of drug resistant human cells.

Antiplasmodial and antileishmanial flavonoids from Mundulea sericea.

Five known compounds (1-5) were isolated from the extract of Mundulea sericea leaves. Similar investigation of the roots of this plant afforded an additional three known compounds (6-8). The structures were elucidated using NMR spectroscopic and mass spectrometric analyses. The absolute configuration of 1 was established using ECD spectroscopy. In an antiplasmodial activity assay, compound 1 showed good activity with an IC50 of 2.0 µM against chloroquine-resistant W2, and 6.6 µM against the chloroquine-sensitive 3D7 strains of Plasmodium falciparum. Some of the compounds were also tested for antileishmanial activity. Dehydrolupinifolinol (2) and sericetin (5) were active against drug-sensitive Leishmania donovani (MHOM/IN/83/AG83) with IC50 values of 9.0 and 5.0 µM, respectively. In a cytotoxicity assay, lupinifolin (3) showed significant activity on BEAS-2B (IC50 4.9 µM) and HePG2 (IC50 10.8 µM) human cell lines. All the other compounds showed low cytotoxicity (IC50 > 30 µM) against human lung adenocarcinoma cells (A549), human liver cancer cells (HepG2), lung/bronchus cells (epithelial virus transformed) (BEAS-2B) and immortal human hepatocytes (LO2).

Maytenus disticha Extract and an Isolated ß-Dihydroagarofuran Induce Mitochondrial Depolarization and Apoptosis in Human Cancer Cells by Increasing Mitochondrial Reactive Oxygen Species.

Maytenus disticha (Hook F.), belonging to the Celastraceae family, is an evergreen shrub, native of the central southern mountains of Chile. Previous studies demonstrated that the total extract of M. disticha (MD) has an acetylcholinesterase inhibitory activity along with growth regulatory and insecticidal activities. ß-Dihydroagarofurans sesquiterpenes are the most active components in the plant. However, its activity in cancer has not been analyzed yet. Here, we demonstrate that MD has a cytotoxic activity on breast (MCF-7), lung (PC9), and prostate (C4-2B) human cancer cells with an IC50 (µg/mL) of 40, 4.7, and 5 µg/mL, respectively, an increasing Bax/Bcl2 ratio, and inducing a mitochondrial membrane depolarization. The ß-dihydroagarofuran-type sesquiterpene (MD-6), dihydromyricetin (MD-9), and dihydromyricetin-3-O-ß-glucoside (MD-10) were isolated as the major compounds from MD extracts. From these compounds, only MD-6 showed cytotoxic activity on MCF-7, PC9, and C4-2B with an IC50 of 31.02, 17.58, and 42.19 µM, respectively. Furthermore, the MD-6 increases cell ROS generation, and MD and MD-6 induce a mitochondrial superoxide generation and apoptosis on MCF-7, PC9, and C4-2B, which suggests that the cytotoxic effect of MD is mediated in part by the ß-dihydroagarofuran-type that induces apoptosis by a mitochondrial dysfunction.

Cytotoxicity of isoflavones and biflavonoids from Ormocarpum kirkii towards multi-factorial drug resistant cancer.

BACKGROUND: While incidences of cancer are continuously increasing, drug resistance of malignant cells is observed towards almost all pharmaceuticals. Several isoflavonoids and flavonoids are known for their cytotoxicity towards various cancer cells. PURPOSE: The aim of this study was to determine the cytotoxicity of isoflavones: osajin (1), 5,7-dihydroxy-4'-methoxy-6,8-diprenylisoflavone (2) and biflavonoids: chamaejasmin (3), 7,7″-di-O-methylchamaejasmin (4) and campylospermone A (5), a dimeric chromene [diphysin(6)] and an ester of ferullic acid with long alkyl chain [erythrinasinate (7)] isolated from the stem bark and roots of the Kenyan medicinal plant, Ormocarpum kirkii. The mode of action of compounds 2 and 4 was further investigated. METHODS: The cytotoxicity of compounds was determined based on the resazurin reduction assay. Caspases activation was evaluated using the caspase-Glo assay. Flow cytometry was used to analyze the cell cycle (propodium iodide (PI) staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP) (JC-1) and reactive oxygen species (ROS) (H2DCFH-DA). CCRF-CEM leukemia cells were used as model cells for mechanistic studies. RESULTS: Compounds 1, 2 and 4 displayed IC50 values below 20 µM towards CCRF-CEM and CEM/ADR5000 leukemia cells, and were further tested towards a panel of 7 carcinoma cells. The IC50 values of the compounds against carcinoma cells varied from 16.90 µM (in resistant U87MG.ΔEGFR glioblastoma cells) to 48.67 µM (against HepG2 hepatocarcinoma cells) for 1, from 7.85 µM (in U87MG.ΔEGFR cells) to 14.44 µM (in resistant MDA-MB231/BCRP breast adenocarcinoma cells) for 2, from 4.96 µM (towards U87MG.ΔEGFRcells) to 7.76 µM (against MDA-MB231/BCRP cells) for 4, and from 0.07 µM (against MDA-MB231 cells) to 2.15 µM (against HepG2 cells) for doxorubicin. Compounds 2 and 4 induced apoptosis in CCRF-CEM cells mediated by MMP alteration and increased ROS production. CONCLUSION: The present report indicates that isoflavones and biflavonoids from Ormocarpum kirkii are cytotoxic compounds with the potential of being exploited in cancer chemotherapy. Compounds 2 and 4 deserve further studies to develop new anticancer drugs to fight sensitive and resistant cancer cell lines.

Cytotoxic benzylbenzofuran derivatives from Dorstenia kameruniana.

Chromatographic separation of the extract of the roots of Dorstenia kameruniana (family Moraceae) led to the isolation of three new benzylbenzofuran derivatives, 2-(p-hydroxybenzyl)benzofuran-6-ol (1), 2-(p-hydroxybenzyl)-7-methoxybenzofuran-6-ol (2) and 2-(p-hydroxy)-3-(3-methylbut-2-en-1-yl)benzyl)benzofuran-6-ol(3) (named dorsmerunin A, B and C, respectively), along with the known furanocoumarin, bergapten (4). The twigs of Dorstenia kameruniana also produced compounds 1-4 as well as the known chalcone licoagrochalcone A (5). The structures were elucidated by NMR spectroscopy and mass spectrometry. The isolated compounds displayed cytotoxicity against the sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 leukemia cells, where compounds 4 and 5 had the highest activities (IC50 values of 7.17 µM and 5.16 µM, respectively) against CCRF-CEM leukemia cells. Compound 5 also showed cytotoxicity against 7 sensitive or drug-resistant solid tumor cell lines (breast carcinoma, colon carcinoma, glioblastoma), with IC50 below 50 µM, whilst 4 showed selective activity.

Antiplasmodial prenylated flavanonols from Tephrosia subtriflora.

The CH2Cl2/MeOH (1:1) extract of the aerial parts of Tephrosia subtriflora afforded a new flavanonol, named subtriflavanonol (1), along with the known flavanone spinoflavanone B, and the known flavanonols MS-II (2) and mundulinol. The structures were elucidated by the use of NMR spectroscopy and mass spectrometry. The absolute configuration of the flavanonols was determined based on quantum chemical ECD calculations. In the antiplasmodial assay, compound 2 showed the highest activity against chloroquine-sensitive Plasmodium falciparum reference clones (D6 and 3D7), artemisinin-sensitive isolate (F32-TEM) as well as field isolate (KSM 009) with IC50 values 1.4-4.6 µM without significant cytotoxicity against Vero and HEp2 cell lines (IC50 > 100 µM). The new compound (1) showed weak antiplasmodial activity, IC50 12.5-24.2 µM, but also showed selective anticancer activity against HEp2 cell line (CC50 16.9 µM).

Anti-plasmodial activity of Norcaesalpin D and extracts of four medicinal plants used traditionally for treatment of malaria.

BACKGROUND: Malaria is an old life-threatening parasitic disease that is still affecting many people, mainly children living in sub-Saharan Africa. Availability of effective antimalarial drugs played a significant role in the treatment and control of malaria. However, recent information on the emergence of P. falciparum parasites resistant to one of the artemisinin-based combination therapies suggests the need for discovery of new drug molecules. Therefore, this study aimed to evaluate the antiplasmodial activity of extracts, fractions and isolated compound from medicinal plants traditionally used in the treatment of malaria in Tanzania. METHODS: Dry powdered plant materials were extracted by cold macerations using different solvents. Norcaesalpin D was isolated by column chromatography from dichloromethane root extract of Caesalpinia bonducella and its structure was assigned based on the spectral data. Crude extracts, fractions and isolated compound were evaluated for antiplasmodial activity against chloroquine-sensitive P. falciparum (3D7), chloroquine-resistant P. falciparum (Dd2, K1) and artemisinin-resistant P. falciparum (IPC 5202 Battambang, IPC 4912 Mondolkiri) strains using the parasite lactate dehydrogenase assay. RESULTS: The results indicated that extracts of Erythrina schliebenii, Holarrhena pubescens, Dissotis melleri and C. bonducella exhibited antiplasmodial activity against Dd2 parasites. Ethanolic root extract of E. schliebenii had an IC50 of 1.87 µg/mL while methanolic and ethanolic root extracts of H. pubescens exhibited an IC50 = 2.05 µg/mL and IC50 = 2.43 µg/mL, respectively. Fractions from H. pubescens and C. bonducella roots were found to be highly active against K1, Dd2 and artemisinin-resistant parasites. Norcaesalpin D from C. bonducella root extract was active with IC50 of 0.98, 1.85 and 2.13 µg/mL against 3D7, Dd2 and IPC 4912-Mondolkiri parasites, respectively. CONCLUSIONS: Antiplasmodial activity of norcaesalpin D and extracts of E. schliebenii, H. pubescens, D. melleri and C. bonducella reported in this study requires further attention for the discovery of antimalarial lead compounds for future drug development.

Three Chalconoids and a Pterocarpene from the Roots of Tephrosia aequilata.

In our search for new antiplasmodial agents, the CH2Cl2/CH3OH (1:1) extract of the roots of Tephrosia aequilata was investigated, and observed to cause 100% mortality of the chloroquine-sensitive (3D7) strain of Plasmodium falciparum at a 10 mg/mL concentration. From this extract three new chalconoids, E-2',6'-dimethoxy-3',4'-(2'',2''-dimethyl)pyranoretrochalcone (1, aequichalcone A), Z-2',6'-dimethoxy-3',4'-(2'',2''-dimethyl)pyranoretrochalcone (2, aequichalcone B), 4''-ethoxy-3''-hydroxypraecansone B (3, aequichalcone C) and a new pterocarpene, 3,4:8,9-dimethylenedioxy-6a,11a-pterocarpene (4), along with seven known compounds were isolated. The purified compounds were characterized by NMR spectroscopic and mass spectrometric analyses. Compound 1 slowly converts into 2 in solution, and thus the latter may have been enriched, or formed, during the extraction and separation process. The isomeric compounds 1 and 2 were both observed in the crude extract. Some of the isolated constituents showed good to moderate antiplasmodial activity against the chloroquine-sensitive (3D7) strain of Plasmodium falciparum.

Antimicrobial Coumarins from the Oyster Culinary-Medicinal Mushroom, Pleurotus ostreatus (Agaricomycetes), from Kenya.

Pleurotus ostreatus has been widely used as food because of its nutritional and medicinal properties. These have been attributed to the presence of macronutrients, minerals, vitamins, and amino acids, among other secondary metabolites. There are, however, few reports on the antimicrobial activities of different classes of purified compounds from P. ostreatus. This led to the current study, the objective of which was to chemically characterize the antibiotic activities of P. ostreatus against selected human pathogenic bacteria and endophytic fungi. Chemical structures were determined using spectroscopic methods and by comparison with values of related structures reported in the literature. Pure compounds from P. ostreatus were tested in vitro against pathogenic bacteria (Staphylococcus aureus and Escherichia coli) and endophytic fungi (Pencillium digitatum and Fusarium proliferatum). A new compound, (E)-5,7-dimethoxy-6-(3-methylbuta-1,3-dienyl)-2H-chromen-2-one (5-methoxy-(E)-suberodiene) (compound 2), along with ergosterol (compound 1) and 5,7-dimethoxy-6-(3-methylbut-2-enyl)-2H-chromen-2-one (toddaculin; compound 3), were isolated from the fruiting bodies of P. ostreatus. The growth of S. aureus, F. proliferatum, and P. digitatum colonies was inhibited in media containing compound 2, with minimum inhibitory concentrations closely comparable to those of conventional antibiotics.

Rotenoids, Flavonoids, and Chalcones from the Root Bark of Millettia usaramensis.

Five new compounds, 4-O-geranylisoliquiritigenin (1), 12-dihydrousararotenoid B (2), 12-dihydrousararotenoid C (3), 4'-O-geranyl-7-hydroxyflavanone (4), and 4'-O-geranyl-7-hydroxydihydroflavanol (5), along with 12 known natural products (6-17) were isolated from the CH2Cl2/MeOH (1:1) extract of the root bark of Millettia usaramensis ssp. usaramensis by chromatographic separation. The purified metabolites were identified by NMR spectroscopic and mass spectrometric analyses, whereas their absolute configurations were established on the basis of chiroptical data and in some cases also by X-ray crystallography. The crude extract was moderately active (IC50 = 11.63 µg/mL) against the ER-negative MDB-MB-231 human breast cancer cell line, and accordingly compounds 6, 8, 9, 10, 12, and 16 also showed moderate to low cytotoxic activities (IC50 25.7-207.2 µM). The new natural product 1 exhibited antiplasmodial activity with IC50 values of 3.7 and 5.3 µM against the chloroquine-sensitive 3D7 and the chloroquine-resistant Dd2 Plasmodium falciparum strains, respectively, and was also cytotoxic to the HEK293 cell line.

(-)-Pentylsedinine, a New Alkaloid from the Leaves of Lobelia tupa with Agonist Activity at Nicotinic Acetylcholine Receptor.

Lobelia tupa, also called devil's tobacco, is a native plant from the center-south of Chile which has been used by the native people of Chile as a hallucinogenic and anesthetic plant. A new piperidine alkaloid, called pentylsedinine, which comprises five carbons in the side chain, was isolated from the aerial part of L. tupa, along with lobeline and lobelanidine. The structure was established on the basis of 1D and 2D NMR spectroscopy. While lobeline is a neutral antagonist at α3ß2/α3ß4 nAChR and α7 nAChR, both lobelanidine and pentylsedinine act as partial agonists at nAChR.

Antiplasmodial and cytotoxic activities of the constituents of Turraea robusta and Turraea nilotica.

ETHNOPHARMACOLOGICAL RELEVANCE: Turraea robusta and Turraea nilotica are African medicinal plants used for the treatment of a wide variety of diseases, including malaria. The genus Turraea is rich in limonoids and other triterpenoids known to possess various biological activities. MATERIALS AND METHODS: From the stem bark of T. robusta six compounds, and from various parts of T. nilotica eleven compounds were isolated by the use of a combination of chromatographic techniques. The structures of the isolated compounds were elucidated using NMR and MS, whilst the relative configuration of one of the isolated compounds, toonapubesin F, was established by X-ray crystallography. The antiplasmodial activities of the crude extracts and the isolated constituents against the D6 and W2 strains of Plasmodium falciparum were determined using the semiautomated micro dilution technique that measures the ability of the extracts to inhibit the incorporation of (G-(3)H, where G is guanine) hypoxanthine into the malaria parasite. The cytotoxicity of the crude extracts and their isolated constituents was evaluated against the mammalian cell lines African monkey kidney (vero), mouse breast cancer (4T1) and human larynx carcinoma (HEp2). RESULTS: The extracts showed good to moderate antiplasmodial activities, where the extract of the stem bark of T. robusta was also cytotoxic against the 4T1 and the HEp2 cells (IC50<10 µg/ml). The compounds isolated from these extracts were characterized as limonoids, protolimonoids and phytosterol glucosides. These compounds showed good to moderate activities with the most active one being azadironolide, IC50 2.4 ± 0.03 µM and 1.1 ± 0.01 µM against the D6 and W2 strains of Plasmodium falciparum, respectively; all other compounds possessed IC50 14.4-40.5 µM. None of the compounds showed significant cytotoxicity against vero cells, yet four of them were toxic against the 4T1 and HEp2 cancer cell lines with piscidinol A having IC50 8.0 ± 0.03 and 8.4 ± 0.01 µM against the 4T1 and HEp2 cells, respectively. Diacetylation of piscidinol A resulted in reduced cytotoxicity. CONCLUSION: From the medicinal plants T. robusta and T. nilotica, twelve compounds were isolated and characterized; two of the isolated compounds, namely 11-epi-toonacilin and azadironolide showed good antiplasmodial activity with the highest selectivity indices.

Antiplasmodial quinones from the rhizomes of Kniphofia foliosa.

Extracts of the rhizomes of Kniphofia foliosa exhibited antiplasmodial activities against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum with IC50 values of 3-5 microg/mL. A phenyloxanthrone, named 10-acetonylknipholone cyclooxanthrone (1) and an anthraquinone-anthrone dimer, chryslandicin 10-methyl ether (2), were isolated from the rhizomes, along with known quinones, including the rare phenylanthraquinone dimers, joziknipholones A and B. The structures of these compounds were determined based on spectroscopic data. This is the second report on the occurrence of the dimeric phenylanthraquinones in nature. In an in vitro antiplasmodial assay of the isolated compounds, activity was observed for phenylanthraquinones, anthraquinone-anthrone dimers and dimeric phenylanthraquinones, with joziknipholone A being the most active. The new compound, 10-acetonylknipholone cyclooxanthrone, also showed anti-plasmodial activity. In an in vivo assay, knipholone anthrone displayed marginal antimalarial activity.