Isolation and in vitro antimalarial activity of hexane extract from Thai Picrasma javanica B1 stembark.

The in vitro antimalarial activities against Plasmodium falciparum K1 of four extracts from the stembark of Picrasma javanica B1; ie water, methanol, chloroform and hexane extracts were studied using a modification of the [3H]hypoxanthine incorporation method. It was found that the hexane extract showed in vitro antimalarial activity with IC50 of 3.3 microg/ml. The extract was further fractionated using quick column chromatography, resulting in ten fractions. Fraction V was the most effective against P. falciparum K1 with IC50 of 4.4 microg/ml. Further isolation of fraction V using a column chromatographic technique provided six fractions. According to 1H- and 13C-NMR spectra, it could be concluded that the major compound in fraction V-3 was beta-sitosterol. Unfortunately, the antimalarial activity of beta-sitosterol could not be determined because of its low solubility in DMSO. However, fractions V-2 and V-4 still showed in vitro antimalarial activities with IC50 of 2.8 and 3.4 microg/ml, respectively. The further fractionation of these two active fractions could lead to promising candidates as antimalarial agents.

Alterations and pathology of thalassemic red cells: comparison between alpha- and beta-thalassemia.

Two main types of thalassemia have been categorized according to defective production of the globin gene ie alpha-thalassemia and beta-thalassemia. We report different red cell abnormalities between these two types. The study included 139 thalassemic patients including 91 patients with hemoglobin (Hb) H disease (52 cases with the classical genotype and 39 cases with Hb Constant Spring) and 48 were beta-thalassemia/Hb E disease. The deformability index of thalassemic red cells measured by laser diffractometer was significantly lower than that of normal red cells. Increased susceptibility of the thalassemic red cells to monocyte phagocytosis was markedly noted. Few sialic acid molecules were scattered on red cell surface of thalassemic red cells. Reticulocytes with delayed maturation stage were also observed in thalassemia indicating enhanced release from the bone marrow. The alpha-thalassemic red cells had relatively better deformability, increased susceptibility to phagocytosis, reduced sialic acid content and greater degree irregular distribution of sialic acid on red cell surface as compared to beta-thalassemic red cells. The alpha-type with hemoglobin Constant Spring (Hb CS) had increased percentage of reticulocyte and young reticulocyte (high fluorescent intensity) as compared to beta-thalassemic red cells. The different abnormalities between alpha- and beta-thalassemic red cells may lead to different mechanism of red cell destruction and different severity of the disease.