In Vitro Activities of Strychnos Alkaloids and Extracts against Plasmodium Falciparum

in Antimicrobial Agents and Chemotherapy (1999), 43(9), 2328-31

The in vitro antimalarial activities of 46 alkaloids and extracts from Strychnos species were evaluated. Two types of quasidimeric alkaloids exhibit high and selective activities against Plasmodium ... [more ▼]

The in vitro antimalarial activities of 46 alkaloids and extracts from Strychnos species were evaluated. Two types of quasidimeric alkaloids exhibit high and selective activities against Plasmodium. Strychnopentamine and isostrychnopentamine were active against chloroquine-sensitive and -resistant strains (50% inhibitory concentration [IC(50)] approximately 0.15 microM), while dihydrousambarensine exhibited a 30-fold higher activity against the chloroquine-resistant strain (IC(50) = 0.03 microM) than it did against the chloroquine-sensitive strain. [less ▲]

10'-Hydroxyusambarensine, a New Antimalarial Bisindole Alkaloid from the Roots of Strychnos Usambarensis

in Journal of Natural Products (1999), 62(4), 619-21

Reinvestigation of Strychnos usambarensis Gilg resulted in the isolation of a tertiary phenolic bisindole alkaloid, 10'-hydroxyusambarensine (1), which was identified by detailed spectroscopic methods ... [more ▼]

Reinvestigation of Strychnos usambarensis Gilg resulted in the isolation of a tertiary phenolic bisindole alkaloid, 10'-hydroxyusambarensine (1), which was identified by detailed spectroscopic methods. Compound 1 was moderately active against two strains of Plasmodium falciparum in vitro. [less ▲]

The plant alkaloid usambarensine intercalates into DNA and induces apoptosis in human HL60 leukemia cells

in Anticancer Research (1999), 19(6B), 5245-5250

Anti-inflammatory properties of capsular polymers from blue-green algae.

Conference (1999)

Strychnochrysine, a New Bisindole Alkaloid from the Roots of Strychnos Nux-Vomica

in Journal of Natural Products (1998), 61(1), 139-41

The reinvestigation of Strychnos nux-vomica resulted in the isolation of a colored monoquaternary bisindole alkaloid from the roots. The structure of this new orange substance, strychnochrysine (1), was ... [more ▼]

The reinvestigation of Strychnos nux-vomica resulted in the isolation of a colored monoquaternary bisindole alkaloid from the roots. The structure of this new orange substance, strychnochrysine (1), was defined by detailed spectroscopic methods. [less ▲]

3 ',4 ',5 ',6 ' tetradehydrolongicaudatine Y, an anhydronium base from Strychnos usambarensis

in Phytochemistry (1998), 48(7), 1263-1266

The DNA intercalating alkaloid cryptolepine interferes with topoisomerase II and inhibits primarily DNA synthesis in B16 melanoma cells.

in Biochemistry (1998), 37(15), 5136-46

Cryptolepine hydrochloride is an indoloquinoline alkaloid isolated from the roots of Cryptolepis sanguinolenta. It is characterized by a multiplicity of host-mediated biological activities, including ... [more ▼]

Cryptolepine hydrochloride is an indoloquinoline alkaloid isolated from the roots of Cryptolepis sanguinolenta. It is characterized by a multiplicity of host-mediated biological activities, including antibacterial, antiviral, and antimalarial properties. To date, the molecular basis for its diverse biological effects remains largely uncertain. Several lines of evidence strongly suggest that DNA might correspond to its principal cellular target. Consequently, we studied the strength and mode of binding to DNA of cryptolepine by means of absorption, fluorescence, circular, and linear dichroism, as well as by a relaxation assay using DNA topoisomerases. The results of various optical and gel electrophoresis techniques converge to reveal that the alkaloid binds tightly to DNA and behaves as a typical intercalating agent. In DNAase I footprinting experiments it was found that the drug interacts preferentially with GC-rich sequences and discriminates against homo-oligomeric runs of A and T. This study has also led to the discovery that cryptolepine is a potent topoisomerase II inhibitor and a promising antitumor agent. It stabilizes topoisomerase II-DNA covalent complexes and stimulates the cutting of DNA at a subset of preexisting topoisomerase II cleavage sites. Taking advantage of the fluorescence of the indoloquinoline chromophore, fluorescence microscopy was used to map cellular uptake of the drug. Cryptolepine easily crosses the cell membranes and accumulates selectively into the nuclei rather than in the cytoplasm of B16 melanoma cells. Quantitative analyses of DNA in cells after Feulgen reaction and image cytometry reveal that the drug blocks the cell cycle in G2/M phases. It is also shown that the alkaloid is more potent at inhibiting DNA synthesis rather than RNA and protein synthesis. Altogether, the results provide direct evidence that DNA is the primary target of cryptolepine and suggest that this alkaloid is a valid candidate for the development of tumor active compounds. [less ▲]

Glucoindole Alkaloids from Stem Bark of Strychnos Mellodora

in Planta Medica (1996), 62(1), 73-4

Three glucoindole alkaloids, dolichantoside (1), strictosidine (2), and palicoside (3), have been identified in the stem bark of Strychnos mellodora (Loganiaceae), collected in Zimbabwe. The chiroptical ... [more ▼]

Three glucoindole alkaloids, dolichantoside (1), strictosidine (2), and palicoside (3), have been identified in the stem bark of Strychnos mellodora (Loganiaceae), collected in Zimbabwe. The chiroptical (CD) data are compared. [less ▲]

Quantitative Densitometric Evaluation of Harpagoside in the Secondary Roots of Harpagophytum procumbens D.C.

in Journal of Planar Chromatography- Modern TLC (1996), 9(May/June), 199-202

Harpagophytum procumbens D.C. (Devil's Claw) secondary roots are used in Europe as a home remedy for lack of appetite, dyspeptic complaints, and in supportive therapy for degenerative disorders of the ... [more ▼]

Harpagophytum procumbens D.C. (Devil's Claw) secondary roots are used in Europe as a home remedy for lack of appetite, dyspeptic complaints, and in supportive therapy for degenerative disorders of the locomotor system. The main characteristic iridoid glucoside of the plant is harapagoside. An HPTLC method has been developed for the quantitative determination of harpagoside in the secondary roots and extracts of this plant. The mobile phase used is an optimized version of one described in the literature.It furnished the most homogenous spots for quantitative densitometric evaluation ( at lambda= 286 nm, the wavelenght of maximum absorption for harapgoside).The results have been compared with those obtained afetr visualization with sulfuric acid-vanillin reagent and those obtained using a previously published HPLC method; To check that separation was complete, the spectra of harpagoside obtained from Devil's Claw extracts before and after visualization were superimposed on thos of harpagoside standard. [less ▲]

Selective Antiprotozoal Activity of Some Strychnos Alkaloids

in Phytotherapy Research (1994), 8

The in vitro activities of 28 Strychnos alkaloids have been determined against three species of protozoa and the most active compounds were then assessed for in vitro cytotoxic activity against KB cells ... [more ▼]

The in vitro activities of 28 Strychnos alkaloids have been determined against three species of protozoa and the most active compounds were then assessed for in vitro cytotoxic activity against KB cells. 3',4'-dihydrousambarensine was the most active against Plasmodium falciparum and was relatively nontoxic to KB cells (cytotoxic/antiplasmodial ratio, 1474). Usambarensine displayed the most selectivity against Entamoeba histolytica while "',4'-dihydrousambarensine was the most selective compound against Giardia intestinalis although the cytotoxic/antiprotozoal ratios (20.4 and 6.6 respectively) were less favourable than the above.The four strychnobiline-type alkaloids were found devoid of activity against E. histolytica and G. intestinalis but to have weak antiplasmodial properties (7-13 times less active than chloroquine). None of the compounds containing only one indole ring system displayed antiprotozoal properties. [less ▲]