Manzamine A, a ␤-carboline alkaloid present in several marine sponge species, inhibits the growth of the rodent malaria parasite Plasmodium berghei in vivo. More than 90% of the asexual erythrocytic stages of P. berghei were inhibited after a single intraperitoneal injection of manzamine A into infected mice. A remarkable aspect of manzamine A treatment is its ability to prolong the survival of highly parasitemic mice, with 40% recovery 60 days after a single injection. Oral administration of an oil suspension of manzamine A also produced significant reductions in parasitemia. The plasma manzamine A concentration peaked 4 h after injection and remained high even at 48 h. Morphological changes of P. berghei were observed 1 h after treatment of infected mice. (؊)-8-Hydroxymanzamine A also displayed antimalarial activity, whereas manzamine F, a ketone analog of manzamine A, did not. Our results suggest that manzamine A and (؊)-8-hydroxymanzamine A are promising new antimalarial agents.Malaria remains the most devastating infectious parasitic disease, inflicting both death and economic losses on at least half the world's population. Numerous attempts have been made to control the disease by using vector control measures and/or chemoprophylaxis, but they have had limited success (18). Immunoprophylaxis holds promise, but effective vaccines are still not available. Presently, the most effective way of dealing with malaria is the administration of chemotherapeutic agents. Although drug treatments of malaria are currently the best means of disease management, there is an urgent need for the development of structurally novel and effective antimalarial drugs because of increasing resistance to most presently available antimalarial drugs (15,16,19).Some of the most effective antimalarial drugs available, quinine and artemisinin, are natural products derived from terrestrial plants. However, recent research suggests that marine organisms may also produce compounds with activity against malaria parasites (4,11,21). Manzamines are a structurally unique group of ␤-carboline alkaloids isolated from several marine sponge species found in waters of the Indian Ocean and the Pacific Ocean. Manzamine A (Fig. 1) was initially isolated from a Haliclona sp. (17) but has been subsequently found in other genera of marine sponges, including Pellina (14), Pachypellina (7), Xestospongia (3, 8), Ircinia (10), and Amphimedon (9). In addition, more than 30 other compounds structurally related to manzamine A have been isolated from sponges and characterized; these include 8-hydroxymanzamine A and the ketone derivative manzamine F (Fig. 1). The origin, isolation, and chemistry of various manzamines have been reviewed (6, 13), with the complete synthesis of manzamine A being recently reported (20). The manzamines previously received considerable interest because of their potential as anticancer agents, with both manzamine A and manzamine F inhibiting the growth of P-388 mouse leukemia cells (6) and 8-hydroxymanzamine A showing moderate cytotoxici...

The isolation of the new enantiomers of 8-hydroxymanzamine A (1), manzamine F (2), along with the unprecedented manzamine dimer, neo-kauluamine from an undescribed genus of Indo-Pacific sponge (family Petrosiidae, order Haplosclerida) is reported. The relative stereochemistry of neo-kauluamine was established through detailed analysis of NOE-correlations combined with molecular modeling. The significance of the manzamines as in vivo antimalarial agents with superior activity to the clinically used drugs artemisinin and chloroquine is discussed along with the activity in vitro against the AIDS-opportunistic infectious diseases tuberculosis and toxoplasmosis. Reexamination of the sponges identified as Prianos, and Pachypellina, in earlier publications has confirmed that these are members of the same genus as the sponge described here, but differ at the species level.

Resonance Raman microspectroscopy has been applied to study normal and Plasmodium berghei-infected mouse erythrocytes. The spectra of these two types of samples can be distinguished by the CaNCa deformation mode band at 747 cm−1 for the normal erythrocytes and at 754 cm−1 for the infected erythrocytes. It is believed that this difference in the spectra is due to the presence of haemozoin in the parasite, as a result of the polymerization of haem. The spectra obtained for the normal erythrocytes are due to the porphyrin group in the haemoglobin, whereas the spectra for the infected erythrocytes are due to those in the haemozoin. The spectral difference between the normal and infected erythrocytes enables us to identify the infected cells in the trophozoite or schizont stage from the normal cells. When the normal erythrocytes are subjected to high laser power, photoreduction of the sample occurs, and the spectra of these erythrocytes correspond to the spectra of deoxy Hb.

A rapid procedure for the diagnosis of malaria infections directly from dried blood spots by PCR amplification was evaluated with samples from 52 patients. Plasmodium infections were identified with a genus-specific primer set, and species differentiation betweenPlasmodium falciparum and Plasmodium vivax was analyzed by multiplex PCR. The PCR test with any of the three primer sets was able to detect as few as four parasites per microliter by gel electrophoresis or by nonisotopic paper hybridization chromatography. The diagnoses obtained by PCR correlated closely with those obtained by Giemsa staining except for two samples observed to have mixed P. falciparum-P. vivax infections. These were initially missed by microscopic analysis. In comparison with antigen-capture assays forP. falciparum, the PCR assays were able to detect three infections that were missed by the ParaSight-F test. The PCR test was negative for nine ParaSight-F-positive samples and one ICT Malaria Pf-positive sample, and these were confirmed to be false-positive results. The PCR thus gave no false-negative or false-positive results. Patients undergoing antimalarial therapy were also monitored by the PCR assay. Four of seven patients who were PCR positive forP. vivax at the time of discharge were later readmitted to the hospital with a recurrence of P. vivax infection. We would like to propose that PCR is a sensitive and easy method that can serve as a useful addition to microscopy for the diagnosis and the clinical monitoring of treatment of malaria.