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PubMedDate not supplied

Microbial metabolism studies of the antimalarial sesquiterpene artemisinin.

Microbial metabolism of the sesquiterpene lactone antimalarial drug artemisinin [1] was studied. Screening studies have shown a number of microorganisms capable of metabolizing artemisinin [1]. Scale-up fermentation with Nocardia corallina (ATCC 19070) and Penicillium chrysogenum (ATCC 9480) have resulted in the production of two major microbial metabolites that have been characterized with the use of 2D-nmr techniques. These metabolites have been identified as deoxyartemisinin [2] and 3 alpha-hydroxydeoxyartemisinin [3].

Antimalarials↗
PubMedDate not supplied

Cytotoxic and antimalarial constituents of the roots of Eurycoma longifolia.

By bioactivity-directed fractionation, five cytotoxic constituents have been characterized from the roots of Eurycoma longifolia collected in Kalimantan, Indonesia. Four canthin-6-one alkaloids, namely, 9-methoxycanthin-6-one, 9-methoxycanthin-6-one-N-oxide, 9-hydroxycanthin-6-one, and 9-hydroxycanthin-6-one-N-oxide, and one quassinoid, eurycomanone, were found to be cytotoxic principles. Each of these compounds was evaluated against a panel of cell lines comprising a number of human cancer cell types [breast, colon, fibrosarcoma, lung, melanoma, KB, and KB-V1 (a multi-drug resistant cell line derived from KB)] and murine lymphocytic leukemia (P-388). The canthin-6-ones 1-4 were found to be active with all cell lines tested except for the KB-V1 cell line. Eurycomanone was inactive against murine lymphocytic leukemia (P-388) but was significantly active against the human cell lines tested. Two additional isolates, the beta-carboline alkaloids beta-carboline-1-propionic acid and 7-methoxy-beta-carboline-1-propionic acid, were not significantly active with these cultured cells. However, compounds 5 and 7 were found to demonstrate significant antimalarial activity as judged by studies conducted with cultured Plasmodium falciparum strains. The structures of the novel compounds 2-4 and 7 were established by spectral and chemical methods.

Alkaloids↗
PubMed1992

Antimalarial activity of sesquiterpenes from the marine sponge Acanthella klethra.

Five sesquiterpenoids containing isonitrile or isothiocyanate groups were isolated from the sponge Acanthella klethra. Compounds 1 and 2 were identified as axisonitrile 3 and the corresponding isothiocyanate derivative, respectively. Compounds 3-5 were found to be eudesmane sesquiterpenes. None of these compounds was cytotoxic toward cultured KB-3 cells, but varying degrees of activity were observed with cultured Plasmodium falciparum. Compound 1 demonstrated greatest promise as an antimalarial agent.

Animals↗
PubMed1993

Cytotoxic and antimalarial bisbenzylisoquinoline alkaloids from Cyclea barbata.

An alkaloid extract derived from the roots of Cyclea barbata demonstrated cytotoxic and antimalarial activities, and five bisbenzylisoquinoline alkaloids, (+)-tetrandrine [1], (-)-limacine [2], (+)-thalrugosine [3], (+)-homoaromoline [4], and (-)-cycleapeltine [5], were isolated as the active principles. The complete and unambiguous assignments of the 1H- and 13C-nmr data of these substances were made by 1D and 2D nmr techniques (COSY, phase-sensitive ROESY, HETCOR, and FLOCK).

Alkaloids↗
PubMed1993

Cytotoxic and antimalarial bisbenzylisoquinoline alkaloids from Stephania erecta.

(+)-2-N-Methyltelobine [1], a new alkaloid, together with twelve known bisbenzylisoquinolines, was isolated from the tubers of Stephania erecta. The structure determination and the complete 1H- and unambiguous 13C-nmr assignments of 1 were obtained through extensive use of several 1D and 2D nmr techniques. All alkaloids inhibited the growth of cultured Plasmodium falciparum strains D-6 and W-2 and displayed nonselective cytotoxicity with a battery of cultured mammalian cells. These data were used for the calculation of selectivity indices. Relative to known antimalarial agents, these bisbenzylisoquinoline alkaloids do not appear to be promising clinical candidates at the present time.

Alkaloids↗
PubMed1993

Crystal structure of artemisinic acid: a possible biogenetic precursor of antimalarial artemisinin from Artemisia annua.

Artemisinic acid [1], a possible biogenetic precursor of the antimalarial artemisinin [2], was isolated from the hexane extract of Artemisia annua. X-ray crystallography of the dimer of artemisinic acid shows that the cyclization during intermolecular hydrogen bonding occurs by the opposite orientation of the alpha, beta-methylene group in each molecule. Complete spectroscopic data of 1 are also given.

Antimalarials↗
PubMed1993

Cytotoxic and antimalarial alkaloids from the bulbs of Crinum amabile.

From the bulbs of Crinum amabile (Amaryllidaceae), a new alkaloid (-)-amabiline [1], together with the known alkaloids (-)-lycorine [2], (-)-buphanisine [3], (-)-augustine [4], and (+)-crinamine [5], were isolated. The structural characterization of 1 and the revised 1H- and 13C-nmr assignments of 2 are discussed. Alkaloids 2, 4, and 5 were found to be the principal cytotoxic and antimalarial constituents.

Alkaloids↗
PubMed1997

Antimalarial activity of tropical Meliaceae extracts and gedunin derivatives.

Extracts of 22 species of Meliaceae were examined for antimalarial activity using in vitro tests with two clones of Plasmodium falciparum, one sensitive to chloroquine (W2) and one chloroquine-resistant (D6). Twelve extracts were found to have activity, including extracts of Cedrela odorata wood and Azadirachta indica leaves, which contained the limonoid gedunin. These extracts were more effective against the W2 clone than the D6 clone, suggesting there is no cross-resistance to chloroquine. Gedunin was extracted in quantity, and nine derivatives prepared for a structure-activity study, which revealed essential functionalities for activity. The study also included four other limonoids derived from related Meliaceae. Only gedunin had better activity than chloroquine against the W2 clone. This active principle could be used to standardize a popular crude drug based on traditional use of A. indica in West Africa.

Animals↗
PubMed1997

New anti-HIV-1, antimalarial, and antifungal compounds from Terminalia bellerica.

A bioactivity-guided fractionation of an extract of Terminalia bellerica fruit rind led to the isolation of two new lignans named termilignan (1) and thannilignan (2), together with 7-hydroxy-3',4'-(methylenedioxy)flavan (3) and anolignan B (4). All four compounds possessed demonstrable anti-HIV-1, antimalarial, and antifungal activity in vitro.

Anti-HIV Agents↗
PubMed1997

Michellamines D-F, new HIV-inhibitory dimeric naphthylisoquinoline alkaloids, and korupensamine E, a new antimalarial monomer, from Ancistrocladus korupensis.

New monomeric (korupensamine E, 6) and dimeric (michellamines D-F, 7-9) naphthylisoquinoline alkaloids have been isolated from exracts of the tropical liana Ancistrocladus korupensis. Structures were determined by spectroanalytical methods, and stereochemistry was defined through NOE correlations, chemical degradation, and CD spectroscopy. Michellamines D-F exhibited in vitro HIV-inhibitory activity comparable to michellamine B, and korupensamine E exhibited in vitro antimalarial activity comparable to korupensamines A-D.

Anti-HIV Agents↗
PubMed1998

Novel quinone methides from Salacia kraussii with in vitro antimalarial activity.

Three novel quinone methides, i.e., 28-nor-isoiguesterin-17-carbaldehyde (1), 17-(methoxycarbonyl)-28-nor-isoiguesterin (2), and 28-hydroxyisoiguesterin (3), together with the known celastrol (5), pristimerin (6), and isoiguesterol (7), were isolated from the roots of Salacia kraussii (Celastraceae) by bioassay-guided fractionation. The structures of the compounds were determined by DEPT and 2D NMR techniques. The isolates showed antimalarial activity 30-50-fold greater than their cytotoxicity (in HT-29 cells) in vitro, and they showed an additive effect when combined with each other. In vivo, 2 was found to be inactive against blood stages of Plasmodium berghei in mice after oral and parenteral administration, and the compound was toxic with increasing concentrations.

Animals↗
PubMed1998

Enhancement of NO production in activated macrophages in vivo by an antimalarial crude drug, Dichroa febrifuga.

The effect of an antimalarial crude drug, Dichroafebrifuga Lour. on nitric oxide (NO) production in bacillus Calmette Guérin-induced mouse peritoneal macrophages activated by lipopolysaccharide was investigated. The NO production was significantly enhanced by an oral administration of a MeOH extract of D. febrifuga. Febrifugine (1) was isolated as the main active compound, and the activation was dose-dependent in the dosage range of 0.1-1 mg/kg/day.

Animals↗
PubMed1998

Antimalarial principles from Artemisia indica.

Activity-guided investigation of Artemisia indica Willd. has led to isolation of exiguaflavone A, exiguaflavone B, maackiain, and 2-(2, 4-dihydroxyphenyl)-5,6-methylenedioxybenzofuran. Exiguaflavones A and B exhibit in vitro antimalarial activities of 4.60 x 10(-6) and 7.05 x 10(-6) g/mL, respectively, against Plasmodium falciparum.

Animals↗
PubMed2001

A concise enantioselective synthesis of antimalarial febrifugine alkaloids.

Reaction of (S)-2-(tert-butyldiphenylsilyloxy)-5-(mesyloxy)pentanal with hydroxylamine in allyl alcohol brought about simultaneous 1,3-dipolar cycloaddition of the resulting nitrone to allyl alcohol to give three diastereoisomeric adducts, from which (+)-febrifugine and (+)-isofebrifugine, potent antimalarial alkaloids, were synthesized.

Alkaloids↗
PubMed1997

State of the art of the production of the antimalarial compound artemisinin in plants.

For more than three centuries we have relied on the extracts of the bark of Cinchona species to treat malaria. Now, it seems we may be changing to the leaves of a Chinese weed, Artemisia annua, and its active compound artemisinin. Artemisinin-derived drugs have been proved particularly effective treatments for severe malaria, even for multidrug-resistant malaria. However, this promising antimalarial compound remains expensive and is hardly available on a global scale. Therefore, many research groups have directed their investigations toward the enhancement of artemisinin production in A. annua cell cultures or whole plants in order to overproduce artemisinin or one of its precursors. This article provides a brief review of the state of art of the different aspects in A. annua research.

Antimalarials↗