Chemotherapeutic and prophylactic antimalarial drugs induce cell death through mitochondrial-mediated apoptosis in murine models.

Malaria is a parasitic disease that has defied many treatment plans. This study was carried out to investigate the host mitochondrial response to malarial infection and selected antimalarial chemotherapy using murine models. The effects of artesunate (ART) and proguanil (PRG) on mitochondrial Permeability Transition (mPT), mitochondrial ATPase (mATPase), level of malondialdehyde (MDA) and activities of antioxidant enzymes; catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), Xanthine oxidase (XO), glutathione S-transferase (GST) and reduced glutathione (GSH) were estimated in Plasmodium berghei-infected mice treated with ART and PRG. Besides, apoptotic markers, such as caspases 3, 9 and DNA fragmentation were estimated. Unparasitised (NORMAL) and parasitized but untreated (PU) animals were used as controls. The mPT pore opening fold of 9 (ART), 3 (PRG), and 4 (PU) were observed relative to calcium (23) for in vivo study. In vitro, graded concentrations (20, 40, 80 and 160 µg/mL) of ART gave mPT induction folds of 1, 21, 23 and 25, respectively, relative to calcium (9) while PRG did not have effect in the absence of calcium. In vivo, ART significantly (p < 0.001) enhanced mATPase activity than PRG. The PRG and ART increased the MDA levels in vivo. Oral administration of ART and PRG altered antioxidant enzymes status, Caspases 3 and 9 were significantly activated in PRG-treated groups; there was significant increase in DNA fragmentation in PU and PRG groups compared with the normal control. The results obtained showed that malaria parasite and antimalarial drugs cause mitochondrial-mediated apoptosis.

Prolonged administration of proguanil induces reproductive toxicity in male rats.

The toxicity of proguanil was studied on reproductive activities in male rats using in vivo and in vitro methods. Groups of ten to twelve-week-old rats were administered proguanil (2.9 mg/kg body weight) daily for 5 days and 6 weeks respectively. Thereafter, body and reproductive organ weights were taken, sperm parameters were analyzed, while the histology of the testis and epididymis were carried out. Also, serum levels of testosterone, luteinizing hormone and follicle stimulating hormone were determined. Sertoli cells obtained from sixteen to eighteen day-old-rats were cultured and treated with 0.3 µM to 10 µM of proguanil for 5 days after which Sertoli cell viability and nuclei integrity were determined. Also, the genetic expressions of transferrin and Glial cell line-derived neurotrophic factor (G.D.N.F.) were assessed. The data obtained were analyzed using the analysis of variance (ANOVA) with Students-Newman-Keuls multiple comparison test. The results showed duration dependent significant decrease in body and organ weights and also in sperm parameters. Serum testosterone level was significantly decreased while luteinizing hormone and follicle stimulating hormone showed no significant change. Duration dependent degeneration was also observed in the testis and epididymis of treated rats. These changes were restored in recovery experiment. Viability and DNA integrity of treated Sertoli cells reduced in a dose and duration dependent manner. However, the genetic expressions of transferrin and Glial cell line-derived neurotropic factor were normal. These results show that proguanil could induce infertility in rats which may act by distorting the blood-testis barrier formed by the Sertoli cells.

Pancytopenia due to proguanil toxicity in a returning traveller with fever.

A patient known to have renal insufficiency was admitted to the hospital with fever and pancytopenia after returning from a trip to Mali. Pancytopenia was not caused by a tropical infection but was a side effect of atovaquone/proguanil used as malaria chemoprophylaxis. High and prolonged detectable proguanil serum levels can result in bone marrow suppression in patients with renal insufficiency. This should be taken into account in a returning traveller with fever and pancytopenia.

Developmental toxicity of artesunate and an artesunate combination in the rat and rabbit.

The artemisinins are playing an increasingly important role in treating multidrug-resistant malaria. The artemisinin, artesunate, is currently in use in Southeast Asia and is advocated for use in Africa. In these areas, more than one million people die of malaria each year, with the highest mortality occurring in children and pregnant women. To test the developmental toxicity in ICH-compliant animal studies, embryofetal development studies were conducted in rats and rabbits treated with artesunate alone or a three-drug combination (CDA) consisting of chlorproguanil hydrochloride, Dapsone, and artesunate in the ratio 1.00:1.25:2.00. Developmental toxicity seen with CDA could be attributed to the administered dose of artesunate. The hallmark effect of artesunate exposure was a dramatic induction of embryo loss, apparent as abortions in rabbits and resorptions in both rats and rabbits. In addition, low incidences of cardiovascular malformations and a syndrome of skeletal defects were induced at or close to embryolethal doses of artesunate in both rats and rabbits. The cardiovascular malformations consisted of ventricular septal and vessel defects. The skeletal syndrome consisted of shortened and/or bent long bones and scapulae, misshapen ribs, cleft sternebrae, and incompletely ossified pelvic bones. These developmental effects were observed largely in the absence of any apparent maternal toxicity. The no or low adverse effect levels were in the range of 5 to 7 mg/kg/day artesunate. Encouragingly, no adverse drug-related developmental effects have been observed in a limited number of pregnant women (more than 100 first trimester and 600 second and third trimester) treated with artemisinins, primarily artesunate. Investigations of the mechanism of developmental toxicity are ongoing to attempt to determine whether rats and rabbits are more sensitive to artemisinins than humans.

Phenoxypropoxybiguanides, prodrugs of DHFR-inhibiting diaminotriazine antimalarials.

A total of 34 analogues of the biguanide PS-15 (5s), a prodrug of the diaminotriazine WR-99210 (8s), have been prepared. Several of them, such as 5b (PS-33) and 5m (PS-26), maintain or exceed the in vivo activity of PS-15 while not requiring the use of highly regulated starting materials. The putative diaminotriazine metabolites of these new analogues (compounds 8) have also been prepared and shown to maintain the activity against resistant P. falciparum strains. The structure-activity relationships of biguanides 5 and putative metabolites 8 are discussed.