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PubMed1999

Antimalarial, antiproliferative, and antitumor activities of artemisinin-derived, chemically robust, trioxane dimers.

Nine C-10 non-acetal derivatives of the natural trioxane artemisinin (1) were prepared as dimers using some novel chemistry. As designed, each dimer was stable chemically. C-10 Olefinic dimers 7 and C-10 saturated dimers 8-13 all showed good to excellent antimalarial and antiproliferative activities in vitro. Dimers 8, 10, and 12 were especially potent and selective at inhibiting growth of some human cancer cell lines in the NCI in vitro 60-cell line assay.

Animals↗
PubMed2001

Structures of cordypyridones A-D, antimalarial N-hydroxy- and N-methoxy-2-pyridones from the insect pathogenic fungus Cordyceps nipponica.

Bioassay-guided fractionation of the extracts from the insect pathogenic fungus Cordyceps nipponica BCC 1389 led to the isolation of N-hydroxy- and N-methoxy-2-pyridones, cordypyridones A-D (1-4). Structures of these compounds, including absolute configuration, were determined by spectroscopic methods, chemical conversions and single-crystal X-ray diffraction analyses. Codypyridones A and B, atropisomers of each other, exhibited potent in vitro antimalarial activity with IC(50) values of 0.066 and 0.037 microg/mL, respectively, while their cytotoxicity was much weaker.

Animals↗
PubMed2003

Synthesis of antimalarial yingzhaosu A analogues by the peroxidation of dienes with Co(II)/O2/Et3SiH.

Co(II)-catalyzed peroxidation of dienes including (S)-limonene in the presence of molecular oxygen and triethylsilane provided in each case the corresponding 2,3-dioxabicyclo[3.3.1]nonane derivatives via the intramolecular cyclization of the unsaturated peroxy radical intermediates. The product composition was remarkably influenced by the structure of the dienes, the nature of the solvents, and the concentration of the substrates and the catalyst. Some of the yingzhaosu A analogues obtained in this study showed notable antimalarial activities in vitro.

Alkadienes↗
PubMed2000

First atropo-divergent total synthesis of the antimalarial korupensamines A and B by the "lactone method".

The stereoselective total synthesis of the antimalarial korupensamines A (1a) and B (1b) by application of the "lactone method" is described. Key steps of this first atropo-selective access to 5,8'-coupled naphthylisoquinoline alkaloids were the regioselective intramolecular coupling of ester 8 to give the configurationally labile lactone-bridged biaryl 9 and its atropisomer-selective cleavage with a variety of chiral and achiral H-nucleophiles, yielding the configurationally stable P-diol 10a or, optionally, the M-product 10b. From the axially chiral phenylisoquinolines thus obtained atropo-diastereodivergently, the authentic natural naphthylisoquinolines with the respective axial configurations, korupensamines A (1a) and B (1b), were obtained by completion of the second naphthalene ring, starting from the previous "bridgehead" C1 unit.

Antimalarials↗
PubMed2001

Antimalarial, cytotoxic, and antifungal alkaloids from Duguetia hadrantha.

Bioassay-guided isolation of Duguetia hadrantha yielded two new 4,5-dioxo-1-azaaporphinoids, hadranthine A (1) and hadranthine B (2), together with the known alkaloids imbiline-1 (3), sampangine (4), and 3-methoxysampangine (5), whose structures were determined primarily from 2D-NMR 1H-13C HMBC, and 1H-15N HMBC experiments. This is the first report of the co-occurrence of the copyrine alkaloids 4 and 5, as well as the first report of either copyrine or imbiline type alkaloids from a Duguetia species. Compounds 1, 4, and 5 demonstrated in vitro antimalarial activity against Plasmodium falciparum (W-2 clone), while 2 was inactive. Instead, 2 showed in vitro cytotoxicity to selected human cancer cell lines (IC50 = 3-6 microg/mL against SK-MEL, KB, BT-549, and SK-OV-3), and 4 was also cytotoxic to human malignant melanoma (IC50 = 0.37 microg/mL). Sampangine (4) also inhibited cell aggregation with a MIC value of <0.15 microg/mL, while 3-methoxysampangine (5) was only weakly active.

Alkaloids↗
PubMed2001

Antimalarial, antiviral, and antitoxoplasmosis norsesterterpene peroxide acids from the Red Sea sponge Diacarnus erythraeanus.

A new norsesterterpene acid, named muqubilone (1), along with the known sigmosceptrellin-B and muqubilin were isolated from the Red Sea sponge Diacarnus erythraeanus. The structure determination of 1 was based primarily on 1D and 2D NMR analyses. Sigmosceptrellin-B exhibits significant in vitro antimalarial activity against Plasmodium falciparum (D6 and W2 clones) with IC(50) values of 1200 and 3400 ng/mL, respectively. Muqubilin and 1 show in vitro antiviral activity against herpes simplex type 1 (HSV-1) with ED(50) values of 7.5 and 30 microg/mL, respectively. Muqubilin and sigmosceptrellin-B display potent in vitro activity against Toxoplasma gondii at a concentration of 0.1 microM without significant toxicity.

Animals↗
PubMed2001

Synthesis of new artemisinin analogues from artemisinic acid modified at C-3 and C-13 and their antimalarial activity.

Artemisinic acid (2) was modified through allylic oxidation at C-3 or conjugate addition at C-13 to afford 12 methyl artemisinate derivatives (4-15). Photooxidation of the derivatives yielded eight new artemisinin analogues, including 13-cyanoartemisinin (16), 13-methoxycarbonyl artemisinin (17), 13-methoxyartemisinin (18), 13-ethylsulfonylartemisinin (19), 13-nitromethylartemisinin (20), 13-(1-nitroethyl)artemisinin (21), (3R)-3-hydroxyartemisinin (22), and (3R)-3-acetoxyartemisinin (23). Among the analogues, only compound 20 had antimalarial activity comparable to artemisinin (1).

Animals↗
PubMed2001

Antimalarial (+)-trans-hexahydrodibenzopyran derivatives from Machaerium multiflorum.

Bioassay-guided fractionation of Machaerium multiflorum yielded the hitherto unreported (+)-trans-hexahydrodibenzopyrans machaeriol A (1) and machaeriol B (2), as well as the known guaiane sesquiterpene (-)-kessane. Structure elucidation was based on (1)H and (13)C NMR data, mainly 2D NMR (1)H-(1)H COSY, (1)H-(13)C HMQC, (1)H-(13)C HMBC, and (1)H-(1)H NOESY experiments. This is the first report of the hexahydrodibenzopyrans from a higher plant other than the genus Cannabis. The cannabimimetic activity was thus evaluated by radioligand binding assay for cannabinoid receptor CB1, which indicated, notably, that both 1 and 2 were inactive. In addition, the cross reactivity of 1 and 2 toward antibodies designed for urinary metabolites of cannabinoids was evaluated with the EMIT and On Line cannabinoids assays. Both compounds showed no response at 100 000 ng/mL in both assays. Machaeriol B (2) demonstrated in vitro antimalarial activity (IC(50) = 120 ng/mL) against Plasmodium falciparum W-2 clone.

Amphotericin B↗
PubMed2003

Briarellins J-P and polyanthellin A: new eunicellin-based diterpenes from the gorgonian coral Briareum polyanthes and their antimalarial activity.

A new chemical study of the hexane extract of the gorgonian Briareum polyanthes collected in Puerto Rico afforded 10 new diterpenes of the eunicellin class, briarellins 1-9 and polyanthellin A (10), along with the known diterpene briarellin D (11). The structures and relative stereochemistry of metabolites 1-10 were assigned on the basis of NMR studies, chemical methods, and comparisons to the spectral properties of 11. A reassessment of prior structural assignment for briarellin A and two known sclerophytin-type diterpenes, 13 and 14, is proposed. Antimalarial tests on 1-6 and 8-12 indicated that they were active against Plasmodium falciparum.

Acetylation↗
PubMed2003

New antimalarial bis-dehydroaporphine alkaloids from Polyalthia debilis.

Four new dimeric aporphinoids named bidebilines A-D (1-4), bis-7,7'-dehydroanonaine (1), 7-dehydroanonaine-7'-dehydro-8'-methoxyanonaine (2), bis-7,7'-dehydro-8,8'-dimethoxyanonaine (3), and bis-7,7'-dehydro-10,10'-dimethoxyanonaine (4), were isolated from the roots of Polyalthia debilis. Their structures were established on the basis of spectral evidence. Compounds 3 and 4 exhibited moderate antimalarial activity with IC(50) values of 5.4 and 4.1 microg/mL, respectively.

Alkaloids↗
PubMed2003

Antimalarial dihydroisocoumarins produced by Geotrichum sp., an endophytic fungus of Crassocephalum crepidioides.

Three novel dihydroisocoumarin derivatives (1-3) with antimalarial, antituberculous, and antifungal activities have been isolated by bioassay-guided fractionation from an endophytic fungus, Geotrichum sp., collected from Crassocephalum crepidioides. Structures were established as 7-butyl-6,8-dihydroxy-3(R)-pent-11-enylisochroman-1-one (1), 7-but-15-enyl-6,8-dihydroxy-3(R)-pent-11-enylisochroman-1-one (2), and 7-butyl-6,8-dihydroxy-3(R)-pentylisochroman-1-one (3) using spectroscopic data.

Animals↗
PubMed2003

New antimycobacterial and antimalarial 8,9-secokaurane diterpenes from Croton kongensis.

Two new 8,9-secokaurane diterpenes, ent-8,9-seco-7alpha,11beta-diacetoxykaura-8(14),16-dien-9,15-dione (1) and ent-8,9-seco-8,14-epoxy-7alpha-hydroxy-11beta-acetoxy-16-kauren-9,15-dione (2), together with two known compounds, ent-8,9-seco-7alpha-hydroxy-11beta-acetoxykaura-8(14),16-dien-9,15-dione (3) and ent-7beta-hydroxy-15-oxokaur-16-en-18-yl acetate, were isolated from Croton kongensis. This is the first report on the presence of 8,9-secokauranes in the plant genus Croton. Diterpenes 1-3 exhibited antimycobacterial activity with minimum inhibitory concentrations (MICs) of 25.0, 6.25, and 6.25 microg/mL, respectively, and possessed antimalarial activity with IC(50) ranges of 1.0-2.8 microg/mL. They also demonstrated comparable cytotoxicity toward the Vero (IC(50) ranged from 0.9 to 3.2 microg/mL), KB (IC(50) from 1.2 to 13.8 microg/mL), and BC cell lines (IC(50) from 1.1 to 2.2 microg/mL, except for compound 1, which was inactive against BC cells).

Animals↗
PubMed2003

Cytotoxic and antimalarial beta-carboline alkaloids from the roots of Eurycoma longifolia.

Three new [n-pentyl beta-carboline-1-propionate (1), 5-hydroxymethyl-9-methoxycanthin-6-one (2), and 1-hydroxy-9-methoxycanthin-6-one (3)] and 19 known beta-carboline alkaloids were isolated from the roots of Eurycoma longifolia. The new structures were determined by comprehensive analyses of their 1D and 2D NMR and mass spectral data and by chemical transformation. These compounds were screened for in vitro cytotoxic and antimalarial activities, and 9-methoxycanthin-6-one (4) and canthin-6-one (5) demonstrated significant cytotoxicity against human lung cancer (A-549) and human breast cancer (MCF-7) cell lines.

Alkaloids↗
PubMed2004

A new antimalarial quassinoid from Simaba orinocensis.

A new antimalarial quassinoid, namely, orinocinolide (1), was isolated from the root bark of Simaba orinocensis, together with the previously reported simalikalactone D (2). The structure of 1 was determined primarily from 1D and 2D NMR analysis, as well as by chemical derivatization. Compound 1 was found to be as equally potent as 2 against Plasmodium falciparum clones D6 and W2 (IC(50) 3.27 and 8.53 ng/mL vs 3.0 and 3.67 ng/mL, respectively), but was 4- and 28-fold less toxic than 2 against VERO cells (IC(50) 10 vs 2.3 microg/mL) and HL-60 (IC(50) 0.7 vs 0.025 microg/mL), respectively. In addition, 2 was >46- and >31-fold more potent than pentamidine and amphotericin B (IC(50) 0.035 vs 1.6 and 1.1 microg/mL) against Leishmania donovani, while 1 was inactive. Orinocinolide (1) inhibited growth of human cancer cells SK-MEL, KB, BT-549, and SK-OV-3, but was less potent than 2 (IC(50) 0.8-1.9 vs 0.3-1.0 microg/mL) against these cells.

Animals↗
PubMed2005

Cassane- and norcassane-type diterpenes from Caesalpinia crista of Indonesia and their antimalarial activity against the growth of Plasmodium falciparum.

The CH2Cl2 extract of the seed kernels of Caesalpinia crista, which exhibited promising antimalarial activity against Plasmodium berghei-infected mice in vivo, was examined and resulted in the isolation of seven new furanocassane-type diterpenes [caesalpinins C-G (1-5) and norcaesalpinins D and E (6, 7)] together with norcaesalpinins A-C (8-10) and 11 known compounds (norcaesalpinins A-C, 2-acetoxy-3-deacetoxycaesaldekarin e, caesalmin B, caesaldekarin e, caesalpin F, 14(17)-dehydrocaesalpin F, 2-acetoxycaesaldekarin e, 7-acetoxybonducellpin C, and caesalmin G). Their structures were determined on the basis of spectroscopic analysis. The isolated diterpenes showed significant dose-dependent inhibitory effects on Plasmodium falciparum FCR-3/A2 growth in vitro. Their IC50 values ranged from 90 nM to 6.5 microM, and norcaesalpinin E (7) showed the most potent inhibitory activity (IC50, 90 nM).

Animals↗
PubMed2006

Antimalarial compounds from Grewia bilamellata.

Bioassay-directed fractionation led to the isolation of 12 compounds from a sample of the dried leaves, twigs, and stems of Grewia bilamellata. Five of the isolates, 3alpha,20-lupandiol (1), grewin (2), nitidanin (4), 2alpha,3beta-dihydroxy-olean-12-en-28-oic acid (5), and 2,6-dimethoxy-1-acetonylquinol (6), showed varying degrees of in vitro antimalarial activity against Plasmodium falciparum, but were devoid of significant cytotoxicity to the human oral epidermoid KB cancer cell line. Of the 12 isolates, compounds 1, 2, and 3 (bilagrewin) were determined to be a new triterpene, a new coumarinolignan, and a new neolignan, respectively. Other known compounds isolated in this study were 8-O-4' neolignan guaiacylglycerol-beta-coniferyl ether isomers (threo and erythro), cleomiscosin D, icariol A(2), ciwujiatone, and daucosterol. The structures of 1-3 were elucidated and identified on the basis of spectroscopic data including 1D and 2D NMR analysis.

Animals↗
PubMed2006

Lupeol long-chain fatty acid esters with antimalarial activity from Holarrhena floribunda.

An ethnopharmacological investigation was conducted among the Baka pygmies of Dja biosphere reserve (Cameroon) to collect information on the antimalarial plants used in their daily life. Holarrhena floribunda is one of those plants. Extracts of the stem barks of H. floribunda showed remarkable inhibitory activity against drug-resistant strains of Plasmodium falciparum at doses of 1.02-18.53 microg/mL when tested in vitro against two parasite clones designated as Indochina (W-2) and Sierra Leone (D-6). The aqueous extract was the most active against Indochina (W-2), with IC50 values of 1.02 microg/mL, while the ethanolic extract appeared to be the most active against Sierra Leone (D-6), with an IC50 of 4.33 microg/mL. The bioassay-guided fractionation of the neutral fraction of the crude extract led to the isolation of lupeol (1) and its three new long-chain fatty acid ester derivatives, namely, 3-O-(3'-hydroxyeicosanoyl)lupeol (2), 3-O-[(2'-(tetracosyloxy)acetyl]lupeol (3), and 3-O-[(1' '-hydroxyoctadecyloxy)-2'-hydroxypropanoyl]lupeol (4). These new compounds displayed some in vitro inhibition activity against the chloroquine-resistant strain FCR-3 isolated from Gambia and the chloroquine-sensitive standard strain 3D7. The hydroxy group of the fatty acid side chain appears to decrease the observed activity.

Animals↗
PubMedDate not supplied

Plants as sources of antimalarial drugs, Part 4: Activity of Brucea javanica fruits against chloroquine-resistant Plasmodium falciparum in vitro and against Plasmodium berghei in vivo.

Extracts of Brucea javanica fruit have been prepared and monitored for their in vitro and in vivo antiplasmodial activities. The antimalarial activity of the fruit was found to be attributable to its quassinoid constituents. Nine of the quassinoids possessed in vitro IC50 values between 0.046-0.0008 microgram/ml against the chloroquine resistant Plasmodium falciparum strain (Kl) tested. The two quassinoid glycosides tested were considerably less active in vitro than the aglycones. Four quassinoids were found to possess activity in vivo against Plasmodium berghei infections in mice after oral dosing. All five quassinoids tested in vivo showed some toxicity.

Animals↗