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.

Anthraquinones have been isolated by bioassay-guided fractionation from Morinda lucida. Structure-activity studies show that an aldehyde group at C-2 and a phenolic hydroxy group at C-3 enhance the activity of the anthraquinones against the growth of Plasmodium falciparum and promastigotes of Leishmania major in vitro.

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Dehydroabietinol isolated from Hyptis suaveolens (L.) Poit. was found to inhibit growth of chloroquine-sensitive as well as chloroquine-resistant strains of Plasmodium falciparum cultivated in erythrocytes in vitro (IC 50 26-27 microM). However, erythrocytes exposed to dehydroabietinol were transformed in a dose-dependent manner towards spherostomatocytic forms with concomitant formation of endovesicles, as disclosed by transmission electron microscopy. The erythrocyte shape alterations caused by dehydroabietinol correlated well with its apparent IC 50 value. Thus, dehydroabietinol incorporates into the erythrocyte membrane, and since invasion and survival of Plasmodium parasites is known to depend on the function of the erythrocyte membrane, the observed antiplasmodial effect of dehydroabietinol is presumably an indirect effect on the host cell. Because of these findings, microscopic investigations should be generally used to support claims of antimalarial effects of apolar natural products.

ABSTRACT. Phyllanthus niruri is a medicinal plant (commonly known as stone breaker) found in the tropics and other parts of the world. It is known for its capacity to block the formation of calcium oxalate crystals and kidney stone formation in urolithiasis. This plant has been used to treat hyperglycemia, hypertension, pain, and mild cases of malaria. We examined the geno-, cyto-and overall toxicity of P. niruri whole plant ethanolic extract. The extract was administered as a single dose of 30 or 300 mg/kg to laboratory rats by gavage, accompanied by negative (0.9% saline) and positive (10 mg/mL N-ethyl-N-nitrosourea) controls that were injected intramuscularly 48 h after extract administration. The ratio of polychromatic (PCE)/normochromatic erythrocytes (NCE) from femur bone marrow was scored for genotoxicity. Cytotoxicity was determined using descending concentrations (0.2-0.0125 g/mL) of the extract incubated with peripheral blood mononuclear cells. Phyllanthus niruri geno-and cytotoxicity Lactate dehydrogenase release from damaged cells was determined and the CC 50 calculated. Subchronic administration of the extract at 30 or 300 mg/kg was done for 90 days to determine general toxicity. PCE:NCE (%) for the extract and negative control was 63, compared to 168 (positive control). The CC 50 was 26.3 mg/mL and hepato-renal toxicity after subchronic extract administration was nil. We conclude that ethanol extract of P. niruri is not cytotoxic or genotoxic, and is generally non-toxic on subchronic administration.

Fractionation of an ethanol extract of roots of Cochlospermum tinctorium afforded five compounds: 3-O-E-p-coumaroylalphitolic acid (1), cochloxanthin (2), dihydrocochloxanthin (3), alphitolic acid (4), and 1-hydroxytetradecan-3-one (5). This is the first example of a 1-hydroxyalkan-3-one obtained from plant material after gentle workup. The antiplasmodial activities of the compounds were determined, and the IC(50) value of 3-O-E-p-coumaroylalphitolic acid was 2.3 microM.

Two alkamides E,E-2,4-octadienamide and E,Z-2,4-decadienamide have been isolated from Phyllanthus fraternus, a plant used in Ghanaian traditional medicine to treat malaria. The compounds possess an alpha, beta, gamma, delta-unsaturated conjugated amide, a feature believed to enhance antiplasmodial activity. By means of an in vitro assay the two alkamides have been shown to possess moderate antiplasmodial activity.

Indigofera arrecta, an anti diabetic plant was investigated in ddY mice to determine its acute and subchronic effects, and whether it modulated hepatic cytochrome P450 (CYP) isozymes and glutathione (GSH). No mortality was observed in the acute (up to 10 g I. arrecta/kg body wt, p.o.) and subchronic (2 g I. arrecta/kg body wt, p.o. daily for 30 days) studies. The extract did not alter haematological indices, serum and tissue lipids and glutathione but lowered serum bile acids. The latter phenomenon is under further investigation. Neither the duration of pentobarbital (PB) and zoxazolamine (ZA) effects in vivo, nor CYP‐dependent 7‐ethoxyresorufin‐O‐deethylase (EROD), 7‐pentoxyresorufin‐O‐depentylase (PROD) and p‐nitrophenol hydroxylase (PNPH) activities in vitro were altered by I. arrecta. The extract was thus devoid of overt acute and subchronic toxic effects, and did not affect CYPs and GSH whose modulation may cause interactions of components in a multiple drug therapy. Copyright © 1999 John Wiley & Sons, Ltd.