Characterization of enzymes from Ancistrocladus (Ancistrocladaceae) and Triphyophyllum (Dioncophyllaceae) catalyzing oxidative coupling of naphthylisoquinoline alkaloids to michellamines.

Peroxidase active preparations from three Ancistrocladus species and from Triphyophyllum peltatum have been partially purified. They catalyze the oxidative dimerization of korupensamines A and B to michellamines A and C, respectively, as well as the mixed coupling to michellamines A, B, and C. All of these enzymes consist of single polypeptides of approximately 65 kDa with peroxidase activity as monomers. They were characterized as soluble proteins predominantly localized in the leaf phloem of all species examined. Comparative studies with various naphthol precursors revealed an unexpected substrate specificity. Only korupensamines were dimerized by the enzymes, while other monomers, even if closely related, were not accepted as substrates. The coupling reactions described here represent the first direct synthesis of michellamines from korupensamines without previous protection of these precursors.

Retarded development of exoerythrocytic stages of the rodent malaria parasite Plasmodium berghei in human hepatoma cells by extracts from Dioncophyllaceae and Ancistrocladaceae species.

Retarded development of exoerythrocytic stages of the rodent malaria parasite Plasmodium berghei in human hepatoma cells by extracts from Dioncophyllaceae and Ancistrocladaceae species. International Journal for Parasitology 27: 29-32. Naphthylisoquinoline alkaloid-containing extracts (10 micrograms ml-1) of species belonging to the Dioncophyllaceae and the Ancistrocladaceae, 2 small tropical plant families, display pronounced in vitro activities against exoerythrocytic stages of Plasmodium berghei (Anka), developing in human hepatoma cells (Hep G2). The highest activities were obtained with CH2Cl2 root and bark extracts, and a CH2Cl2/NH3 leaf extract from Triphyophyllum peltatum, a CH2Cl2/NH3 root extract from Ancistrocladus abbreviatus, and a CH2Cl2 leaf extract from A. tectorius. The degrees of growth inhibition ranged within 27.7-70.0%. The commercially available drug primaquine diphosphate (25 micrograms ml-1) caused a comparable effect (62.1%) in the same test system.

Fatal theileriosis in eland (Taurotragus oryx): pathology of natural and experimental cases.

Clinical, parasitological and pathological studies were made on five eland infected with Theileria. Three were natural Theileria infections while the other two were experimental cases. All eland died. Generalised lymph node enlargement was a common feature. Wasting occurred in the more prolonged cases and in two of the field cases severe terminal diarrhoea developed. The third field case died in severe respiratory distress. In all cases, up to 50 per cent piroplasm parasitaemia was wound and schizonts were seen in lymph node biopsy samples and in lymphoid smears prepared at necropsy. These parasites showed the morphological characteristics of Theileria taurotragi. The cells parasitised by schizonts had the morphological features of large lymphoid cells. These were infiltrated widely throughout the tissues and organs examined including the lymphoid organs, the gastrointestinal tract (in two cases this was the cause of death), adrenal glands, liver, lungs and to a lesser extent the heart and kidneys. In the one case in which the brain was examined, it was found to be involved. The severely affected organs were diffusely infiltrated with parasitised cells both intravascularly and extravascularly. Lymphocytolysis, necrosis, thrombosis and haemorrhage were frequently encountered in association with parasitised cells. All eland involved except one were males despite the fact that there were more females in the herds.